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2013. Mammalian heart renewal by pre-existing cardiomyocytes. Nature. 493(7432):433-6. Pubmed: 23222518 DOI:10.1038/nature11682 Senyo SE, Steinhauser ML, Pizzimenti CL, Yang VK, Cai L, Wang M, Wu TD, Guerquin-Kern JL, Lechene CP, Lee RT. 2013. Mammalian heart renewal by pre-existing cardiomyocytes. Nature. 493(7432):433-6. Pubmed: 23222518 DOI:10.1038/nature11682 Although recent studies have revealed that heart cells are generated in adult mammals, the frequency of generation and the source of new heart cells are not yet known. Some studies suggest a high rate of stem cell activity with differentiation of progenitors to cardiomyocytes. Other studies suggest that new cardiomyocytes are born at a very low rate, and that they may be derived from the division of pre-existing cardiomyocytes. Here we show, by combining two different pulse-chase approaches--genetic fate-mapping with stable isotope labelling, and multi-isotope imaging mass spectrometry--that the genesis of cardiomyocytes occurs at a low rate by the division of pre-existing cardiomyocytes during normal ageing, a process that increases adjacent to areas of myocardial injury. We found that cell cycle activity during normal ageing and after injury led to polyploidy and multinucleation, but also to new diploid, mononucleate cardiomyocytes. These data reveal pre-existing cardiomyocytes as the dominant source of cardiomyocyte replacement in normal mammalian myocardial homeostasis as well as after myocardial injury. -
Vujic A, Lerchenmüller C, Wu TD, Guillermier C, Rabolli CP, Gonzalez E, Senyo SE, Liu X, Guerquin-Kern JL, Steinhauser ML, Lee RT, Rosenzweig A. 2018. Exercise induces new cardiomyocyte generation in the adult mammalian heart. Nature communications. 9(1):1659. Pubmed: 29695718 DOI:10.1038/s41467-018-04083-1 Vujic A, Lerchenmüller C, Wu TD, Guillermier C, Rabolli CP, Gonzalez E, Senyo SE, Liu X, Guerquin-Kern JL, Steinhauser ML, Lee RT, Rosenzweig A. 2018. Exercise induces new cardiomyocyte generation in the adult mammalian heart. Nature communications. 9(1):1659. Pubmed: 29695718 DOI:10.1038/s41467-018-04083-1 Loss of cardiomyocytes is a major cause of heart failure, and while the adult heart has a limited capacity for cardiomyogenesis, little is known about what regulates this ability or whether it can be effectively harnessed. Here we show that 8 weeks of running exercise increase birth of new cardiomyocytes in adult mice (~4.6-fold). New cardiomyocytes are identified based on incorporation of N-thymidine by multi-isotope imaging mass spectrometry (MIMS) and on being mononucleate/diploid. Furthermore, we demonstrate that exercise after myocardial infarction induces a robust cardiomyogenic response in an extended border zone of the infarcted area. Inhibition of miR-222, a microRNA increased by exercise in both animal models and humans, completely blocks the cardiomyogenic exercise response. These findings demonstrate that cardiomyogenesis can be activated by exercise in the normal and injured adult mouse heart and suggest that stimulation of endogenous cardiomyocyte generation could contribute to the benefits of exercise. -
Natarajan N, Abbas Y, Bryant DM, Gonzalez-Rosa JM, Sharpe M, Uygur A, Cocco-Delgado LH, Ho NN, Gerard NP, Gerard CJ, MacRae CA, Burns CE, Burns CG, Whited JL, Lee RT. 2018. Complement Receptor C5aR1 Plays an Evolutionarily Conserved Role in Successful Cardiac Regeneration. Circulation. 137(20):2152-2165. Pubmed: 29348261 DOI:10.1161/CIRCULATIONAHA.117.030801 Natarajan N, Abbas Y, Bryant DM, Gonzalez-Rosa JM, Sharpe M, Uygur A, Cocco-Delgado LH, Ho NN, Gerard NP, Gerard CJ, MacRae CA, Burns CE, Burns CG, Whited JL, Lee RT. 2018. Complement Receptor C5aR1 Plays an Evolutionarily Conserved Role in Successful Cardiac Regeneration. Circulation. 137(20):2152-2165. Pubmed: 29348261 DOI:10.1161/CIRCULATIONAHA.117.030801 Array© 2018 American Heart Association, Inc. -
Walker RG, Czepnik M, Goebel EJ, McCoy JC, Vujic A, Cho M, Oh J, Aykul S, Walton KL, Schang G, Bernard DJ, Hinck AP, Harrison CA, Martinez-Hackert E, Wagers AJ, Lee RT, Thompson TB. 2017. Structural basis for potency differences between GDF8 and GDF11. BMC biology. 15(1):19. Pubmed: 28257634 DOI:10.1186/s12915-017-0350-1 Walker RG, Czepnik M, Goebel EJ, McCoy JC, Vujic A, Cho M, Oh J, Aykul S, Walton KL, Schang G, Bernard DJ, Hinck AP, Harrison CA, Martinez-Hackert E, Wagers AJ, Lee RT, Thompson TB. 2017. Structural basis for potency differences between GDF8 and GDF11. BMC biology. 15(1):19. Pubmed: 28257634 DOI:10.1186/s12915-017-0350-1 Array
All Publications
2024
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Ellison GL, Helzlsouer KJ, Rosenfield SM, Kim Y, Ashare RL, Blaes AH, Cullen J, Doran N, Ebbert JO, Egan KM, Heffner JL, Lee RT, McClure EA, McDaniels-Davidson C, Meghani SH, Newcomb PA, Nugent S, Hernandez-Ortega N, Salz T, Vidot DC, Worster B, Zylla DM. 2024. Perceptions, prevalence, and patterns of cannabis use among cancer patients treated at 12 NCI-Designated Cancer Centers. Journal of the National Cancer Institute. Monographs. 2024(66):202-217. Pubmed: 39108244 DOI:10.1093/jncimonographs/lgae029 Ellison GL, Helzlsouer KJ, Rosenfield SM, Kim Y, Ashare RL, Blaes AH, Cullen J, Doran N, Ebbert JO, Egan KM, Heffner JL, Lee RT, McClure EA, McDaniels-Davidson C, Meghani SH, Newcomb PA, Nugent S, Hernandez-Ortega N, Salz T, Vidot DC, Worster B, Zylla DM. 2024. Perceptions, prevalence, and patterns of cannabis use among cancer patients treated at 12 NCI-Designated Cancer Centers. Journal of the National Cancer Institute. Monographs. 2024(66):202-217. Pubmed: 39108244 DOI:10.1093/jncimonographs/lgae029 ArrayPublished by Oxford University Press 2024. -
Li Y, Wu S, Zhao Y, Dinh T, Jiang D, Selfridge JE, Myers G, Wang Y, Zhao X, Tomchuck S, Dubyak G, Lee RT, Estfan B, Shapiro M, Kamath S, Mohamed A, Huang SC, Huang AY, Conlon R, Krishnamurthi S, Eads J, Willis JE, Khorana AA, Bajor D, Wang Z. 2024. Neutrophil extracellular traps induced by chemotherapy inhibit tumor growth in murine models of colorectal cancer. The Journal of clinical investigation. 134(5). Pubmed: 38194275 DOI:10.1172/JCI175031 Li Y, Wu S, Zhao Y, Dinh T, Jiang D, Selfridge JE, Myers G, Wang Y, Zhao X, Tomchuck S, Dubyak G, Lee RT, Estfan B, Shapiro M, Kamath S, Mohamed A, Huang SC, Huang AY, Conlon R, Krishnamurthi S, Eads J, Willis JE, Khorana AA, Bajor D, Wang Z. 2024. Neutrophil extracellular traps induced by chemotherapy inhibit tumor growth in murine models of colorectal cancer. The Journal of clinical investigation. 134(5). Pubmed: 38194275 DOI:10.1172/JCI175031 Neutrophil extracellular traps (NETs), a web-like structure of cytosolic and granule proteins assembled on decondensed chromatin, kill pathogens and cause tissue damage in diseases. Whether NETs can kill cancer cells is unexplored. Here, we report that a combination of glutaminase inhibitor CB-839 and 5-FU inhibited the growth of PIK3CA-mutant colorectal cancers (CRCs) in xenograft, syngeneic, and genetically engineered mouse models in part through NETs. Disruption of NETs by either DNase I treatment or depletion of neutrophils in CRCs attenuated the efficacy of the drug combination. Moreover, NETs were present in tumor biopsies from patients treated with the drug combination in a phase II clinical trial. Increased NET levels in tumors were associated with longer progression-free survival. Mechanistically, the drug combination induced the expression of IL-8 preferentially in PIK3CA-mutant CRCs to attract neutrophils into the tumors. Further, the drug combination increased the levels of ROS in neutrophils, thereby inducing NETs. Cathepsin G (CTSG), a serine protease localized in NETs, entered CRC cells through the RAGE cell surface protein. The internalized CTSG cleaved 14-3-3 proteins, released BAX, and triggered apoptosis in CRC cells. Thus, our studies illuminate a previously unrecognized mechanism by which chemotherapy-induced NETs kill cancer cells. -
Velayutham N, Garbern JC, Elwell HLT, Zhuo Z, Rüland L, Elcure Alvarez F, Frontini S, Rodriguez Carreras Y, Eichholtz M, Ricci-Blair E, Shaw JY, Bouffard AH, Sokol M, Mancheño Juncosa E, Rhoades S, van den Berg D, Kreymerman A, Aoyama J, Höfflin J, Ryan H, Ho Sui S, Lee RT. 2024. P53 Activation Promotes Maturational Characteristics of Pluripotent Stem Cell-Derived Cardiomyocytes in 3-Dimensional Suspension Culture Via FOXO-FOXM1 Regulation. Journal of the American Heart Association. 13(13):e033155. Pubmed: 38934864 DOI:10.1161/JAHA.123.033155 Velayutham N, Garbern JC, Elwell HLT, Zhuo Z, Rüland L, Elcure Alvarez F, Frontini S, Rodriguez Carreras Y, Eichholtz M, Ricci-Blair E, Shaw JY, Bouffard AH, Sokol M, Mancheño Juncosa E, Rhoades S, van den Berg D, Kreymerman A, Aoyama J, Höfflin J, Ryan H, Ho Sui S, Lee RT. 2024. P53 Activation Promotes Maturational Characteristics of Pluripotent Stem Cell-Derived Cardiomyocytes in 3-Dimensional Suspension Culture Via FOXO-FOXM1 Regulation. Journal of the American Heart Association. 13(13):e033155. Pubmed: 38934864 DOI:10.1161/JAHA.123.033155 Array 2023
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Lian J, Walker RG, D'Amico A, Vujic A, Mills MJ, Messemer KA, Mendello KR, Goldstein JM, Leacock KA, Epp S, Stimpfl EV, Thompson TB, Wagers AJ, Lee RT. 2023. Functional substitutions of amino acids that differ between GDF11 and GDF8 impact skeletal development and skeletal muscle. Life science alliance. 6(3). Pubmed: 36631218 DOI:10.26508/lsa.202201662 Lian J, Walker RG, D'Amico A, Vujic A, Mills MJ, Messemer KA, Mendello KR, Goldstein JM, Leacock KA, Epp S, Stimpfl EV, Thompson TB, Wagers AJ, Lee RT. 2023. Functional substitutions of amino acids that differ between GDF11 and GDF8 impact skeletal development and skeletal muscle. Life science alliance. 6(3). Pubmed: 36631218 DOI:10.26508/lsa.202201662 Growth differentiation factor 11 (GDF11) and GDF8 (MSTN) are closely related TGF-β family proteins that interact with nearly identical signaling receptors and antagonists. However, GDF11 appears to activate SMAD2/3 more potently than GDF8 in vitro and in vivo. The ligands possess divergent structural properties, whereby substituting unique GDF11 amino acids into GDF8 enhanced the activity of the resulting chimeric GDF8. We investigated potentially distinct endogenous activities of GDF11 and GDF8 in vivo by genetically modifying their mature signaling domains. Full recoding of GDF8 to that of GDF11 yielded mice lacking GDF8, with GDF11 levels ∼50-fold higher than normal, and exhibiting modestly decreased muscle mass, with no apparent negative impacts on health or survival. Substitution of two specific amino acids in the fingertip region of GDF11 with the corresponding GDF8 residues resulted in prenatal axial skeletal transformations, consistent with -deficient mice, without apparent perturbation of skeletal or cardiac muscle development or homeostasis. These experiments uncover distinctive features between the GDF11 and GDF8 mature domains in vivo and identify a specific requirement for GDF11 in early-stage skeletal development.© 2023 Lian et al. -
Dagdeviren S, Lee RT, Wu N. 2023. Physiological and Pathophysiological Roles of Thioredoxin Interacting Protein: A Perspective on Redox Inflammation and Metabolism. Antioxidants & redox signaling. 38(4-6):442-460. Pubmed: 35754346 DOI:10.1089/ars.2022.0022 Dagdeviren S, Lee RT, Wu N. 2023. Physiological and Pathophysiological Roles of Thioredoxin Interacting Protein: A Perspective on Redox Inflammation and Metabolism. Antioxidants & redox signaling. 38(4-6):442-460. Pubmed: 35754346 DOI:10.1089/ars.2022.0022 Array -
Lin Z, Garbern JC, Liu R, Li Q, Mancheño Juncosa E, Elwell HLT, Sokol M, Aoyama J, Deumer US, Hsiao E, Sheng H, Lee RT, Liu J. 2023. Tissue-embedded stretchable nanoelectronics reveal endothelial cell-mediated electrical maturation of human 3D cardiac microtissues. Science advances. 9(10):eade8513. Pubmed: 36888704 DOI:10.1126/sciadv.ade8513 Lin Z, Garbern JC, Liu R, Li Q, Mancheño Juncosa E, Elwell HLT, Sokol M, Aoyama J, Deumer US, Hsiao E, Sheng H, Lee RT, Liu J. 2023. Tissue-embedded stretchable nanoelectronics reveal endothelial cell-mediated electrical maturation of human 3D cardiac microtissues. Science advances. 9(10):eade8513. Pubmed: 36888704 DOI:10.1126/sciadv.ade8513 Clinical translation of stem cell therapies for heart disease requires electrical integration of transplanted cardiomyocytes. Generation of electrically matured human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is critical for electrical integration. Here, we found that hiPSC-derived endothelial cells (hiPSC-ECs) promoted the expression of selected maturation markers in hiPSC-CMs. Using tissue-embedded stretchable mesh nanoelectronics, we achieved a long-term stable map of human three-dimensional (3D) cardiac microtissue electrical activity. The results revealed that hiPSC-ECs accelerated the electrical maturation of hiPSC-CMs in 3D cardiac microtissues. Machine learning-based pseudotime trajectory inference of cardiomyocyte electrical signals further revealed the electrical phenotypic transition path during development. Guided by the electrical recording data, single-cell RNA sequencing identified that hiPSC-ECs promoted cardiomyocyte subpopulations with a more mature phenotype, and multiple ligand-receptor interactions were up-regulated between hiPSC-ECs and hiPSC-CMs, revealing a coordinated multifactorial mechanism of hiPSC-CM electrical maturation. Collectively, these findings show that hiPSC-ECs drive hiPSC-CM electrical maturation via multiple intercellular pathways. -
Paul KC, Krolewski RC, Lucumi Moreno E, Blank J, Holton KM, Ahfeldt T, Furlong M, Yu Y, Cockburn M, Thompson LK, Kreymerman A, Ricci-Blair EM, Li YJ, Patel HB, Lee RT, Bronstein J, Rubin LL, Khurana V, Ritz B. 2023. A pesticide and iPSC dopaminergic neuron screen identifies and classifies Parkinson-relevant pesticides. Nature communications. 14(1):2803. Pubmed: 37193692 DOI:10.1038/s41467-023-38215-z Paul KC, Krolewski RC, Lucumi Moreno E, Blank J, Holton KM, Ahfeldt T, Furlong M, Yu Y, Cockburn M, Thompson LK, Kreymerman A, Ricci-Blair EM, Li YJ, Patel HB, Lee RT, Bronstein J, Rubin LL, Khurana V, Ritz B. 2023. A pesticide and iPSC dopaminergic neuron screen identifies and classifies Parkinson-relevant pesticides. Nature communications. 14(1):2803. Pubmed: 37193692 DOI:10.1038/s41467-023-38215-z Parkinson's disease (PD) is a complex neurodegenerative disease with etiology rooted in genetic vulnerability and environmental factors. Here we combine quantitative epidemiologic study of pesticide exposures and PD with toxicity screening in dopaminergic neurons derived from PD patient induced pluripotent stem cells (iPSCs) to identify Parkinson's-relevant pesticides. Agricultural records enable investigation of 288 specific pesticides and PD risk in a comprehensive, pesticide-wide association study. We associate long-term exposure to 53 pesticides with PD and identify co-exposure profiles. We then employ a live-cell imaging screening paradigm exposing dopaminergic neurons to 39 PD-associated pesticides. We find that 10 pesticides are directly toxic to these neurons. Further, we analyze pesticides typically used in combinations in cotton farming, demonstrating that co-exposures result in greater toxicity than any single pesticide. We find trifluralin is a driver of toxicity to dopaminergic neurons and leads to mitochondrial dysfunction. Our paradigm may prove useful to mechanistically dissect pesticide exposures implicated in PD risk and guide agricultural policy.© 2023. The Author(s). -
Kato T, Lee RT. 2023. GDF-11 as a Potential Cardiac Pro-Angiogenic Factor. JACC. Basic to translational science. 8(6):636-637. Pubmed: 37426538 DOI:10.1016/j.jacbts.2023.04.003 Kato T, Lee RT. 2023. GDF-11 as a Potential Cardiac Pro-Angiogenic Factor. JACC. Basic to translational science. 8(6):636-637. Pubmed: 37426538 DOI:10.1016/j.jacbts.2023.04.003 -
Paul KC, Krolewski RC, Lucumi Moreno E, Blank J, Holton KM, Ahfeldt T, Furlong M, Yu Y, Cockburn M, Thompson LK, Kreymerman A, Ricci-Blair EM, Li YJ, Patel HB, Lee RT, Bronstein J, Rubin LL, Khurana V, Ritz B. 2023. Publisher Correction: A pesticide and iPSC dopaminergic neuron screen identifies and classifies Parkinson-relevant pesticides. Nature communications. 14(1):3747. Pubmed: 37353544 DOI:10.1038/s41467-023-39001-7 Paul KC, Krolewski RC, Lucumi Moreno E, Blank J, Holton KM, Ahfeldt T, Furlong M, Yu Y, Cockburn M, Thompson LK, Kreymerman A, Ricci-Blair EM, Li YJ, Patel HB, Lee RT, Bronstein J, Rubin LL, Khurana V, Ritz B. 2023. Publisher Correction: A pesticide and iPSC dopaminergic neuron screen identifies and classifies Parkinson-relevant pesticides. Nature communications. 14(1):3747. Pubmed: 37353544 DOI:10.1038/s41467-023-39001-7 -
Velayutham N, Lee RT. 2023. A Grim link: the association between subclinical atherosclerosis and epigenetic age. European heart journal. 44(29):2710-2712. Pubmed: 37309608 DOI:10.1093/eurheartj/ehad326 Velayutham N, Lee RT. 2023. A Grim link: the association between subclinical atherosclerosis and epigenetic age. European heart journal. 44(29):2710-2712. Pubmed: 37309608 DOI:10.1093/eurheartj/ehad326 -
Guilbaud A, Ghanegolmohammadi F, Wang Y, Leng J, Kreymerman A, Gamboa Varela J, Garbern J, Elwell H, Cao F, Ricci-Blair EM, Liang C, Balamkundu S, Vidoudez C, DeMott MS, Bedi K, Margulies KB, Bennett DA, Palmer AA, Barkley-Levenson A, Lee RT, Dedon PC. 2023. Discovery adductomics provides a comprehensive portrait of tissue-, age- and sex-specific DNA modifications in rodents and humans. Nucleic acids research. 51(20):10829-10845. Pubmed: 37843128 DOI:10.1093/nar/gkad822 Guilbaud A, Ghanegolmohammadi F, Wang Y, Leng J, Kreymerman A, Gamboa Varela J, Garbern J, Elwell H, Cao F, Ricci-Blair EM, Liang C, Balamkundu S, Vidoudez C, DeMott MS, Bedi K, Margulies KB, Bennett DA, Palmer AA, Barkley-Levenson A, Lee RT, Dedon PC. 2023. Discovery adductomics provides a comprehensive portrait of tissue-, age- and sex-specific DNA modifications in rodents and humans. Nucleic acids research. 51(20):10829-10845. Pubmed: 37843128 DOI:10.1093/nar/gkad822 DNA damage causes genomic instability underlying many diseases, with traditional analytical approaches providing minimal insight into the spectrum of DNA lesions in vivo. Here we used untargeted chromatography-coupled tandem mass spectrometry-based adductomics (LC-MS/MS) to begin to define the landscape of DNA modifications in rat and human tissues. A basis set of 114 putative DNA adducts was identified in heart, liver, brain, and kidney in 1-26-month-old rats and 111 in human heart and brain by 'stepped MRM' LC-MS/MS. Subsequent targeted analysis of these species revealed species-, tissue-, age- and sex-biases. Structural characterization of 10 selected adductomic signals as known DNA modifications validated the method and established confidence in the DNA origins of the signals. Along with strong tissue biases, we observed significant age-dependence for 36 adducts, including N2-CMdG, 5-HMdC and 8-Oxo-dG in rats and 1,N6-ϵdA in human heart, as well as sex biases for 67 adducts in rat tissues. These results demonstrate the potential of adductomics for discovering the true spectrum of disease-driving DNA adducts. Our dataset of 114 putative adducts serves as a resource for characterizing dozens of new forms of DNA damage, defining mechanisms of their formation and repair, and developing them as biomarkers of aging and disease.© The Author(s) 2023. Published by Oxford University Press on behalf of Nucleic Acids Research. -
Driss LB, Lian J, Walker RG, Howard JA, Thompson TB, Rubin LL, Wagers AJ, Lee RT. 2023. GDF11 and aging biology - controversies resolved and pending. The journal of cardiovascular aging. 3(4). Pubmed: 38235060 DOI:10.20517/jca.2023.23 Driss LB, Lian J, Walker RG, Howard JA, Thompson TB, Rubin LL, Wagers AJ, Lee RT. 2023. GDF11 and aging biology - controversies resolved and pending. The journal of cardiovascular aging. 3(4). Pubmed: 38235060 DOI:10.20517/jca.2023.23 Since the exogenous administration of GDF11, a TGF-ß superfamily member, was reported to have beneficial effects in some models of human disease, there have been many research studies in GDF11 biology. However, many studies have now confirmed that exogenous administration of GDF11 can improve physiology in disease models, including cardiac fibrosis, experimental stroke, and disordered metabolism. GDF11 is similar to GDF8 (also called Myostatin), differing only by 11 amino acids in their mature signaling domains. These two proteins are now known to be biochemically different both and . GDF11 is much more potent than GDF8 and induces more strongly SMAD2 phosphorylation in the myocardium compared to GDF8. GDF8 and GDF11 prodomain are only 52% identical and are cleaved by different Tolloid proteases to liberate the mature signaling domain from inhibition of the prodomain. Here, we review the state of GDF11 biology, highlighting both resolved and remaining controversies. -
Dagdeviren S, Hoang MF, Sarikhani M, Meier V, Benoit JC, Okawa MC, Melnik VY, Ricci-Blair EM, Foot N, Friedline RH, Hu X, Tauer LA, Srinivasan A, Prigozhin MB, Shenoy SK, Kumar S, Kim JK, Lee RT. 2023. An insulin-regulated arrestin domain protein controls hepatic glucagon action. The Journal of biological chemistry. 299(8):105045. Pubmed: 37451484 DOI:10.1016/j.jbc.2023.105045 Dagdeviren S, Hoang MF, Sarikhani M, Meier V, Benoit JC, Okawa MC, Melnik VY, Ricci-Blair EM, Foot N, Friedline RH, Hu X, Tauer LA, Srinivasan A, Prigozhin MB, Shenoy SK, Kumar S, Kim JK, Lee RT. 2023. An insulin-regulated arrestin domain protein controls hepatic glucagon action. The Journal of biological chemistry. 299(8):105045. Pubmed: 37451484 DOI:10.1016/j.jbc.2023.105045 Glucagon signaling is essential for maintaining normoglycemia in mammals. The arrestin fold superfamily of proteins controls the trafficking, turnover, and signaling of transmembrane receptors as well as other intracellular signaling functions. Further investigation is needed to understand the in vivo functions of the arrestin domain-containing 4 (ARRDC4) protein family member and whether it is involved in mammalian glucose metabolism. Here, we show that mice with a global deletion of the ARRDC4 protein have impaired glucagon responses and gluconeogenesis at a systemic and molecular level. Mice lacking ARRDC4 exhibited lower glucose levels after fasting and could not suppress gluconeogenesis at the refed state. We also show that ARRDC4 coimmunoprecipitates with the glucagon receptor, and ARRDC4 expression is suppressed by insulin. These results define ARRDC4 as a critical regulator of glucagon signaling and glucose homeostasis and reveal a novel intersection of insulin and glucagon pathways in the liver.Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved. 2022
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Chen MS, Lee RT, Garbern JC. 2022. Senescence mechanisms and targets in the heart. Cardiovascular research. 118(5):1173-1187. Pubmed: 33963378 DOI:10.1093/cvr/cvab161 Chen MS, Lee RT, Garbern JC. 2022. Senescence mechanisms and targets in the heart. Cardiovascular research. 118(5):1173-1187. Pubmed: 33963378 DOI:10.1093/cvr/cvab161 Cellular senescence is a state of irreversible cell cycle arrest associated with ageing. Senescence of different cardiac cell types can direct the pathophysiology of cardiovascular diseases (CVDs) such as atherosclerosis, myocardial infarction, and cardiac fibrosis. While age-related telomere shortening represents a major cause of replicative senescence, the senescent state can also be induced by oxidative stress, metabolic dysfunction, and epigenetic regulation, among other stressors. It is critical that we understand the molecular pathways that lead to cellular senescence and the consequences of cellular senescence in order to develop new therapeutic approaches to treat CVD. In this review, we discuss molecular mechanisms of cellular senescence, explore how cellular senescence of different cardiac cell types (including cardiomyocytes, cardiac endothelial cells, cardiac fibroblasts, vascular smooth muscle cells, and valve interstitial cells) can lead to CVD, and highlight potential therapeutic approaches that target molecular mechanisms of cellular senescence to prevent or treat CVD.Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com. -
Lerchenmüller C, Vujic A, Mittag S, Wang A, Rabolli CP, Heß C, Betge F, Rangrez AY, Chaklader M, Guillermier C, Gyngard F, Roh JD, Li H, Steinhauser ML, Frey N, Rothermel B, Dieterich C, Rosenzweig A, Lee RT. 2022. Restoration of Cardiomyogenesis in Aged Mouse Hearts by Voluntary Exercise. Circulation. 146(5):412-426. Pubmed: 35862076 DOI:10.1161/CIRCULATIONAHA.121.057276 Lerchenmüller C, Vujic A, Mittag S, Wang A, Rabolli CP, Heß C, Betge F, Rangrez AY, Chaklader M, Guillermier C, Gyngard F, Roh JD, Li H, Steinhauser ML, Frey N, Rothermel B, Dieterich C, Rosenzweig A, Lee RT. 2022. Restoration of Cardiomyogenesis in Aged Mouse Hearts by Voluntary Exercise. Circulation. 146(5):412-426. Pubmed: 35862076 DOI:10.1161/CIRCULATIONAHA.121.057276 Array -
Cheon SY, Park JH, Ameri AH, Lee RT, Nazarian RM, Demehri S. 2022. IL-33/Regulatory T-Cell Axis Suppresses Skin Fibrosis. The Journal of investigative dermatology. 142(10):2668-2676.e4. Pubmed: 35341735 DOI:S0022-202X(22)00207-X Cheon SY, Park JH, Ameri AH, Lee RT, Nazarian RM, Demehri S. 2022. IL-33/Regulatory T-Cell Axis Suppresses Skin Fibrosis. The Journal of investigative dermatology. 142(10):2668-2676.e4. Pubmed: 35341735 DOI:S0022-202X(22)00207-X Fibrosis is a pathological hallmark of systemic sclerosis, a deadly autoimmune disease affecting the connective tissues of multiple organs. However, the immune mechanisms underlying fibrosis and systemic sclerosis remain unclear. To determine the initiating immune pathway in fibrosis, we investigated the role of type 2 alarmin cytokines in the mouse model of skin fibrosis. Wild-type mice that received subcutaneous bleomycin injections developed skin fibrosis accompanied by elevated IL-33 expression in the dermis. Likewise, we found IL-33 upregulation in human skin fibrosis. Mice with germline deletion of IL-33 receptor (ST2 knockout) showed markedly exacerbated skin fibrosis in association with significantly increased T helper 2 cell to regulatory T-cell ratio in the skin. Mice that lacked ST2 specifically on regulatory T cells (Foxp3,ST2) showed significantly worse skin fibrosis, increased T helper 2 to regulatory T cell ratio and IL-13 expression in the skin compared with wild-type mice. Our findings show that IL-33 cytokine signaling to regulatory T cells suppresses skin fibrosis and highlight a potential therapeutic axis to alleviate the debilitating manifestations of systemic sclerosis.Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved. -
Garbern JC, Lee RT. 2022. Heart regeneration: 20 years of progress and renewed optimism. Developmental cell. 57(4):424-439. Pubmed: 35231426 DOI:S1534-5807(22)00037-5 Garbern JC, Lee RT. 2022. Heart regeneration: 20 years of progress and renewed optimism. Developmental cell. 57(4):424-439. Pubmed: 35231426 DOI:S1534-5807(22)00037-5 Cardiovascular disease is a leading cause of death worldwide, and thus there remains great interest in regenerative approaches to treat heart failure. In the past 20 years, the field of heart regeneration has entered a renaissance period with remarkable progress in the understanding of endogenous heart regeneration, stem cell differentiation for exogenous cell therapy, and cell-delivery methods. In this review, we highlight how this new understanding can lead to viable strategies for human therapy. For the near term, drugs, electrical and mechanical devices, and heart transplantation will remain mainstays of cardiac therapies, but eventually regenerative therapies based on fundamental regenerative biology may offer more permanent solutions for patients with heart failure.Copyright © 2022 Elsevier Inc. All rights reserved. -
Gu W, Wang H, Huang X, Kraiczy J, Singh PNP, Ng C, Dagdeviren S, Houghton S, Pellon-Cardenas O, Lan Y, Nie Y, Zhang J, Banerjee KK, Onufer EJ, Warner BW, Spence J, Scherl E, Rafii S, Lee RT, Verzi MP, Redmond D, Longman R, Helin K, Shivdasani RA, Zhou Q. 2022. SATB2 preserves colon stem cell identity and mediates ileum-colon conversion via enhancer remodeling. Cell stem cell. 29(1):101-115.e10. Pubmed: 34582804 DOI:S1934-5909(21)00380-5 Gu W, Wang H, Huang X, Kraiczy J, Singh PNP, Ng C, Dagdeviren S, Houghton S, Pellon-Cardenas O, Lan Y, Nie Y, Zhang J, Banerjee KK, Onufer EJ, Warner BW, Spence J, Scherl E, Rafii S, Lee RT, Verzi MP, Redmond D, Longman R, Helin K, Shivdasani RA, Zhou Q. 2022. SATB2 preserves colon stem cell identity and mediates ileum-colon conversion via enhancer remodeling. Cell stem cell. 29(1):101-115.e10. Pubmed: 34582804 DOI:S1934-5909(21)00380-5 Adult stem cells maintain regenerative tissue structure and function by producing tissue-specific progeny, but the factors that preserve their tissue identities are not well understood. The small and large intestines differ markedly in cell composition and function, reflecting their distinct stem cell populations. Here we show that SATB2, a colon-restricted chromatin factor, singularly preserves LGR5 adult colonic stem cell and epithelial identity in mice and humans. Satb2 loss in adult mice leads to stable conversion of colonic stem cells into small intestine ileal-like stem cells and replacement of the colonic mucosa with one that resembles the ileum. Conversely, SATB2 confers colonic properties on the mouse ileum. Human colonic organoids also adopt ileal characteristics upon SATB2 loss. SATB2 regulates colonic identity in part by modulating enhancer binding of the intestinal transcription factors CDX2 and HNF4A. Our study uncovers a conserved core regulator of colonic stem cells able to mediate cross-tissue plasticity in mature intestines.Copyright © 2021 Elsevier Inc. All rights reserved. 2021
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Marian AJ, Asatryan B, Bolli R, Cheedipudi SM, Dhalla NS, Finkel T, Frangogiannis NG, Gurha P, Belmonte JCI, Hare JM, Hong K, Kirshenbaum LA, Lee RT, Leesar MA, Libby P, Madonna R, Nagueh SF, Roberts R, Rosenzweig A, Rouhi L, Sadoshima J, Sussman MA, Taffet GE, Tanaka H, Torella D, Wang Y, Wang DW. 2021. Editors' Preamble to. The journal of cardiovascular aging. 1. Pubmed: 34327514 DOI:10.20517/jca.2021.01 Marian AJ, Asatryan B, Bolli R, Cheedipudi SM, Dhalla NS, Finkel T, Frangogiannis NG, Gurha P, Belmonte JCI, Hare JM, Hong K, Kirshenbaum LA, Lee RT, Leesar MA, Libby P, Madonna R, Nagueh SF, Roberts R, Rosenzweig A, Rouhi L, Sadoshima J, Sussman MA, Taffet GE, Tanaka H, Torella D, Wang Y, Wang DW. 2021. Editors' Preamble to. The journal of cardiovascular aging. 1. Pubmed: 34327514 DOI:10.20517/jca.2021.01 -
Garbern JC, Lee RT. 2021. Mitochondria and metabolic transitions in cardiomyocytes: lessons from development for stem cell-derived cardiomyocytes. Stem cell research & therapy. 12(1):177. Pubmed: 33712058 DOI:10.1186/s13287-021-02252-6 Garbern JC, Lee RT. 2021. Mitochondria and metabolic transitions in cardiomyocytes: lessons from development for stem cell-derived cardiomyocytes. Stem cell research & therapy. 12(1):177. Pubmed: 33712058 DOI:10.1186/s13287-021-02252-6 Current methods to differentiate cardiomyocytes from human pluripotent stem cells (PSCs) inadequately recapitulate complete development and result in PSC-derived cardiomyocytes (PSC-CMs) with an immature or fetal-like phenotype. Embryonic and fetal development are highly dynamic periods during which the developing embryo or fetus is exposed to changing nutrient, oxygen, and hormone levels until birth. It is becoming increasingly apparent that these metabolic changes initiate developmental processes to mature cardiomyocytes. Mitochondria are central to these changes, responding to these metabolic changes and transitioning from small, fragmented mitochondria to large organelles capable of producing enough ATP to support the contractile function of the heart. These changes in mitochondria may not simply be a response to cardiomyocyte maturation; the metabolic signals that occur throughout development may actually be central to the maturation process in cardiomyocytes. Here, we review methods to enhance maturation of PSC-CMs and highlight evidence from development indicating the key roles that mitochondria play during cardiomyocyte maturation. We evaluate metabolic transitions that occur during development and how these affect molecular nutrient sensors, discuss how regulation of nutrient sensing pathways affect mitochondrial dynamics and function, and explore how changes in mitochondrial function can affect metabolite production, the cell cycle, and epigenetics to influence maturation of cardiomyocytes. -
Dans M, Kutner JS, Agarwal R, Baker JN, Bauman JR, Beck AC, Campbell TC, Carey EC, Case AA, Dalal S, Doberman DJ, Epstein AS, Fecher L, Jones J, Kapo J, Lee RT, Loggers ET, McCammon S, Mitchell W, Ogunseitan AB, Portman DG, Ramchandran K, Sutton L, Temel J, Teply ML, Terauchi SY, Thomas J, Walling AM, Zachariah F, Bergman MA, Ogba N, Campbell M. 2021. NCCN Guidelines® Insights: Palliative Care, Version 2.2021. Journal of the National Comprehensive Cancer Network : JNCCN. 19(7):780-788. Pubmed: 34340208 DOI:jnccnGLINS1907 Dans M, Kutner JS, Agarwal R, Baker JN, Bauman JR, Beck AC, Campbell TC, Carey EC, Case AA, Dalal S, Doberman DJ, Epstein AS, Fecher L, Jones J, Kapo J, Lee RT, Loggers ET, McCammon S, Mitchell W, Ogunseitan AB, Portman DG, Ramchandran K, Sutton L, Temel J, Teply ML, Terauchi SY, Thomas J, Walling AM, Zachariah F, Bergman MA, Ogba N, Campbell M. 2021. NCCN Guidelines® Insights: Palliative Care, Version 2.2021. Journal of the National Comprehensive Cancer Network : JNCCN. 19(7):780-788. Pubmed: 34340208 DOI:jnccnGLINS1907 Palliative care has evolved to be an integral part of comprehensive cancer care with the goal of early intervention to improve quality of life and patient outcomes. The NCCN Guidelines for Palliative Care provide recommendations to help the primary oncology team promote the best quality of life possible throughout the illness trajectory for each patient with cancer. The NCCN Palliative Care Panel meets annually to evaluate and update recommendations based on panel members' clinical expertise and emerging scientific data. These NCCN Guidelines Insights summarize the panel's recent discussions and highlights updates on the importance of fostering adaptive coping strategies for patients and families, and on the role of pharmacologic and nonpharmacologic interventions to optimize symptom management. -
Keller JP, Marvin JS, Lacin H, Lemon WC, Shea J, Kim S, Lee RT, Koyama M, Keller PJ, Looger LL. 2021. In vivo glucose imaging in multiple model organisms with an engineered single-wavelength sensor. Cell reports. 35(12):109284. Pubmed: 34161775 DOI:S2211-1247(21)00655-0 Keller JP, Marvin JS, Lacin H, Lemon WC, Shea J, Kim S, Lee RT, Koyama M, Keller PJ, Looger LL. 2021. In vivo glucose imaging in multiple model organisms with an engineered single-wavelength sensor. Cell reports. 35(12):109284. Pubmed: 34161775 DOI:S2211-1247(21)00655-0 Glucose is arguably the most important molecule in metabolism, and its dysregulation underlies diabetes. We describe a family of single-wavelength genetically encoded glucose sensors with a high signal-to-noise ratio, fast kinetics, and affinities varying over four orders of magnitude (1 μM to 10 mM). The sensors allow mechanistic characterization of glucose transporters expressed in cultured cells with high spatial and temporal resolution. Imaging of neuron/glia co-cultures revealed ∼3-fold faster glucose changes in astrocytes. In larval Drosophila central nervous system explants, intracellular neuronal glucose fluxes suggested a rostro-caudal transport pathway in the ventral nerve cord neuropil. In zebrafish, expected glucose-related physiological sequelae of insulin and epinephrine treatments were directly visualized. Additionally, spontaneous muscle twitches induced glucose uptake in muscle, and sensory and pharmacological perturbations produced large changes in the brain. These sensors will enable rapid, high-resolution imaging of glucose influx, efflux, and metabolism in behaving animals.Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved. -
Garbern JC, Escalante GO, Lee RT. 2021. Pluripotent stem cell-derived cardiomyocytes for treatment of cardiomyopathic damage: Current concepts and future directions. Trends in cardiovascular medicine. 31(2):85-90. Pubmed: 31983535 DOI:S1050-1738(20)30006-2 Garbern JC, Escalante GO, Lee RT. 2021. Pluripotent stem cell-derived cardiomyocytes for treatment of cardiomyopathic damage: Current concepts and future directions. Trends in cardiovascular medicine. 31(2):85-90. Pubmed: 31983535 DOI:S1050-1738(20)30006-2 Today, cell replacement therapy using pluripotent stem cell-derived cardiomyocytes (PSC-CMs) remains a research endeavor, with several hurdles that must be overcome before delivery of PSC-CMs can become a therapeutic reality. In this review, we highlight major findings to date from pre-clinical studies involving delivery of PSC-CMs and consider remaining challenges that must be addressed for successful clinical translation. Our goal is to provide an overview of the current status of cardiomyocyte replacement therapy and what challenges must be addressed before successful clinical translation of such therapies will be possible.Copyright © 2020. Published by Elsevier Inc. 2020
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Walker RG+, Barrandon O+, Poggioli T, Dagdeviren S, Carroll SH, Mills M.J, Mendello KR, Gomez Y, Loffredo FS, Pancoast JR, Macias-Trevino C, Marts C, LeClair KB, Noh H, Taekyoon K, Banks AS, Kim JK, Cohen DE, Wagers AJ, Melton DA, Lee RT. 2020. Exogenous GDF11, but not GDF8, reduces body weight and improves glucose homeostasis in mice. Scientific Reports. Walker RG+, Barrandon O+, Poggioli T, Dagdeviren S, Carroll SH, Mills M.J, Mendello KR, Gomez Y, Loffredo FS, Pancoast JR, Macias-Trevino C, Marts C, LeClair KB, Noh H, Taekyoon K, Banks AS, Kim JK, Cohen DE, Wagers AJ, Melton DA, Lee RT. 2020. Exogenous GDF11, but not GDF8, reduces body weight and improves glucose homeostasis in mice. Scientific Reports. -
Batista TM*, Dagdeviren S*, Carroll SH, Cai W, Melnik VY, Noh HL, Saengnipanthkul S, Kahn CR+, Lee RT+. 2020. Arrestin Domain Containing 3 (Arrdc3) Modulates Insulin Action and Glucose Metabolism in Liver. Proceedings of the National Academy of Sciences of the United States. Batista TM*, Dagdeviren S*, Carroll SH, Cai W, Melnik VY, Noh HL, Saengnipanthkul S, Kahn CR+, Lee RT+. 2020. Arrestin Domain Containing 3 (Arrdc3) Modulates Insulin Action and Glucose Metabolism in Liver. Proceedings of the National Academy of Sciences of the United States. -
Walker RG, Barrandon O, Poggioli T, Dagdeviren S, Carroll SH, Mills MJ, Mendello KR, Gomez Y, Loffredo FS, Pancoast JR, Macias-Trevino C, Marts C, LeClair KB, Noh HL, Kim T, Banks AS, Kim JK, Cohen DE, Wagers AJ, Melton DA, Lee RT. 2020. Exogenous GDF11, but not GDF8, reduces body weight and improves glucose homeostasis in mice. Scientific reports. 10(1):4561. Pubmed: 32165710 DOI:10.1038/s41598-020-61443-y Walker RG, Barrandon O, Poggioli T, Dagdeviren S, Carroll SH, Mills MJ, Mendello KR, Gomez Y, Loffredo FS, Pancoast JR, Macias-Trevino C, Marts C, LeClair KB, Noh HL, Kim T, Banks AS, Kim JK, Cohen DE, Wagers AJ, Melton DA, Lee RT. 2020. Exogenous GDF11, but not GDF8, reduces body weight and improves glucose homeostasis in mice. Scientific reports. 10(1):4561. Pubmed: 32165710 DOI:10.1038/s41598-020-61443-y Insulin resistance is associated with aging in mice and humans. We have previously shown that administration of recombinant GDF11 (rGDF11) to aged mice alters aging phenotypes in the brain, skeletal muscle, and heart. While the closely related protein GDF8 has a role in metabolism, limited data are available on the potential metabolic effects of GDF11 or GDF8 in aging. To determine the metabolic effects of these two ligands, we administered rGDF11 or rGDF8 protein to young or aged mice fed a standard chow diet, short-term high-fat diet (HFD), or long-term HFD. Under nearly all of these diet conditions, administration of exogenous rGDF11 reduced body weight by 3-17% and significantly improved glucose tolerance in aged mice fed a chow (~30% vs. saline) or HF (~50% vs. saline) diet and young mice fed a HFD (~30%). On the other hand, exogenous rGDF8 showed signifcantly lesser effect or no effect at all on glucose tolerance compared to rGDF11, consistent with data demonstrating that GFD11 is a more potent signaling ligand than GDF8. Collectively, our results show that administration of exogenous rGDF11, but not rGDF8, can reduce diet-induced weight gain and improve metabolic homeostasis. -
Sarikhani M, Garbern JC, Ma S, Sereda R, Conde J, Krähenbühl G, Escalante GO, Ahmed A, Buenrostro JD, Lee RT. 2020. Sustained Activation of AMPK Enhances Differentiation of Human iPSC-Derived Cardiomyocytes via Sirtuin Activation. Stem cell reports. 15(2):498-514. Pubmed: 32649901 DOI:S2213-6711(20)30233-2 Sarikhani M, Garbern JC, Ma S, Sereda R, Conde J, Krähenbühl G, Escalante GO, Ahmed A, Buenrostro JD, Lee RT. 2020. Sustained Activation of AMPK Enhances Differentiation of Human iPSC-Derived Cardiomyocytes via Sirtuin Activation. Stem cell reports. 15(2):498-514. Pubmed: 32649901 DOI:S2213-6711(20)30233-2 Recent studies suggest that metabolic regulation may improve differentiation of cardiomyocytes derived from induced pluripotent stem cells (iPSCs). AMP-activated protein kinase (AMPK) is a master regulator of metabolic activities. We investigated whether AMPK participates in iPSC-derived cardiomyocyte differentiation. We observed that AMPK phosphorylation at Thr172 increased at day 9 but then decreased after day 11 of differentiation to cardiomyocytes. Inhibition of AMPK with compound C significantly reduced mRNA and protein expression of cardiac troponins TNNT2 and TNNI3. Moreover, sustained AMPK activation using AICAR from days 9 to 14 of differentiation increased mRNA and protein expression of both TNNT2 and TNNI3. AICAR decreased acetylation of histone 3 at Lys9 and 56 and histone 4 at Lys16 (known target sites for nuclear-localized sirtuins [SIRT1, SIRT6]), suggesting that AMPK activation enhances sirtuin activity. Sustained AMPK activation during days 9-14 of differentiation induces sirtuin-mediated histone deacetylation and may enhance cardiomyocyte differentiation from iPSCs.Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved. -
Shah A, Dagdeviren S, Lewandowski JP, Schmider AB, Ricci-Blair EM, Natarajan N, Hundal H, Noh HL, Friedline RH, Vidoudez C, Kim JK, Wagers AJ, Soberman RJ, Lee RT. 2020. Thioredoxin Interacting Protein Is Required for a Chronic Energy-Rich Diet to Promote Intestinal Fructose Absorption. iScience. 23(9):101521. Pubmed: 32927265 DOI:10.1016/j.isci.2020.101521 Shah A, Dagdeviren S, Lewandowski JP, Schmider AB, Ricci-Blair EM, Natarajan N, Hundal H, Noh HL, Friedline RH, Vidoudez C, Kim JK, Wagers AJ, Soberman RJ, Lee RT. 2020. Thioredoxin Interacting Protein Is Required for a Chronic Energy-Rich Diet to Promote Intestinal Fructose Absorption. iScience. 23(9):101521. Pubmed: 32927265 DOI:10.1016/j.isci.2020.101521 Increased consumption of fats and added sugars has been associated with an increase in metabolic syndromes. Here we show that mice chronically fed an energy-rich diet (ERD) with high fat and moderate sucrose have enhanced the absorption of a gastrointestinal fructose load, and this required expression of the arrestin domain protein Txnip in the intestinal epithelial cells. ERD feeding induced gene and protein expression of Glut5, and this required the expression of Txnip. Furthermore, Txnip interacted with Rab11a, a small GTPase that facilitates the apical localization of Glut5. We also demonstrate that ERD promoted Txnip/Glut5 complexes in the apical intestinal epithelial cell. Our findings demonstrate that ERD facilitates fructose absorption through a Txnip-dependent mechanism in the intestinal epithelial cell, suggesting that increased fructose absorption could potentially provide a mechanism for worsening of metabolic syndromes in the setting of a chronic ERD.© 2020 The Author(s). -
Roh JD, Houstis N, Yu A, Chang B, Yeri A, Li H, Hobson R, Lerchenmüller C, Vujic A, Chaudhari V, Damilano F, Platt C, Zlotoff D, Lee RT, Shah R, Jerosch-Herold M, Rosenzweig A. 2020. Exercise training reverses cardiac aging phenotypes associated with heart failure with preserved ejection fraction in male mice. Aging cell. 19(6):e13159. Pubmed: 32441410 DOI:10.1111/acel.13159 Roh JD, Houstis N, Yu A, Chang B, Yeri A, Li H, Hobson R, Lerchenmüller C, Vujic A, Chaudhari V, Damilano F, Platt C, Zlotoff D, Lee RT, Shah R, Jerosch-Herold M, Rosenzweig A. 2020. Exercise training reverses cardiac aging phenotypes associated with heart failure with preserved ejection fraction in male mice. Aging cell. 19(6):e13159. Pubmed: 32441410 DOI:10.1111/acel.13159 Heart failure with preserved ejection fraction (HFpEF) is the most common type of HF in older adults. Although no pharmacological therapy has yet improved survival in HFpEF, exercise training (ExT) has emerged as the most effective intervention to improving functional outcomes in this age-related disease. The molecular mechanisms by which ExT induces its beneficial effects in HFpEF, however, remain largely unknown. Given the strong association between aging and HFpEF, we hypothesized that ExT might reverse cardiac aging phenotypes that contribute to HFpEF pathophysiology and additionally provide a platform for novel mechanistic and therapeutic discovery. Here, we show that aged (24-30 months) C57BL/6 male mice recapitulate many of the hallmark features of HFpEF, including preserved left ventricular ejection fraction, subclinical systolic dysfunction, diastolic dysfunction, impaired cardiac reserves, exercise intolerance, and pathologic cardiac hypertrophy. Similar to older humans, ExT in old mice improved exercise capacity, diastolic function, and contractile reserves, while reducing pulmonary congestion. Interestingly, RNAseq of explanted hearts showed that ExT did not significantly modulate biological pathways targeted by conventional HF medications. However, it reversed multiple age-related pathways, including the global downregulation of cell cycle pathways seen in aged hearts, which was associated with increased capillary density, but no effects on cardiac mass or fibrosis. Taken together, these data demonstrate that the aged C57BL/6 male mouse is a valuable model for studying the role of aging biology in HFpEF pathophysiology, and provide a molecular framework for how ExT potentially reverses cardiac aging phenotypes in HFpEF.© 2020 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd. -
Vujic A, Natarajan N, Lee RT. 2020. Molecular mechanisms of heart regeneration. Seminars in cell & developmental biology. 100:20-28. Pubmed: 31587963 DOI:S1084-9521(19)30170-3 Vujic A, Natarajan N, Lee RT. 2020. Molecular mechanisms of heart regeneration. Seminars in cell & developmental biology. 100:20-28. Pubmed: 31587963 DOI:S1084-9521(19)30170-3 The adult mammalian heart is incapable of clinically relevant regeneration. The regenerative deficit in adult mammalian heart contrasts with the fetal and neonatal heart, which demonstrate substantial regenerative capacity after injury. This deficiency in adult mammals is attributable to the lack of resident stem cells after birth, combined with an inability of pre-existing cardiomyocytes to complete cytokinesis. Studies of neonatal heart regeneration in mammals suggest that latent regenerative potential can be re-activated. Dissecting the cellular and molecular mechanisms that promote cardiomyocyte proliferation is key to stimulating true regeneration in adult humans. Here, we review recent advances in our understanding of cardiomyocyte proliferation that suggest molecular approaches to heart regeneration.Copyright © 2019 Elsevier Ltd. All rights reserved. -
Garbern JC, Helman A, Sereda R, Sarikhani M, Ahmed A, Escalante GO, Ogurlu R, Kim SL, Zimmerman JF, Cho A, MacQueen L, Bezzerides VJ, Parker KK, Melton DA, Lee RT. 2020. Inhibition of mTOR Signaling Enhances Maturation of Cardiomyocytes Derived From Human-Induced Pluripotent Stem Cells via p53-Induced Quiescence. Circulation. 141(4):285-300. Pubmed: 31707831 DOI:10.1161/CIRCULATIONAHA.119.044205 Garbern JC, Helman A, Sereda R, Sarikhani M, Ahmed A, Escalante GO, Ogurlu R, Kim SL, Zimmerman JF, Cho A, MacQueen L, Bezzerides VJ, Parker KK, Melton DA, Lee RT. 2020. Inhibition of mTOR Signaling Enhances Maturation of Cardiomyocytes Derived From Human-Induced Pluripotent Stem Cells via p53-Induced Quiescence. Circulation. 141(4):285-300. Pubmed: 31707831 DOI:10.1161/CIRCULATIONAHA.119.044205 Array -
Batista TM, Dagdeviren S, Carroll SH, Cai W, Melnik VY, Noh HL, Saengnipanthkul S, Kim JK, Kahn CR, Lee RT. 2020. Arrestin domain-containing 3 (Arrdc3) modulates insulin action and glucose metabolism in liver. Proceedings of the National Academy of Sciences of the United States of America. 117(12):6733-6740. Pubmed: 32156724 DOI:10.1073/pnas.1922370117 Batista TM, Dagdeviren S, Carroll SH, Cai W, Melnik VY, Noh HL, Saengnipanthkul S, Kim JK, Kahn CR, Lee RT. 2020. Arrestin domain-containing 3 (Arrdc3) modulates insulin action and glucose metabolism in liver. Proceedings of the National Academy of Sciences of the United States of America. 117(12):6733-6740. Pubmed: 32156724 DOI:10.1073/pnas.1922370117 Insulin action in the liver is critical for glucose homeostasis through regulation of glycogen synthesis and glucose output. Arrestin domain-containing 3 () is a member of the α-arrestin family previously linked to human obesity. Here, we show that is differentially regulated by insulin in vivo in mice undergoing euglycemic-hyperinsulinemic clamps, being highly up-regulated in liver and down-regulated in muscle and fat. Mice with liver-specific knockout (KO) of the insulin receptor (IR) have a 50% reduction in messenger RNA, while, conversely, mice with liver-specific KO of (L- KO) have increased IR protein in plasma membrane. This leads to increased hepatic insulin sensitivity with increased phosphorylation of FOXO1, reduced expression of PEPCK, and increased glucokinase expression resulting in reduced hepatic glucose production and increased hepatic glycogen accumulation. These effects are due to interaction of ARRDC3 with IR resulting in phosphorylation of ARRDC3 on a conserved tyrosine (Y382) in the carboxyl-terminal domain. Thus, is an insulin target gene, and ARRDC3 protein directly interacts with IR to serve as a feedback regulator of insulin action in control of liver metabolism. 2019
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Goldstein JM, Sengul H, Messemer KA, Fernández-Alfara M, Garbern JC, Kristl AC, Lee RT, Wagers AJ. 2019. Steady-state and regenerative hematopoiesis occurs normally in mice in the absence of GDF11. Blood. 134(20):1712-1716. Pubmed: 31530563 DOI:10.1182/blood.2019002066 Goldstein JM, Sengul H, Messemer KA, Fernández-Alfara M, Garbern JC, Kristl AC, Lee RT, Wagers AJ. 2019. Steady-state and regenerative hematopoiesis occurs normally in mice in the absence of GDF11. Blood. 134(20):1712-1716. Pubmed: 31530563 DOI:10.1182/blood.2019002066 Tightly regulated production of mature blood cells is essential for health and survival in vertebrates and dependent on discrete populations of blood-forming (hematopoietic) stem and progenitor cells. Prior studies suggested that inhibition of growth differentiation factor 11 (GDF11) through soluble activin receptor type II (ActRII) ligand traps or neutralizing antibodies promotes erythroid precursor cell maturation and red blood cell formation in contexts of homeostasis and anemia. As Gdf11 is expressed by mature hematopoietic cells, and erythroid precursor cell expression of Gdf11 has been implicated in regulating erythropoiesis, we hypothesized that genetic disruption of Gdf11 in blood cells might perturb normal hematopoiesis or recovery from hematopoietic insult. Contrary to these predictions, we found that deletion of Gdf11 in the hematopoietic lineage in mice does not alter erythropoiesis or erythroid precursor cell frequency under normal conditions or during hematopoietic recovery after irradiation and transplantation. In addition, although hematopoietic cell-derived Gdf11 may contribute to the pool of circulating GDF11 protein during adult homeostasis, loss of Gdf11 specifically in the blood system does not impair hematopoietic stem cell function or induce overt pathological consequences. Taken together, these results reveal that hematopoietic cell-derived Gdf11 is largely dispensable for native and transplant-induced blood formation.© 2019 by The American Society of Hematology. -
Goldstein JM, Valido A, Lewandowski JP, Walker RG, Mills MJ, Messemer KA, Besseling P, Lee KH, Wattrus SJ, Cho M, Lee RT, Wagers AJ. 2019. Variation in zygotic CRISPR/Cas9 gene editing outcomes generates novel reporter and deletion alleles at the Gdf11 locus. Scientific reports. 9(1):18613. Pubmed: 31819086 DOI:10.1038/s41598-019-54766-y Goldstein JM, Valido A, Lewandowski JP, Walker RG, Mills MJ, Messemer KA, Besseling P, Lee KH, Wattrus SJ, Cho M, Lee RT, Wagers AJ. 2019. Variation in zygotic CRISPR/Cas9 gene editing outcomes generates novel reporter and deletion alleles at the Gdf11 locus. Scientific reports. 9(1):18613. Pubmed: 31819086 DOI:10.1038/s41598-019-54766-y Recent advances in CRISPR/Cas gene editing technology have significantly expanded the possibilities and accelerated the pace of creating genetically engineered animal models. However, CRISPR/Cas-based strategies designed to precisely edit the genome can often yield unintended outcomes. Here, we report the use of zygotic CRISPR/Cas9 injections to generate a knock-in GFP reporter mouse at the Gdf11 locus. Phenotypic and genomic characterization of founder animals from these injections revealed a subset that contained the correct targeting event and exhibited GFP expression that, within the hematopoietic system, was restricted predominantly to lymphoid cells. Yet, in another subset of founder mice, we detected aberrant integration events at the target site that dramatically and inaccurately shifted hematopoietic GFP expression from the lymphoid to the myeloid lineage. Additionally, we recovered multiple Gdf11 deletion alleles that modified the C-terminus of the GDF11 protein. When bred to homozygosity, most of these alleles recapitulated skeletal phenotypes reported previously for Gdf11 knockout mice, suggesting that these represent null alleles. However, we also recovered one Gdf11 deletion allele that encodes a novel GDF11 variant protein ("GDF11-WE") predicted to contain two additional amino acids (tryptophan (W) and glutamic acid (E)) at the C-terminus of the mature ligand. Unlike the other Gdf11 deletion alleles recovered in this study, homozygosity for the Gdf11 allele did not phenocopy Gdf11 knockout skeletal phenotypes. Further investigation using in vivo and in vitro approaches demonstrated that GDF11-WE retains substantial physiological function, indicating that GDF11 can tolerate at least some modifications of its C-terminus and providing unexpected insights into its biochemical activities. Altogether, our study confirms that one-step zygotic injections of CRISPR/Cas gene editing complexes provide a quick and powerful tool to generate gene-modified mouse models. Moreover, our findings underscore the critical importance of thorough characterization and validation of any modified alleles generated by CRISPR, as unintended on-target effects that fail to be detected by simple PCR screening can produce substantially altered phenotypic readouts. -
Garbern JC, Williams J, Kristl AC, Malick A, Rachmin I, Gaeta B, Ahmed N, Vujic A, Libby P, Lee RT. 2019. Dysregulation of IL-33/ST2 signaling and myocardial periarteriolar fibrosis. Journal of molecular and cellular cardiology. 128:179-186. Pubmed: 30763587 DOI:S0022-2828(18)30888-5 Garbern JC, Williams J, Kristl AC, Malick A, Rachmin I, Gaeta B, Ahmed N, Vujic A, Libby P, Lee RT. 2019. Dysregulation of IL-33/ST2 signaling and myocardial periarteriolar fibrosis. Journal of molecular and cellular cardiology. 128:179-186. Pubmed: 30763587 DOI:S0022-2828(18)30888-5 Microvascular dysfunction in the heart and its association with periarteriolar fibrosis may contribute to the diastolic dysfunction seen in heart failure with preserved ejection fraction. Interleukin-33 (IL-33) prevents global myocardial fibrosis in a pressure overloaded left ventricle by acting via its receptor, ST2 (encoded by the gene, Il1rl1); however, whether this cytokine can also modulate periarteriolar fibrosis remains unclear. We utilized two approaches to explore the role of IL-33/ST2 in periarteriolar fibrosis. First, we studied young and old wild type mice to test the hypothesis that IL-33 and ST2 expression change with age. Second, we produced pressure overload in mice deficient in IL-33 or ST2 by transverse aortic constriction (TAC). With age, IL-33 expression increased and ST2 expression decreased. These alterations accompanied increased periarteriolar fibrosis in aged mice. Mice deficient in ST2 but not IL-33 had a significant increase in periarteriolar fibrosis following TAC compared to wild type mice. Thus, loss of ST2 signaling rather than changes in IL-33 expression may contribute to periarteriolar fibrosis during aging or pressure overload, but manipulating this pathway alone may not prevent or reverse fibrosis.Copyright © 2019 Elsevier Ltd. All rights reserved. -
Natarajan N, Vujic A, Das J, Wang AC, Phu KK, Kiehm SH, Ricci-Blair EM, Zhu AY, Vaughan KL, Colman RJ, Mattison JA, Lee RT. 2019. Effect of dietary fat and sucrose consumption on cardiac fibrosis in mice and rhesus monkeys. JCI insight. 4(18). Pubmed: 31415241 DOI:10.1172/jci.insight.128685 Natarajan N, Vujic A, Das J, Wang AC, Phu KK, Kiehm SH, Ricci-Blair EM, Zhu AY, Vaughan KL, Colman RJ, Mattison JA, Lee RT. 2019. Effect of dietary fat and sucrose consumption on cardiac fibrosis in mice and rhesus monkeys. JCI insight. 4(18). Pubmed: 31415241 DOI:10.1172/jci.insight.128685 Calorie restriction (CR) improved health span in 2 longitudinal studies in nonhuman primates (NHPs), yet only the University of Wisconsin (UW) study demonstrated an increase in survival in CR monkeys relative to controls; the National Institute on Aging (NIA) study did not. Here, analysis of left ventricle samples showed that CR did not reduce cardiac fibrosis relative to controls. However, there was a 5.9-fold increase of total fibrosis in UW hearts, compared with NIA hearts. Diet composition was a prominent difference between the studies; therefore, we used the NHP diets to characterize diet-associated molecular and functional changes in the hearts of mice. Consistent with the findings from the NHP samples, mice fed a UW or a modified NIA diet with increased sucrose and fat developed greater cardiac fibrosis compared with mice fed the NIA diet, and transcriptomics analysis revealed diet-induced activation of myocardial oxidative phosphorylation and cardiac muscle contraction pathways. -
Garbern J, Kristl AC, Bassaneze V, Vujic A, Schoemaker H, Sereda R, Peng L, Ricci-Blair EM, Goldstein JM, Walker RG, Bhasin S, Wagers AJ, Lee RT. 2019. Analysis of Cre-mediated genetic deletion of in cardiomyocytes of young mice. American journal of physiology. Heart and circulatory physiology. 317(1):H201-H212. Pubmed: 31125255 DOI:10.1152/ajpheart.00615.2018 Garbern J, Kristl AC, Bassaneze V, Vujic A, Schoemaker H, Sereda R, Peng L, Ricci-Blair EM, Goldstein JM, Walker RG, Bhasin S, Wagers AJ, Lee RT. 2019. Analysis of Cre-mediated genetic deletion of in cardiomyocytes of young mice. American journal of physiology. Heart and circulatory physiology. 317(1):H201-H212. Pubmed: 31125255 DOI:10.1152/ajpheart.00615.2018 Administration of active growth differentiation factor 11 (GDF11) to aged mice can reduce cardiac hypertrophy, and low serum levels of GDF11 measured together with the related protein, myostatin (also known as GDF8), predict future morbidity and mortality in coronary heart patients. Using mice with a loxP-flanked ("floxed") allele of and -driven expression of Cre recombinase to delete in cardiomyocytes, we tested the hypothesis that cardiac-specific deficiency might lead to cardiac hypertrophy in young adulthood. We observed that targeted deletion of in cardiomyocytes does not cause cardiac hypertrophy but rather leads to left ventricular dilation when compared with control mice carrying only the or -floxed alleles, suggesting a possible etiology for dilated cardiomyopathy. However, the mechanism underlying this finding remains unclear because of multiple confounding effects associated with the selected model. First, whole heart expression did not decrease in -floxed mice, possibly because of upregulation of in noncardiomyocytes in the heart. Second, we observed Cre-associated toxicity, with lower body weights and increased global fibrosis, in Cre-only control male mice compared with flox-only controls, making it challenging to infer which changes in floxed mice were the result of Cre toxicity versus deletion of . Third, we observed differential expression of mRNA in Cre-only controls compared with the cardiomyocyte-specific knockout mice, also making comparison between these two groups difficult. Thus, targeted deletion in cardiomyocytes may lead to left ventricular dilation without hypertrophy, but alternative animal models are necessary to understand the mechanism for these findings. We observed that targeted deletion of growth differentiation factor 11 in cardiomyocytes does not cause cardiac hypertrophy but rather leads to left ventricular dilation compared with control mice carrying only the or growth differentiation factor 11-floxed alleles. However, the mechanism underlying this finding remains unclear because of multiple confounding effects associated with the selected mouse model. -
Ameri AH, Moradi Tuchayi S, Zaalberg A, Park JH, Ngo KH, Li T, Lopez E, Colonna M, Lee RT, Mino-Kenudson M, Demehri S. 2019. IL-33/regulatory T cell axis triggers the development of a tumor-promoting immune environment in chronic inflammation. Proceedings of the National Academy of Sciences of the United States of America. 116(7):2646-2651. Pubmed: 30696763 DOI:10.1073/pnas.1815016116 Ameri AH, Moradi Tuchayi S, Zaalberg A, Park JH, Ngo KH, Li T, Lopez E, Colonna M, Lee RT, Mino-Kenudson M, Demehri S. 2019. IL-33/regulatory T cell axis triggers the development of a tumor-promoting immune environment in chronic inflammation. Proceedings of the National Academy of Sciences of the United States of America. 116(7):2646-2651. Pubmed: 30696763 DOI:10.1073/pnas.1815016116 Chronic inflammation's tumor-promoting potential is well-recognized; however, the mechanism underlying the development of this immune environment is unknown. Studying the transition from acute, tumor-suppressive to chronic, tumor-promoting allergic contact dermatitis (ACD) revealed how tumor-promoting chronic inflammation develops. Epidermis-derived interleukin (IL)-33 up-regulation and its induction of regulatory T cell (Treg) accumulation in the skin preceded the transition from acute to chronic ACD and triggered the tumor-promoting immune environment in chronic ACD. Mice lacking IL-33 were protected from chronic ACD and its skin cancer sequela compared with wild-type controls ( = 0.0002). IL-33's direct signaling onto Tregs was required for the development of the tumor-promoting immune environment in the skin. IL-33-Treg signaling was also required for chronic colitis and its associated colorectal cancer development in a colitis model ( < 0.0001). Significantly increased IL-33 and Tregs marked the perilesional skin and colon in patients with cancer-prone chronic inflammatory diseases. Our findings elucidate the role of the IL-33/Treg axis in creating a tumor-promoting immune environment in chronic inflammatory diseases and suggest therapeutic targets for cancer prevention and treatment in high-risk patients. -
Yang P, Jiang Y, Pan Y, Ding X, Rhea P, Ding J, Hawke DH, Felsher D, Narla G, Lu Z, Lee RT. 2019. Mistletoe extract Fraxini inhibits the proliferation of liver cancer by down-regulating c-Myc expression. Scientific reports. 9(1):6428. Pubmed: 31015523 DOI:10.1038/s41598-019-41444-2 Yang P, Jiang Y, Pan Y, Ding X, Rhea P, Ding J, Hawke DH, Felsher D, Narla G, Lu Z, Lee RT. 2019. Mistletoe extract Fraxini inhibits the proliferation of liver cancer by down-regulating c-Myc expression. Scientific reports. 9(1):6428. Pubmed: 31015523 DOI:10.1038/s41598-019-41444-2 Mistletoe (Viscum album) is a type of parasitic plant reported to have anticancer activity including in hepatocellular carcinoma (HCC). However, the mechanism of mistletoe's anticancer activity, and its effectiveness in treating HCC are not fully understood. We report here that mistletoe extracts, including Fraxini (grown on ash trees) and Iscador Q and M (grown on oak and maple trees), exert strong antiproliferative activity in Hep3B cells, with median inhibitory concentrations (IC) of 0.5 µg/mL, 7.49 µg/mL, and 7.51 µg/mL, respectively. Results of Reversed Phase Proteomic Array analysis (RPPA) suggests that Fraxini substantially down-regulates c-Myc expression in Hep3B cells. Fraxini-induced growth inhibition (at a concentration of 1.25 μg/ml) was less pronounced in c-Myc knockdown Hep3B cells than in control cells. Furthermore, in the Hep3B xenograft model, Fraxini-treated (8 mg/kg body weight) mice had significantly smaller tumors (34.6 ± 11.9 mm) than control mice (161.6 ± 79.4 mm, p < 0.036). Similarly, c-Myc protein expression was reduced in Fraxini treated Hep3B cell xenografts compared to that of control mice. The reduction of c-Myc protein levels in vitro Hep3B cells appears to be mediated by the ubiquitin-proteasome system. Our results suggest the importance of c-Myc in Fraxini's antiproliferative activity, which warrants further investigation. -
Triposkiadis F, Butler J, Abboud FM, Armstrong PW, Adamopoulos S, Atherton JJ, Backs J, Bauersachs J, Burkhoff D, Bonow RO, Chopra VK, de Boer RA, de Windt L, Hamdani N, Hasenfuss G, Heymans S, Hulot JS, Konstam M, Lee RT, Linke WA, Lunde IG, Lyon AR, Maack C, Mann DL, Mebazaa A, Mentz RJ, Nihoyannopoulos P, Papp Z, Parissis J, Pedrazzini T, Rosano G, Rouleau J, Seferovic PM, Shah AM, Starling RC, Tocchetti CG, Trochu JN, Thum T, Zannad F, Brutsaert DL, Segers VF, De Keulenaer GW. 2019. The continuous heart failure spectrum: moving beyond an ejection fraction classification. European heart journal. 40(26):2155-2163. Pubmed: 30957868 DOI:10.1093/eurheartj/ehz158 Triposkiadis F, Butler J, Abboud FM, Armstrong PW, Adamopoulos S, Atherton JJ, Backs J, Bauersachs J, Burkhoff D, Bonow RO, Chopra VK, de Boer RA, de Windt L, Hamdani N, Hasenfuss G, Heymans S, Hulot JS, Konstam M, Lee RT, Linke WA, Lunde IG, Lyon AR, Maack C, Mann DL, Mebazaa A, Mentz RJ, Nihoyannopoulos P, Papp Z, Parissis J, Pedrazzini T, Rosano G, Rouleau J, Seferovic PM, Shah AM, Starling RC, Tocchetti CG, Trochu JN, Thum T, Zannad F, Brutsaert DL, Segers VF, De Keulenaer GW. 2019. The continuous heart failure spectrum: moving beyond an ejection fraction classification. European heart journal. 40(26):2155-2163. Pubmed: 30957868 DOI:10.1093/eurheartj/ehz158 Randomized clinical trials initially used heart failure (HF) patients with low left ventricular ejection fraction (LVEF) to select study populations with high risk to enhance statistical power. However, this use of LVEF in clinical trials has led to oversimplification of the scientific view of a complex syndrome. Descriptive terms such as 'HFrEF' (HF with reduced LVEF), 'HFpEF' (HF with preserved LVEF), and more recently 'HFmrEF' (HF with mid-range LVEF), assigned on arbitrary LVEF cut-off points, have gradually arisen as separate diseases, implying distinct pathophysiologies. In this article, based on pathophysiological reasoning, we challenge the paradigm of classifying HF according to LVEF. Instead, we propose that HF is a heterogeneous syndrome in which disease progression is associated with a dynamic evolution of functional and structural changes leading to unique disease trajectories creating a spectrum of phenotypes with overlapping and distinct characteristics. Moreover, we argue that by recognizing the spectral nature of the disease a novel stratification will arise from new technologies and scientific insights that will shape the design of future trials based on deeper understanding beyond the LVEF construct alone.Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com. -
Hajipour MJ, Mehrani M, Abbasi SH, Amin A, Kassaian SE, Garbern JC, Caracciolo G, Zanganeh S, Chitsazan M, Aghaverdi H, Kamali Shahri SM, Ashkarran A, Raoufi M, Bauser-Heaton H, Zhang J, Muehlschlegel JD, Moore A, Lee RT, Wu JC, Serpooshan V, Mahmoudi M. 2019. Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities. Chemical reviews. 119(21):11352-11390. Pubmed: 31490059 DOI:10.1021/acs.chemrev.8b00323 Hajipour MJ, Mehrani M, Abbasi SH, Amin A, Kassaian SE, Garbern JC, Caracciolo G, Zanganeh S, Chitsazan M, Aghaverdi H, Kamali Shahri SM, Ashkarran A, Raoufi M, Bauser-Heaton H, Zhang J, Muehlschlegel JD, Moore A, Lee RT, Wu JC, Serpooshan V, Mahmoudi M. 2019. Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities. Chemical reviews. 119(21):11352-11390. Pubmed: 31490059 DOI:10.1021/acs.chemrev.8b00323 The adult myocardium has a limited regenerative capacity following heart injury, and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF postmyocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nanobioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients. -
Leyva-Castillo JM, Galand C, Kam C, Burton O, Gurish M, Musser MA, Goldsmith JD, Hait E, Nurko S, Brombacher F, Dong C, Finkelman FD, Lee RT, Ziegler S, Chiu I, Austen KF, Geha RS. 2019. Mechanical Skin Injury Promotes Food Anaphylaxis by Driving Intestinal Mast Cell Expansion. Immunity. 50(5):1262-1275.e4. Pubmed: 31027995 DOI:S1074-7613(19)30140-2 Leyva-Castillo JM, Galand C, Kam C, Burton O, Gurish M, Musser MA, Goldsmith JD, Hait E, Nurko S, Brombacher F, Dong C, Finkelman FD, Lee RT, Ziegler S, Chiu I, Austen KF, Geha RS. 2019. Mechanical Skin Injury Promotes Food Anaphylaxis by Driving Intestinal Mast Cell Expansion. Immunity. 50(5):1262-1275.e4. Pubmed: 31027995 DOI:S1074-7613(19)30140-2 Mast cell (MC) mediator release after crosslinking of surface-bound IgE antibody by ingested antigen underlies food allergy. However, IgE antibodies are not uniformly associated with food allergy, and intestinal MC load is an important determinant. Atopic dermatitis (AD), characterized by pruritis and cutaneous sensitization to allergens, including foods, is strongly associated with food allergy. Tape stripping mouse skin, a surrogate for scratching, caused expansion and activation of small intestinal MCs, increased intestinal permeability, and promoted food anaphylaxis in sensitized mice. Tape stripping caused keratinocytes to systemically release interleukin-33 (IL-33), which synergized with intestinal tuft-cell-derived IL-25 to drive the expansion and activation of intestinal type-2 innate lymphoid cells (ILC2s). These provided IL-4, which targeted MCs to expand in the intestine. Duodenal MCs were expanded in AD. In addition to promoting cutaneous sensitization to foods, scratching may promote food anaphylaxis in AD by expanding and activating intestinal MCs.Copyright © 2019 Elsevier Inc. All rights reserved. 2018
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Natarajan N, Abbas Y, Bryant DM, Gonzalez-Rosa JM, Sharpe M, Uygur A, Cocco-Delgado LH, Ho NN, Gerard NP, Gerard CJ, MacRae CA, Burns CE, Burns CG, Whited JL, Lee RT. 2018. Complement Receptor C5aR1 Plays an Evolutionarily Conserved Role in Successful Cardiac Regeneration. Circulation. 137(20):2152-2165. Pubmed: 29348261 DOI:10.1161/CIRCULATIONAHA.117.030801 Natarajan N, Abbas Y, Bryant DM, Gonzalez-Rosa JM, Sharpe M, Uygur A, Cocco-Delgado LH, Ho NN, Gerard NP, Gerard CJ, MacRae CA, Burns CE, Burns CG, Whited JL, Lee RT. 2018. Complement Receptor C5aR1 Plays an Evolutionarily Conserved Role in Successful Cardiac Regeneration. Circulation. 137(20):2152-2165. Pubmed: 29348261 DOI:10.1161/CIRCULATIONAHA.117.030801 Array© 2018 American Heart Association, Inc. -
Walker RG, McCoy JC, Czepnik M, Mills MJ, Hagg A, Walton KL, Cotton TR, Hyvönen M, Lee RT, Gregorevic P, Harrison CA, Thompson TB. 2018. Molecular characterization of latent GDF8 reveals mechanisms of activation. Proceedings of the National Academy of Sciences of the United States of America. 115(5):E866-E875. Pubmed: 29348202 DOI:10.1073/pnas.1714622115 Walker RG, McCoy JC, Czepnik M, Mills MJ, Hagg A, Walton KL, Cotton TR, Hyvönen M, Lee RT, Gregorevic P, Harrison CA, Thompson TB. 2018. Molecular characterization of latent GDF8 reveals mechanisms of activation. Proceedings of the National Academy of Sciences of the United States of America. 115(5):E866-E875. Pubmed: 29348202 DOI:10.1073/pnas.1714622115 Growth/differentiation factor 8 (GDF8), or myostatin, negatively regulates muscle mass. GDF8 is held in a latent state through interactions with its N-terminal prodomain, much like TGF-β. Using a combination of small-angle X-ray scattering and mutagenesis, we characterized the interactions of GDF8 with its prodomain. Our results show that the prodomain:GDF8 complex can exist in a fully latent state and an activated or "triggered" state where the prodomain remains in complex with the mature domain. However, these states are not reversible, indicating the latent GDF8 is "spring-loaded." Structural analysis shows that the prodomain:GDF8 complex adopts an "open" configuration, distinct from the latency state of TGF-β and more similar to the open state of Activin A and BMP9 (nonlatent complexes). We determined that GDF8 maintains similar features for latency, including the alpha-1 helix and fastener elements, and identified a series of mutations in the prodomain of GDF8 that alleviate latency, including I56E, which does not require activation by the protease Tolloid. In vivo, active GDF8 variants were potent negative regulators of muscle mass, compared with WT GDF8. Collectively, these results help characterize the latency and activation mechanisms of GDF8. -
Bassaneze V, Lee RT. 2018. Molecular events that lead to cardiomyocyte binucleation. Cardiovascular research. 114(8):1053-1054. Pubmed: 29800235 DOI:10.1093/cvr/cvy114 Bassaneze V, Lee RT. 2018. Molecular events that lead to cardiomyocyte binucleation. Cardiovascular research. 114(8):1053-1054. Pubmed: 29800235 DOI:10.1093/cvr/cvy114 -
Mahmoud AI, Galdos FX, Dinan KA, Jedrychowski MP, Davis JC, Vujic A, Rachmin I, Shigley C, Pancoast JR, Lee S, Hollister-Lock J, MacGillivray CM, Gygi SP, Melton DA, Weir GC, Lee RT. 2018. Apolipoprotein E is a pancreatic extracellular factor that maintains mature β-cell gene expression. PloS one. 13(10):e0204595. Pubmed: 30303984 DOI:10.1371/journal.pone.0204595 Mahmoud AI, Galdos FX, Dinan KA, Jedrychowski MP, Davis JC, Vujic A, Rachmin I, Shigley C, Pancoast JR, Lee S, Hollister-Lock J, MacGillivray CM, Gygi SP, Melton DA, Weir GC, Lee RT. 2018. Apolipoprotein E is a pancreatic extracellular factor that maintains mature β-cell gene expression. PloS one. 13(10):e0204595. Pubmed: 30303984 DOI:10.1371/journal.pone.0204595 The in vivo microenvironment of tissues provides myriad unique signals to cells. Thus, following isolation, many cell types change in culture, often preserving some but not all of their in vivo characteristics in culture. At least some of the in vivo microenvironment may be mimicked by providing specific cues to cultured cells. Here, we show that after isolation and during maintenance in culture, adherent rat islets reduce expression of key β-cell transcription factors necessary for β-cell function and that soluble pancreatic decellularized matrix (DCM) can enhance β-cell gene expression. Following chromatographic fractionation of pancreatic DCM, we performed proteomics to identify soluble factors that can maintain β-cell stability and function. We identified Apolipoprotein E (ApoE) as an extracellular protein that significantly increased the expression of key β-cell genes. The ApoE effect on beta cells was mediated at least in part through the JAK/STAT signaling pathway. Together, these results reveal a role for ApoE as an extracellular factor that can maintain the mature β-cell gene expression profile. -
Vujic A, Lerchenmüller C, Wu TD, Guillermier C, Rabolli CP, Gonzalez E, Senyo SE, Liu X, Guerquin-Kern JL, Steinhauser ML, Lee RT, Rosenzweig A. 2018. Exercise induces new cardiomyocyte generation in the adult mammalian heart. Nature communications. 9(1):1659. Pubmed: 29695718 DOI:10.1038/s41467-018-04083-1 Vujic A, Lerchenmüller C, Wu TD, Guillermier C, Rabolli CP, Gonzalez E, Senyo SE, Liu X, Guerquin-Kern JL, Steinhauser ML, Lee RT, Rosenzweig A. 2018. Exercise induces new cardiomyocyte generation in the adult mammalian heart. Nature communications. 9(1):1659. Pubmed: 29695718 DOI:10.1038/s41467-018-04083-1 Loss of cardiomyocytes is a major cause of heart failure, and while the adult heart has a limited capacity for cardiomyogenesis, little is known about what regulates this ability or whether it can be effectively harnessed. Here we show that 8 weeks of running exercise increase birth of new cardiomyocytes in adult mice (~4.6-fold). New cardiomyocytes are identified based on incorporation of N-thymidine by multi-isotope imaging mass spectrometry (MIMS) and on being mononucleate/diploid. Furthermore, we demonstrate that exercise after myocardial infarction induces a robust cardiomyogenic response in an extended border zone of the infarcted area. Inhibition of miR-222, a microRNA increased by exercise in both animal models and humans, completely blocks the cardiomyogenic exercise response. These findings demonstrate that cardiomyogenesis can be activated by exercise in the normal and injured adult mouse heart and suggest that stimulation of endogenous cardiomyocyte generation could contribute to the benefits of exercise. -
Lee RT. 2018. Adult Cardiac Stem Cell Concept and the Process of Science. Circulation. 138(25):2940-2942. Pubmed: 30566005 DOI:10.1161/CIRCULATIONAHA.118.036407 Lee RT. 2018. Adult Cardiac Stem Cell Concept and the Process of Science. Circulation. 138(25):2940-2942. Pubmed: 30566005 DOI:10.1161/CIRCULATIONAHA.118.036407 2017
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Vujic A, Bassaneze V, Lee RT. 2017. Genetic insights into mammalian heart regeneration. Nature genetics. 49(9):1292-1293. Pubmed: 28854178 DOI:10.1038/ng.3942 Vujic A, Bassaneze V, Lee RT. 2017. Genetic insights into mammalian heart regeneration. Nature genetics. 49(9):1292-1293. Pubmed: 28854178 DOI:10.1038/ng.3942 Genetic and functional analyses of 120 mouse strains have identified a heart regeneration candidate gene that modulates the contractile sarcomeric apparatus. This gene, Tnni3k, controls the frequency of the mononuclear, diploid cardiomyocyte population, which affects cardiomyocyte proliferative potential after injury. -
Carroll SH, Zhang E, Wang BF, LeClair KB, Rahman A, Cohen DE, Plutzky J, Patwari P, Lee RT. 2017. Correction: Adipocyte arrestin domain-containing 3 protein (Arrdc3) regulates uncoupling protein 1 (Ucp1) expression in white adipose independently of canonical changes in β-adrenergic receptor signaling. PloS one. 12(7):e0181492. Pubmed: 28700749 DOI:10.1371/journal.pone.0181492 Carroll SH, Zhang E, Wang BF, LeClair KB, Rahman A, Cohen DE, Plutzky J, Patwari P, Lee RT. 2017. Correction: Adipocyte arrestin domain-containing 3 protein (Arrdc3) regulates uncoupling protein 1 (Ucp1) expression in white adipose independently of canonical changes in β-adrenergic receptor signaling. PloS one. 12(7):e0181492. Pubmed: 28700749 DOI:10.1371/journal.pone.0181492 [This corrects the article DOI: 10.1371/journal.pone.0173823.]. -
Guillermier C, Fazeli PK, Kim S, Lun M, Zuflacht JP, Milian J, Lee H, Francois-Saint-Cyr H, Horreard F, Larson D, Rosen ED, Lee RT, Lechene CP, Steinhauser ML. 2017. Imaging mass spectrometry demonstrates age-related decline in human adipose plasticity. JCI insight. 2(5):e90349. Pubmed: 28289709 DOI:10.1172/jci.insight.90349 Guillermier C, Fazeli PK, Kim S, Lun M, Zuflacht JP, Milian J, Lee H, Francois-Saint-Cyr H, Horreard F, Larson D, Rosen ED, Lee RT, Lechene CP, Steinhauser ML. 2017. Imaging mass spectrometry demonstrates age-related decline in human adipose plasticity. JCI insight. 2(5):e90349. Pubmed: 28289709 DOI:10.1172/jci.insight.90349 Quantification of stable isotope tracers has revealed the dynamic state of living tissues. A new form of imaging mass spectrometry quantifies isotope ratios in domains much smaller than a cubic micron, enabling measurement of cell turnover and metabolism with stable isotope tracers at the single-cell level with a methodology we refer to as multi-isotope imaging mass spectrometry. In a first-in-human study, we utilize stable isotope tracers of DNA synthesis and de novo lipogenesis to prospectively measure cell birth and adipocyte lipid turnover. In a study of healthy adults, we elucidate an age-dependent decline in new adipocyte generation and adipocyte lipid turnover. A linear regression model suggests that the aging effect could be mediated by a decline in insulin-like growth factor-1 (IGF-1). This study therefore establishes a method for measurement of cell turnover and metabolism in humans with subcellular resolution while implicating the growth hormone/IGF-1 axis in adipose tissue aging. -
Carroll SH, Zhang E, Wang BF, LeClair KB, Rahman A, Cohen DE, Plutzky J, Patwari P, Lee RT. 2017. Adipocyte arrestin domain-containing 3 protein (Arrdc3) regulates uncoupling protein 1 (Ucp1) expression in white adipose independently of canonical changes in β-adrenergic receptor signaling. PloS one. 12(3):e0173823. Pubmed: 28291835 DOI:10.1371/journal.pone.0173823 Carroll SH, Zhang E, Wang BF, LeClair KB, Rahman A, Cohen DE, Plutzky J, Patwari P, Lee RT. 2017. Adipocyte arrestin domain-containing 3 protein (Arrdc3) regulates uncoupling protein 1 (Ucp1) expression in white adipose independently of canonical changes in β-adrenergic receptor signaling. PloS one. 12(3):e0173823. Pubmed: 28291835 DOI:10.1371/journal.pone.0173823 Adaptive thermogenesis and cold-induced activation of uncoupling protein 1 (Ucp1) in brown adipose tissue in rodents is well-described and attributed to sympathetic activation of β-adrenergic signaling. The arrestin domain containing protein Arrdc3 is a regulator of obesity in mice and also appears linked to obesity in humans. We generated a mouse with conditional deletion of Arrdc3, and here we present evidence that genetic ablation of Arrdc3 specifically in adipocytes results in increased Ucp1 expression in subcutaneous and parametrial adipose tissue. Although this increase in expression did not correspond with significant changes in body weight or energy expenditure, adipocyte-specific Arrdc3-null mice had improved glucose tolerance. It was previously hypothesized that Arrdc3 ablation leads to increased β-adrenergic receptor sensitivity; however, in vitro experiments show that Arrdc3-null adipocytes responded to β-adrenergic receptor agonist with decreased Ucp1 levels. Additionally, canonical β-adrenergic receptor signaling was not different in Arrdc3-null adipocytes. These data reveal a role for Arrdc3 in the regulation of Ucp1 expression in adipocytes. However, this adipocyte effect is insufficient to generate the obesity-resistant phenotype of mice with ubiquitous deletion of Arrdc3, indicating a likely role for Arrdc3 in cells other than adipocytes. -
Mahmoudi M, Yu M, Serpooshan V, Wu JC, Langer R, Lee RT, Karp JM, Farokhzad OC. 2017. Multiscale technologies for treatment of ischemic cardiomyopathy. Nature nanotechnology. 12(9):845-855. Pubmed: 28875984 DOI:10.1038/nnano.2017.167 Mahmoudi M, Yu M, Serpooshan V, Wu JC, Langer R, Lee RT, Karp JM, Farokhzad OC. 2017. Multiscale technologies for treatment of ischemic cardiomyopathy. Nature nanotechnology. 12(9):845-855. Pubmed: 28875984 DOI:10.1038/nnano.2017.167 The adult mammalian heart possesses only limited capacity for innate regeneration and the response to severe injury is dominated by the formation of scar tissue. Current therapy to replace damaged cardiac tissue is limited to cardiac transplantation and thus many patients suffer progressive decay in the heart's pumping capacity to the point of heart failure. Nanostructured systems have the potential to revolutionize both preventive and therapeutic approaches for treating cardiovascular disease. Here, we outline recent advancements in nanotechnology that could be exploited to overcome the major obstacles in the prevention of and therapy for heart disease. We also discuss emerging trends in nanotechnology affecting the cardiovascular field that may offer new hope for patients suffering massive heart attacks. -
Eschenhagen T, Bolli R, Braun T, Field LJ, Fleischmann BK, Frisén J, Giacca M, Hare JM, Houser S, Lee RT, Marbán E, Martin JF, Molkentin JD, Murry CE, Riley PR, Ruiz-Lozano P, Sadek HA, Sussman MA, Hill JA. 2017. Cardiomyocyte Regeneration: A Consensus Statement. Circulation. 136(7):680-686. Pubmed: 28684531 DOI:10.1161/CIRCULATIONAHA.117.029343 Eschenhagen T, Bolli R, Braun T, Field LJ, Fleischmann BK, Frisén J, Giacca M, Hare JM, Houser S, Lee RT, Marbán E, Martin JF, Molkentin JD, Murry CE, Riley PR, Ruiz-Lozano P, Sadek HA, Sussman MA, Hill JA. 2017. Cardiomyocyte Regeneration: A Consensus Statement. Circulation. 136(7):680-686. Pubmed: 28684531 DOI:10.1161/CIRCULATIONAHA.117.029343 -
Rachmin I, O'Meara CC, Ricci-Blair EM, Feng Y, Christensen EM, Duffy JF, Zitting KM, Czeisler CA, Pancoast JR, Cannon CP, O'Donoghue ML, Morrow DA, Lee RT. 2017. Soluble interleukin-13rα1: a circulating regulator of glucose. American journal of physiology. Endocrinology and metabolism. 313(6):E663-E671. Pubmed: 28874358 DOI:10.1152/ajpendo.00168.2017 Rachmin I, O'Meara CC, Ricci-Blair EM, Feng Y, Christensen EM, Duffy JF, Zitting KM, Czeisler CA, Pancoast JR, Cannon CP, O'Donoghue ML, Morrow DA, Lee RT. 2017. Soluble interleukin-13rα1: a circulating regulator of glucose. American journal of physiology. Endocrinology and metabolism. 313(6):E663-E671. Pubmed: 28874358 DOI:10.1152/ajpendo.00168.2017 Soluble IL-13 receptor-α1, or sIL13rα1, is a soluble protein that binds to interleukin-13 (IL-13) that has been previously described in mice. The function of sIL13rα1 remains unclear, but it has been hypothesized to act as a decoy receptor for IL-13. Recent studies have identified a role for IL-13 in glucose metabolism, suggesting that a decoy receptor for IL-13 might increase circulating glucose levels. Here, we report that delivery of sIL13rα1 to mice by either gene transfer or recombinant protein decreases blood glucose levels. Surprisingly, the glucose-lowering effect of sIL13rα1 was preserved in mice lacking IL-13, demonstrating that IL-13 was not required for the effect. In contrast, deletion of IL-4 in mice eliminated the hypoglycemic effect of sIL13rα1. In humans, endogenous blood levels of IL13rα1 varied substantially, although there were no differences between diabetic and nondiabetic patients. There was no circadian variation of sIL13rα1 in normal human volunteers. Delivery of sIL13rα1 fused to a fragment crystallizable (Fc) domain provided sustained glucose lowering in mice on a high-fat diet, suggesting a potential therapeutic strategy. These data reveal sIL13rα1 as a circulating human protein with an unexpected role in glucose metabolism.Copyright © 2017 the American Physiological Society. -
Walker RG, Czepnik M, Goebel EJ, McCoy JC, Vujic A, Cho M, Oh J, Aykul S, Walton KL, Schang G, Bernard DJ, Hinck AP, Harrison CA, Martinez-Hackert E, Wagers AJ, Lee RT, Thompson TB. 2017. Structural basis for potency differences between GDF8 and GDF11. BMC biology. 15(1):19. Pubmed: 28257634 DOI:10.1186/s12915-017-0350-1 Walker RG, Czepnik M, Goebel EJ, McCoy JC, Vujic A, Cho M, Oh J, Aykul S, Walton KL, Schang G, Bernard DJ, Hinck AP, Harrison CA, Martinez-Hackert E, Wagers AJ, Lee RT, Thompson TB. 2017. Structural basis for potency differences between GDF8 and GDF11. BMC biology. 15(1):19. Pubmed: 28257634 DOI:10.1186/s12915-017-0350-1 Array 2016
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Mahmoud AI, Lee RT. 2016. Adrenergic function restoration in the transplanted heart: a role for neural crest-derived cells. Cardiovascular research. 109(3):348-9. Pubmed: 26786156 DOI:10.1093/cvr/cvw013 Mahmoud AI, Lee RT. 2016. Adrenergic function restoration in the transplanted heart: a role for neural crest-derived cells. Cardiovascular research. 109(3):348-9. Pubmed: 26786156 DOI:10.1093/cvr/cvw013 -
Poggioli T, Vujic A, Yang P, Macias-Trevino C, Uygur A, Loffredo FS, Pancoast JR, Cho M, Goldstein J, Tandias RM, Gonzalez E, Walker RG, Thompson TB, Wagers AJ, Fong YW, Lee RT. 2016. Circulating Growth Differentiation Factor 11/8 Levels Decline With Age. Circulation research. 118(1):29-37. Pubmed: 26489925 DOI:10.1161/CIRCRESAHA.115.307521 Poggioli T, Vujic A, Yang P, Macias-Trevino C, Uygur A, Loffredo FS, Pancoast JR, Cho M, Goldstein J, Tandias RM, Gonzalez E, Walker RG, Thompson TB, Wagers AJ, Fong YW, Lee RT. 2016. Circulating Growth Differentiation Factor 11/8 Levels Decline With Age. Circulation research. 118(1):29-37. Pubmed: 26489925 DOI:10.1161/CIRCRESAHA.115.307521 Array© 2015 American Heart Association, Inc. -
Uzel SG, Amadi OC, Pearl TM, Lee RT, So PT, Kamm RD. 2016. Simultaneous or Sequential Orthogonal Gradient Formation in a 3D Cell Culture Microfluidic Platform. Small (Weinheim an der Bergstrasse, Germany). 12(5):612-22. Pubmed: 26619365 DOI:10.1002/smll.201501905 Uzel SG, Amadi OC, Pearl TM, Lee RT, So PT, Kamm RD. 2016. Simultaneous or Sequential Orthogonal Gradient Formation in a 3D Cell Culture Microfluidic Platform. Small (Weinheim an der Bergstrasse, Germany). 12(5):612-22. Pubmed: 26619365 DOI:10.1002/smll.201501905 Biochemical gradients are ubiquitous in biology. At the tissue level, they dictate differentiation patterning or cell migration. Recapitulating in vitro the complexity of such concentration profiles with great spatial and dynamic control is crucial in order to understand the underlying mechanisms of biological phenomena. Here, a microfluidic design capable of generating diffusion-driven, simultaneous or sequential, orthogonal linear concentration gradients in a 3D cell-embedded scaffold is described. Formation and stability of the orthogonal gradients are demonstrated by computational and fluorescent dextran-based characterizations. Then, system utility is explored in two biological systems. First, stem cells are subjected to orthogonal gradients of morphogens in order to mimic the localized differentiation of motor neurons in the neural tube. Similarly to in vivo, motor neurons preferentially differentiate in regions of high concentration of retinoic acid and smoothened agonist (acting as sonic hedgehog), in a concentration-dependent fashion. Then, a rotating gradient is applied to HT1080 cancer cells and the change in migration direction is investigated as the cells adapt to a new chemical environment. The response time of ≈4 h is reported. These two examples demonstrate the versatility of this new design that can also prove useful in many applications including tissue engineering and drug screening.© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. -
Lee RT, Walsh K. 2016. The Future of Cardiovascular Regenerative Medicine. Circulation. 133(25):2618-25. Pubmed: 27324357 DOI:10.1161/CIRCULATIONAHA.115.019214 Lee RT, Walsh K. 2016. The Future of Cardiovascular Regenerative Medicine. Circulation. 133(25):2618-25. Pubmed: 27324357 DOI:10.1161/CIRCULATIONAHA.115.019214 Regeneration of lost or injured tissues is very common in biology. Unfortunately, humans lack adequate regeneration in the heart and many other organs that are commonly ravaged by modern diseases. A revolution in stem cell biology has led to an explosion of interest in therapies that can awaken the regeneration potential in patients. In just the past decade, we have learned that any cell type from any patient, including cells from a blood sample or skin biopsies, can potentially be reprogrammed into a stem cell, and that patient’s stem cell can generate billions of new cells of a variety of differentiated cell types, including cardiomyocytes, endothelial cells and neurons. Stem cell biology is already changing how we approach human genetics and drug discovery, and clinical efforts to harness stem cell biology for heart failure are well underway. Here we predict that regenerative biology will initially struggle to hurdle economic and technical barriers for realistic treatments of heart diseases. However, regenerative biologists are beginning to design new approaches that were previously unimaginable, and ultimately regenerative medicine will have a profound impact for heart diseases. -
Dotimas JR, Lee AW, Schmider AB, Carroll SH, Shah A, Bilen J, Elliott KR, Myers RB, Soberman RJ, Yoshioka J, Lee RT. 2016. Diabetes regulates fructose absorption through thioredoxin-interacting protein. eLife. 5. Pubmed: 27725089 DOI:10.7554/eLife.18313 Dotimas JR, Lee AW, Schmider AB, Carroll SH, Shah A, Bilen J, Elliott KR, Myers RB, Soberman RJ, Yoshioka J, Lee RT. 2016. Diabetes regulates fructose absorption through thioredoxin-interacting protein. eLife. 5. Pubmed: 27725089 DOI:10.7554/eLife.18313 Metabolic studies suggest that the absorptive capacity of the small intestine for fructose is limited, though the molecular mechanisms controlling this process remain unknown. Here we demonstrate that thioredoxin-interacting protein (Txnip), which regulates glucose homeostasis in mammals, binds to fructose transporters and promotes fructose absorption by the small intestine. Deletion of in mice reduced fructose transport into the peripheral bloodstream and liver, as well as the severity of adverse metabolic outcomes resulting from long-term fructose consumption. We also demonstrate that fructose consumption induces expression of Txnip in the small intestine. Diabetic mice had increased expression of Txnip in the small intestine as well as enhanced fructose uptake and transport into the hepatic portal circulation. The deletion of in mice abolished the diabetes-induced increase in fructose absorption. Our results indicate that Txnip is a critical regulator of fructose metabolism and suggest that a diabetic state can promote fructose uptake. -
Uygur A, Lee RT. 2016. Mechanisms of Cardiac Regeneration. Developmental cell. 36(4):362-74. Pubmed: 26906733 DOI:S1534-5807(16)00085-X Uygur A, Lee RT. 2016. Mechanisms of Cardiac Regeneration. Developmental cell. 36(4):362-74. Pubmed: 26906733 DOI:S1534-5807(16)00085-X Adult humans fail to regenerate their hearts following injury, and this failure to regenerate myocardium is a leading cause of heart failure and death worldwide. Although all adult mammals appear to lack significant cardiac regeneration potential, some vertebrates can regenerate myocardium throughout life. In addition, new studies indicate that mammals have cardiac regeneration potential during development and very soon after birth. The mechanisms of heart regeneration among model organisms, including neonatal mice, appear remarkably similar. Orchestrated waves of inflammation, matrix deposition and remodeling, and cardiomyocyte proliferation are commonly seen in heart regeneration models. Understanding why adult mammals develop extensive scarring instead of regeneration is a crucial goal for regenerative biology.Copyright © 2016 Elsevier Inc. All rights reserved. -
Daley GQ, Hyun I, Apperley JF, Barker RA, Benvenisty N, Bredenoord AL, Breuer CK, Caulfield T, Cedars MI, Frey-Vasconcells J, Heslop HE, Jin Y, Lee RT, McCabe C, Munsie M, Murry CE, Piantadosi S, Rao M, Rooke HM, Sipp D, Studer L, Sugarman J, Takahashi M, Zimmerman M, Kimmelman J. 2016. Setting Global Standards for Stem Cell Research and Clinical Translation: The 2016 ISSCR Guidelines. Stem cell reports. 6(6):787-797. Pubmed: 27185282 DOI:S2213-6711(16)30041-8 Daley GQ, Hyun I, Apperley JF, Barker RA, Benvenisty N, Bredenoord AL, Breuer CK, Caulfield T, Cedars MI, Frey-Vasconcells J, Heslop HE, Jin Y, Lee RT, McCabe C, Munsie M, Murry CE, Piantadosi S, Rao M, Rooke HM, Sipp D, Studer L, Sugarman J, Takahashi M, Zimmerman M, Kimmelman J. 2016. Setting Global Standards for Stem Cell Research and Clinical Translation: The 2016 ISSCR Guidelines. Stem cell reports. 6(6):787-797. Pubmed: 27185282 DOI:S2213-6711(16)30041-8 The International Society for Stem Cell Research (ISSCR) presents its 2016 Guidelines for Stem Cell Research and Clinical Translation (ISSCR, 2016). The 2016 guidelines reflect the revision and extension of two past sets of guidelines (ISSCR, 2006; ISSCR, 2008) to address new and emerging areas of stem cell discovery and application and evolving ethical, social, and policy challenges. These guidelines provide an integrated set of principles and best practices to drive progress in basic, translational, and clinical research. The guidelines demand rigor, oversight, and transparency in all aspects of practice, providing confidence to practitioners and public alike that stem cell science can proceed efficiently and remain responsive to public and patient interests. Here, we highlight key elements and recommendations in the guidelines and summarize the recommendations and deliberations behind them.Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved. -
Walker RG, Poggioli T, Katsimpardi L, Buchanan SM, Oh J, Wattrus S, Heidecker B, Fong YW, Rubin LL, Ganz P, Thompson TB, Wagers AJ, Lee RT. 2016. Biochemistry and Biology of GDF11 and Myostatin: Similarities, Differences, and Questions for Future Investigation. Circulation research. 118(7):1125-41; discussion 1142. Pubmed: 27034275 DOI:10.1161/CIRCRESAHA.116.308391 Walker RG, Poggioli T, Katsimpardi L, Buchanan SM, Oh J, Wattrus S, Heidecker B, Fong YW, Rubin LL, Ganz P, Thompson TB, Wagers AJ, Lee RT. 2016. Biochemistry and Biology of GDF11 and Myostatin: Similarities, Differences, and Questions for Future Investigation. Circulation research. 118(7):1125-41; discussion 1142. Pubmed: 27034275 DOI:10.1161/CIRCRESAHA.116.308391 Growth differentiation factor 11 (GDF11) and myostatin (or GDF8) are closely related members of the transforming growth factor β superfamily and are often perceived to serve similar or overlapping roles. Yet, despite commonalities in protein sequence, receptor utilization and signaling, accumulating evidence suggests that these 2 ligands can have distinct functions in many situations. GDF11 is essential for mammalian development and has been suggested to regulate aging of multiple tissues, whereas myostatin is a well-described negative regulator of postnatal skeletal and cardiac muscle mass and modulates metabolic processes. In this review, we discuss the biochemical regulation of GDF11 and myostatin and their functions in the heart, skeletal muscle, and brain. We also highlight recent clinical findings with respect to a potential role for GDF11 and/or myostatin in humans with heart disease. Finally, we address key outstanding questions related to GDF11 and myostatin dynamics and signaling during development, growth, and aging.© 2016 American Heart Association, Inc. -
Vujic A, Mahmoud AI, Lee RT. 2016. A Breakdown in Cooperativity Leads to Cardiac Identity Crisis. Cell. 167(7):1674-1676. Pubmed: 27984717 DOI:S0092-8674(16)31671-3 Vujic A, Mahmoud AI, Lee RT. 2016. A Breakdown in Cooperativity Leads to Cardiac Identity Crisis. Cell. 167(7):1674-1676. Pubmed: 27984717 DOI:S0092-8674(16)31671-3 Using induced pluripotent stem cells, Ang et al. elucidate how a mutation in the transcription factor GATA4 causes congenital heart disease. They find that, although the recruitment of GATA4 to cardiac super-enhancers is retained, it no longer functions in partnership with another key transcription factor, leading to misexpression of non-cardiomyocyte genes.Copyright © 2016 Elsevier Inc. All rights reserved. -
Natarajan N, Lee RT. 2016. Basic research: Suffocating the heart to stimulate regeneration. Nature reviews. Cardiology. 14(1):7-8. Pubmed: 27941858 DOI:10.1038/nrcardio.2016.197 Natarajan N, Lee RT. 2016. Basic research: Suffocating the heart to stimulate regeneration. Nature reviews. Cardiology. 14(1):7-8. Pubmed: 27941858 DOI:10.1038/nrcardio.2016.197 -
Liebesny PH, Byun S, Hung HH, Pancoast JR, Mroszczyk KA, Young WT, Lee RT, Frisbie DD, Kisiday JD, Grodzinsky AJ. 2016. Growth Factor-Mediated Migration of Bone Marrow Progenitor Cells for Accelerated Scaffold Recruitment. Tissue engineering. Part A. 22(13-14):917-27. Pubmed: 27268956 DOI:10.1089/ten.TEA.2015.0524 Liebesny PH, Byun S, Hung HH, Pancoast JR, Mroszczyk KA, Young WT, Lee RT, Frisbie DD, Kisiday JD, Grodzinsky AJ. 2016. Growth Factor-Mediated Migration of Bone Marrow Progenitor Cells for Accelerated Scaffold Recruitment. Tissue engineering. Part A. 22(13-14):917-27. Pubmed: 27268956 DOI:10.1089/ten.TEA.2015.0524 Tissue engineering approaches using growth factor-functionalized acellular scaffolds to support and guide repair driven by endogenous cells are thought to require a careful balance between cell recruitment and growth factor release kinetics. The objective of this study was to identify a growth factor combination that accelerates progenitor cell migration into self-assembling peptide hydrogels in the context of cartilage defect repair. A novel 3D gel-to-gel migration assay enabled quantification of the chemotactic impact of platelet-derived growth factor-BB (PDGF-BB), heparin-binding insulin-like growth factor-1 (HB-IGF-1), and transforming growth factor-β1 (TGF-β1) on progenitor cells derived from subchondral bovine trabecular bone (bone-marrow progenitor cells, BM-PCs) encapsulated in the peptide hydrogel [KLDL]3. Only the combination of PDGF-BB and TGF-β1 stimulated significant migration of BM-PCs over a 4-day period, measured by confocal microscopy. Both PDGF-BB and TGF-β1 were slowly released from the gel, as measured using their (125)I-labeled forms, and they remained significantly present in the gel at 4 days. In the context of augmenting microfracture surgery for cartilage repair, our strategy of delivering chemotactic and proanabolic growth factors in KLD may provide the necessary local stimulus to help increase defect cellularity, providing more cells to generate repair tissue. 2015
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Bryant DM, O'Meara CC, Ho NN, Gannon J, Cai L, Lee RT. 2015. A systematic analysis of neonatal mouse heart regeneration after apical resection. Journal of molecular and cellular cardiology. 79:315-8. Pubmed: 25533939 DOI:S0022-2828(14)00423-4 Bryant DM, O'Meara CC, Ho NN, Gannon J, Cai L, Lee RT. 2015. A systematic analysis of neonatal mouse heart regeneration after apical resection. Journal of molecular and cellular cardiology. 79:315-8. Pubmed: 25533939 DOI:S0022-2828(14)00423-4 The finding that neonatal mice are able to regenerate myocardium after apical resection has recently been questioned. We determined if heart regeneration is influenced by the size of cardiac resection and whether surgical retraction of the ventricular apex results in an increase in cardiomyocyte cell cycle activity. We performed moderate or large apical ventricular resections on neonatal mice and quantified scar infiltration into the left ventricular wall at 21 days post-surgery. Moderately resected hearts had 15±2% of the wall infiltrated by a collagen scar; significantly greater scar infiltration (23±4%) was observed in hearts with large resections. Resected hearts had higher levels of cardiomyocyte cell cycle activity relative to sham hearts. Surgically retracting the ventricle often resulted in fibrosis and induced cardiomyocyte cell cycle activity that were comparable to that of resected hearts. We conclude that apical resection in neonatal mice induces cardiomyocyte cell cycle activity and neomyogenesis, although scarring can occur. Surgical technique and definition of approach to assessing the extent of regeneration are both critical when using the neonatal mouse apical resection model.Copyright © 2014 Elsevier Ltd. All rights reserved. -
Jiang J, Burgon PG, Wakimoto H, Onoue K, Gorham JM, O'Meara CC, Fomovsky G, McConnell BK, Lee RT, Seidman JG, Seidman CE. 2015. Cardiac myosin binding protein C regulates postnatal myocyte cytokinesis. Proceedings of the National Academy of Sciences of the United States of America. 112(29):9046-51. Pubmed: 26153423 DOI:10.1073/pnas.1511004112 Jiang J, Burgon PG, Wakimoto H, Onoue K, Gorham JM, O'Meara CC, Fomovsky G, McConnell BK, Lee RT, Seidman JG, Seidman CE. 2015. Cardiac myosin binding protein C regulates postnatal myocyte cytokinesis. Proceedings of the National Academy of Sciences of the United States of America. 112(29):9046-51. Pubmed: 26153423 DOI:10.1073/pnas.1511004112 Homozygous cardiac myosin binding protein C-deficient (Mybpc(t/t)) mice develop dramatic cardiac dilation shortly after birth; heart size increases almost twofold. We have investigated the mechanism of cardiac enlargement in these hearts. Throughout embryogenesis myocytes undergo cell division while maintaining the capacity to pump blood by rapidly disassembling and reforming myofibrillar components of the sarcomere throughout cell cycle progression. Shortly after birth, myocyte cell division ceases. Cardiac MYBPC is a thick filament protein that regulates sarcomere organization and rigidity. We demonstrate that many Mybpc(t/t) myocytes undergo an additional round of cell division within 10 d postbirth compared with their wild-type counterparts, leading to increased numbers of mononuclear myocytes. Short-hairpin RNA knockdown of Mybpc3 mRNA in wild-type mice similarly extended the postnatal window of myocyte proliferation. However, adult Mybpc(t/t) myocytes are unable to fully regenerate the myocardium after injury. MYBPC has unexpected inhibitory functions during postnatal myocyte cytokinesis and cell cycle progression. We suggest that human patients with homozygous MYBPC3-null mutations develop dilated cardiomyopathy, coupled with myocyte hyperplasia (increased cell number), as observed in Mybpc(t/t) mice. Human patients, with heterozygous truncating MYBPC3 mutations, like mice with similar mutations, have hypertrophic cardiomyopathy. However, the mechanism leading to hypertrophic cardiomyopathy in heterozygous MYBPC3(+/-) individuals is myocyte hypertrophy (increased cell size), whereas the mechanism leading to cardiac dilation in homozygous Mybpc3(-/-) mice is primarily myocyte hyperplasia. -
Alvarez LM, Rivera JJ, Stockdale L, Saini S, Lee RT, Griffith LG. 2015. Tethering of Epidermal Growth Factor (EGF) to Beta Tricalcium Phosphate (βTCP) via Fusion to a High Affinity, Multimeric βTCP-Binding Peptide: Effects on Human Multipotent Stromal Cells/Connective Tissue Progenitors. PloS one. 10(6):e0129600. Pubmed: 26121597 DOI:10.1371/journal.pone.0129600 Alvarez LM, Rivera JJ, Stockdale L, Saini S, Lee RT, Griffith LG. 2015. Tethering of Epidermal Growth Factor (EGF) to Beta Tricalcium Phosphate (βTCP) via Fusion to a High Affinity, Multimeric βTCP-Binding Peptide: Effects on Human Multipotent Stromal Cells/Connective Tissue Progenitors. PloS one. 10(6):e0129600. Pubmed: 26121597 DOI:10.1371/journal.pone.0129600 Transplantation of freshly-aspirated autologous bone marrow, together with a scaffold, is a promising clinical alternative to harvest and transplantation of autologous bone for treatment of large defects. However, survival proliferation, and osteogenic differentiation of the marrow-resident stem and progenitor cells with osteogenic potential can be limited in large defects by the inflammatory microenvironment. Previous studies using EGF tethered to synthetic polymer substrates have demonstrated that surface-tethered EGF can protect human bone marrow-derived osteogenic stem and progenitor cells from pro-death inflammatory cues and enhance their proliferation without detriment to subsequent osteogenic differentiation. The objective of this study was to identify a facile means of tethering EGF to clinically-relevant βTCP scaffolds and to demonstrate the bioactivity of EGF tethered to βTCP using stimulation of the proliferative response of human bone-marrow derived mesenchymal stem cells (hBMSC) as a phenotypic metric. We used a phage display library and panned against βTCP and composites of βTCP with a degradable polyester biomaterial, together with orthogonal blocking schemes, to identify a 12-amino acid consensus binding peptide sequence, LLADTTHHRPWT, with high affinity for βTCP. When a single copy of this βTCP-binding peptide sequence was fused to EGF via a flexible peptide tether domain and expressed recombinantly in E. coli together with a maltose-binding domain to aid purification, the resulting fusion protein exhibited modest affinity for βTCP. However, a fusion protein containing a linear concatamer containing 10 repeats of the binding motif the resulting fusion protein showed high affinity stable binding to βTCP, with only 25% of the protein released after 7 days at 37oC. The fusion protein was bioactive, as assessed by its abilities to activate kinase signaling pathways downstream of the EGF receptor when presented in soluble form, and to enhance the proliferation of hBMSC when presented in tethered form on commercial βTCP bone regeneration scaffolds. -
Chen WY, Hong J, Gannon J, Kakkar R, Lee RT. 2015. Myocardial pressure overload induces systemic inflammation through endothelial cell IL-33. Proceedings of the National Academy of Sciences of the United States of America. 112(23):7249-54. Pubmed: 25941360 DOI:10.1073/pnas.1424236112 Chen WY, Hong J, Gannon J, Kakkar R, Lee RT. 2015. Myocardial pressure overload induces systemic inflammation through endothelial cell IL-33. Proceedings of the National Academy of Sciences of the United States of America. 112(23):7249-54. Pubmed: 25941360 DOI:10.1073/pnas.1424236112 Hypertension increases the pressure load on the heart and is associated with a poorly understood chronic systemic inflammatory state. Interleukin 33 (IL-33) binds to membrane-bound ST2 (ST2L) and has antihypertrophic and antifibrotic effects in the myocardium. In contrast, soluble ST2 appears to act as a decoy receptor for IL-33, blocking myocardial and vascular benefits, and is a prognostic biomarker in patients with cardiovascular diseases. Here we report that a highly local intramyocardial IL-33/ST2 conversation regulates the heart's response to pressure overload. Either endothelial-specific deletion of IL33 or cardiomyocyte-specific deletion of ST2 exacerbated cardiac hypertrophy with pressure overload. Furthermore, pressure overload induced systemic circulating IL-33 as well as systemic circulating IL-13 and TGF-beta1; this was abolished by endothelial-specific deletion of IL33 but not by cardiomyocyte-specific deletion of IL33. Our study reveals that endothelial cell secretion of IL-33 is crucial for translating myocardial pressure overload into a selective systemic inflammatory response. -
Florine EM, Miller RE, Liebesny PH, Mroszczyk KA, Lee RT, Patwari P, Grodzinsky AJ. 2015. Delivering heparin-binding insulin-like growth factor 1 with self-assembling peptide hydrogels. Tissue engineering. Part A. 21(3-4):637-46. Pubmed: 25231349 DOI:10.1089/ten.TEA.2013.0679 Florine EM, Miller RE, Liebesny PH, Mroszczyk KA, Lee RT, Patwari P, Grodzinsky AJ. 2015. Delivering heparin-binding insulin-like growth factor 1 with self-assembling peptide hydrogels. Tissue engineering. Part A. 21(3-4):637-46. Pubmed: 25231349 DOI:10.1089/ten.TEA.2013.0679 Heparin-binding insulin-like growth factor 1 (HB-IGF-1) is a fusion protein of IGF-1 with the HB domain of heparin-binding epidermal growth factor-like growth factor. A single dose of HB-IGF-1 has been shown to bind specifically to cartilage and to promote sustained upregulation of proteoglycan synthesis in cartilage explants. Achieving strong integration between native cartilage and tissue-engineered cartilage remains challenging. We hypothesize that if a growth factor delivered by the tissue engineering scaffold could stimulate enhanced matrix synthesis by both the cells within the scaffold and the adjacent native cartilage, integration could be enhanced. In this work, we investigated methods for adsorbing HB-IGF-1 to self-assembling peptide hydrogels to deliver the growth factor to encapsulated chondrocytes and cartilage explants cultured with growth factor-loaded hydrogels. We tested multiple methods for adsorbing HB-IGF-1 in self-assembling peptide hydrogels, including adsorption prior to peptide assembly, following peptide assembly, and with/without heparan sulfate (HS, a potential linker between peptide molecules and HB-IGF-1). We found that HB-IGF-1 and HS were retained in the peptide for all tested conditions. A subset of these conditions was then studied for their ability to stimulate increased matrix production by gel-encapsulated chondrocytes and by chondrocytes within adjacent native cartilage. Adsorbing HB-IGF-1 or IGF-1 prior to peptide assembly was found to stimulate increased sulfated glycosaminoglycan per DNA and hydroxyproline content of chondrocyte-seeded hydrogels compared with basal controls at day 10. Cartilage explants cultured adjacent to functionalized hydrogels had increased proteoglycan synthesis at day 10 when HB-IGF-1 was adsorbed, but not IGF-1. We conclude that delivery of HB-IGF-1 to focal defects in cartilage using self-assembling peptide hydrogels is a promising technique that could aid cartilage repair via enhanced matrix production and integration with native tissue. -
Qiao S, Dennis M, Song X, Vadysirisack DD, Salunke D, Nash Z, Yang Z, Liesa M, Yoshioka J, Matsuzawa S, Shirihai OS, Lee RT, Reed JC, Ellisen LW. 2015. A REDD1/TXNIP pro-oxidant complex regulates ATG4B activity to control stress-induced autophagy and sustain exercise capacity. Nature communications. 6:7014. Pubmed: 25916556 DOI:10.1038/ncomms8014 Qiao S, Dennis M, Song X, Vadysirisack DD, Salunke D, Nash Z, Yang Z, Liesa M, Yoshioka J, Matsuzawa S, Shirihai OS, Lee RT, Reed JC, Ellisen LW. 2015. A REDD1/TXNIP pro-oxidant complex regulates ATG4B activity to control stress-induced autophagy and sustain exercise capacity. Nature communications. 6:7014. Pubmed: 25916556 DOI:10.1038/ncomms8014 Macroautophagy (autophagy) is a critical cellular stress response; however, the signal transduction pathways controlling autophagy induction in response to stress are poorly understood. Here we reveal a new mechanism of autophagy control whose deregulation disrupts mitochondrial integrity and energy homeostasis in vivo. Stress conditions including hypoxia and exercise induce reactive oxygen species (ROS) through upregulation of a protein complex involving REDD1, an mTORC1 inhibitor and the pro-oxidant protein TXNIP. Decreased ROS in cells and tissues lacking either REDD1 or TXNIP increases catalytic activity of the redox-sensitive ATG4B cysteine endopeptidase, leading to enhanced LC3B delipidation and failed autophagy. Conversely, REDD1/TXNIP complex expression is sufficient to induce ROS, suppress ATG4B activity and activate autophagy. In Redd1(-/-) mice, deregulated ATG4B activity and disabled autophagic flux cause accumulation of defective mitochondria, leading to impaired oxidative phosphorylation, muscle ATP depletion and poor exercise capacity. Thus, ROS regulation through REDD1/TXNIP is physiological rheostat controlling stress-induced autophagy. -
O'Meara CC, Wamstad JA, Gladstone RA, Fomovsky GM, Butty VL, Shrikumar A, Gannon JB, Boyer LA, Lee RT. 2015. Transcriptional reversion of cardiac myocyte fate during mammalian cardiac regeneration. Circulation research. 116(5):804-15. Pubmed: 25477501 DOI:10.1161/CIRCRESAHA.116.304269 O'Meara CC, Wamstad JA, Gladstone RA, Fomovsky GM, Butty VL, Shrikumar A, Gannon JB, Boyer LA, Lee RT. 2015. Transcriptional reversion of cardiac myocyte fate during mammalian cardiac regeneration. Circulation research. 116(5):804-15. Pubmed: 25477501 DOI:10.1161/CIRCRESAHA.116.304269 Array© 2014 American Heart Association, Inc. -
O'Meara CC, Lee RT. 2015. Peering Into the Cardiomyocyte Nuclear Epigenetic State. Circulation research. 117(5):392-4. Pubmed: 26271534 DOI:10.1161/CIRCRESAHA.115.307093 O'Meara CC, Lee RT. 2015. Peering Into the Cardiomyocyte Nuclear Epigenetic State. Circulation research. 117(5):392-4. Pubmed: 26271534 DOI:10.1161/CIRCRESAHA.115.307093 -
Mahmoud AI, O'Meara CC, Gemberling M, Zhao L, Bryant DM, Zheng R, Gannon JB, Cai L, Choi WY, Egnaczyk GF, Burns CE, Burns CG, MacRae CA, Poss KD, Lee RT. 2015. Nerves Regulate Cardiomyocyte Proliferation and Heart Regeneration. Developmental cell. 34(4):387-99. Pubmed: 26256209 DOI:S1534-5807(15)00424-4 Mahmoud AI, O'Meara CC, Gemberling M, Zhao L, Bryant DM, Zheng R, Gannon JB, Cai L, Choi WY, Egnaczyk GF, Burns CE, Burns CG, MacRae CA, Poss KD, Lee RT. 2015. Nerves Regulate Cardiomyocyte Proliferation and Heart Regeneration. Developmental cell. 34(4):387-99. Pubmed: 26256209 DOI:S1534-5807(15)00424-4 Some organisms, such as adult zebrafish and newborn mice, have the capacity to regenerate heart tissue following injury. Unraveling the mechanisms of heart regeneration is fundamental to understanding why regeneration fails in adult humans. Numerous studies have revealed that nerves are crucial for organ regeneration, thus we aimed to determine whether nerves guide heart regeneration. Here, we show using transgenic zebrafish that inhibition of cardiac innervation leads to reduction of myocyte proliferation following injury. Specifically, pharmacological inhibition of cholinergic nerve function reduces cardiomyocyte proliferation in the injured hearts of both zebrafish and neonatal mice. Direct mechanical denervation impairs heart regeneration in neonatal mice, which was rescued by the administration of neuregulin 1 (NRG1) and nerve growth factor (NGF) recombinant proteins. Transcriptional analysis of mechanically denervated hearts revealed a blunted inflammatory and immune response following injury. These findings demonstrate that nerve function is required for both zebrafish and mouse heart regeneration.Copyright © 2015 Elsevier Inc. All rights reserved. 2014
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Loffredo FS, Pancoast JR, Cai L, Vannelli T, Dong JZ, Lee RT, Patwari P. 2014. Targeted delivery to cartilage is critical for in vivo efficacy of insulin-like growth factor 1 in a rat model of osteoarthritis. Arthritis & rheumatology (Hoboken, N.J.). 66(5):1247-55. Pubmed: 24470361 DOI:10.1002/art.38357 Loffredo FS, Pancoast JR, Cai L, Vannelli T, Dong JZ, Lee RT, Patwari P. 2014. Targeted delivery to cartilage is critical for in vivo efficacy of insulin-like growth factor 1 in a rat model of osteoarthritis. Arthritis & rheumatology (Hoboken, N.J.). 66(5):1247-55. Pubmed: 24470361 DOI:10.1002/art.38357 ArrayCopyright © 2014 by the American College of Rheumatology. -
Sadek HA, Martin JF, Takeuchi JK, Leor J, Nie Y, Giacca M, Lee RT. 2014. Multi-investigator letter on reproducibility of neonatal heart regeneration following apical resection. Stem cell reports. 3(1):1. Pubmed: 25068114 DOI:10.1016/j.stemcr.2014.06.009 Sadek HA, Martin JF, Takeuchi JK, Leor J, Nie Y, Giacca M, Lee RT. 2014. Multi-investigator letter on reproducibility of neonatal heart regeneration following apical resection. Stem cell reports. 3(1):1. Pubmed: 25068114 DOI:10.1016/j.stemcr.2014.06.009 -
Senyo SE, Lee RT, Kühn B. 2014. Cardiac regeneration based on mechanisms of cardiomyocyte proliferation and differentiation. Stem cell research. 13(3 Pt B):532-41. Pubmed: 25306390 DOI:S1873-5061(14)00105-6 Senyo SE, Lee RT, Kühn B. 2014. Cardiac regeneration based on mechanisms of cardiomyocyte proliferation and differentiation. Stem cell research. 13(3 Pt B):532-41. Pubmed: 25306390 DOI:S1873-5061(14)00105-6 Cardiomyocyte proliferation and progenitor differentiation are endogenous mechanisms of myocardial development. Cardiomyocytes continue to proliferate in mammals for part of post-natal development. In adult mammals under homeostatic conditions, cardiomyocytes proliferate at an extremely low rate. Because the mechanisms of cardiomyocyte generation provide potential targets for stimulating myocardial regeneration, a deep understanding is required for developing such strategies. We will discuss approaches for examining cardiomyocyte regeneration, review the specific advantages, challenges, and controversies, and recommend approaches for interpretation of results. We will also draw parallels between developmental and regenerative principles of these mechanisms and how they could be targeted for treating heart failure.Copyright © 2014. Published by Elsevier B.V. -
Sinha M, Jang YC, Oh J, Khong D, Wu EY, Manohar R, Miller C, Regalado SG, Loffredo FS, Pancoast JR, Hirshman MF, Lebowitz J, Shadrach JL, Cerletti M, Kim MJ, Serwold T, Goodyear LJ, Rosner B, Lee RT, Wagers AJ. 2014. Restoring systemic GDF11 levels reverses age-related dysfunction in mouse skeletal muscle. Science (New York, N.Y.). 344(6184):649-52. Pubmed: 24797481 DOI:10.1126/science.1251152 Sinha M, Jang YC, Oh J, Khong D, Wu EY, Manohar R, Miller C, Regalado SG, Loffredo FS, Pancoast JR, Hirshman MF, Lebowitz J, Shadrach JL, Cerletti M, Kim MJ, Serwold T, Goodyear LJ, Rosner B, Lee RT, Wagers AJ. 2014. Restoring systemic GDF11 levels reverses age-related dysfunction in mouse skeletal muscle. Science (New York, N.Y.). 344(6184):649-52. Pubmed: 24797481 DOI:10.1126/science.1251152 Parabiosis experiments indicate that impaired regeneration in aged mice is reversible by exposure to a young circulation, suggesting that young blood contains humoral "rejuvenating" factors that can restore regenerative function. Here, we demonstrate that the circulating protein growth differentiation factor 11 (GDF11) is a rejuvenating factor for skeletal muscle. Supplementation of systemic GDF11 levels, which normally decline with age, by heterochronic parabiosis or systemic delivery of recombinant protein, reversed functional impairments and restored genomic integrity in aged muscle stem cells (satellite cells). Increased GDF11 levels in aged mice also improved muscle structural and functional features and increased strength and endurance exercise capacity. These data indicate that GDF11 systemically regulates muscle aging and may be therapeutically useful for reversing age-related skeletal muscle and stem cell dysfunction. -
Zhao L, Borikova AL, Ben-Yair R, Guner-Ataman B, MacRae CA, Lee RT, Burns CG, Burns CE. 2014. Notch signaling regulates cardiomyocyte proliferation during zebrafish heart regeneration. Proceedings of the National Academy of Sciences of the United States of America. 111(4):1403-8. Pubmed: 24474765 DOI:10.1073/pnas.1311705111 Zhao L, Borikova AL, Ben-Yair R, Guner-Ataman B, MacRae CA, Lee RT, Burns CG, Burns CE. 2014. Notch signaling regulates cardiomyocyte proliferation during zebrafish heart regeneration. Proceedings of the National Academy of Sciences of the United States of America. 111(4):1403-8. Pubmed: 24474765 DOI:10.1073/pnas.1311705111 The human heart's failure to replace ischemia-damaged myocardium with regenerated muscle contributes significantly to the worldwide morbidity and mortality associated with coronary artery disease. Remarkably, certain vertebrate species, including the zebrafish, achieve complete regeneration of amputated or injured myocardium through the proliferation of spared cardiomyocytes. Nonetheless, the genetic and cellular determinants of natural cardiac regeneration remain incompletely characterized. Here, we report that cardiac regeneration in zebrafish relies on Notch signaling. Following amputation of the zebrafish ventricular apex, Notch receptor expression becomes activated specifically in the endocardium and epicardium, but not the myocardium. Using a dominant negative approach, we discovered that suppression of Notch signaling profoundly impairs cardiac regeneration and induces scar formation at the amputation site. We ruled out defects in endocardial activation, epicardial activation, and dedifferentiation of compact myocardial cells as causative for the regenerative failure. Furthermore, coronary endothelial tubes, which we lineage traced from preexisting endothelium in wild-type hearts, formed in the wound despite the myocardial regenerative failure. Quantification of myocardial proliferation in Notch-suppressed hearts revealed a significant decrease in cycling cardiomyocytes, an observation consistent with a noncell autonomous requirement for Notch signaling in cardiomyocyte proliferation. Unexpectedly, hyperactivation of Notch signaling also suppressed cardiomyocyte proliferation and heart regeneration. Taken together, our data uncover the exquisite sensitivity of regenerative cardiomyocyte proliferation to perturbations in Notch signaling. -
Lee S, Min Kim S, Dotimas J, Li L, Feener EP, Baldus S, Myers RB, Chutkow WA, Patwari P, Yoshioka J, Lee RT. 2014. Thioredoxin-interacting protein regulates protein disulfide isomerases and endoplasmic reticulum stress. EMBO molecular medicine. 6(6):732-43. Pubmed: 24843047 DOI:10.15252/emmm.201302561 Lee S, Min Kim S, Dotimas J, Li L, Feener EP, Baldus S, Myers RB, Chutkow WA, Patwari P, Yoshioka J, Lee RT. 2014. Thioredoxin-interacting protein regulates protein disulfide isomerases and endoplasmic reticulum stress. EMBO molecular medicine. 6(6):732-43. Pubmed: 24843047 DOI:10.15252/emmm.201302561 The endoplasmic reticulum (ER) is responsible for protein folding, modification, and trafficking. Accumulation of unfolded or misfolded proteins represents the condition of ER stress and triggers the unfolded protein response (UPR), a key mechanism linking supply of excess nutrients to insulin resistance and type 2 diabetes in obesity. The ER harbors proteins that participate in protein folding including protein disulfide isomerases (PDIs). Changes in PDI activity are associated with protein misfolding and ER stress. Here, we show that thioredoxin-interacting protein (Txnip), a member of the arrestin protein superfamily and one of the most strongly induced proteins in diabetic patients, regulates PDI activity and UPR signaling. We found that Txnip binds to PDIs and increases their enzymatic activity. Genetic deletion of Txnip in cells and mice led to increased protein ubiquitination and splicing of the UPR regulated transcription factor X-box-binding protein 1 (Xbp1s) at baseline as well as under ER stress. Our results reveal Txnip as a novel direct regulator of PDI activity and a feedback mechanism of UPR signaling to decrease ER stress.© 2014 Brigham and Women's Hospital. Published under the terms of the CC BY 4.0 license. -
Katsimpardi L, Litterman NK, Schein PA, Miller CM, Loffredo FS, Wojtkiewicz GR, Chen JW, Lee RT, Wagers AJ, Rubin LL. 2014. Vascular and neurogenic rejuvenation of the aging mouse brain by young systemic factors. Science (New York, N.Y.). 344(6184):630-4. Pubmed: 24797482 DOI:10.1126/science.1251141 Katsimpardi L, Litterman NK, Schein PA, Miller CM, Loffredo FS, Wojtkiewicz GR, Chen JW, Lee RT, Wagers AJ, Rubin LL. 2014. Vascular and neurogenic rejuvenation of the aging mouse brain by young systemic factors. Science (New York, N.Y.). 344(6184):630-4. Pubmed: 24797482 DOI:10.1126/science.1251141 In the adult central nervous system, the vasculature of the neurogenic niche regulates neural stem cell behavior by providing circulating and secreted factors. Age-related decline of neurogenesis and cognitive function is associated with reduced blood flow and decreased numbers of neural stem cells. Therefore, restoring the functionality of the niche should counteract some of the negative effects of aging. We show that factors found in young blood induce vascular remodeling, culminating in increased neurogenesis and improved olfactory discrimination in aging mice. Further, we show that GDF11 alone can improve the cerebral vasculature and enhance neurogenesis. The identification of factors that slow the age-dependent deterioration of the neurogenic niche in mice may constitute the basis for new methods of treating age-related neurodegenerative and neurovascular diseases. -
Yoshioka J, Lee RT. 2014. Thioredoxin-interacting protein and myocardial mitochondrial function in ischemia-reperfusion injury. Trends in cardiovascular medicine. 24(2):75-80. Pubmed: 23891554 DOI:S1050-1738(13)00101-1 Yoshioka J, Lee RT. 2014. Thioredoxin-interacting protein and myocardial mitochondrial function in ischemia-reperfusion injury. Trends in cardiovascular medicine. 24(2):75-80. Pubmed: 23891554 DOI:S1050-1738(13)00101-1 Cellular metabolism and reactive oxygen species (ROS) formation are interrelated processes in mitochondria and are implicated in a variety of human diseases including ischemic heart disease. During ischemia, mitochondrial respiration rates fall. Though seemingly paradoxical, reduced respiration has been observed to be cardioprotective due in part to reduced generation of ROS. Enhanced myocardial glucose uptake is considered beneficial for the myocardium under stress, as glucose is the primary substrate to support anaerobic metabolism. Thus, inhibition of mitochondrial respiration and uncoupling oxidative phosphorylation can protect the myocardium from irreversible ischemic damage. Growing evidence now positions the TXNIP/thioredoxin system at a nodal point linking pathways of antioxidant defense, cell survival, and energy metabolism. This emerging picture reveals TXNIP's function as a regulator of glucose homeostasis and may prove central to regulation of mitochondrial function during ischemia. In this review, we summarize how TXNIP and its binding partner thioredoxin act as regulators of mitochondrial metabolism. While the precise mechanism remains incompletely defined, the TXNIP-thioredoxin interaction has the potential to affect signaling that regulates mitochondrial bioenergetics and respiratory function with potential cardioprotection against ischemic injury.Copyright © 2013 Elsevier Inc. All rights reserved. -
Loffredo FS, Nikolova AP, Pancoast JR, Lee RT. 2014. Heart failure with preserved ejection fraction: molecular pathways of the aging myocardium. Circulation research. 115(1):97-107. Pubmed: 24951760 DOI:10.1161/CIRCRESAHA.115.302929 Loffredo FS, Nikolova AP, Pancoast JR, Lee RT. 2014. Heart failure with preserved ejection fraction: molecular pathways of the aging myocardium. Circulation research. 115(1):97-107. Pubmed: 24951760 DOI:10.1161/CIRCRESAHA.115.302929 Age-related diastolic dysfunction is a major factor in the epidemic of heart failure. In patients hospitalized with heart failure, HFpEF is now as common as heart failure with reduced ejection fraction. We now have many successful treatments for heart failure with reduced ejection fraction, while specific treatment options for HFpEF patients remain elusive. The lack of treatments for HFpEF reflects our very incomplete understanding of this constellation of diseases. There are many pathophysiological factors in HFpEF, but aging appears to play an important role. Here, we propose that aging of the myocardium is itself a specific pathophysiological process. New insights into the aging heart, including hormonal controls and specific molecular pathways, such as microRNAs, are pointing to myocardial aging as a potentially reversible process. While the overall process of aging remains mysterious, understanding the molecular pathways of myocardial aging has never been more important. Unraveling these pathways could lead to new therapies for the enormous and growing problem of HFpEF.© 2014 American Heart Association, Inc. 2013
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Steinhauser ML, Lee RT. 2013. Pericyte progenitors at the crossroads between fibrosis and regeneration. Circulation research. 112(2):230-2. Pubmed: 23329790 DOI:10.1161/CIRCRESAHA.111.300287 Steinhauser ML, Lee RT. 2013. Pericyte progenitors at the crossroads between fibrosis and regeneration. Circulation research. 112(2):230-2. Pubmed: 23329790 DOI:10.1161/CIRCRESAHA.111.300287 Tissue repair after injury is generally inversely related to the extent of scarring, suggesting the possibility that regeneration could be promoted by interventions that inhibit scar formation. New work by Dulauroy et al has identified a myofibroblast progenitor with pericyte characteristics as an important mediator of scarring in skin and skeletal muscle after injury. The genetic ablation of this lineage, which was identifiable by the expression of ADAM12, led to a dramatic reduction in scarring and more complete regeneration. This work sharpens the conceptual rationale for therapeutic targeting of soluble or cellular mediators of scarring to promote tissue regeneration. -
Klattenhoff CA, Scheuermann JC, Surface LE, Bradley RK, Fields PA, Steinhauser ML, Ding H, Butty VL, Torrey L, Haas S, Abo R, Tabebordbar M, Lee RT, Burge CB, Boyer LA. 2013. Braveheart, a long noncoding RNA required for cardiovascular lineage commitment. Cell. 152(3):570-83. Pubmed: 23352431 DOI:S0092-8674(13)00004-4 Klattenhoff CA, Scheuermann JC, Surface LE, Bradley RK, Fields PA, Steinhauser ML, Ding H, Butty VL, Torrey L, Haas S, Abo R, Tabebordbar M, Lee RT, Burge CB, Boyer LA. 2013. Braveheart, a long noncoding RNA required for cardiovascular lineage commitment. Cell. 152(3):570-83. Pubmed: 23352431 DOI:S0092-8674(13)00004-4 Long noncoding RNAs (lncRNAs) are often expressed in a development-specific manner, yet little is known about their roles in lineage commitment. Here, we identified Braveheart (Bvht), a heart-associated lncRNA in mouse. Using multiple embryonic stem cell (ESC) differentiation strategies, we show that Bvht is required for progression of nascent mesoderm toward a cardiac fate. We find that Bvht is necessary for activation of a core cardiovascular gene network and functions upstream of mesoderm posterior 1 (MesP1), a master regulator of a common multipotent cardiovascular progenitor. We also show that Bvht interacts with SUZ12, a component of polycomb-repressive complex 2 (PRC2), during cardiomyocyte differentiation, suggesting that Bvht mediates epigenetic regulation of cardiac commitment. Finally, we demonstrate a role for Bvht in maintaining cardiac fate in neonatal cardiomyocytes. Together, our work provides evidence for a long noncoding RNA with critical roles in the establishment of the cardiovascular lineage during mammalian development.Copyright © 2013 Elsevier Inc. All rights reserved. -
Jay SM, Murthy AC, Hawkins JF, Wortzel JR, Steinhauser ML, Alvarez LM, Gannon J, Macrae CA, Griffith LG, Lee RT. 2013. An engineered bivalent neuregulin protects against doxorubicin-induced cardiotoxicity with reduced proneoplastic potential. Circulation. 128(2):152-61. Pubmed: 23757312 DOI:10.1161/CIRCULATIONAHA.113.002203 Jay SM, Murthy AC, Hawkins JF, Wortzel JR, Steinhauser ML, Alvarez LM, Gannon J, Macrae CA, Griffith LG, Lee RT. 2013. An engineered bivalent neuregulin protects against doxorubicin-induced cardiotoxicity with reduced proneoplastic potential. Circulation. 128(2):152-61. Pubmed: 23757312 DOI:10.1161/CIRCULATIONAHA.113.002203 Array -
Jay SM, Lee RT. 2013. Protein engineering for cardiovascular therapeutics: untapped potential for cardiac repair. Circulation research. 113(7):933-43. Pubmed: 24030023 DOI:10.1161/CIRCRESAHA.113.300215 Jay SM, Lee RT. 2013. Protein engineering for cardiovascular therapeutics: untapped potential for cardiac repair. Circulation research. 113(7):933-43. Pubmed: 24030023 DOI:10.1161/CIRCRESAHA.113.300215 A number of new and innovative approaches for repairing damaged myocardium are currently undergoing investigation, with several encouraging results. In addition to the progression of stem cell-based approaches and gene therapy/silencing methods, evidence continues to emerge that protein therapeutics may be used to directly promote cardiac repair and even regeneration. However, proteins are often limited in their therapeutic potential by short local half-lives and insufficient bioavailability and bioactivity, and many academic laboratories studying cardiovascular diseases are more comfortable with molecular and cellular biology than with protein biochemistry. Protein engineering has been used broadly to overcome weaknesses traditionally associated with protein therapeutics and has the potential to specifically enhance the efficacy of molecules for cardiac repair. However, protein engineering as a strategy has not yet been used in the development of cardiovascular therapeutics to the degree that it has been used in other fields. In this review, we discuss the role of engineered proteins in cardiovascular therapies to date. Further, we address the promise of applying emerging protein engineering technologies to cardiovascular medicine and the barriers that must be overcome to enable the ultimate success of this approach. -
Senyo SE, Steinhauser ML, Pizzimenti CL, Yang VK, Cai L, Wang M, Wu TD, Guerquin-Kern JL, Lechene CP, Lee RT. 2013. Mammalian heart renewal by pre-existing cardiomyocytes. Nature. 493(7432):433-6. Pubmed: 23222518 DOI:10.1038/nature11682 Senyo SE, Steinhauser ML, Pizzimenti CL, Yang VK, Cai L, Wang M, Wu TD, Guerquin-Kern JL, Lechene CP, Lee RT. 2013. Mammalian heart renewal by pre-existing cardiomyocytes. Nature. 493(7432):433-6. Pubmed: 23222518 DOI:10.1038/nature11682 Although recent studies have revealed that heart cells are generated in adult mammals, the frequency of generation and the source of new heart cells are not yet known. Some studies suggest a high rate of stem cell activity with differentiation of progenitors to cardiomyocytes. Other studies suggest that new cardiomyocytes are born at a very low rate, and that they may be derived from the division of pre-existing cardiomyocytes. Here we show, by combining two different pulse-chase approaches--genetic fate-mapping with stable isotope labelling, and multi-isotope imaging mass spectrometry--that the genesis of cardiomyocytes occurs at a low rate by the division of pre-existing cardiomyocytes during normal ageing, a process that increases adjacent to areas of myocardial injury. We found that cell cycle activity during normal ageing and after injury led to polyploidy and multinucleation, but also to new diploid, mononucleate cardiomyocytes. These data reveal pre-existing cardiomyocytes as the dominant source of cardiomyocyte replacement in normal mammalian myocardial homeostasis as well as after myocardial injury. -
Lee S, Kim SM, Lee RT. 2013. Thioredoxin and thioredoxin target proteins: from molecular mechanisms to functional significance. Antioxidants & redox signaling. 18(10):1165-207. Pubmed: 22607099 DOI:10.1089/ars.2011.4322 Lee S, Kim SM, Lee RT. 2013. Thioredoxin and thioredoxin target proteins: from molecular mechanisms to functional significance. Antioxidants & redox signaling. 18(10):1165-207. Pubmed: 22607099 DOI:10.1089/ars.2011.4322 The thioredoxin (Trx) system is one of the central antioxidant systems in mammalian cells, maintaining a reducing environment by catalyzing electron flux from nicotinamide adenine dinucleotide phosphate through Trx reductase to Trx, which reduces its target proteins using highly conserved thiol groups. While the importance of protecting cells from the detrimental effects of reactive oxygen species is clear, decades of research in this field revealed that there is a network of redox-sensitive proteins forming redox-dependent signaling pathways that are crucial for fundamental cellular processes, including metabolism, proliferation, differentiation, migration, and apoptosis. Trx participates in signaling pathways interacting with different proteins to control their dynamic regulation of structure and function. In this review, we focus on Trx target proteins that are involved in redox-dependent signaling pathways. Specifically, Trx-dependent reductive enzymes that participate in classical redox reactions and redox-sensitive signaling molecules are discussed in greater detail. The latter are extensively discussed, as ongoing research unveils more and more details about the complex signaling networks of Trx-sensitive signaling molecules such as apoptosis signal-regulating kinase 1, Trx interacting protein, and phosphatase and tensin homolog, thus highlighting the potential direct and indirect impact of their redox-dependent interaction with Trx. Overall, the findings that are described here illustrate the importance and complexity of Trx-dependent, redox-sensitive signaling in the cell. Our increasing understanding of the components and mechanisms of these signaling pathways could lead to the identification of new potential targets for the treatment of diseases, including cancer and diabetes. -
Mummery CL, Lee RT. 2013. Is heart regeneration on the right track?. Nature medicine. 19(4):412-3. Pubmed: 23558629 DOI:10.1038/nm.3158 Mummery CL, Lee RT. 2013. Is heart regeneration on the right track?. Nature medicine. 19(4):412-3. Pubmed: 23558629 DOI:10.1038/nm.3158 -
Green EM, Lee RT. 2013. Proteins and small molecules for cellular regenerative medicine. Physiological reviews. 93(1):311-25. Pubmed: 23303911 DOI:10.1152/physrev.00005.2012 Green EM, Lee RT. 2013. Proteins and small molecules for cellular regenerative medicine. Physiological reviews. 93(1):311-25. Pubmed: 23303911 DOI:10.1152/physrev.00005.2012 Regenerative medicine seeks to understand tissue development and homeostasis and build on that knowledge to enhance regeneration of injured tissues. By replenishing lost functional tissues and cells, regenerative medicine could change the treatment paradigm for a broad range of degenerative and ischemic diseases. Multipotent cells hold promise as potential building blocks for regenerating lost tissues, but successful tissue regeneration will depend on comprehensive control of multipotent cells-differentiation into a target cell type, delivery to a desired tissue, and integration into a durable functional structure. At each step of this process, proteins and small molecules provide essential signals and, in some cases, may themselves act as effective therapies. Identifying these signals is thus a fundamental goal of regenerative medicine. In this review we discuss current progress using proteins and small molecules to regulate tissue regeneration, both in combination with cellular therapies and as monotherapy. -
Li W, Lee S, Ma M, Kim SM, Guye P, Pancoast JR, Anderson DG, Weiss R, Lee RT, Hammond PT. 2013. Microbead-based biomimetic synthetic neighbors enhance survival and function of rat pancreatic β-cells. Scientific reports. 3:2863. Pubmed: 24091640 DOI:10.1038/srep02863 Li W, Lee S, Ma M, Kim SM, Guye P, Pancoast JR, Anderson DG, Weiss R, Lee RT, Hammond PT. 2013. Microbead-based biomimetic synthetic neighbors enhance survival and function of rat pancreatic β-cells. Scientific reports. 3:2863. Pubmed: 24091640 DOI:10.1038/srep02863 Diabetes is caused by the loss or dysfunction of insulin-secreting β-cells in the pancreas. β-cells reduce their mass and lose insulin-producing ability in vitro, likely due to insufficient cell-cell and cell-extracellular matrix (ECM) interactions as β-cells lose their native microenvironment. Herein, we built an ex-vivo cell microenvironment by culturing primary β-cells in direct contact with 'synthetic neighbors', cell-sized soft polymer microbeads that were modified with cell-cell signaling factors as well as components from pancreatic-tissue-specific ECMs. This biomimetic 3D microenvironment was able to promote native cell-cell and cell-ECM interactions. We obtained sustained maintenance of β-cell function in vitro enhanced cell viability from the few days usually observed in 2D culture to periods exceeding three weeks, with enhanced β-cell stability and insulin production. Our approach can be extended to create a general 3D culture platform for other cell types. -
Loffredo FS, Steinhauser ML, Jay SM, Gannon J, Pancoast JR, Yalamanchi P, Sinha M, Dall'Osso C, Khong D, Shadrach JL, Miller CM, Singer BS, Stewart A, Psychogios N, Gerszten RE, Hartigan AJ, Kim MJ, Serwold T, Wagers AJ, Lee RT. 2013. Growth differentiation factor 11 is a circulating factor that reverses age-related cardiac hypertrophy. Cell. 153(4):828-39. Pubmed: 23663781 DOI:S0092-8674(13)00456-X Loffredo FS, Steinhauser ML, Jay SM, Gannon J, Pancoast JR, Yalamanchi P, Sinha M, Dall'Osso C, Khong D, Shadrach JL, Miller CM, Singer BS, Stewart A, Psychogios N, Gerszten RE, Hartigan AJ, Kim MJ, Serwold T, Wagers AJ, Lee RT. 2013. Growth differentiation factor 11 is a circulating factor that reverses age-related cardiac hypertrophy. Cell. 153(4):828-39. Pubmed: 23663781 DOI:S0092-8674(13)00456-X The most common form of heart failure occurs with normal systolic function and often involves cardiac hypertrophy in the elderly. To clarify the biological mechanisms that drive cardiac hypertrophy in aging, we tested the influence of circulating factors using heterochronic parabiosis, a surgical technique in which joining of animals of different ages leads to a shared circulation. After 4 weeks of exposure to the circulation of young mice, cardiac hypertrophy in old mice dramatically regressed, accompanied by reduced cardiomyocyte size and molecular remodeling. Reversal of age-related hypertrophy was not attributable to hemodynamic or behavioral effects of parabiosis, implicating a blood-borne factor. Using modified aptamer-based proteomics, we identified the TGF-β superfamily member GDF11 as a circulating factor in young mice that declines with age. Treatment of old mice to restore GDF11 to youthful levels recapitulated the effects of parabiosis and reversed age-related hypertrophy, revealing a therapeutic opportunity for cardiac aging.Copyright © 2013 Elsevier Inc. All rights reserved. -
Ho JE, Chen WY, Chen MH, Larson MG, McCabe EL, Cheng S, Ghorbani A, Coglianese E, Emilsson V, Johnson AD, Walter S, Franceschini N, O'Donnell CJ, Dehghan A, Lu C, Levy D, Newton-Cheh C, Lin H, Felix JF, Schreiter ER, Vasan RS, Januzzi JL, Lee RT, Wang TJ. 2013. Common genetic variation at the IL1RL1 locus regulates IL-33/ST2 signaling. The Journal of clinical investigation. 123(10):4208-18. Pubmed: 23999434 DOI:67119 Ho JE, Chen WY, Chen MH, Larson MG, McCabe EL, Cheng S, Ghorbani A, Coglianese E, Emilsson V, Johnson AD, Walter S, Franceschini N, O'Donnell CJ, Dehghan A, Lu C, Levy D, Newton-Cheh C, Lin H, Felix JF, Schreiter ER, Vasan RS, Januzzi JL, Lee RT, Wang TJ. 2013. Common genetic variation at the IL1RL1 locus regulates IL-33/ST2 signaling. The Journal of clinical investigation. 123(10):4208-18. Pubmed: 23999434 DOI:67119 The suppression of tumorigenicity 2/IL-33 (ST2/IL-33) pathway has been implicated in several immune and inflammatory diseases. ST2 is produced as 2 isoforms. The membrane-bound isoform (ST2L) induces an immune response when bound to its ligand, IL-33. The other isoform is a soluble protein (sST2) that is thought to be a decoy receptor for IL-33 signaling. Elevated sST2 levels in serum are associated with an increased risk for cardiovascular disease. We investigated the determinants of sST2 plasma concentrations in 2,991 Framingham Offspring Cohort participants. While clinical and environmental factors explained some variation in sST2 levels, much of the variation in sST2 production was driven by genetic factors. In a genome-wide association study (GWAS), multiple SNPs within IL1RL1 (the gene encoding ST2) demonstrated associations with sST2 concentrations. Five missense variants of IL1RL1 correlated with higher sST2 levels in the GWAS and mapped to the intracellular domain of ST2, which is absent in sST2. In a cell culture model, IL1RL1 missense variants increased sST2 expression by inducing IL-33 expression and enhancing IL-33 responsiveness (via ST2L). Our data suggest that genetic variation in IL1RL1 can result in increased levels of sST2 and alter immune and inflammatory signaling through the ST2/IL-33 pathway. -
Loffredo FS, Pancoast JR, Lee RT. 2013. Keep PNUTS in your heart. Circulation research. 113(2):97-9. Pubmed: 23833289 DOI:10.1161/CIRCRESAHA.113.301933 Loffredo FS, Pancoast JR, Lee RT. 2013. Keep PNUTS in your heart. Circulation research. 113(2):97-9. Pubmed: 23833289 DOI:10.1161/CIRCRESAHA.113.301933 Aging is a major factor in many cardiovascular diseases. The molecular factors that regulate age-related changes in cardiac physiology and contribute to the increased cardiovascular risk in the elderly are not fully understood. A study recently published in Nature suggests a specific role for microRNAs (miRNAs) in regulating cardiac aging and function, challenging the concept that aging is an inevitable process in the heart. -
Garbern JC, Lee RT. 2013. Cardiac stem cell therapy and the promise of heart regeneration. Cell stem cell. 12(6):689-98. Pubmed: 23746978 DOI:S1934-5909(13)00201-4 Garbern JC, Lee RT. 2013. Cardiac stem cell therapy and the promise of heart regeneration. Cell stem cell. 12(6):689-98. Pubmed: 23746978 DOI:S1934-5909(13)00201-4 Stem cell therapy for cardiac disease is an exciting but highly controversial research area. Strategies such as cell transplantation and reprogramming have demonstrated both intriguing and sobering results. Yet as clinical trials proceed, our incomplete understanding of stem cell behavior is made evident by numerous unresolved matters, such as the mechanisms of cardiomyocyte turnover or the optimal therapeutic strategies to achieve clinical efficacy. In this Perspective, we consider how cardiac stem cell biology has led us into clinical trials, and we suggest that achieving true cardiac regeneration in patients may ultimately require resolution of critical controversies in experimental cardiac regeneration.Copyright © 2013 Elsevier Inc. All rights reserved. -
Garbern JC, Mummery CL, Lee RT. 2013. Model systems for cardiovascular regenerative biology. Cold Spring Harbor perspectives in medicine. 3(4):a014019. Pubmed: 23545574 DOI:10.1101/cshperspect.a014019 Garbern JC, Mummery CL, Lee RT. 2013. Model systems for cardiovascular regenerative biology. Cold Spring Harbor perspectives in medicine. 3(4):a014019. Pubmed: 23545574 DOI:10.1101/cshperspect.a014019 There is an urgent clinical need to develop new therapeutic approaches to treat heart failure, but the biology of cardiovascular regeneration is complex. Model systems are required to advance our understanding of biological mechanisms of cardiac regeneration as well as to test therapeutic approaches to regenerate tissue and restore cardiac function following injury. An ideal model system should be inexpensive, easily manipulated, easily reproducible, physiologically representative of human disease, and ethically sound. In this review, we discuss computational, cell-based, tissue, and animal models that have been used to elucidate mechanisms of cardiovascular regenerative biology or to test proposed therapeutic methods to restore cardiac function following disease or injury. -
Zhang C, Jang S, Amadi OC, Shimizu K, Lee RT, Mitchell RN. 2013. A sensitive chemotaxis assay using a novel microfluidic device. BioMed research international. 2013:373569. Pubmed: 24151597 DOI:10.1155/2013/373569 Zhang C, Jang S, Amadi OC, Shimizu K, Lee RT, Mitchell RN. 2013. A sensitive chemotaxis assay using a novel microfluidic device. BioMed research international. 2013:373569. Pubmed: 24151597 DOI:10.1155/2013/373569 Existing chemotaxis assays do not generate stable chemotactic gradients and thus--over time--functionally measure only nonspecific random motion (chemokinesis). In comparison, microfluidic technology has the capacity to generate a tightly controlled microenvironment that can be stably maintained for extended periods of time and is, therefore, amenable to adaptation for assaying chemotaxis. We describe here a novel microfluidic device for sensitive assay of cellular migration and show its application for evaluating the chemotaxis of smooth muscle cells in a chemokine gradient. 2012
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Gottumukkala RV, Lv H, Cornivelli L, Wagers AJ, Kwong RY, Bronson R, Stewart GC, Schulze PC, Chutkow W, Wolpert HA, Lee RT, Lipes MA. 2012. Myocardial infarction triggers chronic cardiac autoimmunity in type 1 diabetes. Science translational medicine. 4(138):138ra80. Pubmed: 22700956 DOI:10.1126/scitranslmed.3003551 Gottumukkala RV, Lv H, Cornivelli L, Wagers AJ, Kwong RY, Bronson R, Stewart GC, Schulze PC, Chutkow W, Wolpert HA, Lee RT, Lipes MA. 2012. Myocardial infarction triggers chronic cardiac autoimmunity in type 1 diabetes. Science translational medicine. 4(138):138ra80. Pubmed: 22700956 DOI:10.1126/scitranslmed.3003551 Patients with type 1 diabetes (T1D) suffer excessive morbidity and mortality after myocardial infarction (MI) that is not fully explained by the metabolic effects of diabetes. Acute MI is known to trigger a profound innate inflammatory response with influx of mononuclear cells and production of proinflammatory cytokines that are crucial for cardiac repair. We hypothesized that these same pathways might exert "adjuvant effects" and induce pathological responses in autoimmune-prone T1D hosts. Here, we show that experimental MI in nonobese diabetic mice, but not in control C57BL/6 mice, results in a severe post-infarction autoimmune (PIA) syndrome characterized by destructive lymphocytic infiltrates in the myocardium, infarct expansion, sustained cardiac autoantibody production, and T helper type 1 effector cell responses against cardiac (α-)myosin. PIA was prevented by inducing tolerance to α-myosin, demonstrating that immune responses to cardiac myosin are essential for this disease process. Extending these findings to humans, we developed a panel of immunoassays for cardiac autoantibody detection and found autoantibody positivity in 83% post-MI T1D patients. We further identified shared cardiac myosin autoantibody signatures between post-MI T1D patients and nondiabetic patients with myocarditis, which were absent in post-MI type 2 diabetic patients, and confirmed the presence of myocarditis in T1D by cardiac magnetic resonance imaging techniques. These data provide experimental and clinical evidence for a distinct post-MI autoimmune syndrome in T1D. Our findings suggest that PIA may contribute to worsened post-MI outcomes in T1D and highlight a role for antigen-specific immunointervention to selectively block this pathway. -
Yoshioka J, Chutkow WA, Lee S, Kim JB, Yan J, Tian R, Lindsey ML, Feener EP, Seidman CE, Seidman JG, Lee RT. 2012. Deletion of thioredoxin-interacting protein in mice impairs mitochondrial function but protects the myocardium from ischemia-reperfusion injury. The Journal of clinical investigation. 122(1):267-79. Pubmed: 22201682 DOI:44927 Yoshioka J, Chutkow WA, Lee S, Kim JB, Yan J, Tian R, Lindsey ML, Feener EP, Seidman CE, Seidman JG, Lee RT. 2012. Deletion of thioredoxin-interacting protein in mice impairs mitochondrial function but protects the myocardium from ischemia-reperfusion injury. The Journal of clinical investigation. 122(1):267-79. Pubmed: 22201682 DOI:44927 Classic therapeutics for ischemic heart disease are less effective in individuals with the metabolic syndrome. As the prevalence of the metabolic syndrome is increasing, better understanding of cardiac metabolism is needed to identify potential new targets for therapeutic intervention. Thioredoxin-interacting protein (Txnip) is a regulator of metabolism and an inhibitor of the antioxidant thioredoxins, but little is known about its roles in the myocardium. We examined hearts from Txnip-KO mice by polony multiplex analysis of gene expression and an independent proteomic approach; both methods indicated suppression of genes and proteins participating in mitochondrial metabolism. Consistently, Txnip-KO mitochondria were functionally and structurally altered, showing reduced oxygen consumption and ultrastructural derangements. Given the central role that mitochondria play during hypoxia, we hypothesized that Txnip deletion would enhance ischemia-reperfusion damage. Surprisingly, Txnip-KO hearts had greater recovery of cardiac function after an ischemia-reperfusion insult. Similarly, cardiomyocyte-specific Txnip deletion reduced infarct size after reversible coronary ligation. Coordinated with reduced mitochondrial function, deletion of Txnip enhanced anaerobic glycolysis. Whereas mitochondrial ATP synthesis was minimally decreased by Txnip deletion, cellular ATP content and lactate formation were higher in Txnip-KO hearts after ischemia-reperfusion injury. Pharmacologic inhibition of glycolytic metabolism completely abolished the protection afforded the heart by Txnip deficiency under hypoxic conditions. Thus, although Txnip deletion suppresses mitochondrial function, protection from myocardial ischemia is enhanced as a result of a coordinated shift to enhanced anaerobic metabolism, which provides an energy source outside of mitochondria. -
Steinhauser ML, Bailey A, Senyo SE, Guillermier C, Perlstein TS, Gould AP, Lee RT, Lechene CP. 2012. Quantitating subcellular metabolism with multi-isotope imaging mass spectrometry. Nature. DOI:10.1038/nature10734. Steinhauser ML, Bailey A, Senyo SE, Guillermier C, Perlstein TS, Gould AP, Lee RT, Lechene CP. 2012. Quantitating subcellular metabolism with multi-isotope imaging mass spectrometry. Nature. DOI:10.1038/nature10734. Mass spectrometry with stable isotope labels has been seminal in discovering the dynamic state of living matter, but is limited to bulk tissues or cells. We developed multi-isotope imaging mass spectrometry (MIMS) that allowed us to view and measure stable isotope incorporation with submicrometre resolution. Here we apply MIMS to diverse organisms, including Drosophila, mice and humans. We test the 'immortal strand hypothesis', which predicts that during asymmetric stem cell division chromosomes containing older template DNA are segregated to the daughter destined to remain a stem cell, thus insuring lifetime genetic stability. After labelling mice with (15)N-thymidine from gestation until post-natal week 8, we find no (15)N label retention by dividing small intestinal crypt cells after a four-week chase. In adult mice administered (15)N-thymidine pulse-chase, we find that proliferating crypt cells dilute the (15)N label, consistent with random strand segregation. We demonstrate the broad utility of MIMS with proof-of-principle studies of lipid turnover in Drosophila and translation to the human haematopoietic system. These studies show that MIMS provides high-resolution quantification of stable isotope labels that cannot be obtained using other techniques and that is broadly applicable to biological and medical research. -
Chen WY, Lee RT. 2012. Endothelial cardiac cell therapy: large-animal studies and the elephant in the room. Circulation research. 111(7):824-6. Pubmed: 22982870 DOI:10.1161/CIRCRESAHA.112.278002 Chen WY, Lee RT. 2012. Endothelial cardiac cell therapy: large-animal studies and the elephant in the room. Circulation research. 111(7):824-6. Pubmed: 22982870 DOI:10.1161/CIRCRESAHA.112.278002 -
Steinhauser ML, Bailey AP, Senyo SE, Guillermier C, Perlstein TS, Gould AP, Lee RT, Lechene CP. 2012. Multi-isotope imaging mass spectrometry quantifies stem cell division and metabolism. Nature. 481(7382):516-9. Pubmed: 22246326 DOI:10.1038/nature10734 Steinhauser ML, Bailey AP, Senyo SE, Guillermier C, Perlstein TS, Gould AP, Lee RT, Lechene CP. 2012. Multi-isotope imaging mass spectrometry quantifies stem cell division and metabolism. Nature. 481(7382):516-9. Pubmed: 22246326 DOI:10.1038/nature10734 Mass spectrometry with stable isotope labels has been seminal in discovering the dynamic state of living matter, but is limited to bulk tissues or cells. We developed multi-isotope imaging mass spectrometry (MIMS) that allowed us to view and measure stable isotope incorporation with submicrometre resolution. Here we apply MIMS to diverse organisms, including Drosophila, mice and humans. We test the 'immortal strand hypothesis', which predicts that during asymmetric stem cell division chromosomes containing older template DNA are segregated to the daughter destined to remain a stem cell, thus insuring lifetime genetic stability. After labelling mice with (15)N-thymidine from gestation until post-natal week 8, we find no (15)N label retention by dividing small intestinal crypt cells after a four-week chase. In adult mice administered (15)N-thymidine pulse-chase, we find that proliferating crypt cells dilute the (15)N label, consistent with random strand segregation. We demonstrate the broad utility of MIMS with proof-of-principle studies of lipid turnover in Drosophila and translation to the human haematopoietic system. These studies show that MIMS provides high-resolution quantification of stable isotope labels that cannot be obtained using other techniques and that is broadly applicable to biological and medical research. -
Patwari P, Lee RT. 2012. An expanded family of arrestins regulate metabolism. Trends in endocrinology and metabolism: TEM. 23(5):216-22. Pubmed: 22520962 DOI:10.1016/j.tem.2012.03.003 Patwari P, Lee RT. 2012. An expanded family of arrestins regulate metabolism. Trends in endocrinology and metabolism: TEM. 23(5):216-22. Pubmed: 22520962 DOI:10.1016/j.tem.2012.03.003 The classical visual and β-arrestins belong to a larger family of proteins that likely share structural similarity. Humans have an additional six related proteins sometimes termed the α-arrestins, whose functions are now emerging. Surprisingly, several α-arrestins play prominent roles in the regulation of metabolism and obesity. One α-arrestin, thioredoxin-interacting protein (Txnip), has crucial functions in regulating glucose uptake and glycolytic flux through the mitochondria. Another α-arrestin, Arrdc3, is linked to obesity in men and was recently identified in mice as a regulator of body mass, adiposity, and energy expenditure. Here we discuss recent evidence suggesting potential common themes for all arrestins, including physiological roles for classical arrestins in metabolism and the functions of α-arrestins in receptor signaling and endocytosis.Copyright © 2012 Elsevier Ltd. All rights reserved. -
Kakkar R, Hei H, Dobner S, Lee RT. 2012. Interleukin 33 as a mechanically responsive cytokine secreted by living cells. The Journal of biological chemistry. 287(9):6941-8. Pubmed: 22215666 DOI:10.1074/jbc.M111.298703 Kakkar R, Hei H, Dobner S, Lee RT. 2012. Interleukin 33 as a mechanically responsive cytokine secreted by living cells. The Journal of biological chemistry. 287(9):6941-8. Pubmed: 22215666 DOI:10.1074/jbc.M111.298703 Interleukin 33 (IL-33), a member of the Interleukin 1 cytokine family, is implicated in numerous human inflammatory diseases such as asthma, atherosclerosis, and rheumatoid arthritis. Despite its pathophysiologic importance, fundamental questions regarding the basic biology of IL-33 remain. Nuclear localization and lack of an export signal sequence are consistent with the view of IL-33 as a nuclear factor with the ability to repress RNA transcription. However, signaling via the transmembrane receptor ST2 and documented caspase-dependent inactivation have suggested IL-33 is liberated during cellular necrosis to effect paracrine signaling. We determined the subcellular localization of IL-33 and tracked its intracellular mobility and extracellular release. In contrast to published data, IL-33 localized simultaneously to nuclear euchromatin and membrane-bound cytoplasmic vesicles. Fluorescent pulse-chase fate-tracking documented dynamic nucleo-cytoplasmic flux, which was dependent on nuclear pore complex function. In murine fibroblasts in vitro and in vivo, mechanical strain induced IL-33 secretion in the absence of cellular necrosis. These data document IL-33 dynamic inter-organelle trafficking and release during biomechanical overload. As such we recharacterize IL-33 as both an inflammatory as well as mechanically responsive cytokine secreted by living cells. -
Kaieda S, Wang JX, Shnayder R, Fishgal N, Hei H, Lee RT, Stevens RL, Nigrovic PA. 2012. Interleukin-33 primes mast cells for activation by IgG immune complexes. PloS one. 7(10):e47252. Pubmed: 23071771 DOI:10.1371/journal.pone.0047252 Kaieda S, Wang JX, Shnayder R, Fishgal N, Hei H, Lee RT, Stevens RL, Nigrovic PA. 2012. Interleukin-33 primes mast cells for activation by IgG immune complexes. PloS one. 7(10):e47252. Pubmed: 23071771 DOI:10.1371/journal.pone.0047252 Mast cells (MCs) are heterogeneous cells whose phenotype is modulated by signals received from the local microenvironment. Recent studies have identified the mesenchymal-derived cytokine IL-33 as a potent direct activator of MCs, as well as regulator of their effector phenotype, and have implicated this activity in the ability of mast cells to contribute to murine experimental arthritis. We explored the hypothesis that IL-33 enables participation of synovial MCs in murine K/BxN arthritis by promoting their activation by IgG immune complexes. Compared to wild-type (WT) control mice, transgenic animals lacking the IL-33 receptor ST2 exhibited impaired MC-dependent immune complex-induced vascular permeability (flare) and attenuated K/BxN arthritis. Whereas participation of MCs in this model is mediated by the activating IgG receptor FcγRIII, we pre-incubated bone marrow-derived MCs with IL-33 and found not only direct induction of cytokine release but also a marked increase in FcγRIII-driven production of critical arthritogenic mediators including IL-1β and CXCL2. This "priming" effect was associated with mRNA accumulation rather than altered expression of Fcγ receptors, could be mimicked by co-culture of WT but not ST2(-/-) MCs with synovial fibroblasts, and was blocked by antibodies against IL-33. In turn, WT but not ST2(-/-) MCs augmented fibroblast expression of IL-33, forming a positive feedback circuit. Together, these findings confirm a novel role for IL-33 as an amplifier of IgG immune complex-mediated inflammation and identify a potential MC-fibroblast amplification loop dependent on IL-33 and ST2. -
Kohli P, Bonaca MP, Kakkar R, Kudinova AY, Scirica BM, Sabatine MS, Murphy SA, Braunwald E, Lee RT, Morrow DA. 2012. Role of ST2 in non-ST-elevation acute coronary syndrome in the MERLIN-TIMI 36 trial. Clinical chemistry. 58(1):257-66. Pubmed: 22096031 DOI:10.1373/clinchem.2011.173369 Kohli P, Bonaca MP, Kakkar R, Kudinova AY, Scirica BM, Sabatine MS, Murphy SA, Braunwald E, Lee RT, Morrow DA. 2012. Role of ST2 in non-ST-elevation acute coronary syndrome in the MERLIN-TIMI 36 trial. Clinical chemistry. 58(1):257-66. Pubmed: 22096031 DOI:10.1373/clinchem.2011.173369 Array 2011
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Segers VF, Lee RT. 2011. Biomaterials to enhance stem cell function in the heart. Circulation research. 109(8):910-22. Pubmed: 21960724 DOI:10.1161/CIRCRESAHA.111.249052 Segers VF, Lee RT. 2011. Biomaterials to enhance stem cell function in the heart. Circulation research. 109(8):910-22. Pubmed: 21960724 DOI:10.1161/CIRCRESAHA.111.249052 Transplantation of stem cells into the heart can improve cardiac function after myocardial infarction and in chronic heart failure, but the extent of benefit and of reproducibility of this approach are insufficient. Survival of transplanted cells into myocardium is poor, and new strategies are needed to enhance stem cell differentiation and survival in vivo. In this review, we describe how biomaterials can enhance stem cell function in the heart. Biomaterials can mimic or include naturally occurring extracellular matrix and also instruct stem cell function in different ways. Biomaterials can promote angiogenesis, enhance engraftment and differentiation of stem cells, and accelerate electromechanical integration of transplanted stem cells. Biomaterials can also be used to deliver proteins, genes, or small RNAs together with stem cells. Furthermore, recent evidence indicates that the biophysical environment of stem cells is crucial for their proliferation and differentiation, as well as their electromechanical integration. Many approaches in regenerative medicine will likely ultimately require integration of molecularly designed biomaterials and stem cell biology to develop stable tissue regeneration. -
Steinhauser ML, Lee RT. 2011. Regeneration of the heart. EMBO molecular medicine. 3(12):701-12. Pubmed: 22095736 DOI:10.1002/emmm.201100175 Steinhauser ML, Lee RT. 2011. Regeneration of the heart. EMBO molecular medicine. 3(12):701-12. Pubmed: 22095736 DOI:10.1002/emmm.201100175 The death of cardiac myocytes diminishes the heart's pump function and is a major cause of heart failure, one of the dominant causes of death worldwide. Other than transplantation, there are no therapies that directly address the loss of cardiac myocytes, which explains the current excitement in cardiac regeneration. The field is evolving in two important directions. First, although endogenous mammalian cardiac regeneration clearly seems to decline rapidly after birth, it may still persist in adulthood. The careful elucidation of the cellular and molecular mechanisms of endogenous heart regeneration may therefore provide an opportunity for developing therapeutic interventions that amplify this process. Second, recent breakthroughs have enabled reprogramming of cells that were apparently terminally differentiated, either by dedifferentiation into pluripotent stem cells or by transdifferentiation into cardiac myocytes. These achievements challenge our conceptions of what is possible in terms of heart regeneration. In this review, we discuss the current status of research on cardiac regeneration, with a focus on the challenges that hold back therapeutic development.Copyright © 2011 EMBO Molecular Medicine. -
Patwari P, Emilsson V, Schadt EE, Chutkow WA, Lee S, Marsili A, Zhang Y, Dobrin R, Cohen DE, Larsen PR, Zavacki AM, Fong LG, Young SG, Lee RT. 2011. The arrestin domain-containing 3 protein regulates body mass and energy expenditure. Cell metabolism. 14(5):671-83. Pubmed: 21982743 DOI:10.1016/j.cmet.2011.08.011 Patwari P, Emilsson V, Schadt EE, Chutkow WA, Lee S, Marsili A, Zhang Y, Dobrin R, Cohen DE, Larsen PR, Zavacki AM, Fong LG, Young SG, Lee RT. 2011. The arrestin domain-containing 3 protein regulates body mass and energy expenditure. Cell metabolism. 14(5):671-83. Pubmed: 21982743 DOI:10.1016/j.cmet.2011.08.011 A human genome-wide linkage scan for obesity identified a linkage peak on chromosome 5q13-15. Positional cloning revealed an association of a rare haplotype to high body-mass index (BMI) in males but not females. The risk locus contains a single gene, "arrestin domain-containing 3" (ARRDC3), an uncharacterized α-arrestin. Inactivating Arrdc3 in mice led to a striking resistance to obesity, with greater impact on male mice. Mice with decreased ARRDC3 levels were protected from obesity due to increased energy expenditure through increased activity levels and increased thermogenesis of both brown and white adipose tissues. ARRDC3 interacted directly with β-adrenergic receptors, and loss of ARRDC3 increased the response to β-adrenergic stimulation in isolated adipose tissue. These results demonstrate that ARRDC3 is a gender-sensitive regulator of obesity and energy expenditure and reveal a surprising diversity for arrestin family protein functions.Copyright © 2011 Elsevier Inc. All rights reserved. -
Kanki S, Segers VF, Wu W, Kakkar R, Gannon J, Sys SU, Sandrasagra A, Lee RT. 2011. Stromal cell-derived factor-1 retention and cardioprotection for ischemic myocardium. Circulation. Heart failure. 4(4):509-18. Pubmed: 21606214 DOI:10.1161/CIRCHEARTFAILURE.110.960302 Kanki S, Segers VF, Wu W, Kakkar R, Gannon J, Sys SU, Sandrasagra A, Lee RT. 2011. Stromal cell-derived factor-1 retention and cardioprotection for ischemic myocardium. Circulation. Heart failure. 4(4):509-18. Pubmed: 21606214 DOI:10.1161/CIRCHEARTFAILURE.110.960302 Array -
Jay SM, Kurtagic E, Alvarez LM, de Picciotto S, Sanchez E, Hawkins JF, Prince RN, Guerrero Y, Treasure CL, Lee RT, Griffith LG. 2011. Engineered bivalent ligands to bias ErbB receptor-mediated signaling and phenotypes. The Journal of biological chemistry. 286(31):27729-40. Pubmed: 21622572 DOI:10.1074/jbc.M111.221093 Jay SM, Kurtagic E, Alvarez LM, de Picciotto S, Sanchez E, Hawkins JF, Prince RN, Guerrero Y, Treasure CL, Lee RT, Griffith LG. 2011. Engineered bivalent ligands to bias ErbB receptor-mediated signaling and phenotypes. The Journal of biological chemistry. 286(31):27729-40. Pubmed: 21622572 DOI:10.1074/jbc.M111.221093 The ErbB receptor family is dysregulated in many cancers, and its therapeutic manipulation by targeted antibodies and kinase inhibitors has resulted in effective chemotherapies. However, many malignancies remain refractory to current interventions. We describe a new approach that directs ErbB receptor interactions, resulting in biased signaling and phenotypes. Due to known receptor-ligand affinities and the necessity of ErbB receptors to dimerize to signal, bivalent ligands, formed by the synthetic linkage of two neuregulin-1β (NRG) moieties, two epidermal growth factor (EGF) moieties, or an EGF and a NRG moiety, can potentially drive homotypic receptor interactions and diminish formation of HER2-containing heterodimers, which are implicated in many malignancies and are a prevalent outcome of stimulation by native, monovalent EGF, or NRG. We demonstrate the therapeutic potential of this approach by showing that bivalent NRG (NN) can bias signaling in HER3-expressing cancer cells, resulting in some cases in decreased migration, inhibited proliferation, and increased apoptosis, whereas native NRG stimulation increased the malignant potential of the same cells. Hence, this new approach may have therapeutic relevance in ovarian, breast, lung, and other cancers in which HER3 has been implicated. -
Jay SM, Lee RT. 2011. Patching up the myocardium. Circulation research. 109(5):480-1. Pubmed: 21852553 DOI:10.1161/RES.0b013e31822dc619 Jay SM, Lee RT. 2011. Patching up the myocardium. Circulation research. 109(5):480-1. Pubmed: 21852553 DOI:10.1161/RES.0b013e31822dc619 -
Segers VF, Revin V, Wu W, Qiu H, Yan Z, Lee RT, Sandrasagra A. 2011. Protease-resistant stromal cell-derived factor-1 for the treatment of experimental peripheral artery disease. Circulation. 123(12):1306-15. Pubmed: 21403096 DOI:10.1161/CIRCULATIONAHA.110.991786 Segers VF, Revin V, Wu W, Qiu H, Yan Z, Lee RT, Sandrasagra A. 2011. Protease-resistant stromal cell-derived factor-1 for the treatment of experimental peripheral artery disease. Circulation. 123(12):1306-15. Pubmed: 21403096 DOI:10.1161/CIRCULATIONAHA.110.991786 Array -
Loffredo FS, Steinhauser ML, Gannon J, Lee RT. 2011. Bone marrow-derived cell therapy stimulates endogenous cardiomyocyte progenitors and promotes cardiac repair. Cell stem cell. 8(4):389-98. Pubmed: 21474103 DOI:10.1016/j.stem.2011.02.002 Loffredo FS, Steinhauser ML, Gannon J, Lee RT. 2011. Bone marrow-derived cell therapy stimulates endogenous cardiomyocyte progenitors and promotes cardiac repair. Cell stem cell. 8(4):389-98. Pubmed: 21474103 DOI:10.1016/j.stem.2011.02.002 Cell therapy can improve cardiac function in animals and humans after injury, but the mechanism is unclear. We performed cell therapy experiments in genetically engineered mice that permanently express green fluorescent protein (GFP) only in cardiomyocytes after a pulse of 4-OH-tamoxifen. Myocardial infarction diluted the GFP(+) cardiomyocyte pool, indicating refreshment by non-GFP(+) progenitors. Cell therapy with bone marrow-derived c-kit(+) cells, but not mesenchymal stem cells, further diluted the GFP(+) pool, consistent with c-kit(+) cell-mediated augmentation of cardiomyocyte progenitor activity. This effect could not be explained by transdifferentiation to cardiomyocytes by exogenously delivered c-kit(+) cells or by cell fusion. Therapy with c-kit(+) cells but not mesenchymal stem cells improved cardiac function. These findings suggest that stimulation of endogenous cardiogenic progenitor activity is a critical mechanism of cardiac cell therapy.Copyright © 2011 Elsevier Inc. All rights reserved. -
Kanki S, Jaalouk DE, Lee S, Yu AY, Gannon J, Lee RT. 2011. Identification of targeting peptides for ischemic myocardium by in vivo phage display. Journal of molecular and cellular cardiology. 50(5):841-8. Pubmed: 21316369 DOI:10.1016/j.yjmcc.2011.02.003 Kanki S, Jaalouk DE, Lee S, Yu AY, Gannon J, Lee RT. 2011. Identification of targeting peptides for ischemic myocardium by in vivo phage display. Journal of molecular and cellular cardiology. 50(5):841-8. Pubmed: 21316369 DOI:10.1016/j.yjmcc.2011.02.003 Therapies selectively targeting ischemic myocardium could be applied by intravenous injection. Here, we report an approach for ischemic tissue-selective targeting based on in vivo screening of random peptide sequences using phage display. We performed in vivo biopanning using a phage library in a rat model of ischemia-reperfusion and identified three peptide motifs, CSTSMLKAC, CKPGTSSYC, and CPDRSVNNC, that exhibited preferential binding to ischemic heart tissue compared to normal heart as well as other control organs. The CSTSMLKAC sequence was capable of mediating selective homing of phage to ischemic heart tissue. The CSTSMLKAC peptide was then made as a fusion protein with Sumo-mCherry and injected intravenously in a mouse model of myocardial ischemia-reperfusion injury; subsequently, bio-distribution of Sumo-mCherry-CSTSMLKAC was measured with quantitative ELISA. The targeting peptide led to a significant increase in homing to ischemic left ventricle compared to tissues from non-ischemic left ventricle, the right ventricle, lung, liver, spleen, skeletal muscle, and brain (all p<0.001). These results indicate that the peptide sequence CSTSMLKAC represents a novel molecular tool that may be useful in targeting ischemic tissue and delivering bioengineered proteins into the injured myocardium by systemic intravenous administration.Copyright © 2011 Elsevier Ltd. All rights reserved. -
Chutkow WA, Lee RT. 2011. Thioredoxin regulates adipogenesis through thioredoxin-interacting protein (Txnip) protein stability. The Journal of biological chemistry. 286(33):29139-29145. Pubmed: 21705327 DOI:S0021-9258(20)57458-9 Chutkow WA, Lee RT. 2011. Thioredoxin regulates adipogenesis through thioredoxin-interacting protein (Txnip) protein stability. The Journal of biological chemistry. 286(33):29139-29145. Pubmed: 21705327 DOI:S0021-9258(20)57458-9 Txnip (thioredoxin-interacting protein) is a critical mediator of metabolism and adipogenesis in vivo. The mechanisms of action of Txnip are believed to operate at least in part by inhibiting the redox signaling functions of thioredoxin. We tested here whether Txnip suppressed adipogenesis by inhibiting thioredoxin and discovered a reversal of roles; Txnip inhibits adipogenesis directly, and thioredoxin binding regulates Txnip by enhancing Txnip protein stability. Unlike Txnip, a Txnip mutant that cannot bind thioredoxin (C247S) did not prevent adipocyte differentiation, but was degraded more quickly by proteasomal targeting. Finding that endogenous Txnip protein is also rapidly degraded at the onset of adipogenesis suggested that Txnip degradation is required for adipocyte differentiation. Thioredoxin overexpression stabilized Txnip protein levels to inhibit adipogenesis, and adipogenic stimulants such as insulin promoted Txnip-thioredoxin dissociation to the more labile free Txnip state. As an α-arrestin protein, Txnip has two C-terminal tail PPXY motifs that mediate E3 ubiquitin ligase binding and Txnip protein stability. Mutating the PPXY motifs prevented Txnip degradation, even when thioredoxin binding was lost, and restored the ability of C247S Txnip to inhibit adipogenesis. These studies present a novel reconsideration of Txnip-thioredoxin signaling by showing that thioredoxin regulates the intrinsic function of Txnip as an inhibitor of adipogenesis through protein stabilization. -
Kakkar R, Lee RT. 2011. Directions from Hecate: towards a multi-marker approach for heart failure assessment. European journal of heart failure. 13(7):691-3. Pubmed: 21712290 DOI:10.1093/eurjhf/hfr059 Kakkar R, Lee RT. 2011. Directions from Hecate: towards a multi-marker approach for heart failure assessment. European journal of heart failure. 13(7):691-3. Pubmed: 21712290 DOI:10.1093/eurjhf/hfr059 2010
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Segers VF, Lee RT. 2010. Protein therapeutics for cardiac regeneration after myocardial infarction. Journal of cardiovascular translational research. 3(5):469-77. Pubmed: 20607468 DOI:10.1007/s12265-010-9207-5 Segers VF, Lee RT. 2010. Protein therapeutics for cardiac regeneration after myocardial infarction. Journal of cardiovascular translational research. 3(5):469-77. Pubmed: 20607468 DOI:10.1007/s12265-010-9207-5 Although most medicines have historically been small molecules, many newly approved drugs are derived from proteins. Protein therapies have been developed for treatment of diseases in almost every organ system, including the heart. Great excitement has now arisen in the field of regenerative medicine, particularly for cardiac regeneration after myocardial infarction. Every year, millions of people suffer from acute myocardial infarction, but the adult mammalian myocardium has limited regeneration potential. Regeneration of the heart after myocardium infarction is therefore an exciting target for protein therapeutics. In this review, we discuss different classes of proteins that have therapeutic potential to regenerate the heart after myocardial infarction. Protein candidates have been described that induce angiogenesis, including fibroblast growth factors and vascular endothelial growth factors, although thus far clinical development has been disappointing. Chemotactic factors that attract stem cells, e.g., hepatocyte growth factor and stromal cell-derived factor-1, may also be useful. Finally, neuregulins and periostin are proteins that induce cell-cycle reentry of cardiomyocytes, and growth factors like IGF-1 can induce growth and differentiation of stem cells. As our knowledge of the biology of regenerative processes and the role of specific proteins in these processes increases, the use of proteins as regenerative drugs could develop as a cardiac therapy. -
Prince RN, Schreiter ER, Zou P, Wiley HS, Ting AY, Lee RT, Lauffenburger DA. 2010. The heparin-binding domain of HB-EGF mediates localization to sites of cell-cell contact and prevents HB-EGF proteolytic release. Journal of cell science. 123(Pt 13):2308-18. Pubmed: 20530570 DOI:10.1242/jcs.058321 Prince RN, Schreiter ER, Zou P, Wiley HS, Ting AY, Lee RT, Lauffenburger DA. 2010. The heparin-binding domain of HB-EGF mediates localization to sites of cell-cell contact and prevents HB-EGF proteolytic release. Journal of cell science. 123(Pt 13):2308-18. Pubmed: 20530570 DOI:10.1242/jcs.058321 Heparin-binding EGF-like growth factor (HB-EGF) is a ligand for EGF receptor (EGFR) and possesses the ability to signal in juxtacrine, autocrine and/or paracrine mode, with these alternatives being governed by the degree of proteolytic release of the ligand. Although the spatial range of diffusion of released HB-EGF is restricted by binding heparan-sulfate proteoglycans (HSPGs) in the extracellular matrix and/or cellular glycocalyx, ascertaining mechanisms governing non-released HB-EGF localization is also important for understanding its effects. We have employed a new method for independently tracking the localization of the extracellular EGF-like domain of HB-EGF and the cytoplasmic C-terminus. A striking observation was the absence of the HB-EGF transmembrane pro-form from the leading edge of COS-7 cells in a wound-closure assay; instead, this protein localized in regions of cell-cell contact. A battery of detailed experiments found that this localization derives from a trans interaction between extracellular HSPGs and the HB-EGF heparin-binding domain, and that disruption of this interaction leads to increased release of soluble ligand and a switch in cell phenotype from juxtacrine-induced growth inhibition to autocrine-induced proliferation. Our results indicate that extracellular HSPGs serve to sequester the transmembrane pro-form of HB-EGF at the point of cell-cell contact, and that this plays a role in governing the balance between juxtacrine versus autocrine and paracrine signaling. -
Kakkar R, Lee RT. 2010. Intramyocardial fibroblast myocyte communication. Circulation research. 106(1):47-57. Pubmed: 20056945 DOI:10.1161/CIRCRESAHA.109.207456 Kakkar R, Lee RT. 2010. Intramyocardial fibroblast myocyte communication. Circulation research. 106(1):47-57. Pubmed: 20056945 DOI:10.1161/CIRCRESAHA.109.207456 Cardiac fibroblasts are emerging as key components of normal cardiac function, as well as the response to stressors and injury. These most numerous cells of the heart interact with myocytes via paracrine mechanisms, alterations in extracellular matrix homeostasis, and direct cell-cell interactions. It is possible that they are a contributor to the inability of adult myocytes to proliferate and may influence cardiac progenitor biology. Furthering our understanding of how cardiac fibroblasts and myocytes interact may provide an avenue to novel treatments for heart failure prevention. This review discusses the most recent concepts in cardiac fibroblast-myocyte communication and areas of potential future research. -
Lee S, Lee RT. 2010. Mechanical stretch and intimal hyperplasia: the missing link?. Arteriosclerosis, thrombosis, and vascular biology. 30(3):459-60. Pubmed: 20167664 DOI:10.1161/ATVBAHA.109.201509 Lee S, Lee RT. 2010. Mechanical stretch and intimal hyperplasia: the missing link?. Arteriosclerosis, thrombosis, and vascular biology. 30(3):459-60. Pubmed: 20167664 DOI:10.1161/ATVBAHA.109.201509 -
Kaieda S, Shin K, Nigrovic PA, Seki K, Lee RT, Stevens RL, Lee DM. 2010. Synovial fibroblasts promote the expression and granule accumulation of tryptase via interleukin-33 and its receptor ST-2 (IL1RL1). The Journal of biological chemistry. 285(28):21478-86. Pubmed: 20427273 DOI:10.1074/jbc.M110.114991 Kaieda S, Shin K, Nigrovic PA, Seki K, Lee RT, Stevens RL, Lee DM. 2010. Synovial fibroblasts promote the expression and granule accumulation of tryptase via interleukin-33 and its receptor ST-2 (IL1RL1). The Journal of biological chemistry. 285(28):21478-86. Pubmed: 20427273 DOI:10.1074/jbc.M110.114991 A characteristic feature of tissue resident human mast cells (MCs) is their hTryptase-beta-rich cytoplasmic granules. Mouse MC protease-6 (mMCP-6) is the ortholog of hTryptase-beta, and we have shown that this tetramer-forming tryptase has beneficial roles in innate immunity but adverse roles in inflammatory disorders like experimental arthritis. Because the key tissue factors that control tryptase expression in MCs have not been identified, we investigated the mechanisms by which fibroblasts mediate the expression and granule accumulation of mMCP-6. Immature mouse bone marrow-derived MCs (mBMMCs) co-cultured with fibroblast-like synoviocytes (FLS) or mouse 3T3 fibroblasts markedly increased their levels of mMCP-6. This effect was caused by an undefined soluble factor whose levels could be increased by exposing FLS to tumor necrosis factor-alpha or interleukin (IL)-1beta. Gene expression profiling of mBMMCs and FLS for receptor.ligand pairs of potential relevance raised the possibility that IL-33 was a sought after fibroblast-derived factor that promotes tryptase expression and granule maturation via its receptor IL1RL1/ST2. MCs lacking IL1RL1 exhibited defective fibroblast-driven tryptase accumulation, whereas recombinant IL-33 induced mMCP-6 mRNA and protein accumulation in wild-type mBMMCs. In agreement with these data, synovial MCs from IL1RL1-null mice exhibited a marked reduction in mMCP-6 expression. IL-33 is the first factor shown to modulate tryptase expression in MCs at the mRNA and protein levels. We therefore have identified a novel pathway by which mesenchymal cells exposed to inflammatory cytokines modulate the phenotype of local MCs to shape their immune responses. -
Chutkow WA, Birkenfeld AL, Brown JD, Lee HY, Frederick DW, Yoshioka J, Patwari P, Kursawe R, Cushman SW, Plutzky J, Shulman GI, Samuel VT, Lee RT. 2010. Deletion of the alpha-arrestin protein Txnip in mice promotes adiposity and adipogenesis while preserving insulin sensitivity. Diabetes. 59(6):1424-34. Pubmed: 20299477 DOI:10.2337/db09-1212 Chutkow WA, Birkenfeld AL, Brown JD, Lee HY, Frederick DW, Yoshioka J, Patwari P, Kursawe R, Cushman SW, Plutzky J, Shulman GI, Samuel VT, Lee RT. 2010. Deletion of the alpha-arrestin protein Txnip in mice promotes adiposity and adipogenesis while preserving insulin sensitivity. Diabetes. 59(6):1424-34. Pubmed: 20299477 DOI:10.2337/db09-1212 Array -
Miller RE, Grodzinsky AJ, Cummings K, Plaas AH, Cole AA, Lee RT, Patwari P. 2010. Intraarticular injection of heparin-binding insulin-like growth factor 1 sustains delivery of insulin-like growth factor 1 to cartilage through binding to chondroitin sulfate. Arthritis and rheumatism. 62(12):3686-94. Pubmed: 20722014 DOI:10.1002/art.27709 Miller RE, Grodzinsky AJ, Cummings K, Plaas AH, Cole AA, Lee RT, Patwari P. 2010. Intraarticular injection of heparin-binding insulin-like growth factor 1 sustains delivery of insulin-like growth factor 1 to cartilage through binding to chondroitin sulfate. Arthritis and rheumatism. 62(12):3686-94. Pubmed: 20722014 DOI:10.1002/art.27709 ArrayCopyright © 2010 by the American College of Rheumatology. -
Amadi OC, Steinhauser ML, Nishi Y, Chung S, Kamm RD, McMahon AP, Lee RT. 2010. A low resistance microfluidic system for the creation of stable concentration gradients in a defined 3D microenvironment. Biomedical microdevices. 12(6):1027-41. Pubmed: 20661647 DOI:10.1007/s10544-010-9457-7 Amadi OC, Steinhauser ML, Nishi Y, Chung S, Kamm RD, McMahon AP, Lee RT. 2010. A low resistance microfluidic system for the creation of stable concentration gradients in a defined 3D microenvironment. Biomedical microdevices. 12(6):1027-41. Pubmed: 20661647 DOI:10.1007/s10544-010-9457-7 The advent of microfluidic technology allows control and interrogation of cell behavior by defining the local microenvironment with an assortment of biochemical and biophysical stimuli. Many approaches have been developed to create gradients of soluble factors, but the complexity of such systems or their inability to create defined and controllable chemical gradients has limited their widespread implementation. Here we describe a new microfluidic device which employs a parallel arrangement of wells and channels to create stable, linear concentration gradients in a gel region between a source and a sink well. Pressure gradients between the source and sink wells are dissipated through low resistance channels in parallel with the gel channel, thus minimizing the convection of solute in this region. We demonstrate the ability of the new device to quantitate chemotactic responses in a variety of cell types, yielding a complete profile of the migratory response and representing the total number of migrating cells and the distance each cell has migrated. Additionally we show the effect of concentration gradients of the morphogen Sonic hedgehog on the specification of differentiating neural progenitors in a 3-dimensional matrix. 2009
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Huang H, Macgillivray C, Kwon HS, Lammerding J, Robbins J, Lee RT, So P. 2009. Three-dimensional cardiac architecture determined by two-photon microtomy. Journal of biomedical optics. 14(4):044029. Pubmed: 19725740 DOI:10.1117/1.3200939 Huang H, Macgillivray C, Kwon HS, Lammerding J, Robbins J, Lee RT, So P. 2009. Three-dimensional cardiac architecture determined by two-photon microtomy. Journal of biomedical optics. 14(4):044029. Pubmed: 19725740 DOI:10.1117/1.3200939 Cardiac architecture is inherently three-dimensional, yet most characterizations rely on two-dimensional histological slices or dissociated cells, which remove the native geometry of the heart. We previously developed a method for labeling intact heart sections without dissociation and imaging large volumes while preserving their three-dimensional structure. We further refine this method to permit quantitative analysis of imaged sections. After data acquisition, these sections are assembled using image-processing tools, and qualitative and quantitative information is extracted. By examining the reconstructed cardiac blocks, one can observe end-to-end adjacent cardiac myocytes (cardiac strands) changing cross-sectional geometries, merging and separating from other strands. Quantitatively, representative cross-sectional areas typically used for determining hypertrophy omit the three-dimensional component; we show that taking orientation into account can significantly alter the analysis. Using fast-Fourier transform analysis, we analyze the gross organization of cardiac strands in three dimensions. By characterizing cardiac structure in three dimensions, we are able to determine that the alpha crystallin mutation leads to hypertrophy with cross-sectional area increases, but not necessarily via changes in fiber orientation distribution. -
Murry CE, Lee RT. 2009. Development biology. Turnover after the fallout. Science (New York, N.Y.). 324(5923):47-8. Pubmed: 19342577 DOI:10.1126/science.1172255 Murry CE, Lee RT. 2009. Development biology. Turnover after the fallout. Science (New York, N.Y.). 324(5923):47-8. Pubmed: 19342577 DOI:10.1126/science.1172255 -
Chan SS, Chen JH, Hwang SM, Wang IJ, Li HJ, Lee RT, Hsieh PC. 2009. Salvianolic acid B-vitamin C synergy in cardiac differentiation from embryonic stem cells. Biochemical and biophysical research communications. 387(4):723-8. Pubmed: 19643081 DOI:10.1016/j.bbrc.2009.07.122 Chan SS, Chen JH, Hwang SM, Wang IJ, Li HJ, Lee RT, Hsieh PC. 2009. Salvianolic acid B-vitamin C synergy in cardiac differentiation from embryonic stem cells. Biochemical and biophysical research communications. 387(4):723-8. Pubmed: 19643081 DOI:10.1016/j.bbrc.2009.07.122 Inefficient cardiomyocyte differentiation limits the therapeutic use of embryonic stem (ES) cell-derived cardiomyocytes. While large collections of proprietary chemicals had been screened to improve ES cell differentiation into cardiomyocytes, the natural product library remained unexplored. Using a mouse ES cell line transfected with a cardiomyocyte-specific alpha-myosin heavy chain promoter-driven enhanced green fluorescent protein (EGFP) reporter, we screened 24 natural products with known cardioprotective actions. Salvianolic acid B (saB), while produced minimal effect on its own, concentration-dependently synergized with vitamin C in inducing cardiomyocyte differentiation, as demonstrated by an increase in EGFP(+) cells, beating area in embryoid bodies, and expression of cardiomyocyte maturity markers. This synergy is specific to cardiomyocyte differentiation, and is involved with collagen synthesis. The present study demonstrates the saB-vitamin C synergy in inducing ES cell differentiation into matured and functional cardiomyocytes, and this may lead to a practicable cocktail approach to generate ES cell-derived cardiomyocytes for cardiac stem cell therapy. -
Patwari P, Chutkow WA, Cummings K, Verstraeten VL, Lammerding J, Schreiter ER, Lee RT. 2009. Thioredoxin-independent regulation of metabolism by the alpha-arrestin proteins. The Journal of biological chemistry. 284(37):24996-5003. Pubmed: 19605364 DOI:10.1074/jbc.M109.018093 Patwari P, Chutkow WA, Cummings K, Verstraeten VL, Lammerding J, Schreiter ER, Lee RT. 2009. Thioredoxin-independent regulation of metabolism by the alpha-arrestin proteins. The Journal of biological chemistry. 284(37):24996-5003. Pubmed: 19605364 DOI:10.1074/jbc.M109.018093 Thioredoxin-interacting protein (Txnip), originally characterized as an inhibitor of thioredoxin, is now known to be a critical regulator of glucose metabolism in vivo. Txnip is a member of the alpha-arrestin protein family; the alpha-arrestins are related to the classical beta-arrestins and visual arrestins. Txnip is the only alpha-arrestin known to bind thioredoxin, and it is not known whether the metabolic effects of Txnip are related to its ability to bind thioredoxin or related to conserved alpha-arrestin function. Here we show that wild type Txnip and Txnip C247S, a Txnip mutant that does not bind thioredoxin in vitro, both inhibit glucose uptake in mature adipocytes and in primary skin fibroblasts. Furthermore, we show that Txnip C247S does not bind thioredoxin in cells, using thiol alkylation to trap the Txnip-thioredoxin complex. Because Txnip function was independent of thioredoxin binding, we tested whether inhibition of glucose uptake was conserved in the related alpha-arrestins Arrdc4 and Arrdc3. Both Txnip and Arrdc4 inhibited glucose uptake and lactate output, while Arrdc3 had no effect. Structure-function analysis indicated that Txnip and Arrdc4 inhibit glucose uptake independent of the C-terminal WW-domain binding motifs, recently identified as important in yeast alpha-arrestins. Instead, regulation of glucose uptake was intrinsic to the arrestin domains themselves. These data demonstrate that Txnip regulates cellular metabolism independent of its binding to thioredoxin and reveal the arrestin domains as crucial structural elements in metabolic functions of alpha-arrestin proteins. -
Padin-Iruegas ME, Misao Y, Davis ME, Segers VF, Esposito G, Tokunou T, Urbanek K, Hosoda T, Rota M, Anversa P, Leri A, Lee RT, Kajstura J. 2009. Cardiac progenitor cells and biotinylated insulin-like growth factor-1 nanofibers improve endogenous and exogenous myocardial regeneration after infarction. Circulation. 120(10):876-87. Pubmed: 19704095 DOI:10.1161/CIRCULATIONAHA.109.852285 Padin-Iruegas ME, Misao Y, Davis ME, Segers VF, Esposito G, Tokunou T, Urbanek K, Hosoda T, Rota M, Anversa P, Leri A, Lee RT, Kajstura J. 2009. Cardiac progenitor cells and biotinylated insulin-like growth factor-1 nanofibers improve endogenous and exogenous myocardial regeneration after infarction. Circulation. 120(10):876-87. Pubmed: 19704095 DOI:10.1161/CIRCULATIONAHA.109.852285 Array -
Kuhn E, Addona T, Keshishian H, Burgess M, Mani DR, Lee RT, Sabatine MS, Gerszten RE, Carr SA. 2009. Developing multiplexed assays for troponin I and interleukin-33 in plasma by peptide immunoaffinity enrichment and targeted mass spectrometry. Clinical chemistry. 55(6):1108-17. Pubmed: 19372185 DOI:10.1373/clinchem.2009.123935 Kuhn E, Addona T, Keshishian H, Burgess M, Mani DR, Lee RT, Sabatine MS, Gerszten RE, Carr SA. 2009. Developing multiplexed assays for troponin I and interleukin-33 in plasma by peptide immunoaffinity enrichment and targeted mass spectrometry. Clinical chemistry. 55(6):1108-17. Pubmed: 19372185 DOI:10.1373/clinchem.2009.123935 Array -
Kakkar R, Lee RT. 2009. ST2 and adrenomedullin in heart failure. Heart failure clinics. 5(4):515-27. Pubmed: 19631176 DOI:10.1016/j.hfc.2009.04.009 Kakkar R, Lee RT. 2009. ST2 and adrenomedullin in heart failure. Heart failure clinics. 5(4):515-27. Pubmed: 19631176 DOI:10.1016/j.hfc.2009.04.009 ST2 is the receptor for interleukin-33, a cytokine with antihypertrophic and antifibrotic effects on the myocardium. Serum levels of the soluble form of ST2 serve as a biomarker for ventricular biomechanical strain and provide prognostic information in patients who have symptomatic heart failure. Adrenomedullin is a vasoactive peptide whose actions run counter to the physiologic derangements of clinical heart failure. It appears that measurements of serum adrenomedullin levels can be used to identify those patients who have advanced heart failure and who are at increased risk for heart failure-related death. -
Steinhauser ML, Lee RT. 2009. Cardiovascular regeneration: pushing and pulling on progenitors. Cell stem cell. 4(4):277-8. Pubmed: 19341614 DOI:10.1016/j.stem.2009.03.008 Steinhauser ML, Lee RT. 2009. Cardiovascular regeneration: pushing and pulling on progenitors. Cell stem cell. 4(4):277-8. Pubmed: 19341614 DOI:10.1016/j.stem.2009.03.008 In this issue of Cell Stem Cell, Zaruba et al. (2009) describe a pharmacoregenerative strategy for myocardial infarction. Using G-CSF to release progenitors from bone marrow and protease inhibition to prevent degradation of the homing signal, SDF-1, the authors achieve increased recruitment to the heart and improved heart function. -
Seki K, Sanada S, Kudinova AY, Steinhauser ML, Handa V, Gannon J, Lee RT. 2009. Interleukin-33 prevents apoptosis and improves survival after experimental myocardial infarction through ST2 signaling. Circulation. Heart failure. 2(6):684-91. Pubmed: 19919994 DOI:10.1161/CIRCHEARTFAILURE.109.873240 Seki K, Sanada S, Kudinova AY, Steinhauser ML, Handa V, Gannon J, Lee RT. 2009. Interleukin-33 prevents apoptosis and improves survival after experimental myocardial infarction through ST2 signaling. Circulation. Heart failure. 2(6):684-91. Pubmed: 19919994 DOI:10.1161/CIRCHEARTFAILURE.109.873240 Array -
Lammerding J, Lee RT. 2009. Mechanical properties of interphase nuclei probed by cellular strain application. Methods in molecular biology (Clifton, N.J.). 464:13-26. Pubmed: 18951177 DOI:10.1007/978-1-60327-461-6_2 Lammerding J, Lee RT. 2009. Mechanical properties of interphase nuclei probed by cellular strain application. Methods in molecular biology (Clifton, N.J.). 464:13-26. Pubmed: 18951177 DOI:10.1007/978-1-60327-461-6_2 The mechanical properties of the interphase nucleus have important implications for cellular function and can reflect changes in nuclear envelope structure and/or chromatin organization. Mutations in the nuclear envelope proteins lamin A and C cause several human diseases, such as Emery-Dreifuss muscular dystrophy, and dramatic changes in nuclear stiffness have been reported in cells from lamin A/C-deficient mice. We have developed a cellular strain technique to measure nuclear stiffness in intact, adherent cells and have applied this experimental method to fibroblasts from mouse models of Emery-Dreifuss muscular dystrophy and to skin fibroblasts from laminopathy patients and healthy control subjects. The experimental protocol is based on measuring induced nuclear deformations in cells plated on a flexible silicone substrate; the nuclear stiffness can subsequently be inferred from the ratio of induced nuclear strain to the applied membrane strain. These experiments reveal that lamins A and C are important determinants of nuclear stiffness and that lamin mutations associated with muscular dystrophies and other laminopathies often result in disturbed nuclear stiffness that could contribute to the tissue-specific disease phenotypes. -
Deguchi JO, Huang H, Libby P, Aikawa E, Whittaker P, Sylvan J, Lee RT, Aikawa M. 2009. Genetically engineered resistance for MMP collagenases promotes abdominal aortic aneurysm formation in mice infused with angiotensin II. Laboratory investigation; a journal of technical methods and pathology. 89(3):315-26. Pubmed: 19153555 DOI:10.1038/labinvest.2008.167 Deguchi JO, Huang H, Libby P, Aikawa E, Whittaker P, Sylvan J, Lee RT, Aikawa M. 2009. Genetically engineered resistance for MMP collagenases promotes abdominal aortic aneurysm formation in mice infused with angiotensin II. Laboratory investigation; a journal of technical methods and pathology. 89(3):315-26. Pubmed: 19153555 DOI:10.1038/labinvest.2008.167 Clinical evidence links increased aortic collagen content and stiffness to abdominal aortic aneurysm (AAA) formation. However, the possibility that excess collagen contributes to AAA formation remains untested. We investigated the hypothesis that augmented collagen promotes AAA formation, and employed apoE-null mice expressing collagenase-resistant mutant collagen (Col(R/R)/apoE(-/-)), heterozygote (Col(R/+)/apoE(-/-)), or wild-type collagen (Col(+/+)/apoE(-/-)) infused with angiotensin II to induce AAA. As expected, the aortas of Col(R/R)/apoE(-/-) mice contained more interstitial collagen than those from the other groups. Angiotensin II treatment elicited more AAA formation in Col(R/R)/apoE(-/-) mice than Col(R/+)/apoE(-/-) or Col(+/+)/apoE(-/-) mice. Aortic circumferences correlated positively with collagen content, determined by picrosirius red and Masson trichrome staining. Mechanical testing of aortas of Col(R/R)/apoE(-/-) mice showed increased stiffness and susceptibility to mechanical failure compared to those of Col(+/+)/apoE(-/-) mice. Optical analysis further indicated altered collagen fiber orientation in the adventitia of Col(R/R)/apoE(-/-) mice. These results demonstrate that collagen content regulates aortic biomechanical properties and influences AAA formation. -
Maloyan A, Osinska H, Lammerding J, Lee RT, Cingolani OH, Kass DA, Lorenz JN, Robbins J. 2009. Biochemical and mechanical dysfunction in a mouse model of desmin-related myopathy. Circulation research. 104(8):1021-8. Pubmed: 19299643 DOI:10.1161/CIRCRESAHA.108.193516 Maloyan A, Osinska H, Lammerding J, Lee RT, Cingolani OH, Kass DA, Lorenz JN, Robbins J. 2009. Biochemical and mechanical dysfunction in a mouse model of desmin-related myopathy. Circulation research. 104(8):1021-8. Pubmed: 19299643 DOI:10.1161/CIRCRESAHA.108.193516 An R120G mutation in alphaB-crystallin (CryAB(R120G)) causes desmin-related myopathy (DRM). In mice with cardiomyocyte-specific expression of the mutation, CryAB(R120G)-mediated DRM is characterized by CryAB and desmin accumulations within cardiac muscle, mitochondrial deficiencies, activation of apoptosis, and heart failure (HF). Excessive production of reactive oxygen species (ROS) is often a hallmark of HF and treatment with antioxidants can sometimes prevent the progression of HF in terms of contractile dysfunction and cardiomyocyte survival. It is unknown whether blockade of ROS is beneficial for protein misfolding diseases such as DRM. We addressed this question by blocking the activity of xanthine oxidase (XO), a superoxide-generating enzyme that is upregulated in our model of DRM. The XO inhibitor oxypurinol was administered to CryAB(R120G) mice for a period of 1 or 3 months. Mitochondrial function was dramatically improved in treated animals in terms of complex I activity and conservation of mitochondrial membrane potential. Oxypurinol also largely restored normal mitochondrial morphology. Surprisingly, however, cardiac contractile function and cardiac compliance were unimproved, indicating that the contractile deficit might be independent of mitochondrial dysfunction and the initiation of apoptosis. Using magnetic bead microrheology at the single cardiomyocyte level, we demonstrated that sarcomeric disarray and accumulation of the physical aggregates resulted in significant changes in the cytoskeletal mechanical properties in the CryAB(R120G) cardiomyocytes. Our findings indicate that oxypurinol treatment largely prevented mitochondrial deficiency in DRM but that contractility was not improved because of mechanical deficits in passive cytoskeletal stiffness. 2008
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Verstraeten VL, Ji JY, Cummings KS, Lee RT, Lammerding J. 2008. Increased mechanosensitivity and nuclear stiffness in Hutchinson-Gilford progeria cells: effects of farnesyltransferase inhibitors. Aging cell. 7(3):383-93. Pubmed: 18331619 DOI:10.1111/j.1474-9726.2008.00382.x Verstraeten VL, Ji JY, Cummings KS, Lee RT, Lammerding J. 2008. Increased mechanosensitivity and nuclear stiffness in Hutchinson-Gilford progeria cells: effects of farnesyltransferase inhibitors. Aging cell. 7(3):383-93. Pubmed: 18331619 DOI:10.1111/j.1474-9726.2008.00382.x Hutchinson-Gilford progeria syndrome (HGPS), reportedly a model for normal aging, is a genetic disorder in children marked by dramatic signs suggestive for premature aging. It is usually caused by de novo mutations in the nuclear envelope protein lamin A. Lamins are essential to maintaining nuclear integrity, and loss of lamin A/C results in increased cellular sensitivity to mechanical strain and defective mechanotransduction signaling. Since increased mechanical sensitivity in vascular cells could contribute to loss of smooth muscle cells and the development of arteriosclerosis--the leading cause of death in HGPS patients--we investigated the effect of mechanical stress on cells from HGPS patients. We found that skin fibroblasts from HGPS patients developed progressively stiffer nuclei with increasing passage number. Importantly, fibroblasts from HGPS patients had decreased viability and increased apoptosis under repetitive mechanical strain, as well as attenuated wound healing, and these defects preceded changes in nuclear stiffness. Treating fibroblasts with farnesyltransferase inhibitors restored nuclear stiffness in HGPS cells and accelerated the wound healing response in HGPS and healthy control cells by increasing the directional persistence of migrating cells. However, farnesyltransferase inhibitors did not improve cellular sensitivity to mechanical strain. These data suggest that increased mechanical sensitivity in HGPS cells is unrelated to changes in nuclear stiffness and that increased biomechanical sensitivity could provide a potential mechanism for the progressive loss of vascular smooth muscle cells under physiological strain in HGPS patients. -
Chutkow WA, Patwari P, Yoshioka J, Lee RT. 2008. Thioredoxin-interacting protein (Txnip) is a critical regulator of hepatic glucose production. The Journal of biological chemistry. 283(4):2397-406. Pubmed: 17998203 Chutkow WA, Patwari P, Yoshioka J, Lee RT. 2008. Thioredoxin-interacting protein (Txnip) is a critical regulator of hepatic glucose production. The Journal of biological chemistry. 283(4):2397-406. Pubmed: 17998203 Thioredoxin-interacting protein (Txnip) has been recently described as a possible link between cellular redox state and metabolism; Txnip binds thioredoxin and inhibits its disulfide reductase activity in vitro, while a naturally occurring strain of Txnip-deficient mice has hyperlipidemia, hypoglycemia, and ketosis exacerbated by fasting. We generated Txnip-null mice to investigate the role of Txnip in glucose homeostasis. Txnip-null mice were hypoglycemic, hypoinsulinemic, and had blunted glucose production following a glucagon challenge, consistent with a central liver glucose-handling defect. Glucose release from isolated Txnip-null hepatocytes was 2-fold lower than wild-type hepatocytes, whereas beta-hydroxybutyrate release was increased 2-fold, supporting an intrinsic defect in hepatocyte glucose metabolism. While hepatocyte-specific gene deletion of Txnip did not alter glucose clearance compared with littermate controls, Txnip expression in the liver was required for maintaining normal fasting glycemia and glucose production. In addition, hepatic overexpression of a Txnip transgene in wild-type mice resulted in elevated serum glucose levels and decreased ketone levels. Liver homogenates from Txnip-null mice had no significant differences in the glutathione oxidation state or in the amount of available thioredoxin. However, overexpression of wild-type Txnip in Txnip-null hepatocytes rescued cellular glucose production, whereas overexpression of a C247S mutant Txnip, which does not bind thioredoxin, had no effect. These data demonstrate that Txnip is required for normal glucose homeostasis in the liver. While available thioredoxin is not changed in Txnip-null mice, the effects of Txnip on glucose homeostasis are abolished by a single cysteine mutation that inhibits binding to thioredoxin. -
Tokunou T, Miller R, Patwari P, Davis ME, Segers VF, Grodzinsky AJ, Lee RT. 2008. Engineering insulin-like growth factor-1 for local delivery. FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 22(6):1886-93. Pubmed: 18285400 DOI:10.1096/fj.07-100925 Tokunou T, Miller R, Patwari P, Davis ME, Segers VF, Grodzinsky AJ, Lee RT. 2008. Engineering insulin-like growth factor-1 for local delivery. FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 22(6):1886-93. Pubmed: 18285400 DOI:10.1096/fj.07-100925 Insulin-like growth factor-1 (IGF-1) is a small protein that promotes cell survival and growth, often acting over long distances. Although for decades IGF-1 has been considered to have therapeutic potential, systemic side effects of IGF-1 are significant, and local delivery of IGF-1 for tissue repair has been a long-standing challenge. In this study, we designed and purified a novel protein, heparin-binding IGF-1 (Xp-HB-IGF-1), which is a fusion protein of native IGF-1 with the heparin-binding domain of heparin-binding epidermal growth factor-like growth factor. Xp-HB-IGF-1 bound selectively to heparin as well as the cell surfaces of 3T3 fibroblasts, neonatal cardiac myocytes and differentiating ES cells. Xp-HB-IGF-1 activated the IGF-1 receptor and Akt with identical kinetics and dose response, indicating no compromise of biological activity due to the heparin-binding domain. Because cartilage is a proteoglycan-rich environment and IGF-1 is a known stimulus for chondrocyte biosynthesis, we then studied the effectiveness of Xp-HB-IGF-1 in cartilage. Xp-HB-IGF-1 was selectively retained by cartilage explants and led to sustained chondrocyte proteoglycan biosynthesis compared to IGF-1. These data show that the strategy of engineering a "long-distance" growth factor like IGF-1 for local delivery may be useful for tissue repair and minimizing systemic effects. -
Sabatine MS, Morrow DA, Higgins LJ, MacGillivray C, Guo W, Bode C, Rifai N, Cannon CP, Gerszten RE, Lee RT. 2008. Complementary roles for biomarkers of biomechanical strain ST2 and N-terminal prohormone B-type natriuretic peptide in patients with ST-elevation myocardial infarction. Circulation. 117(15):1936-44. Pubmed: 18378613 DOI:10.1161/CIRCULATIONAHA.107.728022 Sabatine MS, Morrow DA, Higgins LJ, MacGillivray C, Guo W, Bode C, Rifai N, Cannon CP, Gerszten RE, Lee RT. 2008. Complementary roles for biomarkers of biomechanical strain ST2 and N-terminal prohormone B-type natriuretic peptide in patients with ST-elevation myocardial infarction. Circulation. 117(15):1936-44. Pubmed: 18378613 DOI:10.1161/CIRCULATIONAHA.107.728022 Array -
Macgillivray C, Sylvan J, Lee RT, Huang H. 2008. Time-Saving Benefits of Intravital Staining. Journal of histotechnology. 31(3):129-134. Pubmed: 20622939 Macgillivray C, Sylvan J, Lee RT, Huang H. 2008. Time-Saving Benefits of Intravital Staining. Journal of histotechnology. 31(3):129-134. Pubmed: 20622939 One of the challenges in labeling tissues for fluorescence microscopy is minimizing sample processing while maintaining or improving the information generated by the fluorescent label. Generally, tissues are extracted, fixed, and embedded in mounting media (such as paraffin), sectioned, and then postprocessed by removing the paraffin, blocking, labeling, and washing. Despite all of these steps, the consistency of labeling quality can vary as a result of several factors, including heterogeneity in labeling efficiency from slide to slide, the necessity of postprocessing to obtain information on sequential sections of tissue, interference from the mounting media, and loss of native three-dimensional structural information, especially in thicker sections. A method for embedding and processing tissues that have been labeled by intravital staining is described in this study. Intravital staining is the process in which live-cell dyes and other labels are injected into the bloodstream before fixation of the tissues. Tissues processed this way can be imaged upon sectioning without further staining and retain their native, three-dimensional information, thereby improving the information retained by the labels and speeding up sample processing. -
Loffredo F, Lee RT. 2008. Therapeutic vasculogenesis: it takes two. Circulation research. 103(2):128-30. Pubmed: 18635829 DOI:10.1161/CIRCRESAHA.108.180604 Loffredo F, Lee RT. 2008. Therapeutic vasculogenesis: it takes two. Circulation research. 103(2):128-30. Pubmed: 18635829 DOI:10.1161/CIRCRESAHA.108.180604 -
Yoshioka J, Lee RT. 2008. Vascularization as a potential enemy in valvular heart disease. Circulation. 118(17):1694-6. Pubmed: 18936337 DOI:10.1161/CIRCULATIONAHA.108.809475 Yoshioka J, Lee RT. 2008. Vascularization as a potential enemy in valvular heart disease. Circulation. 118(17):1694-6. Pubmed: 18936337 DOI:10.1161/CIRCULATIONAHA.108.809475 -
Patwari P, Lee RT. 2008. Mechanical control of tissue morphogenesis. Circulation research. 103(3):234-43. Pubmed: 18669930 DOI:10.1161/CIRCRESAHA.108.175331 Patwari P, Lee RT. 2008. Mechanical control of tissue morphogenesis. Circulation research. 103(3):234-43. Pubmed: 18669930 DOI:10.1161/CIRCRESAHA.108.175331 Mechanical forces participate in morphogenesis from the level of individual cells to whole organism patterning. This article reviews recent research that has identified specific roles for mechanical forces in important developmental events. One well defined example is that dynein-driven cilia create fluid flow that determines left-right patterning in the early mammalian embryo. Fluid flow is also important for vasculogenesis, and evidence suggests that fluid shear stress rather than fluid transport is primarily required for remodeling the early vasculature. Contraction of the actin cytoskeleton, driven by nonmuscle myosins and regulated by the Rho family GTPases, is a recurring mechanism for controlling morphogenesis throughout development, from gastrulation to cardiogenesis. Finally, novel experimental approaches suggest critical roles for the actin cytoskeleton and the mechanical environment in determining differentiation of mesenchymal stem cells. Insights into the mechanisms linking mechanical forces to cell and tissue differentiation pathways are important for understanding many congenital diseases and for developing regenerative medicine strategies. -
Dubois G, Segers VF, Bellamy V, Sabbah L, Peyrard S, Bruneval P, Hagège AA, Lee RT, Menasché P. 2008. Self-assembling peptide nanofibers and skeletal myoblast transplantation in infarcted myocardium. Journal of biomedical materials research. Part B, Applied biomaterials. 87(1):222-8. Pubmed: 18386833 DOI:10.1002/jbm.b.31099 Dubois G, Segers VF, Bellamy V, Sabbah L, Peyrard S, Bruneval P, Hagège AA, Lee RT, Menasché P. 2008. Self-assembling peptide nanofibers and skeletal myoblast transplantation in infarcted myocardium. Journal of biomedical materials research. Part B, Applied biomaterials. 87(1):222-8. Pubmed: 18386833 DOI:10.1002/jbm.b.31099 Cell transplantation is currently limited by poor graft retention and survival in the postinfarction scar. Because this issue could potentially be addressed by embedding cells in bioinjectable scaffolds and boosting cell survival pathways, we induced a myocardial infarction in 72 rats to assess the effects of different self-assembling peptides with or without platelet-derived growth factor (PDGF-BB) on survival of transplanted skeletal myoblasts. Two weeks after coronary artery ligation, rats were randomized to receive in-scar injections of culture medium (controls, n = 11), self-assembling peptide (RAD16-I) nanofibers (NF, n = 9), skeletal myoblasts (n = 12), or skeletal myoblasts in combination with NF (n = 8). In separate experiments with different self-assembling peptides (RAD16-II), rats received in-scar injections of culture medium (controls, n = 6), skeletal myoblasts (n = 10), PDGF-loaded peptides (n = 7), or skeletal myoblasts (5 x 10(6)) in combination with PDGF-loaded peptides (n = 9). After 1 month, left ventricular function, as assessed by echocardiography, was not improved in either of the experimental groups compared with controls. This correlated with the failure of RAD16-I peptides or PDGF-loaded RAD16-II peptides to improve myoblast survival despite a greater angiogenesis. In vitro experiments confirmed that the number of myoblasts decreased over time when seeded on nanofiber gels. These data suggest that the optimal use of biomaterial scaffolds for survival of transplanted cells will require specific tailoring of the biomaterial to the cell type.(c) 2008 Wiley Periodicals, Inc. -
Kakkar R, Lee RT. 2008. The IL-33/ST2 pathway: therapeutic target and novel biomarker. Nature reviews. Drug discovery. 7(10):827-40. Pubmed: 18827826 DOI:10.1038/nrd2660 Kakkar R, Lee RT. 2008. The IL-33/ST2 pathway: therapeutic target and novel biomarker. Nature reviews. Drug discovery. 7(10):827-40. Pubmed: 18827826 DOI:10.1038/nrd2660 For many years, the interleukin-1 receptor family member ST2 was an orphan receptor that was studied in the context of inflammatory and autoimmune disease. However, in 2005, a new cytokine--interleukin-33 (IL-33)--was identified as a functional ligand for ST2. IL-33/ST2 signalling is involved in T-cell mediated immune responses, but more recently, an unanticipated role in cardiovascular disease has been demonstrated. IL-33/ST2 not only represents a promising cardiovascular biomarker but also a novel mechanism of intramyocardial fibroblast-cardiomyocyte communication that may prove to be a therapeutic target for the prevention of heart failure. -
Segers VF, Lee RT. 2008. Stem-cell therapy for cardiac disease. Nature. 451(7181):937-42. Pubmed: 18288183 DOI:10.1038/nature06800 Segers VF, Lee RT. 2008. Stem-cell therapy for cardiac disease. Nature. 451(7181):937-42. Pubmed: 18288183 DOI:10.1038/nature06800 Heart failure is the leading cause of death worldwide, and current therapies only delay progression of the disease. Laboratory experiments and recent clinical trials suggest that cell-based therapies can improve cardiac function, and the implications of this for cardiac regeneration are causing great excitement. Bone-marrow-derived progenitor cells and other progenitor cells can differentiate into vascular cell types, restoring blood flow. More recently, resident cardiac stem cells have been shown to differentiate into multiple cell types present in the heart, including cardiac muscle cells, indicating that the heart is not terminally differentiated. These new findings have stimulated optimism that the progression of heart failure can be prevented or even reversed with cell-based therapy. 2007
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Segers VF, Lee RT. 2007. Local delivery of proteins and the use of self-assembling peptides. Drug discovery today. 12(13-14):561-8. Pubmed: 17631251 Segers VF, Lee RT. 2007. Local delivery of proteins and the use of self-assembling peptides. Drug discovery today. 12(13-14):561-8. Pubmed: 17631251 Self-assembling peptides are members of a new class of molecules designed for tissue engineering and protein delivery. Upon injection in a physiological environment, self-assembling peptides form stable nanofiber hydrogels. Such biocompatible nanofibers can support three-dimensional growth and differentiation of many cell types. Self-assembling peptides are promising candidates for protein delivery, because they allow non-covalent binding of proteins, tethering of proteins, or incorporation of fusion proteins. Self-assembling peptides can be designed to deliver individual proteins or multiple factors, because the building blocks comprising self-assembling peptides can be designed with great flexibility. -
Hsieh PC, Segers VF, Davis ME, MacGillivray C, Gannon J, Molkentin JD, Robbins J, Lee RT. 2007. Evidence from a genetic fate-mapping study that stem cells refresh adult mammalian cardiomyocytes after injury. Nature medicine. 13(8):970-4. Pubmed: 17660827 Hsieh PC, Segers VF, Davis ME, MacGillivray C, Gannon J, Molkentin JD, Robbins J, Lee RT. 2007. Evidence from a genetic fate-mapping study that stem cells refresh adult mammalian cardiomyocytes after injury. Nature medicine. 13(8):970-4. Pubmed: 17660827 An emerging concept is that the mammalian myocardium has the potential to regenerate, but that regeneration might be too inefficient to repair the extensive myocardial injury that is typical of human disease. However, the degree to which stem cells or precursor cells contribute to the renewal of adult mammalian cardiomyocytes remains controversial. Here we report evidence that stem cells or precursor cells contribute to the replacement of adult mammalian cardiomyocytes after injury but do not contribute significantly to cardiomyocyte renewal during normal aging. We generated double-transgenic mice to track the fate of adult cardiomyocytes in a 'pulse-chase' fashion: after a 4-OH-tamoxifen pulse, green fluorescent protein (GFP) expression was induced only in cardiomyocytes, with 82.7% of cardiomyocytes expressing GFP. During normal aging up to one year, the percentage of GFP+ cardiomyocytes remained unchanged, indicating that stem or precursor cells did not refresh uninjured cardiomyocytes at a significant rate during this period of time. By contrast, after myocardial infarction or pressure overload, the percentage of GFP+ cardiomyocytes decreased from 82.8% in heart tissue from sham-treated mice to 67.5% in areas bordering a myocardial infarction, 76.6% in areas away from a myocardial infarction, and 75.7% in hearts subjected to pressure overload, indicating that stem cells or precursor cells had refreshed the cardiomyocytes. -
Yoshioka J, Imahashi K, Gabel SA, Chutkow WA, Burds AA, Gannon J, Schulze PC, MacGillivray C, London RE, Murphy E, Lee RT. 2007. Targeted deletion of thioredoxin-interacting protein regulates cardiac dysfunction in response to pressure overload. Circulation research. 101(12):1328-38. Pubmed: 17916779 Yoshioka J, Imahashi K, Gabel SA, Chutkow WA, Burds AA, Gannon J, Schulze PC, MacGillivray C, London RE, Murphy E, Lee RT. 2007. Targeted deletion of thioredoxin-interacting protein regulates cardiac dysfunction in response to pressure overload. Circulation research. 101(12):1328-38. Pubmed: 17916779 Biomechanical overload induces cardiac hypertrophy and heart failure, and reactive oxygen species (ROS) play a role in both processes. Thioredoxin-Interacting Protein (Txnip) is encoded by a mechanically-regulated gene that controls cell growth and apoptosis in part through interaction with the endogenous dithiol antioxidant thioredoxin. Here we show that Txnip is a critical regulator of the cardiac response to pressure overload. We generated inducible cardiomyocyte-specific and systemic Txnip-null mice (Txnip-KO) using Flp/frt and Cre/loxP technologies. Compared with littermate controls, Txnip-KO hearts had attenuated cardiac hypertrophy and preserved left ventricular (LV) contractile reserve through 4 weeks of pressure overload; however, the beneficial effects were not sustained and Txnip deletion ultimately led to maladaptive LV remodeling at 8 weeks of pressure overload. Interestingly, these effects of Txnip deletion on cardiac performance were not accompanied by global changes in thioredoxin activity or ROS; instead, Txnip-KO hearts had a robust increase in myocardial glucose uptake. Thus, deletion of Txnip plays an unanticipated role in myocardial energy homeostasis rather than redox regulation. These results support the emerging concept that the function of Txnip is not as a simple thioredoxin inhibitor but as a metabolic control protein. -
Segers VF, Tokunou T, Higgins LJ, MacGillivray C, Gannon J, Lee RT. 2007. Local delivery of protease-resistant stromal cell derived factor-1 for stem cell recruitment after myocardial infarction. Circulation. 116(15):1683-92. Pubmed: 17875967 Segers VF, Tokunou T, Higgins LJ, MacGillivray C, Gannon J, Lee RT. 2007. Local delivery of protease-resistant stromal cell derived factor-1 for stem cell recruitment after myocardial infarction. Circulation. 116(15):1683-92. Pubmed: 17875967 Array -
Lammerding J, Lee RT. 2007. Torn apart: membrane rupture in muscular dystrophies and associated cardiomyopathies. The Journal of clinical investigation. 117(7):1749-52. Pubmed: 17607350 Lammerding J, Lee RT. 2007. Torn apart: membrane rupture in muscular dystrophies and associated cardiomyopathies. The Journal of clinical investigation. 117(7):1749-52. Pubmed: 17607350 Muscular dystrophies are often caused by mutations in cytoskeletal proteins that render cells more susceptible to strain-induced injury in mechanically active tissues such as skeletal or cardiac muscle. In this issue of the JCI, Han et al. report that dysferlin participates in membrane resealing in cardiomyocytes and that exercise results in increased membrane damage and disturbed cardiac function in dysferlin-deficient mice (see the related article beginning on page 1805). Thus, in addition to repetitive membrane damage, inadequate membrane repair may participate in the pathogenesis of muscular dystrophies and cardiomyopathies. -
Sanada S, Hakuno D, Higgins LJ, Schreiter ER, McKenzie AN, Lee RT. 2007. IL-33 and ST2 comprise a critical biomechanically induced and cardioprotective signaling system. The Journal of clinical investigation. 117(6):1538-49. Pubmed: 17492053 Sanada S, Hakuno D, Higgins LJ, Schreiter ER, McKenzie AN, Lee RT. 2007. IL-33 and ST2 comprise a critical biomechanically induced and cardioprotective signaling system. The Journal of clinical investigation. 117(6):1538-49. Pubmed: 17492053 ST2 is an IL-1 receptor family member with transmembrane (ST2L) and soluble (sST2) isoforms. sST2 is a mechanically induced cardiomyocyte protein, and serum sST2 levels predict outcome in patients with acute myocardial infarction or chronic heart failure. Recently, IL-33 was identified as a functional ligand of ST2L, allowing exploration of the role of ST2 in myocardium. We found that IL-33 was a biomechanically induced protein predominantly synthesized by cardiac fibroblasts. IL-33 markedly antagonized angiotensin II- and phenylephrine-induced cardiomyocyte hypertrophy. Although IL-33 activated NF-kappaB, it inhibited angiotensin II- and phenylephrine-induced phosphorylation of inhibitor of NF-kappa B alpha (I kappa B alpha) and NF-kappaB nuclear binding activity. sST2 blocked antihypertrophic effects of IL-33, indicating that sST2 functions in myocardium as a soluble decoy receptor. Following pressure overload by transverse aortic constriction (TAC), ST2(-/-) mice had more left ventricular hypertrophy, more chamber dilation, reduced fractional shortening, more fibrosis, and impaired survival compared with WT littermates. Furthermore, recombinant IL-33 treatment reduced hypertrophy and fibrosis and improved survival after TAC in WT mice, but not in ST2(-/-) littermates. Thus, IL-33/ST2 signaling is a mechanically activated, cardioprotective fibroblast-cardiomyocyte paracrine system, which we believe to be novel. IL-33 may have therapeutic potential for beneficially regulating the myocardial response to overload. -
Patwari P, Lee RT. 2007. Thioredoxins, mitochondria, and hypertension. The American journal of pathology. 170(3):805-8. Pubmed: 17322366 Patwari P, Lee RT. 2007. Thioredoxins, mitochondria, and hypertension. The American journal of pathology. 170(3):805-8. Pubmed: 17322366 Endothelial dysfunction, often demonstrated by the loss of the endothelial cell's ability to cause vasodilation in response to appropriate stimuli, is one of the earliest events in the development of atherosclerosis. This has led to intense investigation of the factors affecting both the production and the degradation of NO, the endothelium-derived relaxing factor and a primary mediator of endothelial function. Reactive oxygen species (ROS), particularly superoxide anion, are well known to inhibit NO, and therefore the mechanisms by which endothelium regulates production of ROS are also of high interest. In this issue of The American Journal of Pathology, Zhang et al( 1) demonstrate regulation of such events by a mitochondria-specific thioredoxin, which reduces oxidative stress and increases NO bioavailability, thus preserving vascular endothelial cell function and preventing atherosclerosis development. -
Ji JY, Lee RT, Vergnes L, Fong LG, Stewart CL, Reue K, Young SG, Zhang Q, Shanahan CM, Lammerding J. 2007. Cell nuclei spin in the absence of lamin b1. The Journal of biological chemistry. 282(27):20015-26. Pubmed: 17488709 Ji JY, Lee RT, Vergnes L, Fong LG, Stewart CL, Reue K, Young SG, Zhang Q, Shanahan CM, Lammerding J. 2007. Cell nuclei spin in the absence of lamin b1. The Journal of biological chemistry. 282(27):20015-26. Pubmed: 17488709 Mutations of the nuclear lamins cause a wide range of human diseases, including Emery-Dreifuss muscular dystrophy and Hutchinson-Gilford progeria syndrome. Defects in A-type lamins reduce nuclear structural integrity and affect transcriptional regulation, but few data exist on the biological role of B-type lamins. To assess the functional importance of lamin B1, we examined nuclear dynamics in fibroblasts from Lmnb1(Delta/Delta) and wild-type littermate embryos by time-lapse videomicroscopy. Here, we report that Lmnb1(Delta/Delta) cells displayed striking nuclear rotation, with approximately 90% of Lmnb1(Delta/Delta) nuclei rotating at least 90 degrees during an 8-h period. The rotation involved the nuclear interior as well as the nuclear envelope. The rotation of nuclei required an intact cytoskeletal network and was eliminated by expressing lamin B1 in cells. Nuclear rotation could also be abolished by expressing larger nesprin isoforms with long spectrin repeats. These findings demonstrate that lamin B1 serves a fundamental role within the nuclear envelope: anchoring the nucleus to the cytoskeleton. -
Ragan T, Sylvan JD, Kim KH, Huang H, Bahlmann K, Lee RT, So PT. 2007. High-resolution whole organ imaging using two-photon tissue cytometry. Journal of biomedical optics. 12(1):014015. Pubmed: 17343490 Ragan T, Sylvan JD, Kim KH, Huang H, Bahlmann K, Lee RT, So PT. 2007. High-resolution whole organ imaging using two-photon tissue cytometry. Journal of biomedical optics. 12(1):014015. Pubmed: 17343490 Three-dimensional (3-D) tissue imaging offers substantial benefits to a wide range of biomedical investigations from cardiovascular biology, diabetes, Alzheimer's disease to cancer. Two-photon tissue cytometry is a novel technique based on high-speed multiphoton microscopy coupled with automated histological sectioning, which can quantify tissue morphology and physiology throughout entire organs with subcellular resolution. Furthermore, two-photon tissue cytometry offers all the benefits of fluorescence-based approaches including high specificity and sensitivity and appropriateness for molecular imaging of gene and protein expression. We use two-photon tissue cytometry to image an entire mouse heart at subcellular resolution to quantify the 3-D morphology of cardiac microvasculature and myocyte morphology spanning almost five orders of magnitude in length scales. -
Parikh H, Carlsson E, Chutkow WA, Johansson LE, Storgaard H, Poulsen P, Saxena R, Ladd C, Schulze PC, Mazzini MJ, Jensen CB, Krook A, Björnholm M, Tornqvist H, Zierath JR, Ridderstråle M, Altshuler D, Lee RT, Vaag A, Groop LC, Mootha VK. 2007. TXNIP regulates peripheral glucose metabolism in humans. PLoS medicine. 4(5):e158. Pubmed: 17472435 DOI:e158 Parikh H, Carlsson E, Chutkow WA, Johansson LE, Storgaard H, Poulsen P, Saxena R, Ladd C, Schulze PC, Mazzini MJ, Jensen CB, Krook A, Björnholm M, Tornqvist H, Zierath JR, Ridderstråle M, Altshuler D, Lee RT, Vaag A, Groop LC, Mootha VK. 2007. TXNIP regulates peripheral glucose metabolism in humans. PLoS medicine. 4(5):e158. Pubmed: 17472435 DOI:e158 Array 2006
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Schulze PC, Liu H, Choe E, Yoshioka J, Shalev A, Bloch KD, Lee RT. 2006. Nitric oxide-dependent suppression of thioredoxin-interacting protein expression enhances thioredoxin activity. Arteriosclerosis, thrombosis, and vascular biology. 26(12):2666-72. Pubmed: 17023680 Schulze PC, Liu H, Choe E, Yoshioka J, Shalev A, Bloch KD, Lee RT. 2006. Nitric oxide-dependent suppression of thioredoxin-interacting protein expression enhances thioredoxin activity. Arteriosclerosis, thrombosis, and vascular biology. 26(12):2666-72. Pubmed: 17023680 Array -
Hsieh PC, Davis ME, Gannon J, MacGillivray C, Lee RT. 2006. Controlled delivery of PDGF-BB for myocardial protection using injectable self-assembling peptide nanofibers. The Journal of clinical investigation. 116(1):237-48. Pubmed: 16357943 Hsieh PC, Davis ME, Gannon J, MacGillivray C, Lee RT. 2006. Controlled delivery of PDGF-BB for myocardial protection using injectable self-assembling peptide nanofibers. The Journal of clinical investigation. 116(1):237-48. Pubmed: 16357943 Endothelial cells can protect cardiomyocytes from injury, but the mechanism of this protection is incompletely described. Here we demonstrate that protection of cardiomyocytes by endothelial cells occurs through PDGF-BB signaling. PDGF-BB induced cardiomyocyte Akt phosphorylation in a time- and dose-dependent manner and prevented apoptosis via PI3K/Akt signaling. Using injectable self-assembling peptide nanofibers, which bound PDGF-BB in vitro, sustained delivery of PDGF-BB to the myocardium at the injected sites for 14 days was achieved. A blinded and randomized study in 96 rats showed that injecting nanofibers with PDGF-BB, but not nanofibers or PDGF-BB alone, decreased cardiomyocyte death and preserved systolic function after myocardial infarction. A separate blinded and randomized study in 52 rats showed that PDGF-BB delivered with nanofibers decreased infarct size after ischemia/reperfusion. PDGF-BB with nanofibers induced PDGFR-beta and Akt phosphorylation in cardiomyocytes in vivo. These data demonstrate that endothelial cells protect cardiomyocytes via PDGF-BB signaling and that this in vitro finding can be translated into an effective in vivo method of protecting myocardium after infarction. Furthermore, this study shows that injectable nanofibers allow precise and sustained delivery of proteins to the myocardium with potential therapeutic benefits. -
Hsieh PC, MacGillivray C, Gannon J, Cruz FU, Lee RT. 2006. Local controlled intramyocardial delivery of platelet-derived growth factor improves postinfarction ventricular function without pulmonary toxicity. Circulation. 114(7):637-44. Pubmed: 16894033 Hsieh PC, MacGillivray C, Gannon J, Cruz FU, Lee RT. 2006. Local controlled intramyocardial delivery of platelet-derived growth factor improves postinfarction ventricular function without pulmonary toxicity. Circulation. 114(7):637-44. Pubmed: 16894033 Array -
Cruz F, Lee RT, Huang H. 2006. Three-dimensional reconstruction of tissues. Current protocols in molecular biology. Chapter 14:Unit 14.16. Pubmed: 18265375 DOI:10.1002/0471142727.mb1416s74 Cruz F, Lee RT, Huang H. 2006. Three-dimensional reconstruction of tissues. Current protocols in molecular biology. Chapter 14:Unit 14.16. Pubmed: 18265375 DOI:10.1002/0471142727.mb1416s74 Cellular morphology is inherently three-dimensional. However, most histological techniques for tissue analysis focus on extracting information from two-dimensional slices of fixed samples or dissociated cells. These techniques result in a significant loss of the three-dimensional information of the tissue, including true cell volume, orientation, and whole cell shape. This unit discusses various options for three-dimensional imaging, provides a protocol for performing post-processing reconstruction based on serial slicing, and discusses the current advantages and limitations of the three-dimensional approach to quantitative tissue analysis. The focus of this protocol is on cardiac tissue, but the techniques can be applied to any solid tissue. -
Davis ME, Hsieh PC, Takahashi T, Song Q, Zhang S, Kamm RD, Grodzinsky AJ, Anversa P, Lee RT. 2006. Local myocardial insulin-like growth factor 1 (IGF-1) delivery with biotinylated peptide nanofibers improves cell therapy for myocardial infarction. Proceedings of the National Academy of Sciences of the United States of America. 103(21):8155-60. Pubmed: 16698918 Davis ME, Hsieh PC, Takahashi T, Song Q, Zhang S, Kamm RD, Grodzinsky AJ, Anversa P, Lee RT. 2006. Local myocardial insulin-like growth factor 1 (IGF-1) delivery with biotinylated peptide nanofibers improves cell therapy for myocardial infarction. Proceedings of the National Academy of Sciences of the United States of America. 103(21):8155-60. Pubmed: 16698918 Strategies for cardiac repair include injection of cells, but these approaches have been hampered by poor cell engraftment, survival, and differentiation. To address these shortcomings for the purpose of improving cardiac function after injury, we designed self-assembling peptide nanofibers for prolonged delivery of insulin-like growth factor 1 (IGF-1), a cardiomyocyte growth and differentiation factor, to the myocardium, using a "biotin sandwich" approach. Biotinylated IGF-1 was complexed with tetravalent streptavidin and then bound to biotinylated self-assembling peptides. This biotin sandwich strategy allowed binding of IGF-1 but did not prevent self-assembly of the peptides into nanofibers within the myocardium. IGF-1 that was bound to peptide nanofibers activated Akt, decreased activation of caspase-3, and increased expression of cardiac troponin I in cardiomyocytes. After injection into rat myocardium, biotinylated nanofibers provided sustained IGF-1 delivery for 28 days, and targeted delivery of IGF-1 in vivo increased activation of Akt in the myocardium. When combined with transplanted cardiomyocytes, IGF-1 delivery by biotinylated nanofibers decreased caspase-3 cleavage by 28% and increased the myocyte cross-sectional area by 25% compared with cells embedded within nanofibers alone or with untethered IGF-1. Finally, cell therapy with IGF-1 delivery by biotinylated nanofibers improved systolic function after experimental myocardial infarction, demonstrating how engineering the local cellular microenvironment can improve cell therapy. -
Patwari P, Higgins LJ, Chutkow WA, Yoshioka J, Lee RT. 2006. The interaction of thioredoxin with Txnip. Evidence for formation of a mixed disulfide by disulfide exchange. The Journal of biological chemistry. 281(31):21884-21891. Pubmed: 16766796 DOI:S0021-9258(19)47708-9 Patwari P, Higgins LJ, Chutkow WA, Yoshioka J, Lee RT. 2006. The interaction of thioredoxin with Txnip. Evidence for formation of a mixed disulfide by disulfide exchange. The Journal of biological chemistry. 281(31):21884-21891. Pubmed: 16766796 DOI:S0021-9258(19)47708-9 The thioredoxin system plays an important role in maintaining a reducing environment in the cell. Recently, several thioredoxin binding partners have been identified and proposed to mediate aspects of redox signaling, but the significance of these interactions is unclear in part due to incomplete understanding of the mechanism for thioredoxin binding. Thioredoxin-interacting protein (Txnip) is critical for regulation of glucose metabolism, the only currently known function of which is to bind and inhibit thioredoxin. We explored the mechanism of the Txnip-thioredoxin interaction and present evidence that Txnip and thioredoxin form a stable disulfide-linked complex. We identified two Txnip cysteines that are important for thioredoxin binding and showed that this interaction is consistent with a disulfide exchange reaction between oxidized Txnip and reduced thioredoxin. These cysteines are not conserved in the broader family of arrestin domain-containing proteins, and we demonstrate that the thioredoxin-binding property of Txnip is unique. These data suggest that Txnip is a target of reduced thioredoxin and provide insight into the potential role of Txnip as a redox-sensitive signaling protein. -
Lammerding J, Fong LG, Ji JY, Reue K, Stewart CL, Young SG, Lee RT. 2006. Lamins A and C but not lamin B1 regulate nuclear mechanics. The Journal of biological chemistry. 281(35):25768-80. Pubmed: 16825190 Lammerding J, Fong LG, Ji JY, Reue K, Stewart CL, Young SG, Lee RT. 2006. Lamins A and C but not lamin B1 regulate nuclear mechanics. The Journal of biological chemistry. 281(35):25768-80. Pubmed: 16825190 Mutations in the nuclear envelope proteins lamins A and C cause a broad variety of human diseases, including Emery-Dreifuss muscular dystrophy, dilated cardiomyopathy, and Hutchinson-Gilford progeria syndrome. Cells lacking lamins A and C have reduced nuclear stiffness and increased nuclear fragility, leading to increased cell death under mechanical strain and suggesting a potential mechanism for disease. Here, we investigated the contribution of major lamin subtypes (lamins A, C, and B1) to nuclear mechanics by analyzing nuclear shape, nuclear dynamics over time, nuclear deformations under strain, and cell viability under prolonged mechanical stimulation in cells lacking both lamins A and C, cells lacking only lamin A (i.e. "lamin C-only" cells), cells lacking wild-type lamin B1, and wild-type cells. Lamin A/C-deficient cells exhibited increased numbers of misshapen nuclei and had severely reduced nuclear stiffness and decreased cell viability under strain. Lamin C-only cells had slightly abnormal nuclear shape and mildly reduced nuclear stiffness but no decrease in cell viability under strain. Interestingly, lamin B1-deficient cells exhibited normal nuclear mechanics despite having a significantly increased frequency of nuclear blebs. Our study indicates that lamins A and C are important contributors to the mechanical stiffness of nuclei, whereas lamin B1 contributes to nuclear integrity but not stiffness. -
Lindsey ML, Escobar GP, Dobrucki LW, Goshorn DK, Bouges S, Mingoia JT, McClister DM, Su H, Gannon J, MacGillivray C, Lee RT, Sinusas AJ, Spinale FG. 2006. Matrix metalloproteinase-9 gene deletion facilitates angiogenesis after myocardial infarction. American journal of physiology. Heart and circulatory physiology. 290(1):H232-9. Pubmed: 16126817 Lindsey ML, Escobar GP, Dobrucki LW, Goshorn DK, Bouges S, Mingoia JT, McClister DM, Su H, Gannon J, MacGillivray C, Lee RT, Sinusas AJ, Spinale FG. 2006. Matrix metalloproteinase-9 gene deletion facilitates angiogenesis after myocardial infarction. American journal of physiology. Heart and circulatory physiology. 290(1):H232-9. Pubmed: 16126817 Matrix metalloproteinases (MMPs) are postulated to be necessary for neovascularization during wound healing. MMP-9 deletion alters remodeling postmyocardial infarction (post-MI), but whether and to what degree MMP-9 affects neovascularization post-MI is unknown. Neovascularization was evaluated in wild-type (WT; n = 63) and MMP-9 null (n = 55) mice at 7-days post-MI. Despite similar infarct sizes, MMP-9 deletion improved left ventricular function as evaluated by hemodynamic analysis. Blood vessel quantity and quality were evaluated by three independent studies. First, vessel density was increased in the infarct of MMP-9 null mice compared with WT, as quantified by Griffonia (Bandeiraea) simplicifolia lectin I (GSL-I) immunohistochemistry. Second, preexisting vessels, stained in vivo with FITC-labeled GSL-I pre-MI, were present in the viable but not MI region. Third, a technetium-99m-labeled peptide (NC100692), which selectively binds to activated alpha(v)beta3-integrin in angiogenic vessels, was injected into post-MI mice. Relative NC100692 activity in myocardial segments with diminished perfusion (0-40% nonischemic) was higher in MMP-9 null than in WT mice (383 +/- 162% vs. 250 +/- 118%, respectively; P = 0.002). The unique finding of this study was that MMP-9 deletion stimulated, rather than impaired, neovascularization in remodeling myocardium. Thus targeted strategies to inhibit MMP-9 early post-MI will likely not impair the angiogenic response. -
Fong LG, Ng JK, Lammerding J, Vickers TA, Meta M, Coté N, Gavino B, Qiao X, Chang SY, Young SR, Yang SH, Stewart CL, Lee RT, Bennett CF, Bergo MO, Young SG. 2006. Prelamin A and lamin A appear to be dispensable in the nuclear lamina. The Journal of clinical investigation. 116(3):743-52. Pubmed: 16511604 Fong LG, Ng JK, Lammerding J, Vickers TA, Meta M, Coté N, Gavino B, Qiao X, Chang SY, Young SR, Yang SH, Stewart CL, Lee RT, Bennett CF, Bergo MO, Young SG. 2006. Prelamin A and lamin A appear to be dispensable in the nuclear lamina. The Journal of clinical investigation. 116(3):743-52. Pubmed: 16511604 Lamin A and lamin C, both products of Lmna, are key components of the nuclear lamina. In the mouse, a deficiency in both lamin A and lamin C leads to slow growth, muscle weakness, and death by 6 weeks of age. Fibroblasts deficient in lamins A and C contain misshapen and structurally weakened nuclei, and emerin is mislocalized away from the nuclear envelope. The physiologic rationale for the existence of the 2 different Lmna products lamin A and lamin C is unclear, although several reports have suggested that lamin A may have particularly important functions, for example in the targeting of emerin and lamin C to the nuclear envelope. Here we report the development of lamin C-only mice (Lmna(LCO/LCO)), which produce lamin C but no lamin A or prelamin A (the precursor to lamin A). Lmna(LCO/LCO) mice were entirely healthy, and Lmna(LCO/LCO) cells displayed normal emerin targeting and exhibited only very minimal alterations in nuclear shape and nuclear deformability. Thus, at least in the mouse, prelamin A and lamin A appear to be dispensable. Nevertheless, an accumulation of farnesyl-prelamin A (as occurs with a deficiency in the prelamin A processing enzyme Zmpste24) caused dramatically misshapen nuclei and progeria-like disease phenotypes. The apparent dispensability of prelamin A suggested that lamin A-related progeroid syndromes might be treated with impunity by reducing prelamin A synthesis. Remarkably, the presence of a single Lmna(LCO) allele eliminated the nuclear shape abnormalities and progeria-like disease phenotypes in Zmpste24-/- mice. Moreover, treating Zmpste24-/- cells with a prelamin A-specific antisense oligonucleotide reduced prelamin A levels and significantly reduced the frequency of misshapen nuclei. These studies suggest a new therapeutic strategy for treating progeria and other lamin A diseases. -
Hsieh PC, Davis ME, Lisowski LK, Lee RT. 2006. Endothelial-cardiomyocyte interactions in cardiac development and repair. Annual review of physiology. 68:51-66. Pubmed: 16460266 Hsieh PC, Davis ME, Lisowski LK, Lee RT. 2006. Endothelial-cardiomyocyte interactions in cardiac development and repair. Annual review of physiology. 68:51-66. Pubmed: 16460266 Communication between endothelial cells and cardiomyocytes regulates not only early cardiac development but also adult cardiomyocyte function, including the contractile state. In the normal mammalian myocardium, each cardiomyocyte is surrounded by an intricate network of capillaries and is next to endothelial cells. Cardiomyocytes depend on endothelial cells not only for oxygenated blood supply but also for local protective signals that promote cardiomyocyte organization and survival. While endothelial cells direct cardiomyocytes, cardiomyocytes reciprocally secrete factors that impact endothelial cell function. Understanding how endothelial cells communicate with cardiomyocytes will be critical for cardiac regeneration, in which the ultimate goal is not simply to improve systolic function transiently but to establish new myocardium that is both structurally and functionally normal in the long term. -
Perlstein TS, Lee RT. 2006. Smoking, metalloproteinases, and vascular disease. Arteriosclerosis, thrombosis, and vascular biology. 26(2):250-6. Pubmed: 16339501 Perlstein TS, Lee RT. 2006. Smoking, metalloproteinases, and vascular disease. Arteriosclerosis, thrombosis, and vascular biology. 26(2):250-6. Pubmed: 16339501 Smoking causes up to 11% of total global cardiovascular deaths. Smoking has numerous effects that may promote atherosclerosis through vascular inflammation and oxidative stress, but the pathogenesis of smoking-related cardiovascular disease remains incompletely understood. The matrix metalloproteinases, a family of endopeptidases that can degrade extracellular matrix components in both physiological and pathophysiological states, play an important role in smoking-associated chronic obstructive pulmonary disease, the second leading cause of smoking attributable mortality. Emerging evidence indicates that the matrix metalloproteinases may also contribute to smoking-related vascular disease. Here we discuss the potential relationship between smoking, matrix metalloproteinases, and acceleration of vascular disease. -
Engel FB, Hsieh PC, Lee RT, Keating MT. 2006. FGF1/p38 MAP kinase inhibitor therapy induces cardiomyocyte mitosis, reduces scarring, and rescues function after myocardial infarction. Proceedings of the National Academy of Sciences of the United States of America. 103(42):15546-51. Pubmed: 17032753 Engel FB, Hsieh PC, Lee RT, Keating MT. 2006. FGF1/p38 MAP kinase inhibitor therapy induces cardiomyocyte mitosis, reduces scarring, and rescues function after myocardial infarction. Proceedings of the National Academy of Sciences of the United States of America. 103(42):15546-51. Pubmed: 17032753 Mammalian cardiomyocytes have limited proliferation potential, and acutely injured mammalian hearts do not regenerate adequately. Instead, injured myocardium develops fibrosis and scarring. Here we show that FGF1/p38 MAP kinase inhibitor treatment after acute myocardial injury in 8- to 10-week-old rats increases cardiomyocyte mitosis. At 3 months after injury, 4 weeks of FGF1/p38 MAP kinase inhibitor therapy results in reduced scarring and wall thinning, with markedly improved cardiac function. In contrast, p38 MAP kinase inhibition alone fails to rescue heart function despite increased cardiomyocyte mitosis. FGF1 improves angiogenesis, possibly contributing to the survival of newly generated cardiomyocytes. Our data indicate that FGF1 and p38 MAP kinase, proteins involved in cardiomyocyte proliferation and angiogenesis during development, may be delivered therapeutically to enhance cardiac regeneration. -
Yoshioka J, Schreiter ER, Lee RT. 2006. Role of thioredoxin in cell growth through interactions with signaling molecules. Antioxidants & redox signaling. 8(11-12):2143-51. Pubmed: 17034356 Yoshioka J, Schreiter ER, Lee RT. 2006. Role of thioredoxin in cell growth through interactions with signaling molecules. Antioxidants & redox signaling. 8(11-12):2143-51. Pubmed: 17034356 The thioredoxin system helps maintain a reducing environment in cells, but thioredoxin functions as more than simply an antioxidant. Thioredoxin functions depend on the protein's redox state, as determined by two conserved cysteines. Key biologic activities of thioredoxin include antioxidant, growth control, and antiapoptotic properties, resulting from interaction with target molecules including transcription factors. Mechanisms by which thioredoxin regulates cell growth include binding to signaling molecules such as apoptosis signal-regulating kinase-1 (ASK-1) and thioredoxin-interacting protein (Txnip). The molecular interplay between thioredoxin, ASK-1, and Txnip potentially influences cell growth and survival in diverse human diseases such as cancer, diabetes, and heart disease. In this review, we focus on the structure of thioredoxin and its functional regulation of cell growth through the interactions with signaling molecules. 2005
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Hakuno D, Takahashi T, Lammerding J, Lee RT. 2005. Focal adhesion kinase signaling regulates cardiogenesis of embryonic stem cells. The Journal of biological chemistry. 280(47):39534-44. Pubmed: 16157602 Hakuno D, Takahashi T, Lammerding J, Lee RT. 2005. Focal adhesion kinase signaling regulates cardiogenesis of embryonic stem cells. The Journal of biological chemistry. 280(47):39534-44. Pubmed: 16157602 The signaling steps that induce cardiac differentiation in embryonic stem (ES) cells are incompletely understood. We examined the effect of adhesion signaling including Src and focal adhesion kinase (FAK) on cardiogenesis in mouse ES cells using alpha-myosin heavy chain promoter-driven enhanced green fluorescent protein or luciferase as reporters. Cardiac transcription factors including Nkx2.5 and Tbx5 mRNA were first expressed at day 4 in hanging drop embryoid bodies, and adhesion of embryoid bodies to surfaces at or before that day strongly inhibited differentiation of ES cells to cardiomyocytes. Since adhesion signaling could suppress cardiogenesis through Src kinases, embryoid bodies were exposed to the small molecule PP2, known as a Src family kinase inhibitor. PP2 during embryoid body adhesion dramatically increased cardiomyocyte differentiation and decreased mRNA expression of neuronal cellular adhesion molecule and alpha-fetoprotein, neuroectodermal, and endodermal markers, respectively. Surprisingly, although there was an interaction between Src and FAK in cardiogenesis, the procardiogenic effect of PP2 appeared incompletely explained by Src kinase inhibition, since another Src family kinase inhibitor, SU6656, failed to induce cardiogenesis. Instead, PP2 specifically inhibited adhesion-induced FAK phosphorylation. In ES cells stably expressing FAK-related nonkinase, which functions as a dominant negative FAK, cell migration from embryoid bodies was inhibited, whereas alpha-myosin heavy chain expression and myosin-stained cardiomyocytes were increased, suggesting that reducing cell motility may contribute to cardiogenesis. These data indicate that FAK is a key regulator of cardiogenesis in mouse ES cells and that FAK signaling within embryoid bodies can direct stem cell lineage commitment. -
Weinberg EO, Scherrer-Crosbie M, Picard MH, Nasseri BA, MacGillivray C, Gannon J, Lian Q, Bloch KD, Lee RT. 2005. Rosuvastatin reduces experimental left ventricular infarct size after ischemia-reperfusion injury but not total coronary occlusion. American journal of physiology. Heart and circulatory physiology. 288(4):H1802-9. Pubmed: 15563531 Weinberg EO, Scherrer-Crosbie M, Picard MH, Nasseri BA, MacGillivray C, Gannon J, Lian Q, Bloch KD, Lee RT. 2005. Rosuvastatin reduces experimental left ventricular infarct size after ischemia-reperfusion injury but not total coronary occlusion. American journal of physiology. Heart and circulatory physiology. 288(4):H1802-9. Pubmed: 15563531 This study compared the effects of rosuvastatin on left ventricular infarct size in mice after permanent coronary occlusion vs. 60 min of ischemia followed by 24 h of reperfusion. Statins can inhibit neutrophil adhesion, increase nitric oxide synthase (NOS) expression, and mobilize progenitor stem cells after ischemic injury. Mice received blinded and randomized administration of rosuvastatin (20 mg.kg(-1).day(-1)) or saline from 2 days before surgery until death. After 60 min of ischemia with reperfusion, infarct size was reduced by 18% (P = 0.03) in mice randomized to receive rosuvastatin (n = 18) vs. saline (n = 22) but was similar after permanent occlusion in rosuvastatin (n = 17) and saline (n = 20) groups (P = not significant). Myocardial infarct size after permanent left anterior descending coronary artery occlusion (n = 6) tended to be greater in NOS3-deficient mice than in the wild-type saline group (33 +/- 4 vs. 23 +/- 2%, P = 0.08). Infarct size in NOS3-deficient mice was not modified by treatment with rosuvastatin (34 +/- 5%, n = 6, P = not significant vs. NOS3-deficient saline group). After 60 min of ischemia-reperfusion, neutrophil infiltration was similar in rosuvastatin and saline groups as was the percentage of CD34(+), Sca-1(+), and c-Kit(+) cells. Left ventricular NOS3 mRNA and protein levels were unchanged by rosuvastatin. Rosuvastatin reduces infarct size after 60 min of ischemia-reperfusion but not after permanent coronary occlusion, suggesting a potential anti-inflammatory effect. Although we were unable to demonstrate that the myocardial protection was due to an effect on neutrophil infiltration, stem cell mobilization, or induction of NOS3, these data suggest that rosuvastatin may be particularly beneficial in myocardial protection after ischemia-reperfusion injury. -
Schulze PC, Lee RT. 2005. Oxidative stress and atherosclerosis. Current atherosclerosis reports. 7(3):242-8. Pubmed: 15811260 Schulze PC, Lee RT. 2005. Oxidative stress and atherosclerosis. Current atherosclerosis reports. 7(3):242-8. Pubmed: 15811260 Understanding of the pathophysiology of atherosclerosis can provide new strategies for the prevention and treatment of patients with this common disease. Clinical, epidemiologic, and basic molecular science studies have identified oxidative stress as a factor contributing to the development and progression of atherosclerosis. Oxidative stress also participates in the pathogenesis of endothelial dysfunction and hypertension, two important factors in many patients with atherosclerosis. Further, it contributes to mechanisms of disease progression such as lipid oxidation and vascular remodeling. This article reviews the role of reactive oxygen species and oxidative stress in atherosclerosis. -
Yoshioka J, Prince RN, Huang H, Perkins SB, Cruz FU, MacGillivray C, Lauffenburger DA, Lee RT. 2005. Cardiomyocyte hypertrophy and degradation of connexin43 through spatially restricted autocrine/paracrine heparin-binding EGF. Proceedings of the National Academy of Sciences of the United States of America. 102(30):10622-7. Pubmed: 16020536 Yoshioka J, Prince RN, Huang H, Perkins SB, Cruz FU, MacGillivray C, Lauffenburger DA, Lee RT. 2005. Cardiomyocyte hypertrophy and degradation of connexin43 through spatially restricted autocrine/paracrine heparin-binding EGF. Proceedings of the National Academy of Sciences of the United States of America. 102(30):10622-7. Pubmed: 16020536 Growth factor signaling can affect tissue remodeling through autocrine/paracrine mechanisms. Recent evidence indicates that EGF receptor transactivation by heparin-binding EGF (HB-EGF) contributes to hypertrophic signaling in cardiomyocytes. Here, we show that HB-EGF operates in a spatially restricted circuit in the extracellular space within the myocardium, revealing the critical nature of the local microenvironment in intercellular signaling. This highly localized microenvironment of HB-EGF signaling was demonstrated with 3D morphology, consistent with predictions from a computational model of EGF signaling. HB-EGF secretion by a given cardiomyocyte in mouse left ventricles led to cellular hypertrophy and reduced expression of connexin43 in the overexpressing cell and in immediately adjacent cells but not in cells farther away. Thus, HB-EGF acts as an autocrine and local paracrine cardiac growth factor that leads to loss of gap junction proteins within a spatially confined microenvironment. These findings demonstrate how cells can coordinate remodeling with their immediate neighboring cells with highly localized extracellular EGF signaling. -
Lee RT. 2005. Ask the doctor. My doctor told me that I have "low ejection fraction," but I feel fine. How can this be? I thought this was part of heart failure and would make someone feel bad. Should I do anything about it, even though I don't have any symptoms?. Harvard heart letter : from Harvard Medical School. 16(2):8. Pubmed: 16299909 Lee RT. 2005. Ask the doctor. My doctor told me that I have "low ejection fraction," but I feel fine. How can this be? I thought this was part of heart failure and would make someone feel bad. Should I do anything about it, even though I don't have any symptoms?. Harvard heart letter : from Harvard Medical School. 16(2):8. Pubmed: 16299909 -
Lammerding J, Hsiao J, Schulze PC, Kozlov S, Stewart CL, Lee RT. 2005. Abnormal nuclear shape and impaired mechanotransduction in emerin-deficient cells. The Journal of cell biology. 170(5):781-91. Pubmed: 16115958 Lammerding J, Hsiao J, Schulze PC, Kozlov S, Stewart CL, Lee RT. 2005. Abnormal nuclear shape and impaired mechanotransduction in emerin-deficient cells. The Journal of cell biology. 170(5):781-91. Pubmed: 16115958 Emery-Dreifuss muscular dystrophy can be caused by mutations in the nuclear envelope proteins lamin A/C and emerin. We recently demonstrated that A-type lamin-deficient cells have impaired nuclear mechanics and altered mechanotransduction, suggesting two potential disease mechanisms (Lammerding, J., P.C. Schulze, T. Takahashi, S. Kozlov, T. Sullivan, R.D. Kamm, C.L. Stewart, and R.T. Lee. 2004. J. Clin. Invest. 113:370-378). Here, we examined the function of emerin on nuclear mechanics and strain-induced signaling. Emerin-deficient mouse embryo fibroblasts have abnormal nuclear shape, but in contrast to A-type lamin-deficient cells, exhibit nuclear deformations comparable to wild-type cells in cellular strain experiments, and the integrity of emerin-deficient nuclear envelopes appeared normal in a nuclear microinjection assay. Interestingly, expression of mechanosensitive genes in response to mechanical strain was impaired in emerin-deficient cells, and prolonged mechanical stimulation increased apoptosis in emerin-deficient cells. Thus, emerin-deficient mouse embryo fibroblasts have apparently normal nuclear mechanics but impaired expression of mechanosensitive genes in response to strain, suggesting that emerin mutations may act through altered transcriptional regulation and not by increasing nuclear fragility. -
Narmoneva DA, Oni O, Sieminski AL, Zhang S, Gertler JP, Kamm RD, Lee RT. 2005. Self-assembling short oligopeptides and the promotion of angiogenesis. Biomaterials. 26(23):4837-46. Pubmed: 15763263 Narmoneva DA, Oni O, Sieminski AL, Zhang S, Gertler JP, Kamm RD, Lee RT. 2005. Self-assembling short oligopeptides and the promotion of angiogenesis. Biomaterials. 26(23):4837-46. Pubmed: 15763263 Because an adequate blood supply to and within tissues is an essential factor for successful tissue regeneration, promoting a functional microvasculature is a crucial factor for biomaterials. In this study, we demonstrate that short self-assembling peptides form scaffolds that provide an angiogenic environment promoting long-term cell survival and capillary-like network formation in three-dimensional cultures of human microvascular endothelial cells. Our data show that, in contrast to collagen type I, the peptide scaffold inhibits endothelial cell apoptosis in the absence of added angiogenic factors, accompanied by enhanced gene expression of the angiogenic factor VEGF. In addition, our results suggest that the process of capillary-like network formation and the size and spatial organization of cell networks may be controlled through manipulation of the scaffold properties, with a more rigid scaffold promoting extended structures with a larger inter-structure distance, as compared with more dense structures of smaller size observed in a more compliant scaffold. These findings indicate that self-assembling peptide scaffolds have potential for engineering vascularized tissues with control over angiogenic processes. Since these peptides can be modified in many ways, they may be uniquely valuable in regeneration of vascularized tissues. -
Schulze PC, Fang J, Kassik KA, Gannon J, Cupesi M, MacGillivray C, Lee RT, Rosenthal N. 2005. Transgenic overexpression of locally acting insulin-like growth factor-1 inhibits ubiquitin-mediated muscle atrophy in chronic left-ventricular dysfunction. Circulation research. 97(5):418-26. Pubmed: 16051886 Schulze PC, Fang J, Kassik KA, Gannon J, Cupesi M, MacGillivray C, Lee RT, Rosenthal N. 2005. Transgenic overexpression of locally acting insulin-like growth factor-1 inhibits ubiquitin-mediated muscle atrophy in chronic left-ventricular dysfunction. Circulation research. 97(5):418-26. Pubmed: 16051886 Metabolic abnormalities develop in various chronic diseases and lead to progressive catabolism with decrements in the skeletal musculature that result in muscle atrophy. We investigated pathways of skeletal muscle proteolysis using an experimental model of chronic left-ventricular dysfunction. Skeletal muscle atrophy developed in wild-type mice 12 weeks following myocardial infarction accompanied by an increase in total protein ubiquitination and enhanced proteasome activity, activation of Foxo transcription factors, and robust induction of the ubiquitin-protein ligase atrogin-1/MAFbx. Further studies identified skeletal muscle myosin as a specific target of ubiquitin-mediated degradation in muscle atrophy. In contrast, transgenic overexpression of a local isoform of insulin-like growth factor-1 prevented muscle atrophy and increased proteasome activity, inhibited skeletal muscle activation primarily of Foxo4, and blocked the expression of atrogin-1/MAFbx. These results suggest that skeletal muscle atrophy occurs through increased activity of the ubiquitin-proteasome pathway. The inhibition of muscle atrophy by local insulin-like growth factor-1 provides a promising therapeutic avenue for the prevention of skeletal muscle wasting in chronic heart failure and potentially other chronic diseases associated with skeletal muscle atrophy. -
Davis ME, Hsieh PC, Grodzinsky AJ, Lee RT. 2005. Custom design of the cardiac microenvironment with biomaterials. Circulation research. 97(1):8-15. Pubmed: 16002755 Davis ME, Hsieh PC, Grodzinsky AJ, Lee RT. 2005. Custom design of the cardiac microenvironment with biomaterials. Circulation research. 97(1):8-15. Pubmed: 16002755 Many strategies for repairing injured myocardium are under active investigation, with some early encouraging results. These strategies include cell therapies, despite little evidence of long-term survival of exogenous cells, and gene or protein therapies, often with incomplete control of locally-delivered dose of the factor. We propose that, ultimately, successful repair and regeneration strategies will require quantitative control of the myocardial microenvironment. This precision control can be engineered through designed biomaterials that provide quantitative adhesion, growth, or migration signals. Quantitative timed release of factors can be regulated by chemical design to direct cellular differentiation pathways such as angiogenesis and vascular maturation. Smart biomaterials respond to the local environment, such as protease activity or mechanical forces, with controlled release or activation. Most of these new biomaterials provide much greater flexibility for regenerating tissues ex vivo, but emerging technologies like self-assembling nanofibers can now establish intramyocardial cellular microenvironments by injection. This may allow percutaneous cardiac regeneration and repair approaches, or injectable-tissue engineering. Finally, materials can be made to multifunction by providing sequential signals with custom design of differential release kinetics for individual factors. Thus, new rationally-designed biomaterials no longer simply coexist with tissues, but can provide precision bioactive control of the microenvironment that may be required for cardiac regeneration and repair. -
Lee RT. 2005. The PEACE study: limiting the role of angiotensin-converting enzyme inhibitors in stable coronary artery disease. Current atherosclerosis reports. 7(3):211-2. Pubmed: 15811255 Lee RT. 2005. The PEACE study: limiting the role of angiotensin-converting enzyme inhibitors in stable coronary artery disease. Current atherosclerosis reports. 7(3):211-2. Pubmed: 15811255 -
Davis ME, Motion JP, Narmoneva DA, Takahashi T, Hakuno D, Kamm RD, Zhang S, Lee RT. 2005. Injectable self-assembling peptide nanofibers create intramyocardial microenvironments for endothelial cells. Circulation. 111(4):442-50. Pubmed: 15687132 Davis ME, Motion JP, Narmoneva DA, Takahashi T, Hakuno D, Kamm RD, Zhang S, Lee RT. 2005. Injectable self-assembling peptide nanofibers create intramyocardial microenvironments for endothelial cells. Circulation. 111(4):442-50. Pubmed: 15687132 Array -
Lammerding J, Lee RT. 2005. The nuclear membrane and mechanotransduction: impaired nuclear mechanics and mechanotransduction in lamin A/C deficient cells. Novartis Foundation symposium. 264:264-73; discussion 273-8. Pubmed: 15773759 Lammerding J, Lee RT. 2005. The nuclear membrane and mechanotransduction: impaired nuclear mechanics and mechanotransduction in lamin A/C deficient cells. Novartis Foundation symposium. 264:264-73; discussion 273-8. Pubmed: 15773759 Mutations in the lamin A/C gene cause a variety of human diseases including Emery-Dreifuss muscular dystrophy, dilated cardiomyopathy and Hutchinson-Gilford progeria syndrome. The tissue specific effects of lamin mutations are unclear, in part because the function of lamin A/C is incompletely defined, but the many muscle specific phenotypes suggest that defective lamin A/C could increase cellular mechanical sensitivity. Lamin A/C deficient fibroblasts were subjected to mechanical strain to measure nuclear mechanical properties and strain-induced signalling. We found that lamin A/C deficient fibroblasts are characterized by impaired nuclear mechanics and mechanotransduction, reflected by increased nuclear deformations, increased nuclear fragility, attenuated expression of mechanosensitive genes, and impaired transcriptional activation, leading to impaired viability of mechanically strained cells. Lamins and other nuclear envelope proteins can thus affect several levels of the mechanotransduction cascade, altering nuclear and cytoskeletal mechanics as well as playing an important role in mechanically activated gene regulation. Individual mutations in the lamin A/C gene could potentially selectively interfere with any of these functions, explaining the tissue-specific effects observed in the laminopathies. -
Yamawaki H, Pan S, Lee RT, Berk BC. 2005. Fluid shear stress inhibits vascular inflammation by decreasing thioredoxin-interacting protein in endothelial cells. The Journal of clinical investigation. 115(3):733-8. Pubmed: 15696199 Yamawaki H, Pan S, Lee RT, Berk BC. 2005. Fluid shear stress inhibits vascular inflammation by decreasing thioredoxin-interacting protein in endothelial cells. The Journal of clinical investigation. 115(3):733-8. Pubmed: 15696199 Regions in the vasculature that are exposed to steady laminar blood flow are protected from atherosclerosis as compared with regions where flow is disturbed. We found that flow decreased TNF-mediated VCAM1 expression by inhibiting JNK and p38. JNK inhibition correlated with inhibition of apoptosis signal-regulating kinase 1 (ASK1), a JNK and p38 activator. Thioredoxin-interacting protein (TXNIP) is a stress-responsive protein that inhibits thioredoxin (TRX) activity. Since thioredoxin inhibits ASK1, we hypothesized that changes in TXNIP-TRX-ASK1 interactions mediate the antiinflammatory effects of flow. To explore this, we used perfused vessels and cultured ECs. Exposure of rabbit aortae or ECs to normal flow (12 dyn/cm2, 24 hours) was associated with decreased TXNIP expression and increased TRX activity compared with exposure to low flow (0.4 dyn/cm2). Normal flow inhibited TNF activation of JNK/p38 and VCAM1 expression. In cultured ECs, reduction of TXNIP expression by small interfering RNA increased TRX binding to ASK1 and inhibited TNF activation of JNK/p38 and VCAM1 expression. Conversely, overexpression of TXNIP stimulated JNK and p38. In aortae from TXNIP-deficient mice, TNF-induced VCAM1 expression was inhibited. The data suggest that TXNIP and TRX are key components of biomechanical signal transduction and establish them as potentially novel regulators of TNF signaling and inflammation in ECs. -
Huang H, Sylvan J, Jonas M, Barresi R, So PT, Campbell KP, Lee RT. 2005. Cell stiffness and receptors: evidence for cytoskeletal subnetworks. American journal of physiology. Cell physiology. 288(1):C72-80. Pubmed: 15385268 Huang H, Sylvan J, Jonas M, Barresi R, So PT, Campbell KP, Lee RT. 2005. Cell stiffness and receptors: evidence for cytoskeletal subnetworks. American journal of physiology. Cell physiology. 288(1):C72-80. Pubmed: 15385268 Viscoelastic models of cells often treat cells as homogeneous objects. However, studies have demonstrated that cellular properties are local and can change dramatically on the basis of the location probed. Because membrane receptors are linked in various ways to the intracellular space, with some receptors linking to the cytoskeleton and others diffusing freely without apparent linkages, the cellular physical response to mechanical stresses is expected to depend on the receptor engaged. In this study, we tested the hypothesis that cellular mechanical stiffness as measured via cytoskeletally linked receptors is greater than stiffness measured via receptors that are not cytoskeletally linked. We used a magnetic micromanipulator to apply linear stresses to magnetic beads attached to living cells via selected receptors. One of the receptor classes probed, the dystroglycan receptors, is linked to the cytoskeleton, while the other, the transferrin receptors, is not. Fibronectin-coated beads were used to test cellular mechanical properties of the cytoskeleton without membrane dependence by allowing the beads to endocytose. For epithelial cells, transferrin-dependent stiffness and endocytosed bead-dependent stiffness were similar, while dystroglycan-dependent stiffness was significantly lower. For smooth muscle cells, dystroglycan-dependent stiffness was similar to the endocytosed bead-dependent stiffness, while the transferrin-dependent stiffness was lower. The conclusion of this study is that the measured cellular stiffness is critically influenced by specific receptor linkage and by cell type and raises the intriguing possibility of the existence of separate cytoskeletal networks with distinct mechanical properties that link different classes of receptors. 2004
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Lammerding J, Schulze PC, Takahashi T, Kozlov S, Sullivan T, Kamm RD, Stewart CL, Lee RT. 2004. Lamin A/C deficiency causes defective nuclear mechanics and mechanotransduction. The Journal of clinical investigation. 113(3):370-8. Pubmed: 14755334 Lammerding J, Schulze PC, Takahashi T, Kozlov S, Sullivan T, Kamm RD, Stewart CL, Lee RT. 2004. Lamin A/C deficiency causes defective nuclear mechanics and mechanotransduction. The Journal of clinical investigation. 113(3):370-8. Pubmed: 14755334 Mutations in the lamin A/C gene (LMNA) cause a variety of human diseases including Emery-Dreifuss muscular dystrophy, dilated cardiomyopathy, and Hutchinson-Gilford progeria syndrome. The tissue-specific effects of lamin mutations are unclear, in part because the function of lamin A/C is incompletely defined, but the many muscle-specific phenotypes suggest that defective lamin A/C could increase cellular mechanical sensitivity. To investigate the role of lamin A/C in mechanotransduction, we subjected lamin A/C-deficient mouse embryo fibroblasts to mechanical strain and measured nuclear mechanical properties and strain-induced signaling. We found that Lmna-/- cells have increased nuclear deformation, defective mechanotransduction, and impaired viability under mechanical strain. NF-kappaB-regulated transcription in response to mechanical or cytokine stimulation was attenuated in Lmna-/- cells despite increased transcription factor binding. Lamin A/C deficiency is thus associated with both defective nuclear mechanics and impaired mechanically activated gene transcription. These findings suggest that the tissue-specific effects of lamin A/C mutations observed in the laminopathies may arise from varying degrees of impaired nuclear mechanics and transcriptional activation. -
Maly IV, Lee RT, Lauffenburger DA. 2004. A model for mechanotransduction in cardiac muscle: effects of extracellular matrix deformation on autocrine signaling. Annals of biomedical engineering. 32(10):1319-35. Pubmed: 15535051 Maly IV, Lee RT, Lauffenburger DA. 2004. A model for mechanotransduction in cardiac muscle: effects of extracellular matrix deformation on autocrine signaling. Annals of biomedical engineering. 32(10):1319-35. Pubmed: 15535051 We present a computational model and analysis of the dynamic behavior of epidermal growth factor receptor (EGFR) signaling in cardiac muscle tissue, with the aim of exploring transduction of mechanical loading into cellular signaling that could lead to cardiac hypertrophy. For this purpose, we integrated recently introduced models for ligand dynamics within compliant intercellular spaces and for the spatial dynamics of intracellular signaling with a positive feedback autocrine circuit. These kinetic models are here considered in the setting of a tissue consisting of cardiomyocytes and blood capillaries as a structural model for the myocardium. We show that autocrine EGFR signaling can be induced directly by mechanical deformation of the tissue and demonstrate the possibility of self-organization of signaling that is anisotropic on the tissue level and can reflect anisotropy of the mechanical deformation. These predictions point to the potential capabilities of the EGFR autocrine signaling circuit in mechanotransduction and suggest a new perspective on the cardiac hypertrophic response. -
Narmoneva DA, Vukmirovic R, Davis ME, Kamm RD, Lee RT. 2004. Endothelial cells promote cardiac myocyte survival and spatial reorganization: implications for cardiac regeneration. Circulation. 110(8):962-8. Pubmed: 15302801 Narmoneva DA, Vukmirovic R, Davis ME, Kamm RD, Lee RT. 2004. Endothelial cells promote cardiac myocyte survival and spatial reorganization: implications for cardiac regeneration. Circulation. 110(8):962-8. Pubmed: 15302801 Array -
Lammerding J, Kamm RD, Lee RT. 2004. Mechanotransduction in cardiac myocytes. Annals of the New York Academy of Sciences. 1015:53-70. Pubmed: 15201149 Lammerding J, Kamm RD, Lee RT. 2004. Mechanotransduction in cardiac myocytes. Annals of the New York Academy of Sciences. 1015:53-70. Pubmed: 15201149 Cardiac myocytes react to diverse mechanical demands with a multitude of transient and long-term responses to normalize the cellular mechanical environment. Several stretch-activated signaling pathways have been identified, most prominently guanine nucleotide binding proteins (G-proteins), mitogen-activated protein kinases (MAPK), Janus-associated kinase/signal transducers and activators of transcription (JAK/STAT), protein kinase C (PKC), calcineurin, intracellular calcium regulation, and several autocrine and paracrine factors. Multiple levels of crosstalk exist between pathways. The cellular response to changes in the mechanical environment can lead to cardiac myocyte hypertrophy, cellular growth that can be accompanied by pathological myocyte dysfunction, and tissue fibrosis. Several candidates for the primary mechanosensor in cardiac myocytes have been identified, ranging from stretch-activated ion channels in the membrane to yet-unknown mechanosensitive mechanisms in the nucleus. New and refined experimental techniques will exploit advances in molecular biology and biological imaging to study mechanotransduction in isolated cells and genetically engineered mice to explore the function of individual proteins. -
Zee RY, Cook NR, Cheng S, Erlich HA, Lindpaintner K, Lee RT, Ridker PM. 2004. Threonine for alanine substitution in the eotaxin (CCL11) gene and the risk of incident myocardial infarction. Atherosclerosis. 175(1):91-4. Pubmed: 15186951 Zee RY, Cook NR, Cheng S, Erlich HA, Lindpaintner K, Lee RT, Ridker PM. 2004. Threonine for alanine substitution in the eotaxin (CCL11) gene and the risk of incident myocardial infarction. Atherosclerosis. 175(1):91-4. Pubmed: 15186951 Recent studies suggest that the chemokine eotaxin may participate in atherosclerosis. Threonine (T) for alanine (A) substitution at amino acid 23 in the eotaxin gene (CCL11) has been associated with risk of developing allergic-inflammatory disorders. However, no genetic-epidemiological data are available on the risk of cardiovascular disease associated with this polymorphism. Using DNA samples collected at baseline in a prospective cohort of 14,916 initially healthy American men, we evaluated the A23T polymorphism among 523 individuals who subsequently developed myocardial infarction (MI) and among 2092 individuals who remained free of reported cardiovascular disease over a mean follow-up period of 13.2 years. The T23 allele was significantly associated with risk of myocardial infarction (odds ratio (OR) in an age and smoking adjusted recessive model of inheritance, 1.86; 95% confidence interval (CI), 1.15-3.01; P = 0.012). This risk effect remained statistically significant in analyses further controlling for body mass index, history of hypertension, the presence of diabetes, and randomized treatment assignment (OR, 1.95; 95% CI, 1.19-3.18; P = 0.008). In this cohort, a T for A substitution at amino acid 23 in the eotaxin gene is associated with increased risk for incident myocardial infarction. If confirmed in other cohorts, these data support the emerging hypothesis that eotaxin participates in atherosclerosis. -
Shimizu K, Shichiri M, Libby P, Lee RT, Mitchell RN. 2004. Th2-predominant inflammation and blockade of IFN-gamma signaling induce aneurysms in allografted aortas. The Journal of clinical investigation. 114(2):300-8. Pubmed: 15254597 Shimizu K, Shichiri M, Libby P, Lee RT, Mitchell RN. 2004. Th2-predominant inflammation and blockade of IFN-gamma signaling induce aneurysms in allografted aortas. The Journal of clinical investigation. 114(2):300-8. Pubmed: 15254597 Abdominal aortic aneurysms (AAAs) cause death due to complications related to expansion and rupture. The underlying mechanisms that drive AAA development remain largely unknown. We recently described evidence for a shift toward T helper type 2 (Th2) cell responses in human AAAs compared with stenotic atheromas. To evaluate putative pathways in AAA formation, we induced Th1- or Th2-predominant cytokine environments in an inflammatory aortic lesion using murine aortic transplantation into WT hosts or those lacking the receptors for the hallmark Th1 cytokine IFN-gamma, respectively. Allografts in WT recipients developed intimal hyperplasia, whereas allografts in IFN-gamma receptor-deficient (GRKO) hosts developed severe AAA formation associated with markedly increased levels of MMP-9 and MMP-12. Allografts in GRKO recipients treated with anti-IL-4 antibody to block the characteristic IL-4 Th2 cytokine or allografts in GRKO hosts also congenitally deficient in IL-4 did not develop AAA and likewise exhibited attenuated collagenolytic and elastolytic activities. These observations demonstrate an important dichotomy between cellular immune responses that induce IFN-gamma- or IL-4-dominated cytokine environments. The findings establish important regulatory roles for a Th1/Th2 cytokine balance in modulating matrix remodeling and have important implications for the pathophysiology of AAAs and arteriosclerosis. -
Mack PJ, Kaazempur-Mofrad MR, Karcher H, Lee RT, Kamm RD. 2004. Force-induced focal adhesion translocation: effects of force amplitude and frequency. American journal of physiology. Cell physiology. 287(4):C954-62. Pubmed: 15189816 Mack PJ, Kaazempur-Mofrad MR, Karcher H, Lee RT, Kamm RD. 2004. Force-induced focal adhesion translocation: effects of force amplitude and frequency. American journal of physiology. Cell physiology. 287(4):C954-62. Pubmed: 15189816 Vascular endothelial cells rapidly transduce local mechanical forces into biological signals through numerous processes including the activation of focal adhesion sites. To examine the mechanosensing capabilities of these adhesion sites, focal adhesion translocation was monitored over the course of 5 min with GFP-paxillin while applying nN-level magnetic trap shear forces to the cell apex via integrin-linked magnetic beads. A nongraded steady-load threshold for mechanotransduction was established between 0.90 and 1.45 nN. Activation was greatest near the point of forcing (<7.5 microm), indicating that shear forces imposed on the apical cell membrane transmit nonuniformly to the basal cell surface and that focal adhesion sites may function as individual mechanosensors responding to local levels of force. Results from a continuum, viscoelastic finite element model of magnetocytometry that represented experimental focal adhesion attachments provided support for a nonuniform force transmission to basal surface focal adhesion sites. To further understand the role of force transmission on focal adhesion activation and dynamics, sinusoidally varying forces were applied at 0.1, 1.0, 10, and 50 Hz with a 1.45 nN offset and a 2.25 nN maximum. At 10 and 50 Hz, focal adhesion activation did not vary with spatial location, as observed for steady loading, whereas the response was minimized at 1.0 Hz. Furthermore, applying the tyrosine kinase inhibitors genistein and PP2, a specific Src family kinase inhibitor, showed tyrosine kinase signaling has a role in force-induced translocation. These results highlight the mutual importance of force transmission and biochemical signaling in focal adhesion mechanotransduction. -
Cheng GC, Schulze PC, Lee RT, Sylvan J, Zetter BR, Huang H. 2004. Oxidative stress and thioredoxin-interacting protein promote intravasation of melanoma cells. Experimental cell research. 300(2):297-307. Pubmed: 15474995 Cheng GC, Schulze PC, Lee RT, Sylvan J, Zetter BR, Huang H. 2004. Oxidative stress and thioredoxin-interacting protein promote intravasation of melanoma cells. Experimental cell research. 300(2):297-307. Pubmed: 15474995 Although intravasation may be a critical rate-limiting step in the metastatic cascade, the role of oxidative stress in intravasation is unknown. We tested the hypothesis that reactive oxygen species (ROS), regulated by thioredoxin interacting protein (Txnip) through the action of thioredoxin (Trx), influence human SK-MEL-28 melanoma cell reverse (basolateral-to-apical) transendothelial migration (TEM) in vitro as a model for intravasation. Reverse transendothelial migration was dose-dependently induced by hydrogen peroxide 2.4-fold for 0.1 microM (P < 0.01) and 3.9-fold for 1 microM (P < 0.001) vs. control, and this effect was blocked by the antioxidant N-acetylcysteine. Overexpression of Txnip by infecting melanoma cells with adenovirus increased TEM 3-fold vs. control (P < 0.001), and this increase was blocked by N-acetylcysteine, indicating a redox-sensitive mechanism. Conversely, thioredoxin overexpression blocked hydrogen peroxide-induced TEM. Exposure to ultraviolet-A radiation increased ROS 1.8-fold (P < 0.01), and this was accompanied by a 45% reduction (P < 0.05) in thioredoxin activity and an 11.4-fold (P < 0.001) increase in Txnip gene expression. These data suggest that TEM of melanoma cells during intravasation is in part mediated by ROS-sensitive cellular signaling cascades, may be controlled by Txnip and its interaction with thioredoxin that in turn modulates cellular levels of oxidative stress, and may be initiated by ultraviolet-A induction of this cascade. -
Kaazempur-Mofrad MR, Isasi AG, Younis HF, Chan RC, Hinton DP, Sukhova G, LaMuraglia GM, Lee RT, Kamm RD. 2004. Characterization of the atherosclerotic carotid bifurcation using MRI, finite element modeling, and histology. Annals of biomedical engineering. 32(7):932-46. Pubmed: 15298431 Kaazempur-Mofrad MR, Isasi AG, Younis HF, Chan RC, Hinton DP, Sukhova G, LaMuraglia GM, Lee RT, Kamm RD. 2004. Characterization of the atherosclerotic carotid bifurcation using MRI, finite element modeling, and histology. Annals of biomedical engineering. 32(7):932-46. Pubmed: 15298431 Atherogenesis is known to be associated with the stresses that act on or within the arterial wall. Still, the uneven distribution of atherosclerotic lesions and the impact of vessel remodeling on disease progression are poorly understood. A methodology is proposed to study the correlations between fluid dynamic parameters and histological markers of atherosclerosis. Trends suggested by preliminary data from four patients with advanced carotid bifurcation arterial disease are examined and compared to hypotheses in the literature. Four patients were scanned using MRI and ultrasound, and subsequently underwent carotid endarterectomy. For each patient. a geometric model and a numerical mesh were constructed from MR data, and velocity boundary conditions established. Computations yield values for average wall shear stress (WSS), maximum wall shear stress temporal gradient (WSSTG), and Oscillatory Shear Index (OSI). Following surgery, the excised plaques were sectioned, stained for smooth muscle cells (SMC), macrophages (M phi), lipid (LIP), and collagen (COL), and analyzed quantitatively. Correlations attempted between the various fluid dynamic variables and the biological markers were interesting but inconclusive. Tendencies of WSSTG and WSS to correlate negatively with M phi and LIP, and positively with COL and SMC, as well as tendencies of OSI to correlate positively with Mphi and LIP and negatively with COL and SMC, were observed. These trends agree with hypotheses in the literature, which are based on ex vivo and in vitro experimental studies. -
Shimpo M, Morrow DA, Weinberg EO, Sabatine MS, Murphy SA, Antman EM, Lee RT. 2004. Serum levels of the interleukin-1 receptor family member ST2 predict mortality and clinical outcome in acute myocardial infarction. Circulation. 109(18):2186-90. Pubmed: 15117853 Shimpo M, Morrow DA, Weinberg EO, Sabatine MS, Murphy SA, Antman EM, Lee RT. 2004. Serum levels of the interleukin-1 receptor family member ST2 predict mortality and clinical outcome in acute myocardial infarction. Circulation. 109(18):2186-90. Pubmed: 15117853 Array -
Huang H, Kamm RD, Lee RT. 2004. Cell mechanics and mechanotransduction: pathways, probes, and physiology. American journal of physiology. Cell physiology. 287(1):C1-11. Pubmed: 15189819 Huang H, Kamm RD, Lee RT. 2004. Cell mechanics and mechanotransduction: pathways, probes, and physiology. American journal of physiology. Cell physiology. 287(1):C1-11. Pubmed: 15189819 Cells face not only a complex biochemical environment but also a diverse biomechanical environment. How cells respond to variations in mechanical forces is critical in homeostasis and many diseases. The mechanisms by which mechanical forces lead to eventual biochemical and molecular responses remain undefined, and unraveling this mystery will undoubtedly provide new insight into strengthening bone, growing cartilage, improving cardiac contractility, and constructing tissues for artificial organs. In this article we review the physical bases underlying the mechanotransduction process, techniques used to apply controlled mechanical stresses on living cells and tissues to probe mechanotransduction, and some of the important lessons that we are learning from mechanical stimulation of cells with precisely controlled forces. -
Agrawal RS, Muangman S, Layne MD, Melo L, Perrella MA, Lee RT, Zhang L, Lopez-Ilasaca M, Dzau VJ. 2004. Pre-emptive gene therapy using recombinant adeno-associated virus delivery of extracellular superoxide dismutase protects heart against ischemic reperfusion injury, improves ventricular function and prolongs survival. Gene therapy. 11(12):962-9. Pubmed: 15029230 Agrawal RS, Muangman S, Layne MD, Melo L, Perrella MA, Lee RT, Zhang L, Lopez-Ilasaca M, Dzau VJ. 2004. Pre-emptive gene therapy using recombinant adeno-associated virus delivery of extracellular superoxide dismutase protects heart against ischemic reperfusion injury, improves ventricular function and prolongs survival. Gene therapy. 11(12):962-9. Pubmed: 15029230 In high-risk patients, the ideal cardiovascular gene therapy requires a strategy that provides long-term protection of myocardium against episodes of ischemic/reperfusion injury. We report the development of an efficient, long-lasting pre-emptive gene therapy strategy in a rat model of ischemic-reperfusion (I/R) injury of heart. At 6 weeks prior to myocardial injury, the human extracellular superoxide dismutase (Ec-SOD) gene was delivered by direct intramyocardial injections, using a recombinant adeno-associated virus vector. Significant myocardial protection was documented by the decrease in infarct size at 24 h post I/R, improved left ventricular function at 7 weeks postinjury, and enhanced long-term survival in the SOD treated group. This concept of preinjury delivery and 'pre-emptive' gene therapy via the expression of a secreted protein that renders paracrine therapeutic action can be an effective strategy for organ protection against future injury. -
Yoshioka J, Schulze PC, Cupesi M, Sylvan JD, MacGillivray C, Gannon J, Huang H, Lee RT. 2004. Thioredoxin-interacting protein controls cardiac hypertrophy through regulation of thioredoxin activity. Circulation. 109(21):2581-6. Pubmed: 15123525 Yoshioka J, Schulze PC, Cupesi M, Sylvan JD, MacGillivray C, Gannon J, Huang H, Lee RT. 2004. Thioredoxin-interacting protein controls cardiac hypertrophy through regulation of thioredoxin activity. Circulation. 109(21):2581-6. Pubmed: 15123525 Array -
Schulze PC, Lee RT. 2004. Macrophage-mediated cardiac fibrosis. Circulation research. 95(6):552-3. Pubmed: 15375020 Schulze PC, Lee RT. 2004. Macrophage-mediated cardiac fibrosis. Circulation research. 95(6):552-3. Pubmed: 15375020 -
Schulze PC, Yoshioka J, Takahashi T, He Z, King GL, Lee RT. 2004. Hyperglycemia promotes oxidative stress through inhibition of thioredoxin function by thioredoxin-interacting protein. The Journal of biological chemistry. 279(29):30369-74. Pubmed: 15128745 Schulze PC, Yoshioka J, Takahashi T, He Z, King GL, Lee RT. 2004. Hyperglycemia promotes oxidative stress through inhibition of thioredoxin function by thioredoxin-interacting protein. The Journal of biological chemistry. 279(29):30369-74. Pubmed: 15128745 Increased intracellular reactive oxygen species (ROS) contribute to vascular disease and pro-atherosclerotic effects of diabetes mellitus may be mediated by oxidative stress. Several ROS-scavenging systems tightly control cellular redox balance; however, their role in hyperglycemia-induced oxidative stress is unclear. A ubiquitous antioxidative mechanism for regulating cellular redox balance is thioredoxin, a highly conserved thiol reductase that interacts with an endogenous inhibitor, thioredoxin-interacting protein (Txnip). Here we show that hyperglycemia inhibits thioredoxin ROS-scavenging function through p38 MAPK-mediated induction of Txnip. Overexpression of Txnip increased oxidative stress, while Txnip gene silencing restored thioredoxin activity in hyperglycemia. Diabetic animals exhibited increased vascular expression of Txnip and reduced thioredoxin activity, which normalized with insulin treatment. These results provide evidence for the impairment of a major ROS-scavenging system in hyperglycemia. These studies implicate reduced thioredoxin activity through interaction with Txnip as an important mechanism for vascular oxidative stress in diabetes mellitus. 2003
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Frantz S, Ducharme A, Sawyer D, Rohde LE, Kobzik L, Fukazawa R, Tracey D, Allen H, Lee RT, Kelly RA. 2003. Targeted deletion of caspase-1 reduces early mortality and left ventricular dilatation following myocardial infarction. Journal of molecular and cellular cardiology. 35(6):685-94. Pubmed: 12788386 Frantz S, Ducharme A, Sawyer D, Rohde LE, Kobzik L, Fukazawa R, Tracey D, Allen H, Lee RT, Kelly RA. 2003. Targeted deletion of caspase-1 reduces early mortality and left ventricular dilatation following myocardial infarction. Journal of molecular and cellular cardiology. 35(6):685-94. Pubmed: 12788386 Objective. - Mice with targeted deletion of caspase-1 (interleukin-1beta (IL-1beta)-converting enzyme) lack the active forms of IL-1beta and IL-18, two cytokines implicated in maladaptive ventricular remodeling following cardiac injury. We, therefore, investigated the extent of ventricular dilation in caspase-1-knockout (KO) mice. Methods and results. - Transthoracic echocardiography was performed at days 1, 4, and 9 following left anterior descending artery ligation in caspase-1-KO and wild-type (WT) control animals, including M-mode and short-axis imaging at both mid-papillary and apical levels. Although initial post-operative mortality was lower in KO than in WT animals (21.4% WT, 12.0% KO, P < 0.001), there was no difference in mortality between 24 h and 9 d (P = n.s.). Caspase-1 KOs exhibited significantly less mid-papillary ventricular dilatation at days 4 and 9 compared to day 1 post-myocardial infarction (MI) (P < 0.05). Caspase-1 KOs also had a marked (50%) reduction in the level of matrix metalloproteinase 3 (MMP-3), although no significant changes occurred in other MMPs or in tissue inhibitors of metalloproteinase 1 levels by immunoblot analysis. Although IL-beta plasma levels were not detectable, both IL-18 levels and the rate of apoptosis in remodeling, non-infarcted muscle were significantly higher in WT compared to caspase-1-KO animals.Conclusion. - Mice lacking caspase-1 exhibited both improved peri-infarct survival and a decreased rate of ventricular dilatation, possibly due in part to a decrease in MMP-3 activity, IL-18 production, and a reduction in the rate of apoptosis after experimental MI. -
Takahashi T, Lord B, Schulze PC, Fryer RM, Sarang SS, Gullans SR, Lee RT. 2003. Ascorbic acid enhances differentiation of embryonic stem cells into cardiac myocytes. Circulation. 107(14):1912-6. Pubmed: 12668514 Takahashi T, Lord B, Schulze PC, Fryer RM, Sarang SS, Gullans SR, Lee RT. 2003. Ascorbic acid enhances differentiation of embryonic stem cells into cardiac myocytes. Circulation. 107(14):1912-6. Pubmed: 12668514 Array -
Blake GJ, Ostfeld RJ, Yucel EK, Varo N, Schönbeck U, Blake MA, Gerhard M, Ridker PM, Libby P, Lee RT. 2003. Soluble CD40 ligand levels indicate lipid accumulation in carotid atheroma: an in vivo study with high-resolution MRI. Arteriosclerosis, thrombosis, and vascular biology. 23(1):e11-4. Pubmed: 12524242 Blake GJ, Ostfeld RJ, Yucel EK, Varo N, Schönbeck U, Blake MA, Gerhard M, Ridker PM, Libby P, Lee RT. 2003. Soluble CD40 ligand levels indicate lipid accumulation in carotid atheroma: an in vivo study with high-resolution MRI. Arteriosclerosis, thrombosis, and vascular biology. 23(1):e11-4. Pubmed: 12524242 Array -
Yoshioka J, Lee RT. 2003. Cardiovascular genomics. Cardiovascular pathology : the official journal of the Society for Cardiovascular Pathology. 12(5):249-54. Pubmed: 14507573 Yoshioka J, Lee RT. 2003. Cardiovascular genomics. Cardiovascular pathology : the official journal of the Society for Cardiovascular Pathology. 12(5):249-54. Pubmed: 14507573 The ongoing explosion of genomic information is revolutionizing cardiovascular science. More complete genomic maps allow easier identification of genes that cause monogenic inherited diseases. In addition, analyses of variations in gene expression in cardiovascular diseases are revealing new potential candidate genes as well as novel biomarkers for many common, multifactorial diseases. While experiments are revealing new pathophysiologic pathways, these genomic studies are also generating enormous amounts of data. Even as we learn how to sift through mountains of genomic information, new technologies in proteomics are rapidly advancing and promise to provide additional critical tools for diagnosis and for identifying new therapies. -
Takahashi T, Lee RT. 2003. Dendritic cells in neointima formation: from where did you come, and what are you doing here?. Journal of the American College of Cardiology. 42(5):939-41. Pubmed: 12957446 Takahashi T, Lee RT. 2003. Dendritic cells in neointima formation: from where did you come, and what are you doing here?. Journal of the American College of Cardiology. 42(5):939-41. Pubmed: 12957446 -
Weinberg EO, Shimpo M, Hurwitz S, Tominaga S, Rouleau JL, Lee RT. 2003. Identification of serum soluble ST2 receptor as a novel heart failure biomarker. Circulation. 107(5):721-6. Pubmed: 12578875 Weinberg EO, Shimpo M, Hurwitz S, Tominaga S, Rouleau JL, Lee RT. 2003. Identification of serum soluble ST2 receptor as a novel heart failure biomarker. Circulation. 107(5):721-6. Pubmed: 12578875 Array -
Schmitt JP, Semsarian C, Arad M, Gannon J, Ahmad F, Duffy C, Lee RT, Seidman CE, Seidman JG. 2003. Consequences of pressure overload on sarcomere protein mutation-induced hypertrophic cardiomyopathy. Circulation. 108(9):1133-8. Pubmed: 12925456 Schmitt JP, Semsarian C, Arad M, Gannon J, Ahmad F, Duffy C, Lee RT, Seidman CE, Seidman JG. 2003. Consequences of pressure overload on sarcomere protein mutation-induced hypertrophic cardiomyopathy. Circulation. 108(9):1133-8. Pubmed: 12925456 Array -
Rohde LE, Lee RT. 2003. Pathophysiology of atherosclerotic plaque development and rupture: an overview. Seminars in vascular medicine. 3(4):347-54. Pubmed: 15199441 Rohde LE, Lee RT. 2003. Pathophysiology of atherosclerotic plaque development and rupture: an overview. Seminars in vascular medicine. 3(4):347-54. Pubmed: 15199441 Atherosclerosis is predominantly a clinically silent process, and a substantial percentage of patients are first aware of its consequences through the acute and catastrophic event of thrombosis. Extensive basic and clinical research in the 1990s revealed that plaque disruption initiates the majority of thromboses. Furthermore, recent studies indicate that inflammation plays a major role in the pathophysiology, from initiation of the atheroma to the actual thrombosis itself. Attention has now focused on morphological, mechanical, and biochemical characteristics that increase plaque vulnerability, as determination of these features may allow identification of plaques that are most likely to cause symptoms and acute events in the future. This article reviews basic pathophysiologic aspects of atherosclerotic plaque development and rupture to provide the necessary background for understanding the crucial role of inflammation in acute coronary syndromes. -
Schulze PC, de Keulenaer GW, Kassik KA, Takahashi T, Chen Z, Simon DI, Lee RT. 2003. Biomechanically induced gene iex-1 inhibits vascular smooth muscle cell proliferation and neointima formation. Circulation research. 93(12):1210-7. Pubmed: 14592999 Schulze PC, de Keulenaer GW, Kassik KA, Takahashi T, Chen Z, Simon DI, Lee RT. 2003. Biomechanically induced gene iex-1 inhibits vascular smooth muscle cell proliferation and neointima formation. Circulation research. 93(12):1210-7. Pubmed: 14592999 Mechanotransduction plays a prominent role in vascular pathophysiology but is incompletely understood. In this study, we report the biomechanical induction of the immediate early response gene iex-1 in vascular smooth muscle cells (SMCs). Mechanical induction of iex-1 was confirmed by Northern (30-fold induction after 2 hours) and Western (6-fold induction after 24 hours) analyses. Expression of iex-1 was regulated by mechanical activation of nuclear factor (NF)-kappaB and abolished by overexpression of IkappaB in SMCs. The function of iex-1 in SMCs was explored by gene transfer using adenoviral vectors overexpressing iex-1. After 48 hours of 4% cyclic mechanical strain, adenoviral vectors overexpressing iex-1-infected cells had lower 3[H]-thymidine incorporation compared with AdGFP-infected controls (71.3+/-8.5% versus 180.2+/-19.4% in controls; P<0.001). Overexpression of iex-1 suppressed mitogenesis induced by platelet-derived growth factor (208.1+/-108.3% versus 290.0+/-120.5% in controls; P<0.05). This was accompanied by reduced degradation of p27kip1, inhibition of Rb hyperphosphorylation, and reduced cell cycle progression. To investigate functional effects of iex-1 in vivo, we performed carotid artery mechanical injury and endothelial denudation in low-density lipoprotein receptor-deficient mice followed by intraluminal injection of adenoviral vectors (3x10(9) pfu in 50 microL) for overexpression of iex-1 or gfp (control). Vascular overexpression of iex-1 reduced neointima formation 2 weeks after injury (intima/media ratio, 0.23+/-0.04 versus 0.5+/-0.24 in controls; P<0.05). Our findings demonstrate that biomechanical strain induces iex-1 with subsequent antiproliferative effects in SMCs and that selective gene transfer of iex-1 inhibits the local vascular response after injury. These findings suggest that the induction of iex-1 represents a novel negative biomechanical feedback mechanism limiting the vascular response to injury. -
Karcher H, Lammerding J, Huang H, Lee RT, Kamm RD, Kaazempur-Mofrad MR. 2003. A three-dimensional viscoelastic model for cell deformation with experimental verification. Biophysical journal. 85(5):3336-49. Pubmed: 14581235 Karcher H, Lammerding J, Huang H, Lee RT, Kamm RD, Kaazempur-Mofrad MR. 2003. A three-dimensional viscoelastic model for cell deformation with experimental verification. Biophysical journal. 85(5):3336-49. Pubmed: 14581235 A three-dimensional viscoelastic finite element model is developed for cell micromanipulation by magnetocytometry. The model provides a robust tool for analysis of detailed strain/stress fields induced in the cell monolayer produced by forcing one microbead attached atop a single cell or cell monolayer on a basal substrate. Both the membrane/cortex and the cytoskeleton are modeled as Maxwell viscoelastic materials, but the structural effect of the membrane/cortex was found to be negligible on the timescales corresponding to magnetocytometry. Numerical predictions are validated against experiments performed on NIH 3T3 fibroblasts and previous experimental work. The system proved to be linear with respect to cytoskeleton mechanical properties and bead forcing. Stress and strain patterns were highly localized, suggesting that the effects of magnetocytometry are confined to a region extending <10 microm from the bead. Modulation of cell height has little effect on the results, provided the monolayer is >5 micro m thick. NIH 3T3 fibroblasts exhibited a viscoelastic timescale of approximately 1 s and a shear modulus of approximately 1000 Pa. -
Weinberg EO, Mirotsou M, Gannon J, Dzau VJ, Lee RT, Pratt RE. 2003. Sex dependence and temporal dependence of the left ventricular genomic response to pressure overload. Physiological genomics. 12(2):113-27. Pubmed: 12454204 Weinberg EO, Mirotsou M, Gannon J, Dzau VJ, Lee RT, Pratt RE. 2003. Sex dependence and temporal dependence of the left ventricular genomic response to pressure overload. Physiological genomics. 12(2):113-27. Pubmed: 12454204 To characterize responses of the left ventricle (LV) to pressure overload at the genomic level, we performed high-density microarray analysis on individual mouse LVs. Male and female mice underwent transverse aortic constriction. At 1 day and 30 wk, the LV free wall was harvested and RNA isolated from 27 individual ventricles was analyzed on Mu74Av2 GeneChips, which contain approximately 12,483 distinct genes. Interestingly, a greater number of genes was regulated in response to acute overload than in response to chronic overload. Hierarchical cluster analysis revealed the presence of several distinct expression profiles. Of these clusters, the majority contained genes that were regulated either in response to acute overload or both acute and chronic overload. In addition, clusters revealing sex-specific responses to overload were detected. In summary, the acute and chronic genomic responses to pressure overload are distinct. Moreover, sex modifies these responses. Furthermore, these studies have uncovered several novel and potentially important genes that are regulated in response to overload and may open unrecognized avenues for further functional analysis. -
Lindsey ML, Yoshioka J, MacGillivray C, Muangman S, Gannon J, Verghese A, Aikawa M, Libby P, Krane SM, Lee RT. 2003. Effect of a cleavage-resistant collagen mutation on left ventricular remodeling. Circulation research. 93(3):238-45. Pubmed: 12855673 Lindsey ML, Yoshioka J, MacGillivray C, Muangman S, Gannon J, Verghese A, Aikawa M, Libby P, Krane SM, Lee RT. 2003. Effect of a cleavage-resistant collagen mutation on left ventricular remodeling. Circulation research. 93(3):238-45. Pubmed: 12855673 Matrix metalloproteinase-mediated degradation of type I collagen may play a role in cardiac remodeling after strain or injury. To explore this hypothesis, we used mice homozygous (r/r) for a targeted mutation in Col1a1; these mice synthesize collagen I that resists collagenase cleavage at Gly975-Leu976. A total of 64 r/r and 84 littermate wild-type mice (WT) underwent experimental pressure overload by transverse aortic constriction (TAC) or myocardial infarction (MI). Echocardiographic, hemodynamic, and histological parameters were evaluated up to 12 weeks after TAC or 21 days after MI. At 4 weeks after TAC, collagen levels, wall thickness, and echocardiographic parameters were similar in the 2 groups. At 12 weeks after TAC, r/r mice had smaller LV dimensions (ESD: 2.7+/-0.2 mm WT versus 1.7+/-0.2 mm r/r, P<0.013; EDD: 3.8+/-0.2 mm WT versus 3.1+/-0.1 mm r/r, P<0.013); better fractional shortening (30+/-2% WT versus 46+/-4% r/r; P<0.013); and lower LV/body weight ratios (7.3+/-0.6 WT and 5.1+/-0.5 r/r; P<0.013). Surprisingly, these differences were not accompanied by differences in collagen accumulation, myocyte cross-sectional areas, wall thickness, or microvessel densities. Furthermore, no differences in LV remodeling assessed by echocardiography, fibrosis, or hemodynamic parameters were found between r/r and WT mice after MI. Thus, a mutation that encodes a collagenase cleavage-resistant collagen I does not affect early LV remodeling after TAC or MI, suggesting that collagen cleavage at this site is not the mechanism by which metalloproteinases mediate LV remodeling. Collagen cleavage could, however, have a role in preservation of cardiac function in late remodeling by mechanisms independent of collagen accumulation. We were not able to detect collagen cleavage fragments, and could not, therefore, rule out the possibility of collagen cleavage at additional sites. -
Lammerding J, Kazarov AR, Huang H, Lee RT, Hemler ME. 2003. Tetraspanin CD151 regulates alpha6beta1 integrin adhesion strengthening. Proceedings of the National Academy of Sciences of the United States of America. 100(13):7616-21. Pubmed: 12805567 Lammerding J, Kazarov AR, Huang H, Lee RT, Hemler ME. 2003. Tetraspanin CD151 regulates alpha6beta1 integrin adhesion strengthening. Proceedings of the National Academy of Sciences of the United States of America. 100(13):7616-21. Pubmed: 12805567 The tetraspanin CD151 molecule associates specifically with laminin-binding integrins, including alpha6beta1. To probe strength of alpha6beta1-dependent adhesion to laminin-1, defined forces (0-1.5 nN) were applied to magnetic laminin-coated microbeads bound to NIH 3T3 cells. For NIH 3T3 cells bearing wild-type CD151, adhesion strengthening was observed, as bead detachment became more difficult over time. In contrast, mutant CD151 (with the C-terminal region replaced) showed impaired adhesion strengthening. Static cell adhesion to laminin-1, and detachment of beads coated with fibronectin or anti-alpha6 antibody were all unaffected by CD151 mutation. Hence, CD151 plays a key role in selectively strengthening alpha6beta1 integrin-mediated adhesion to laminin-1. 2002
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Lee RT, Lammerding J. 2002. Signaling pathways that influence extracellular remodeling. Journal of cardiac failure. 8(6 Suppl):S339-43. Pubmed: 12555142 Lee RT, Lammerding J. 2002. Signaling pathways that influence extracellular remodeling. Journal of cardiac failure. 8(6 Suppl):S339-43. Pubmed: 12555142 Array -
Weinberg EO, Shimpo M, De Keulenaer GW, MacGillivray C, Tominaga S, Solomon SD, Rouleau JL, Lee RT. 2002. Expression and regulation of ST2, an interleukin-1 receptor family member, in cardiomyocytes and myocardial infarction. Circulation. 106(23):2961-6. Pubmed: 12460879 Weinberg EO, Shimpo M, De Keulenaer GW, MacGillivray C, Tominaga S, Solomon SD, Rouleau JL, Lee RT. 2002. Expression and regulation of ST2, an interleukin-1 receptor family member, in cardiomyocytes and myocardial infarction. Circulation. 106(23):2961-6. Pubmed: 12460879 Array -
Ohki R, Yamamoto K, Mano H, Lee RT, Ikeda U, Shimada K. 2002. Identification of mechanically induced genes in human monocytic cells by DNA microarrays. Journal of hypertension. 20(4):685-91. Pubmed: 11910304 Ohki R, Yamamoto K, Mano H, Lee RT, Ikeda U, Shimada K. 2002. Identification of mechanically induced genes in human monocytic cells by DNA microarrays. Journal of hypertension. 20(4):685-91. Pubmed: 11910304 Array -
Schulze PC, De Keulenaer GW, Yoshioka J, Kassik KA, Lee RT. 2002. Vitamin D3-upregulated protein-1 (VDUP-1) regulates redox-dependent vascular smooth muscle cell proliferation through interaction with thioredoxin. Circulation research. 91(8):689-95. Pubmed: 12386145 Schulze PC, De Keulenaer GW, Yoshioka J, Kassik KA, Lee RT. 2002. Vitamin D3-upregulated protein-1 (VDUP-1) regulates redox-dependent vascular smooth muscle cell proliferation through interaction with thioredoxin. Circulation research. 91(8):689-95. Pubmed: 12386145 Reactive oxygen species are important cellular signaling molecules, and thioredoxin (TRX) is a key regulator of cellular redox balance. We investigated the interaction of TRX with its endogenous inhibitor, vitamin D3-upregulated protein (VDUP)-1, in human aortic smooth muscle cells (SMCs). Adenoviral gene transfer of TRX enhanced TRX enzyme activity 2.7+/-0.4-fold (P<0.05 versus cells infected with adenoviral vector expressing green fluorescent protein [AdGFP]) and resulted in a 3.8+/-0.5-fold increase of cellular DNA synthesis as detected by methyl-[3H]thymidine incorporation (P<0.001). Platelet-derived growth factor (PDGF) also increased TRX enzyme activity 2.5+/-3.3-fold (P<0.05 versus no stimulation) and DNA synthesis 6.5+/-0.3-fold (P<0.001 versus no stimulation) without significant changes in TRX expression. PDGF and H2O2 time-dependently suppressed VDUP-1 expression (13-fold and 30-fold reduction after 1 hour, respectively; P<0.001), and this was inhibited by the cell-permeable antioxidants N-acetylcysteine and 4,5-dihydroxy-1,3-benzene-disulfonic acid (Tiron). Overexpression of VDUP-1 (AdVDUP-1) reduced TRX activity at baseline (-61+/-23% versus control cells, P<0.05) and abolished PDGF-induced TRX activity (-9+/-27% in AdVDUP-1-infected cells; P=NS versus control cells). In addition, overexpression of VDUP-1 blocked PDGF-induced DNA synthesis (1.3+/-0.4-fold increase in AdVDUP-1-infected cells versus 6.5+/-0.4-fold increase in AdGFP-infected cells, P<0.001). In conclusion, VDUP-1 has marked antiproliferative effects in SMCs through the suppression of TRX activity, suggesting that the regulation of VDUP-1 is a critical molecular switch in the transduction of pro-oxidant mitogenic signals. These data also demonstrate that activation of the reductase TRX plays a pivotal role in the redox-dependent proliferation of SMCs. -
Wang Y, De Keulenaer GW, Lee RT. 2002. Vitamin D(3)-up-regulated protein-1 is a stress-responsive gene that regulates cardiomyocyte viability through interaction with thioredoxin. The Journal of biological chemistry. 277(29):26496-500. Pubmed: 12011048 Wang Y, De Keulenaer GW, Lee RT. 2002. Vitamin D(3)-up-regulated protein-1 is a stress-responsive gene that regulates cardiomyocyte viability through interaction with thioredoxin. The Journal of biological chemistry. 277(29):26496-500. Pubmed: 12011048 The protein-disulfide reductase thioredoxin is critical for redox signaling during apoptosis and growth. In this study, we demonstrate that vitamin D(3)-up-regulated protein-1 regulates thioredoxin in conditions of biomechanical or oxidative stress and critically regulates cardiomyocyte viability. Expression of vitamin D(3)-up-regulated protein-1 but not of thioredoxin in rat cardiomyocytes was rapidly suppressed by biomechanical strain or hydrogen peroxide at both mRNA and protein levels. Mechanical suppression of vitamin D(3)-up-regulated protein-1 gene expression was blocked by N-acetylcysteine. The half-life of vitamin D(3)-up-regulated protein-1 transcripts in cardiomyocytes was only 1.1 h and remained unchanged after mechanical stimulation, suggesting that rapid responses in vitamin D(3)-up-regulated protein-1 gene expression occur through transcriptional control. Vitamin D(3)-up-regulated protein-1 down-regulation by strain or hydrogen peroxide led to increased thioredoxin activity, whereas adenovirus-mediated overexpression of vitamin D(3)-up-regulated protein-1 suppressed thioredoxin activity. Overexpression of vitamin D(3)-up-regulated protein-1 but not of thioredoxin induced cardiomyocyte apoptosis. Furthermore, overexpression of vitamin D(3)-up-regulated protein-1 sensitized cells to hydrogen peroxide-induced apoptosis, whereas overexpression of thioredoxin protected against injury. These data identify vitamin D(3)-up-regulated protein-1 as a key stress-responsive inhibitory switch of thioredoxin activity in cardiomyocytes and demonstrate that the vitamin D(3)-up-regulated protein-1/thioredoxin axis has an important role in the preservation of cellular viability. -
Wang Y, De Keulenaer GW, Weinberg EO, Muangman S, Gualberto A, Landschulz KT, Turi TG, Thompson JF, Lee RT. 2002. Direct biomechanical induction of endogenous calcineurin inhibitor Down Syndrome Critical Region-1 in cardiac myocytes. American journal of physiology. Heart and circulatory physiology. 283(2):H533-9. Pubmed: 12124198 Wang Y, De Keulenaer GW, Weinberg EO, Muangman S, Gualberto A, Landschulz KT, Turi TG, Thompson JF, Lee RT. 2002. Direct biomechanical induction of endogenous calcineurin inhibitor Down Syndrome Critical Region-1 in cardiac myocytes. American journal of physiology. Heart and circulatory physiology. 283(2):H533-9. Pubmed: 12124198 Signaling through the protein phosphatase calcineurin may play a critical role in cardiac hypertrophy. The gene for Down Syndrome Critical Region-1 (DSCR1) encodes a protein that is an endogenous calcineurin inhibitor. This study was designed to test the hypothesis that DSCR1 is directly induced by biomechanical stimuli. Neonatal rat cardiac myocytes were exposed to biaxial cyclic mechanical strain; mechanical strain upregulated DSCR1 mRNA expression in a time- and amplitude-dependent manner (3.4 +/- 0.2-fold at 8% strain for 6 h, n = 11, P < 0.01), and this induction was angiotensin II and endothelin I independent. Biomechanical induction of DSCR1 mRNA was partially blocked by calcineurin inhibition with cyclosporine A (30 +/- 5%, n = 3, P < 0.01). DSCR1 promoter-reporter experiments showed that mechanical strain induced DSCR1 promoter activity by 2.3-fold and that this induction was completely inhibited by cyclosporin A. Furthermore, DSCR1 gene expression was increased in the left ventricles of mice with pressure-overload hypertrophy induced by transverse aortic banding. These data demonstrate that biomechanical strain directly induces gene expression for the calcineurin inhibitor DSCR1 in cardiac myocytes, indicating that mechanically induced DSCR1 may regulate the hypertrophic response to mechanical overload. -
De Keulenaer GW, Wang Y, Feng Y, Muangman S, Yamamoto K, Thompson JF, Turi TG, Landschutz K, Lee RT. 2002. Identification of IEX-1 as a biomechanically controlled nuclear factor-kappaB target gene that inhibits cardiomyocyte hypertrophy. Circulation research. 90(6):690-6. Pubmed: 11934837 De Keulenaer GW, Wang Y, Feng Y, Muangman S, Yamamoto K, Thompson JF, Turi TG, Landschutz K, Lee RT. 2002. Identification of IEX-1 as a biomechanically controlled nuclear factor-kappaB target gene that inhibits cardiomyocyte hypertrophy. Circulation research. 90(6):690-6. Pubmed: 11934837 Biomechanical strain is a stimulus for cardiomyocyte hypertrophy and heart failure, but the underlying molecular mechanisms remain incompletely understood. Using an in vivo murine model of pressure overload and an in vitro model of mechanical stimulation of primary cardiomyocytes, we identified iex-1 as a gene activated during the early response of cardiomyocytes to hypertrophic stimuli and as a gene product that inhibits hypertrophy without affecting cardiomyocyte viability. On stimulation of cardiomyocytes, iex-1 mRNA and protein expression increased and translocation of the gene product to the cardiomyocyte nucleus occurred. iex-1 has previously been proposed as a mediator of NF-kappaB-dependent cell survival and growth in tumor cells. Here, we demonstrate that the biomechanical induction of iex-1 in cardiomyocytes was NF-kappaB-dependent, as overexpression of the NF-kappaB inhibitor IkappaBalpha completely inhibited strain-mediated iex-1 mRNA accumulation. The functional role of iex-1 was investigated by overexpressing wild-type iex-1 with replication-defective adenoviral gene transfer. Overexpression of iex-1 abolished cardiomyocyte hypertrophy by mechanical strain, phenylephrine, or endothelin-1 at levels that did not affect cell viability. These studies identify iex-1 as a biomechanical stress-inducible and NF-kappaB-dependent gene in cardiac muscle cells during the acute phase of hypertrophy with negative growth regulatory effects that may counterbalance early hypertrophic responses in activated cardiomyocytes. -
Lindsey ML, Gannon J, Aikawa M, Schoen FJ, Rabkin E, Lopresti-Morrow L, Crawford J, Black S, Libby P, Mitchell PG, Lee RT. 2002. Selective matrix metalloproteinase inhibition reduces left ventricular remodeling but does not inhibit angiogenesis after myocardial infarction. Circulation. 105(6):753-8. Pubmed: 11839633 Lindsey ML, Gannon J, Aikawa M, Schoen FJ, Rabkin E, Lopresti-Morrow L, Crawford J, Black S, Libby P, Mitchell PG, Lee RT. 2002. Selective matrix metalloproteinase inhibition reduces left ventricular remodeling but does not inhibit angiogenesis after myocardial infarction. Circulation. 105(6):753-8. Pubmed: 11839633 Array 2001
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Sakamoto H, Aikawa M, Hill CC, Weiss D, Taylor WR, Libby P, Lee RT. 2001. Biomechanical strain induces class a scavenger receptor expression in human monocyte/macrophages and THP-1 cells: a potential mechanism of increased atherosclerosis in hypertension. Circulation. 104(1):109-14. Pubmed: 11435347 Sakamoto H, Aikawa M, Hill CC, Weiss D, Taylor WR, Libby P, Lee RT. 2001. Biomechanical strain induces class a scavenger receptor expression in human monocyte/macrophages and THP-1 cells: a potential mechanism of increased atherosclerosis in hypertension. Circulation. 104(1):109-14. Pubmed: 11435347 Array -
Rohde LE, Polanczyk CA, Goldman L, Cook EF, Lee RT, Lee TH. 2001. Usefulness of transthoracic echocardiography as a tool for risk stratification of patients undergoing major noncardiac surgery. The American journal of cardiology. 87(5):505-9. Pubmed: 11230829 Rohde LE, Polanczyk CA, Goldman L, Cook EF, Lee RT, Lee TH. 2001. Usefulness of transthoracic echocardiography as a tool for risk stratification of patients undergoing major noncardiac surgery. The American journal of cardiology. 87(5):505-9. Pubmed: 11230829 Transthoracic echocardiography (TTE) is frequently ordered before noncardiac surgery, although its ability to predict perioperative cardiac complications is uncertain. To evaluate the incremental information provided by TTE after consideration of clinical data for prediction of cardiac complications after noncardiac surgery, 570 patients who underwent TTE before major noncardiac surgery at a university hospital were studied. Preoperative clinical data and clinical outcomes were collected prospectively according to a structured protocol. TTE data included left ventricular (LV) function, hypertrophy indexes, and Doppler-derived measurements. In univariate analyses, preoperative systolic dysfunction was associated with postoperative myocardial infarction (odds ratio [OR] 2.8, 95% confidence interval [CI] 1.1 to 7.0), cardiogenic pulmonary edema (OR 3.2, 95% CI 1.4 to 7.0), and major cardiac complications (OR 2.4, 95% Cl 1.3 to 4.5). Moderate to severe LV hypertrophy, moderate to severe mitral regurgitation, and increased aortic valve gradient were also associated with major cardiac events (OR 2.3, 95% CI 1.2 to 4.6; OR 2.2, 95% CI 1.1 to 4.3; OR 2.1, 95% CI 1.0 to 4.5, respectively). In logistic regression analysis, models with echocardiographic variables predicted major cardiac complications significantly better than those that included only clinical variables (c statistic 0.73 vs 0.68; p <0.05). Echocardiographic data added significant information for patients at increased risk for cardiac complications by clinical criteria, but not in otherwise low-risk patients. In conclusion, preoperative TTE before noncardiac surgery can provide independent information about the risk of postoperative cardiac complications in selected patients. -
Gehrmann J, Frantz S, Maguire CT, Vargas M, Ducharme A, Wakimoto H, Lee RT, Berul CI. 2001. Electrophysiological characterization of murine myocardial ischemia and infarction. Basic research in cardiology. 96(3):237-50. Pubmed: 11403417 Gehrmann J, Frantz S, Maguire CT, Vargas M, Ducharme A, Wakimoto H, Lee RT, Berul CI. 2001. Electrophysiological characterization of murine myocardial ischemia and infarction. Basic research in cardiology. 96(3):237-50. Pubmed: 11403417 Array -
Chae CU, Lee RT, Rifai N, Ridker PM. 2001. Blood pressure and inflammation in apparently healthy men. Hypertension (Dallas, Tex. : 1979). 38(3):399-403. Pubmed: 11566912 Chae CU, Lee RT, Rifai N, Ridker PM. 2001. Blood pressure and inflammation in apparently healthy men. Hypertension (Dallas, Tex. : 1979). 38(3):399-403. Pubmed: 11566912 Inflammation plays an important role in the development of atherosclerosis, but the specific stimuli governing cytokine release in atherogenesis are unknown. We examined the hypothesis that hypertension may increase the risk of atherosclerosis via proinflammatory effects. In a cross-sectional study involving 508 apparently healthy men, we studied the association between blood pressure and baseline plasma concentrations of 2 inflammatory markers, intercellular adhesion molecule-1 (sICAM-1) and interleukin-6 (IL-6). Increase in systolic blood pressure (SBP) (P=0.003), pulse pressure (PP) (P=0.019), and mean arterial pressure (P=0.014) was significantly associated with levels of sICAM-1. All of these measures of blood pressure, as well as diastolic blood pressure (DBP), were significantly associated with levels of IL-6 (all, PHuang H, Kamm RD, So PT, Lee RT. 2001. Receptor-based differences in human aortic smooth muscle cell membrane stiffness. Hypertension (Dallas, Tex. : 1979). 38(5):1158-61. Pubmed: 11711514 Huang H, Kamm RD, So PT, Lee RT. 2001. Receptor-based differences in human aortic smooth muscle cell membrane stiffness. Hypertension (Dallas, Tex. : 1979). 38(5):1158-61. Pubmed: 11711514 Cells respond to mechanical stimuli with diverse molecular responses. The nature of the sensory mechanism involved in mechanotransduction is not known, but integrins may play an important role. The integrins are linked to both the cytoskeleton and extracellular matrix, suggesting that probing cells via integrins should yield different mechanical properties than probing cells via non-cytoskeleton-associated receptors. To test the hypothesis that the mechanical properties of a cell are dependent on the receptor on which the stress is applied, human aortic smooth muscle cells were plated, and magnetic beads, targeted either to the integrins via fibronectin or to the transferrin receptor by use of an IgG antibody, were attached to the cell surface. The resistance of the cell to deformation ("stiffness") was estimated by oscillating the magnetic beads at 1 Hz by use of single-pole magnetic tweezers at 2 different magnitudes. The ratio of bead displacements at different magnitudes was used to explore the mechanical properties of the cells. Cells stressed via the integrins required approximately 10-fold more force to obtain the same bead displacements as the cells stressed via the transferrin receptors. Cells stressed via integrins showed stiffening behavior as the force was increased, whereas this stiffening was significantly less for cells stressed via the transferrin receptor (P<0.001). Mechanical characteristics of vascular smooth muscle cells depend on the receptor by which the stress is applied, with integrin-based linkages demonstrating cell-stiffening behavior.Lee RT, Yamamoto C, Feng Y, Potter-Perigo S, Briggs WH, Landschulz KT, Turi TG, Thompson JF, Libby P, Wight TN. 2001. Mechanical strain induces specific changes in the synthesis and organization of proteoglycans by vascular smooth muscle cells. The Journal of biological chemistry. 276(17):13847-51. Pubmed: 11278699 Lee RT, Yamamoto C, Feng Y, Potter-Perigo S, Briggs WH, Landschulz KT, Turi TG, Thompson JF, Libby P, Wight TN. 2001. Mechanical strain induces specific changes in the synthesis and organization of proteoglycans by vascular smooth muscle cells. The Journal of biological chemistry. 276(17):13847-51. Pubmed: 11278699 In the mechanically active environment of the artery, cells sense mechanical stimuli and regulate extracellular matrix structure. In this study, we explored the changes in synthesis of proteoglycans by vascular smooth muscle cells in response to precisely controlled mechanical strains. Strain increased mRNA for versican (3.2-fold), biglycan (2.0-fold), and perlecan (2.0-fold), whereas decorin mRNA levels decreased to a third of control levels. Strain also increased versican, biglycan, and perlecan core proteins, with a concomitant decrease in decorin core protein. Deformation did not alter the hydrodynamic size of proteoglycans as evidenced by molecular sieve chromatography but increased sulfate incorporation in both chondroitin/dermatan sulfate proteoglycans and heparan sulfate proteoglycans (p < 0.05 for both). Using DNA microarrays, we also identified the gene for the hyaluronan-linking protein TSG6 as mechanically induced in smooth muscle cells. Northern analysis confirmed a 4.0-fold increase in steady state mRNA for TSG6 following deformation. Size exclusion chromatography under associative conditions showed that versican-hyaluronan aggregation was enhanced following deformation. These data demonstrate that mechanical deformation increases specific vascular smooth muscle cell proteoglycan synthesis and aggregation, indicating a highly coordinated extracellular matrix response to biomechanical stimulation.Aikawa Y, Rohde L, Plehn J, Greaves SC, Menapace F, Arnold MO, Rouleau JL, Pfeffer MA, Lee RT, Solomon SD. 2001. Regional wall stress predicts ventricular remodeling after anteroseptal myocardial infarction in the Healing and Early Afterload Reducing Trial (HEART): an echocardiography-based structural analysis. American heart journal. 141(2):234-42. Pubmed: 11174337 Aikawa Y, Rohde L, Plehn J, Greaves SC, Menapace F, Arnold MO, Rouleau JL, Pfeffer MA, Lee RT, Solomon SD. 2001. Regional wall stress predicts ventricular remodeling after anteroseptal myocardial infarction in the Healing and Early Afterload Reducing Trial (HEART): an echocardiography-based structural analysis. American heart journal. 141(2):234-42. Pubmed: 11174337 ArrayHuang H, Virmani R, Younis H, Burke AP, Kamm RD, Lee RT. 2001. The impact of calcification on the biomechanical stability of atherosclerotic plaques. Circulation. 103(8):1051-6. Pubmed: 11222465 Huang H, Virmani R, Younis H, Burke AP, Kamm RD, Lee RT. 2001. The impact of calcification on the biomechanical stability of atherosclerotic plaques. Circulation. 103(8):1051-6. Pubmed: 11222465 Array2000
Yang JH, Sakamoto H, Xu EC, Lee RT. 2000. Biomechanical regulation of human monocyte/macrophage molecular function. The American journal of pathology. 156(5):1797-804. Pubmed: 10793091 Yang JH, Sakamoto H, Xu EC, Lee RT. 2000. Biomechanical regulation of human monocyte/macrophage molecular function. The American journal of pathology. 156(5):1797-804. Pubmed: 10793091 When the monocyte infiltrates a tissue, adhesion to the extracellular matrix provides structural anchors, and the cell may be deformed through these attachments. To test the hypothesis that human monocytes/macrophages are mechanically responsive, we studied the effects of small cyclic mechanical deformations on cultured human monocytes/macrophages. When monocytes/macrophages were subjected to 4% strain at 1 Hz for 24 hours, neither matrix metalloproteinase (MMP)-1 nor MMP-3 was induced; however, in the presence of phorbol myristate acetate, strain augmented MMP-1 expression by 5.1 +/- 0.7-fold (P < 0.05) and MMP-3 expression by 1. 6 +/- 0.1-fold (P < 0.05). In contrast, MMP-9 expression was not changed by mechanical strain in the presence or absence of phorbol myristate acetate. Deformation rapidly induced the immediate early response genes c-fos and c-jun. In addition, mechanical deformation induced the transcription factor PU.1, an ets family member that is essential in monocyte differentiation, as well as mRNA for the M-CSF receptor. These studies demonstrate that human monocytes/macrophages respond to mechanical deformation with selective augmentation of MMPs, induction of immediate early genes, and induction of the M-CSF receptor. In addition to enhancing the proteolytic activity of macrophages within repairing tissues, cellular deformation within tissues may play a role in monocyte differentiation.Ressler B, Lee RT, Randell SH, Drazen JM, Kamm RD. 2000. Molecular responses of rat tracheal epithelial cells to transmembrane pressure. American journal of physiology. Lung cellular and molecular physiology. 278(6):L1264-72. Pubmed: 10835333 Ressler B, Lee RT, Randell SH, Drazen JM, Kamm RD. 2000. Molecular responses of rat tracheal epithelial cells to transmembrane pressure. American journal of physiology. Lung cellular and molecular physiology. 278(6):L1264-72. Pubmed: 10835333 Smooth muscle constriction in asthma causes the airway to buckle into a rosette pattern, folding the epithelium into deep crevasses. The epithelial cells in these folds are pushed up against each other and thereby experience compressive stresses. To study the epithelial cell response to compressive stress, we subjected primary cultures of rat tracheal epithelial cells to constant elevated pressures on their apical surface (i.e., a transmembrane pressure) and examined changes in the expression of genes that are important for extracellular matrix production and maintenance of smooth muscle activation. Northern blot analysis of RNA extracted from cells subjected to transmembrane pressure showed induction of early growth response-1 (Egr-1), endothelin-1, and transforming growth factor-beta1 in a pressure-dependent and time-dependent manner. Increases in Egr-1 protein were detected by immunohistochemistry. Our results demonstrate that airway epithelial cells respond rapidly to compressive stresses. Potential transduction mechanisms of transmembrane pressure were also investigated.Ducharme A, Frantz S, Aikawa M, Rabkin E, Lindsey M, Rohde LE, Schoen FJ, Kelly RA, Werb Z, Libby P, Lee RT. 2000. Targeted deletion of matrix metalloproteinase-9 attenuates left ventricular enlargement and collagen accumulation after experimental myocardial infarction. The Journal of clinical investigation. 106(1):55-62. Pubmed: 10880048 Ducharme A, Frantz S, Aikawa M, Rabkin E, Lindsey M, Rohde LE, Schoen FJ, Kelly RA, Werb Z, Libby P, Lee RT. 2000. Targeted deletion of matrix metalloproteinase-9 attenuates left ventricular enlargement and collagen accumulation after experimental myocardial infarction. The Journal of clinical investigation. 106(1):55-62. Pubmed: 10880048 Matrix metalloproteinase-9 (MMP-9) is prominently overexpressed after myocardial infarction (MI). We tested the hypothesis that mice with targeted deletion of MMP9 have less left ventricular (LV) dilation after experimental MI than do sibling wild-type (WT) mice. Animals that survived ligation of the left coronary artery underwent echocardiographic studies after MI; all analyses were performed without knowledge of mouse genotype. By day 8, MMP9 knockout (KO) mice had significantly smaller increases in end-diastolic and end-systolic ventricular dimensions at both midpapillary and apical levels, compared with infarcted WT mice; these differences persisted at 15 days after MI. MMP-9 KO mice had less collagen accumulation in the infarcted area than did WT mice, and they showed enhanced expression of MMP-2, MMP-13, and TIMP-1 and a reduced number of macrophages. We conclude that targeted deletion of the MMP9 gene attenuates LV dilation after experimental MI in mice. The decrease in collagen accumulation and the enhanced expression of other MMPs suggest that MMP-9 plays a prominent role in extracellular matrix remodeling after MI.Haley KJ, Lilly CM, Yang JH, Feng Y, Kennedy SP, Turi TG, Thompson JF, Sukhova GH, Libby P, Lee RT. 2000. Overexpression of eotaxin and the CCR3 receptor in human atherosclerosis: using genomic technology to identify a potential novel pathway of vascular inflammation. Circulation. 102(18):2185-9. Pubmed: 11056090 Haley KJ, Lilly CM, Yang JH, Feng Y, Kennedy SP, Turi TG, Thompson JF, Sukhova GH, Libby P, Lee RT. 2000. Overexpression of eotaxin and the CCR3 receptor in human atherosclerosis: using genomic technology to identify a potential novel pathway of vascular inflammation. Circulation. 102(18):2185-9. Pubmed: 11056090 ArrayYauch RL, Kazarov AR, Desai B, Lee RT, Hemler ME. 2000. Direct extracellular contact between integrin alpha(3)beta(1) and TM4SF protein CD151. The Journal of biological chemistry. 275(13):9230-8. Pubmed: 10734060 Yauch RL, Kazarov AR, Desai B, Lee RT, Hemler ME. 2000. Direct extracellular contact between integrin alpha(3)beta(1) and TM4SF protein CD151. The Journal of biological chemistry. 275(13):9230-8. Pubmed: 10734060 Previously we established that the alpha(3)beta(1) integrin shows stable, specific, and stoichiometric association with the TM4SF (tetraspannin) protein CD151. Here we used a membrane impermeable cross-linking agent to show a direct association between extracellular domains of alpha(3)beta(1) and CD151. The alpha(3)beta(1)-CD151 association site was then mapped using chimeric alpha(6)/alpha(3) integrins and CD151/NAG2 TM4SF proteins. Complex formation required an extracellular alpha(3) site (amino acids (aa) 570-705) not previously known to be involved in specific integrin contacts with other proteins and a region (aa 186-217) within the large extracellular loop of CD151. Notably, the anti-CD151 monoclonal antibody TS151r binding epitope, previously implicated in alpha(3) integrin association, was mapped to the same region of CD151 (aa 186-217). Finally, we demonstrated that both NH(2)- and COOH-terminal domains of CD151 are located on the inside of the plasma membrane, thus confirming a long suspected model of TM4SF protein topology.1999
McConnell MV, Aikawa M, Maier SE, Ganz P, Libby P, Lee RT. 1999. MRI of rabbit atherosclerosis in response to dietary cholesterol lowering. Arteriosclerosis, thrombosis, and vascular biology. 19(8):1956-9. Pubmed: 10446077 McConnell MV, Aikawa M, Maier SE, Ganz P, Libby P, Lee RT. 1999. MRI of rabbit atherosclerosis in response to dietary cholesterol lowering. Arteriosclerosis, thrombosis, and vascular biology. 19(8):1956-9. Pubmed: 10446077 Direct imaging of the atherosclerotic plaque, rather than the angiographic lumen, may provide greater insight into the response of atherosclerosis to cholesterol-lowering therapy. Aortic plaque was studied in vivo by MRI in rabbits undergoing dietary cholesterol intervention. Thirty-one rabbits underwent aortic balloon injury and high-cholesterol diet for 4 months and then were assigned to low-cholesterol versus continued high-cholesterol diet for up to an additional 16 months. High-resolution (310 micrometer) fast spin-echo MRI of the abdominal aorta was performed at 4, 12, and 20 months and compared with histology. MRI demonstrated a significant reduction in % area stenosis in rabbits placed on low-cholesterol diet (44.6+/-2. 1% at 20 months versus 55.8+/-1.5% at 4 months, P=0.0002). In contrast, % area stenosis increased in rabbits maintained on high-cholesterol diet (69.8+/-3.8% at 20 months versus 55.8+/-1.5% at 4 months, P=0.001). Similarly, plaque thickness decreased significantly in the low-cholesterol group (0.60+/-0.05 mm at 20 months versus 0.85+/-0.06 mm at 4 months, P=0.006), with a trend toward increase in the high-cholesterol group (1.02+/-0.08 mm at 20 months versus 0.85+/-0.06 mm at 4 months, P=0.1). Thus, in rabbits undergoing dietary cholesterol lowering, MRI detected regression of aortic atherosclerotic plaque in vivo. Plaque progression was seen with maintenance of high-cholesterol diet. MRI is a promising noninvasive technology for directly imaging atherosclerosis and its response to therapeutic interventions.Frantz S, Kobzik L, Kim YD, Fukazawa R, Medzhitov R, Lee RT, Kelly RA. 1999. Toll4 (TLR4) expression in cardiac myocytes in normal and failing myocardium. The Journal of clinical investigation. 104(3):271-80. Pubmed: 10430608 Frantz S, Kobzik L, Kim YD, Fukazawa R, Medzhitov R, Lee RT, Kelly RA. 1999. Toll4 (TLR4) expression in cardiac myocytes in normal and failing myocardium. The Journal of clinical investigation. 104(3):271-80. Pubmed: 10430608 Expression of innate immune response proteins, including IL-1beta, TNF, and the cytokine-inducible isoform of nitric oxide synthase (iNOS), have been documented in the hearts of humans and experimental animals with heart failure regardless of etiology, although the proximal events leading to their expression are unknown. Noting that expression of a human homologue of Drosophila Toll, a proximal innate immunity transmembrane signaling protein in the fly, now termed human Toll-like receptor 4 (hTLR4), appeared to be relatively high in the heart, we examined TLR4 mRNA and protein abundance in isolated cellular constituents of cardiac muscle and in normal and abnormal murine, rat, and human myocardium. TLR4 expression levels in cardiac myocytes and in coronary microvascular endothelial cells could be enhanced by either LPS or IL-1beta, an effect inhibited by the oxygen radical scavenger PDTC. Transfection of a constitutively active TLR4 construct, CD4/hTLR4, resulted in activation of a nuclear factor-kappaB reporter construct, but not of an AP-1 or an iNOS reporter construct, in cardiac myocytes. In normal murine, rat, and human myocardium, TLR4 expression was diffuse, and presumably cytoplasmic, in cardiac myocytes. However, in remodeling murine myocardium remote from sites of ischemic injury and in heart tissue from patients with idiopathic dilated cardiomyopathy, focal areas of intense TLR4 staining were observed in juxtaposed regions of 2 or more adjacent myocytes; this staining was not observed in control myocardium. Increased expression and signaling by TLR4, and perhaps other Toll homologues, may contribute to the activation of innate immunity in injured myocardium.Rohde LE, Ducharme A, Arroyo LH, Aikawa M, Sukhova GH, Lopez-Anaya A, McClure KF, Mitchell PG, Libby P, Lee RT. 1999. Matrix metalloproteinase inhibition attenuates early left ventricular enlargement after experimental myocardial infarction in mice. Circulation. 99(23):3063-70. Pubmed: 10368126 Rohde LE, Ducharme A, Arroyo LH, Aikawa M, Sukhova GH, Lopez-Anaya A, McClure KF, Mitchell PG, Libby P, Lee RT. 1999. Matrix metalloproteinase inhibition attenuates early left ventricular enlargement after experimental myocardial infarction in mice. Circulation. 99(23):3063-70. Pubmed: 10368126 ArrayRohde LE, Arroyo LH, Rifai N, Creager MA, Libby P, Ridker PM, Lee RT. 1999. Plasma concentrations of interleukin-6 and abdominal aortic diameter among subjects without aortic dilatation. Arteriosclerosis, thrombosis, and vascular biology. 19(7):1695-9. Pubmed: 10397687 Rohde LE, Arroyo LH, Rifai N, Creager MA, Libby P, Ridker PM, Lee RT. 1999. Plasma concentrations of interleukin-6 and abdominal aortic diameter among subjects without aortic dilatation. Arteriosclerosis, thrombosis, and vascular biology. 19(7):1695-9. Pubmed: 10397687 Previous studies suggest that cytokine-induced tissue inflammation may participate in the pathogenesis of abdominal aortic aneurysms. Serum inflammatory markers may reflect arterial inflammation in asymptomatic phases of the aneurysmal disease. We studied 120 outpatients (62 men; age, 65+/-9 years) by ultrasound evaluation of the abdominal aorta to evaluate the association of circulating levels of interleukin-6 (IL-6) with abdominal aortic diameter in subjects with normal aortic size. Aortic diameter was measured at the infrarenal level and indexed for body surface area. Seven patients with abdominal aortic dilatation (indexed aortic diameter, >1.3 cm/m2) were also identified. Plasma concentrations of IL-6, serum amyloid A (SAA), C-reactive protein (CRP), total homocysteine, and lipids were measured. Among the 113 subjects without aortic dilatation, indexed aortic diameter was positively associated with serum levels of IL-6 (P<0.01), SAA (P<0.01), and total homocysteine (P=0.01). IL-6 levels increased in a stepwise fashion among dichotomized groups of aortic size (low and high aortic diameters) and peaked in patients with aortic dilatation (2.3+/-1.2 versus 2. 7+/-0.9 versus 3.2+/-0.9 pg/mL, respectively; P for trend=0.039). None of the serum lipid measurements correlated with abdominal aortic diameter. Although CRP levels were associated with SAA levels (r=0.60; P<0.001), associations between CRP and aortic diameter were nonsignificant. In multivariate analysis, levels of IL-6 (P=0.02), SAA (P=0.001), and total homocysteine (P<0.001) were independent correlates of indexed aortic diameter. In conclusion, circulating levels of IL-6, SAA, and total homocysteine may reflect processes involved in the early phases of abdominal aortic aneurysm formation, before dilation of the abdominal aorta is established. These data support a role for chronic inflammation in the progression of asymptomatic aortic disease.Yamamoto K, Dang QN, Kennedy SP, Osathanondh R, Kelly RA, Lee RT. 1999. Induction of tenascin-C in cardiac myocytes by mechanical deformation. Role of reactive oxygen species. The Journal of biological chemistry. 274(31):21840-6. Pubmed: 10419501 Yamamoto K, Dang QN, Kennedy SP, Osathanondh R, Kelly RA, Lee RT. 1999. Induction of tenascin-C in cardiac myocytes by mechanical deformation. Role of reactive oxygen species. The Journal of biological chemistry. 274(31):21840-6. Pubmed: 10419501 Mechanical overload may change cardiac structure through angiotensin II-dependent and angiotensin II-independent mechanisms. We investigated the effects of mechanical strain on the gene expression of tenascin-C, a prominent extracellular molecule in actively remodeling tissues, in neonatal rat cardiac myocytes. Mechanical strain induced tenascin-C mRNA (3.9 +/- 0.5-fold, p < 0.01, n = 13) and tenascin-C protein in an amplitude-dependent manner but did not induce secreted protein acidic and rich in cysteine nor fibronectin. RNase protection assay demonstrated that mechanical strain induced all three alternatively spliced isoforms of tenascin-C. An angiotensin II receptor type 1 antagonist inhibited mechanical induction of brain natriuretic peptide but not tenascin-C. Antioxidants such as N-acetyl-L-cysteine, catalase, and 1, 2-dihydroxy-benzene-3,5-disulfonate significantly inhibited induction of tenascin-C. Truncated tenascin-C promoter-reporter assays using dominant negative mutants of IkappaBalpha and IkappaB kinase beta and electrophoretic mobility shift assays indicated that mechanical strain increases tenascin-C gene transcription by activating nuclear factor-kappaB through reactive oxygen species. Our findings demonstrate that mechanical strain induces tenascin-C in cardiac myocytes through a nuclear factor-kappaB-dependent and angiotensin II-independent mechanism. These data also suggest that reactive oxygen species may participate in mechanically induced left ventricular remodeling.Rohde LE, Aikawa M, Cheng GC, Sukhova G, Solomon SD, Libby P, Pfeffer J, Pfeffer MA, Lee RT. 1999. Echocardiography-derived left ventricular end-systolic regional wall stress and matrix remodeling after experimental myocardial infarction. Journal of the American College of Cardiology. 33(3):835-42. Pubmed: 10080489 Rohde LE, Aikawa M, Cheng GC, Sukhova G, Solomon SD, Libby P, Pfeffer J, Pfeffer MA, Lee RT. 1999. Echocardiography-derived left ventricular end-systolic regional wall stress and matrix remodeling after experimental myocardial infarction. Journal of the American College of Cardiology. 33(3):835-42. Pubmed: 10080489 Array1998
Rosario LB, Stevenson LW, Solomon SD, Lee RT, Reimold SC. 1998. The mechanism of decrease in dynamic mitral regurgitation during heart failure treatment: importance of reduction in the regurgitant orifice size. Journal of the American College of Cardiology. 32(7):1819-24. Pubmed: 9857857 Rosario LB, Stevenson LW, Solomon SD, Lee RT, Reimold SC. 1998. The mechanism of decrease in dynamic mitral regurgitation during heart failure treatment: importance of reduction in the regurgitant orifice size. Journal of the American College of Cardiology. 32(7):1819-24. Pubmed: 9857857 ArrayYang JH, Briggs WH, Libby P, Lee RT. 1998. Small mechanical strains selectively suppress matrix metalloproteinase-1 expression by human vascular smooth muscle cells. The Journal of biological chemistry. 273(11):6550-5. Pubmed: 9497391 Yang JH, Briggs WH, Libby P, Lee RT. 1998. Small mechanical strains selectively suppress matrix metalloproteinase-1 expression by human vascular smooth muscle cells. The Journal of biological chemistry. 273(11):6550-5. Pubmed: 9497391 Mechanical forces and biochemical stimuli may interact to regulate cellular responses. In this study, we tested the hypothesis that very small mechanical strains interact with growth factors in the regulation of matrix metalloproteinase (MMP)-1. Human vascular smooth muscle cells (VSMCs) were cultured on a precoated silicone membrane in a device that imposes a highly uniform biaxial strain. VSMCs cultured on fibronectin were treated with cyclic 1-Hz strains of 0, 1, or 4%, and MMPs were assayed by Western analysis or gelatin zymography. Small strains did not induce MMP-1 in VSMCs, but strain was a potent inhibitor of platelet-derived growth factor (PDGF)- or tumor necrosis factor-alpha-induced synthesis of MMP-1. In contrast, MMP-2 and TIMP-2 levels were not changed by PDGF and/or mechanical strain. VSMCs strained on the 120-kDa chymotryptic fragment of fibronectin or RGD peptides suppressed PDGF-induced expression of MMP-1, indicating that this effect is not mediated by the heparin-binding domain or connecting segment-1 of fibronectin. Northern analysis of ets-1, a transcriptional activator of MMP-1 expression, showed that strain down-regulated ets-1 expression, whereas c-fos expression was augmented. Thus, small deformations can selectively suppress MMP-1 synthesis by VSMCs, demonstrating the exquisite sensitivity of the cell to mechanical stimuli.Reimold SC, Orav EJ, Come PC, Caguioa ES, Lee RT. 1998. Progressive enlargement of the regurgitant orifice in patients with chronic aortic regurgitation. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 11(3):259-65. Pubmed: 9560749 Reimold SC, Orav EJ, Come PC, Caguioa ES, Lee RT. 1998. Progressive enlargement of the regurgitant orifice in patients with chronic aortic regurgitation. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 11(3):259-65. Pubmed: 9560749 The severity of aortic regurgitation is dependent on the size of the regurgitant orifice, the left ventricular response to volume overload, and the diastolic pressure difference across the aortic valve. The purpose of this study was to test the hypothesis that the aortic regurgitant orifice increases over time in patients with audible chronic aortic regurgitation. To assess serial changes in aortic regurgitant severity by the use of two-dimensional and Doppler echocardiography, 59 patients (29 men and 30 women) with audible chronic aortic regurgitation were prospectively identified and evaluated annually with two-dimensional and Doppler echocardiograms. Patients were followed for a median of 38 months. We measured two separate indicators of the size of the regurgitant orifice: the color Doppler regurgitant jet width and the Doppler-derived regurgitant orifice area. Jet width increased with time (0.5 +/- 0.4 cm at baseline, 0.04 +/- 0.01 cm/year slope, p < 0.001). The regurgitant orifice area also increased (0.12 +/- 0.14 cm2 at baseline, 0.01 +/- 0.01 cm2/year, p = 0.05). Changes in regurgitant orifice area were related to changes in left ventricular end-diastolic dimension (p < 0.001). There were no significant changes in left ventricular chamber dimensions, volumes, and regurgitant volume over time in this cohort. Increases in jet width and orifice area occurred in patients with all degrees of baseline disease severity, with bicuspid or tricuspid leaflet morphology, and with male or female sex. In this prospective study of chronic aortic regurgitation, both jet width and Doppler-derived regurgitant orifice area increased over time. These findings suggest that one factor in the progression of chronic aortic regurgitation is enlargement of the orifice.Yamamoto K, Dang QN, Kelly RA, Lee RT. 1998. Mechanical strain suppresses inducible nitric-oxide synthase in cardiac myocytes. The Journal of biological chemistry. 273(19):11862-6. Pubmed: 9565611 Yamamoto K, Dang QN, Kelly RA, Lee RT. 1998. Mechanical strain suppresses inducible nitric-oxide synthase in cardiac myocytes. The Journal of biological chemistry. 273(19):11862-6. Pubmed: 9565611 We investigated the effects of precisely controlled mechanical strain on nitric-oxide synthase activity in cultured neonatal rat cardiac myocytes. Incubation of cardiac myocytes for 24 h with 4 ng/ml interleukin-1beta and 100 units/ml interferon-gamma stimulated an increase in nitric oxide production, inducible nitric-oxide synthase (iNOS) mRNA, and iNOS protein. Mechanical strain suppressed nitric oxide production, iNOS mRNA, and iNOS protein stimulated by cytokines in an amplitude-dependent manner. Losartan (1 microM), an angiotensin II type 1 receptor antagonist, weakly inhibited the effect of strain, suggesting that paracrine angiotensin II is not the mediator of the strain effect. In addition, cycloheximide (10 microM), a protein synthesis inhibitor, inhibited the effect of strain by 46%. Transforming growth factor-beta (1 ng/ml) suppressed iNOS mRNA expression, but anti-transforming growth factor-beta antibody (30 microg/ml) did not block the effect of strain. In contrast, staurosporine (100 nM; a nonselective protein kinase inhibitor), calphostin C (1 microM; a selective protein kinase C inhibitor), and pretreatment with phorbol 12-myristate 13-acetate abolished the effect of strain. Genistein (100 microM), a tyrosine kinase inhibitor, partially inhibited the effect of strain. Thus, cyclic mechanical deformation suppresses cytokine-induced iNOS expression in cardiac myocytes, and this effect is mediated at least partially via activation of protein kinase C.Solomon SD, Aikawa Y, Martini MS, Rosario L, Makker G, Gerson D, Greaves S, Lee RT. 1998. Assessment of regional left ventricular wall stress after myocardial infarction by echocardiography-based structural analysis. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 11(10):938-47. Pubmed: 9804098 Solomon SD, Aikawa Y, Martini MS, Rosario L, Makker G, Gerson D, Greaves S, Lee RT. 1998. Assessment of regional left ventricular wall stress after myocardial infarction by echocardiography-based structural analysis. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 11(10):938-47. Pubmed: 9804098 ArrayRohde LE, Lee RT, Rivero J, Jamacochian M, Arroyo LH, Briggs W, Rifai N, Libby P, Creager MA, Ridker PM. 1998. Circulating cell adhesion molecules are correlated with ultrasound-based assessment of carotid atherosclerosis. Arteriosclerosis, thrombosis, and vascular biology. 18(11):1765-70. Pubmed: 9812916 Rohde LE, Lee RT, Rivero J, Jamacochian M, Arroyo LH, Briggs W, Rifai N, Libby P, Creager MA, Ridker PM. 1998. Circulating cell adhesion molecules are correlated with ultrasound-based assessment of carotid atherosclerosis. Arteriosclerosis, thrombosis, and vascular biology. 18(11):1765-70. Pubmed: 9812916 Although cellular adhesion molecules (CAMs) are hypothesized to play an important role in atherogenesis, the relationship between CAMs and systemic atherosclerosis is uncertain. Among 92 outpatients (48 men; mean+/-SD age, 65+/-9 years), we evaluated the association of soluble vascular CAM-1 (sVCAM-1) and intercellular adhesion molecule-1 (sICAM-1) with carotid intimal-medial thickness (IMT), an index of early atherosclerosis. All subjects underwent a 2-dimensional ultrasound examination of both carotid arteries at the distal common carotid arteries and bifurcation. sVCAM-1 and sICAM-1 levels measured by enzyme-linked immunosorbent assay were significantly correlated with mean IMT of the common carotid artery (r=0.34 and r=0.30, respectively; P<0.01) and carotid bifurcation (r=0.31 and r=0.26, respectively; P<0.05), whereas sVCAM-1 was also positively associated with maximal carotid IMT (r=0.35, P<0.01). Adjustment for age attenuated the association between sVCAM-1 and common (r=0.16, P=0.13) and bifurcation (r=0.18, P=0.07) carotid IMT but had minimal effect on the associations between sICAM-1 and carotid measurements (r=0.32, P<0.01; r=0.23, P<0.05; for common and bifurcation IMT, respectively). Age-adjusted sICAM-1 levels increased in a stepwise fashion across common carotid IMT tertiles (253+/-27 versus 275+/-24 versus 384+/-26 pg/mL for the lowest, intermediate, and highest IMT tertiles, respectively; P<0.01). A similar trend was also found between sVCAM-1 levels and common carotid IMT tertiles (625+/-60 versus 650+/-53 versus 714+/-58 pg/mL; P<0.15). These associations were minimally affected in analyses adjusting for hypertension, diabetes, smoking, low and high density lipoprotein cholesterol, lipoprotein(a), and homocysteine, or in a subgroup analysis limited to those with no prior history of atherothrombotic disease. These data demonstrate a positive association between serum CAMs with carotid IMT and further support the hypothesis that systemic inflammation may have a role in atherosclerotic lesion development.1997
Rohde LE, Zhi G, Aranki SF, Beckel NE, Lee RT, Reimold SC. 1997. Gender-associated differences in left ventricular geometry in patients with aortic valve disease and effect of distinct overload subsets. The American journal of cardiology. 80(4):475-80. Pubmed: 9285661 Rohde LE, Zhi G, Aranki SF, Beckel NE, Lee RT, Reimold SC. 1997. Gender-associated differences in left ventricular geometry in patients with aortic valve disease and effect of distinct overload subsets. The American journal of cardiology. 80(4):475-80. Pubmed: 9285661 Gender-associated differences may play an important role in the way the left ventricle adapts to overload. The purpose of this study is to evaluate left ventricular (LV) geometry in patients referred for aortic valve replacement with distinct overload subsets. The echocardiograms of 128 patients with isolated aortic stenosis (n = 44), mixed aortic valvular disease (n = 51), and pure aortic regurgitation (n = 33) before aortic valve replacement were evaluated. Women had better LV function as measured by ejection fraction (58% vs 52%; p = 0.01) and were slightly older (67 vs 62 years, p = 0.11). LV dimensions and volumes indexes were distinctively smaller in women irrespective of the subgroups analyzed. Men had larger LV mass and LV mass index, but women had higher LV mass/volume ratio. Gender-related differences in LV mass/volume ratio were most prominent in the aortic stenosis patients (3.1 g/ml for women vs 2.3 g/ml for men; p = 0.001), tended to decrease in mixed aortic disease (2.3 g/ml for women vs 1.8 g/ml for men; p = 0.01), and were not present in patients with pure aortic regurgitation (1.7 g/ml for women vs 1.7 g/ml for men; p = 0.83). Multivariate analysis showed that gender was independently associated with LV mass/volume ratios, after adjusting for the severity of the valvular lesion, age, LV function, and concomitant coronary bypass graft surgery. Thus, in a selected population of patients with severe aortic valvular disease, there were significant gender-related differences in LV geometry, mainly in patients exposed to chronic pressure overload.Fleischmann KE, Lee TH, Come PC, Goldman L, Cook EF, Caguoia E, Johnson PA, Albano MP, Lee RT. 1997. Echocardiographic prediction of complications in patients with chest pain. The American journal of cardiology. 79(3):292-8. Pubmed: 9036747 Fleischmann KE, Lee TH, Come PC, Goldman L, Cook EF, Caguoia E, Johnson PA, Albano MP, Lee RT. 1997. Echocardiographic prediction of complications in patients with chest pain. The American journal of cardiology. 79(3):292-8. Pubmed: 9036747 The optimal role of Doppler echocardiography in the evaluation of patients with acute chest pain syndromes is unclear. We prospectively studied a cohort of 466 patients admitted with acute chest pain syndromes to clarify the relation between echocardiographic data and the risk of serious predischarge complications, and to determine if echocardiographic data can provide incremental prognostic information beyond clinical and electrocardiographic variables. Doppler echocardiograms, performed an average of 21 hours after presentation, were independently analyzed by 2 echocardiographers for information on global left and right ventricular function and valvular disease. Regional function was assessed by a wall motion index (WMI). A composite complications end point was positive if significant recurrent myocardial ischemia, heart failure, or arrhythmia developed after the echocardiogram. In univariate analysis, left (odds ratio [OR] 2.9, 95% confidence interval [CI] 1.6, 5.1) and right (OR 2.7, 95% CI 1.2, 6.2) ventricular function, left ventricular end-diastolic (OR 1.6/cm, 95% CI 1.1, 2.3) and end-systolic (OR 1.4/cm, 95% CI 1.1, 1.9) dimensions, and WMI (OR 3.0, 95% CI 1.8, 4.8) predicted complications that developed after the echocardiogram. In multivariate analysis, WMI remained an incremental predictor of risk with an OR of 2.2/unit (95% CI 1.2, 3.9) scaled from 1 to 4. Even in the subset of 403 patients without acute myocardial infarction, WMI was associated with an OR of 1.9 (95% CI 1.0, 3.7). We conclude that early echocardiography provides incremental prognostic information concerning risk of subsequent complications in patients hospitalized with chest pain.Fleischmann KE, Lee RT, Come PC, Goldman L, Kuntz KM, Johnson PA, Weissman MA, Lee TH. 1997. Clinical and echocardiographic correlates of health status in patients with acute chest pain. Journal of general internal medicine. 12(12):751-6. Pubmed: 9436894 Fleischmann KE, Lee RT, Come PC, Goldman L, Kuntz KM, Johnson PA, Weissman MA, Lee TH. 1997. Clinical and echocardiographic correlates of health status in patients with acute chest pain. Journal of general internal medicine. 12(12):751-6. Pubmed: 9436894 ArrayLee RT, Briggs WH, Cheng GC, Rossiter HB, Libby P, Kupper T. 1997. Mechanical deformation promotes secretion of IL-1 alpha and IL-1 receptor antagonist. Journal of immunology (Baltimore, Md. : 1950). 159(10):5084-8. Pubmed: 9366437 Lee RT, Briggs WH, Cheng GC, Rossiter HB, Libby P, Kupper T. 1997. Mechanical deformation promotes secretion of IL-1 alpha and IL-1 receptor antagonist. Journal of immunology (Baltimore, Md. : 1950). 159(10):5084-8. Pubmed: 9366437 Both IL-1 alpha and IL-1 beta lack an N terminus secretory sequence, and the mechanism of secretion of these pleiotropic cytokines is incompletely understood. The epidermis contains large quantities of IL-1 alpha in keratinocytes, which may play a role in inducing endothelial adhesion molecules and promoting extravasation of leukocytes. Here we report that mechanical deformation of human keratinocytes leads to rapid release of IL-1 alpha, possibly through transient disruptions in the plasma membrane. Using a device that precisely controls the amplitude of strain on the culture substrate, we found by pulse-chase analysis, Western analysis, and ELISA that the release of IL-1 alpha is dependent on the amplitude of the strain. A cyclic strain of 14% released a small but significant quantity of IL-1 alpha, while strains of 33% released 66 +/- 9% of cytoplasmic IL-1 alpha over 1 h (p < 0.001). Release of IL-1 alpha was accompanied by rapid release of large stores of IL-1R antagonist, approximately 25 to 30 times greater by mass than the quantity of IL-1 alpha released, but only a small fraction of cytoplasmic lactate dehydrogenase. Media conditioned by mechanically stimulated keratinocytes induced expression of E-selectin by human vascular endothelial cells; induction of E-selectin was completely inhibited by an Ab to IL-1 alpha. Therefore, mechanical strain promotes the secretion of IL-1 alpha, and deformation of keratinocytes in the epidermis may activate vascular endothelium through mechanically released IL-1 alpha. This pathophysiologic mechanism may play a role in the anatomic localization of some inflammatory skin diseases, such as psoriasis, which occurs more commonly in locations where the dermis is subjected to repetitive stretch or trauma.Cheng GC, Briggs WH, Gerson DS, Libby P, Grodzinsky AJ, Gray ML, Lee RT. 1997. Mechanical strain tightly controls fibroblast growth factor-2 release from cultured human vascular smooth muscle cells. Circulation research. 80(1):28-36. Pubmed: 8978319 Cheng GC, Briggs WH, Gerson DS, Libby P, Grodzinsky AJ, Gray ML, Lee RT. 1997. Mechanical strain tightly controls fibroblast growth factor-2 release from cultured human vascular smooth muscle cells. Circulation research. 80(1):28-36. Pubmed: 8978319 Although fibroblast growth factor-2 (FGF-2) participates in the response to vascular injury, the role of cellular deformation in FGF-2 release is incompletely understood. To test the hypothesis that mechanical strain tightly controls FGF-2 release, a novel device was used to impose homogeneous and uniform biaxial strain to human vascular smooth muscle cells. Release of FGF-2 increased with the number of cycles of strain (14%, 1 Hz); 1, 9, and 90 cycles of strain, respectively, released 0.55 +/- 0.06%, 2.9 +/- 0.3%, and 5.5 +/- 1.3% of the total cellular FGF-2 (versus 0.00 +/- 0.40% for control, P < .05), but release was not further increased for strain of 90 to 90,000 cycles. Mechanical release of FGF-2 depended on both the frequency and amplitude of deformation. For example, strain (90 cycles, 1 Hz) at 4% amplitude released only 0.1 +/- 0.1% of the total FGF-2, but strain at 14% and 33% amplitudes, respectively, released 5.7 +/- 0.5% and 19.0 +/- 3.0% of the FGF-2 cellular pool (P < .05), suggesting a strain amplitude threshold for FGF-2 release. Injury to a subpopulation of cells increased with the frequency and amplitude of strain, but cells were not injured by strains below 10% amplitude. Strain following pretreatment with heparin released 12.6 +/- 1.6% of the total FGF-2 (versus 15.8 +/- 0.9% for strain alone, P < .05), indicating that most FGF-2 was liberated from the nuclear or cytoplasmic pools and not from low-affinity extracellular receptors. Conversely, strain in the presence of heparin released 25.2 +/- 3.5% of the total FGF-2 (versus 15.6 +/- 2.6% for strain alone, P < .05). Thus, cellular strain closely modulates the release of intracellular FGF-2 from human vascular smooth muscle cells, but FGF-2 release is negligible in response to the smaller strains that occur in the normal artery. In addition, larger mechanical strains lead to transfer of intracellular FGF-2 to the extracellular low-affinity receptors, where FGF-2 may be displaced by heparin. These observations provide insight into the mechanisms by which deforming vascular injury, such as that produced by arterial interventions, may elicit a proliferative response.Pfeffer MA, Greaves SC, Arnold JM, Glynn RJ, LaMotte FS, Lee RT, Menapace FJ, Rapaport E, Ridker PM, Rouleau JL, Solomon SD, Hennekens CH. 1997. Early versus delayed angiotensin-converting enzyme inhibition therapy in acute myocardial infarction. The healing and early afterload reducing therapy trial. Circulation. 95(12):2643-51. Pubmed: 9193433 Pfeffer MA, Greaves SC, Arnold JM, Glynn RJ, LaMotte FS, Lee RT, Menapace FJ, Rapaport E, Ridker PM, Rouleau JL, Solomon SD, Hennekens CH. 1997. Early versus delayed angiotensin-converting enzyme inhibition therapy in acute myocardial infarction. The healing and early afterload reducing therapy trial. Circulation. 95(12):2643-51. Pubmed: 9193433 ArrayFleischmann KE, Lee RT, Come PC, Goldman L, Cook EF, Weissman MA, Johnson PA, Lee TH. 1997. Impact of valvular regurgitation and ventricular dysfunction on long-term survival in patients with chest pain. The American journal of cardiology. 80(10):1266-72. Pubmed: 9388096 Fleischmann KE, Lee RT, Come PC, Goldman L, Cook EF, Weissman MA, Johnson PA, Lee TH. 1997. Impact of valvular regurgitation and ventricular dysfunction on long-term survival in patients with chest pain. The American journal of cardiology. 80(10):1266-72. Pubmed: 9388096 Doppler echocardiography is often used in evaluating patients with chest pain, but information on prognostic value of this testing and data to help guide selective use are limited. We prospectively studied 448 patients admitted from the emergency department for acute chest pain to assess the utility of qualitative echocardiographic data in predicting long-term survival and the incremental value of this information over routine clinical and electrocardiographic data. Doppler echocardiograms, recorded an average of 21 hours after presentation, were analyzed independently by 2 echocardiographers for global left and right ventricular function and valvular disease. Regional function was assessed by wall motion index. Data on long-term survival were collected with an average follow-up of 35.0 +/- 12.1 months. In univariate Cox regression analysis, left ventricular function and size, wall motion index, right ventricular function, and aortic, mitral, and tricuspid insufficiency were significant predictors of total and cardiovascular mortality. In multivariate analysis, moderate or severe left ventricular dysfunction (mortality rate ratio 3.2, 95% confidence intervals 1.8 to 5.8] and more than mild valvular regurgitation (mortality rate ratio 2.0, 95% confidence interval 1.1 to 3.6) were independent predictors of mortality in a model adjusted for clinical and electrocardiographic data. These factors were more common in patients aged >60 years, in those with prior acute myocardial infarction or angina, and in those with rales on physical examination. In the absence of these clinical characteristics, only 8 of 124 patients (7%) had moderate or severe left ventricular dysfunction or valvular regurgitation. In patients with moderate or severe regurgitation, a murmur was noted on the admission physical examination in 41 of 69 cases (59%). We conclude that echocardiographic evidence of moderate or severe left ventricular dysfunction or valvular regurgitation identifies a high-risk group for overall and cardiovascular mortality in patients with chest pain, and this evidence may not be detected clinically.1996
Cheng GC, Libby P, Grodzinsky AJ, Lee RT. 1996. Induction of DNA synthesis by a single transient mechanical stimulus of human vascular smooth muscle cells. Role of fibroblast growth factor-2. Circulation. 93(1):99-105. Pubmed: 8616949 Cheng GC, Libby P, Grodzinsky AJ, Lee RT. 1996. Induction of DNA synthesis by a single transient mechanical stimulus of human vascular smooth muscle cells. Role of fibroblast growth factor-2. Circulation. 93(1):99-105. Pubmed: 8616949 ArrayLee RT, Schoen FJ, Loree HM, Lark MW, Libby P. 1996. Circumferential stress and matrix metalloproteinase 1 in human coronary atherosclerosis. Implications for plaque rupture. Arteriosclerosis, thrombosis, and vascular biology. 16(8):1070-3. Pubmed: 8696948 Lee RT, Schoen FJ, Loree HM, Lark MW, Libby P. 1996. Circumferential stress and matrix metalloproteinase 1 in human coronary atherosclerosis. Implications for plaque rupture. Arteriosclerosis, thrombosis, and vascular biology. 16(8):1070-3. Pubmed: 8696948 Atherosclerotic plaque rupture may occur when regions of weakened extracellular matrix are subjected to increased mechanical stresses. Since collagen is a major determinant of extracellular matrix strength, enzymes that degrade collagen may play an important role in destabilizing the atherosclerotic lesion. To test the hypothesis that matrix metalloproteinase 1 (interstitial collagenase, or MMP-1), which initiates degradation of fibrillar collagens, colocalizes with increased stress in the fibrous cap of the atherosclerotic lesion, 12 unruptured human coronary lesions were studied. Finite-element analysis was used to determine the distribution of stress in the lesion, with estimates of material properties from previous measurements of human tissues. A computerized image analysis system was used to determine the distribution of immunoreactive MMP-1 within the fibrous tissue of the lesion. There was a significant correlation between immunoreactive MMP-1 and circumferential tensile stress in the fibrous cap within a given lesion (median Spearman rank correlation coefficient, .36; interquartile range, -.02 to .81; P < .02). Within a given lesion, the highest-stress region had twofold greater MMP-1 expression than the lowest-stress regions. In unruptured human atherosclerotic coronary lesions, overexpression of MMP-1 is associated with increased circumferential stress in the fibrous plaque. Degradation and weakening of the collagenous extracellular matrix at these critical high-stress regions may play a role in the pathogenesis of plaque rupture and acute ischemic syndromes.McConnell MV, Solomon SD, Rayan ME, Come PC, Goldhaber SZ, Lee RT. 1996. Regional right ventricular dysfunction detected by echocardiography in acute pulmonary embolism. The American journal of cardiology. 78(4):469-73. Pubmed: 8752195 McConnell MV, Solomon SD, Rayan ME, Come PC, Goldhaber SZ, Lee RT. 1996. Regional right ventricular dysfunction detected by echocardiography in acute pulmonary embolism. The American journal of cardiology. 78(4):469-73. Pubmed: 8752195 This study analyzed the regional pattern of right ventricular (RV) dysfunction on transthoracic echocardiograms in patients with and without acute pulmonary embolism. Quantitative (centerline) and qualitative (wall motion score) analyses of segmental RV free wall motion were performed on a "training" cohort of 41 patients (group 1), including 14 patients with acute pulmonary embolism, 9 patients with primary pulmonary hypertension, and 18 normal subjects. Patients with acute pulmonary embolism had a distinct regional pattern of RV dysfunction, with akinesia of the mid-free wall (centerline excursion: -0.2 +/- 0.8 mm, p = 0.0001 vs normal) but normal motion at the apex (centerline excursion: 5.7 +/- 0.8 mm, p = NS vs normal). In contrast, patients with primary pulmonary hypertension had abnormal wall motion in all regions (p <0.03 vs normal). This echocardiographic finding of normal wall motion at the apex and abnormal wall motion in the mid-free wall in acute pulmonary embolism was then tested in a "validation" cohort of 85 patients (group 2), consisting of hospitalized patients with RV dysfunction from any cause, including 13 patients with acute pulmonary embolism. The finding had a 77% sensitivity and a 94% specificity for the diagnosis of acute pulmonary embolism, with a positive predictive value of 71% and a negative predictive value of 96%. Thus, a distinct echocardiographic pattern of regional RV dysfunction, in which the apex is spared occurs in acute pulmonary embolism. This finding should raise the level of clinical suspicion for the diagnosis of acute pulmonary embolism.Reimold SC, Maier SE, Aggarwal K, Fleischmann KE, Piwnica-Worms D, Kikinis R, Lee RT. 1996. Aortic flow velocity patterns in chronic aortic regurgitation: implications for Doppler echocardiography. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 9(5):675-83. Pubmed: 8887871 Reimold SC, Maier SE, Aggarwal K, Fleischmann KE, Piwnica-Worms D, Kikinis R, Lee RT. 1996. Aortic flow velocity patterns in chronic aortic regurgitation: implications for Doppler echocardiography. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 9(5):675-83. Pubmed: 8887871 Aortic regurgitation is associated with retrograde diastolic flow in the aorta. Echocardiographic quantitative analysis of the magnitude of the flow reversal is believed to provide an estimate of severity of regurgitant disease despite variations in flow profiles. The purpose of this study was to evaluate the uniformity of flow patterns in the aorta of patients with aortic regurgitation and to investigate the relationship between these profiles and the echocardiographic estimates of flow reversal. Seventeen patients with chronic aortic regurgitation underwent cine-phase magnetic resonance imaging in an axial section through the ascending and descending aorta. The regurgitant fraction in the ascending aorta 4 cm above the aortic valve and the descending aorta were calculated from the velocity maps. These results were compared with data from nine individual sample volumes in the ascending and descending aorta. The magnetic resonance ascending aortic regurgitant fraction was compared with Doppler echocardiographic descending aortic flow velocity patterns. The descending aortic regurgitant fraction correlated only weakly with the ascending aortic regurgitant fraction (descending aortic regurgitant fraction = 0.62% ascending aortic regurgitant fraction + 0.04%; r = 0.75; p < 0.001). Regurgitant proportions in all sample volumes in the descending aorta, but not in the ascending aorta, were significantly related to the ascending aortic regurgitant fraction. The best descending aortic Doppler echocardiographic parameter for predicting ascending aortic regurgitant fraction was the end-diastolic velocity (end-diastolic velocity = 32.2 cm/sec. ascending aortic regurgitant fraction + 1.4 cm/sec; r = 0.94; p < 0.001). Pulsedwave Doppler sampling of descending aortic flow reflects severity of aortic regurgitant disease, in part the result of more uniform blood-velocity profiles in the descending aorta compared with the ascending aorta. The Doppler end-diastolic velocity in the descending aorta is a useful parameter of severity of aortic regurgitation.1995
Lee RT, Berditchevski F, Cheng GC, Hemler ME. 1995. Integrin-mediated collagen matrix reorganization by cultured human vascular smooth muscle cells. Circulation research. 76(2):209-14. Pubmed: 7834831 Lee RT, Berditchevski F, Cheng GC, Hemler ME. 1995. Integrin-mediated collagen matrix reorganization by cultured human vascular smooth muscle cells. Circulation research. 76(2):209-14. Pubmed: 7834831 Vascular smooth muscle cells perform the important function of modulation of vascular extracellular matrix. Because integrins mediate many cell-matrix interactions, the role of integrins in reorganization of collagen by cultured human vascular smooth muscle cells was studied. Immunoprecipitation demonstrated that human vascular smooth muscle cells express multiple beta 1 integrins. Monoclonal antibody A2-IIE10 (a blocking anti-alpha 2 antibody) inhibited adhesion of smooth muscle cells to collagen by 31%. The blocking anti-alpha 1 antibody 1B3.1 inhibited adhesion by 40%, whereas a blocking anti-alpha 3 antibody had no effect on adhesion. When 1B3.1 and A2-IIE10 were both used, a 79% reduction in adhesion was observed, indicating that active alpha 1 and alpha 2 integrins cooperatively mediate adhesion. The blocking anti-beta 1 antibody Mab13 abolished smooth muscle cell-mediated gel contraction, and the alpha 2-blocking antibody A2-IIE10 had a dose-dependent partial inhibitory effect (37%). In contrast, blocking antibodies to alpha 1 and alpha 3 had no effect. When anti-alpha 1 (1B3.1) and anti-alpha 2 (A2-IIE10) monoclonal antibodies were combined, no synergistic effect on inhibition of gel contraction was observed. Surprisingly, collagen gel contraction was inhibited by 46% by an anti-beta 1 antibody (TS2/16) known for its stimulatory effect on cell adhesion. Thus, whereas alpha 1 beta 1 and alpha 2 beta 1 integrins both participate in adhesion of vascular smooth muscle cells to collagen, only alpha 2 beta 1 integrins mediate collagen reorganization. In addition, collagen reorganization appears to be a dynamic process, adversely affected by excessive adhesion strengthening.Lee E, Grodzinsky AJ, Libby P, Clinton SK, Lark MW, Lee RT. 1995. Human vascular smooth muscle cell-monocyte interactions and metalloproteinase secretion in culture. Arteriosclerosis, thrombosis, and vascular biology. 15(12):2284-9. Pubmed: 7489254 Lee E, Grodzinsky AJ, Libby P, Clinton SK, Lark MW, Lee RT. 1995. Human vascular smooth muscle cell-monocyte interactions and metalloproteinase secretion in culture. Arteriosclerosis, thrombosis, and vascular biology. 15(12):2284-9. Pubmed: 7489254 Degradation of the atherosclerotic plaque extracellular matrix could destabilize the lesion, rendering it more prone to rupture. Both macrophages and vascular smooth muscle cells (SMCs) are potential sources of matrix metalloproteinases (MMPs), secreted enzymes that can digest vascular matrix. We explored interactions between human vascular SMCs and human monocytes that result in the secretion of interstitial collagenase (MMP-1) and stromelysin (MMP-3). Monocytes alone or those treated with SMC-conditioned media did not secrete these metalloproteinases as detectable by Western blot analysis. SMCs increased secretion of both MMP-1 and MMP-3 greater than 20-fold when cocultured with monocytes or when treated with monocyte-conditioned media. Addition of macrophage colony stimulating factor (< or = 1000 U/mL) to cocultures of monocytes and SMCs did not affect metalloproteinase secretion. Recombinant interleukin (IL)-1 receptor antagonist inhibited MMP-1 and MMP-3 induction in SMC cultures treated with monocyte-conditioned media (94% and 96% reduction, respectively), while a neutralizing antibody to tumor necrosis factor-alpha had no significant effect on metalloproteinase secretion. In contrast to the induction by monocyte-conditioned media of MMP-1 and MMP-3 secretion by SMCs, monocyte-conditioned media did not increase secretion of 72-kD gelatinase (MMP-2). Thus, monocytes induce MMP-1 and MMP-3 secretion by vascular SMCs through an IL-1-dependent mechanism. This response of SMCs to a defined macrophage product may contribute to plaque destabilization by mononuclear phagocytes in the lesion.Greaves SC, Reimold SC, Lee RT, Cooke KA, Aranki SF. 1995. Preoperative prediction of prosthetic aortic valve annulus diameter by two-dimensional echocardiography. The Journal of heart valve disease. 4(1):14-7. Pubmed: 7742981 Greaves SC, Reimold SC, Lee RT, Cooke KA, Aranki SF. 1995. Preoperative prediction of prosthetic aortic valve annulus diameter by two-dimensional echocardiography. The Journal of heart valve disease. 4(1):14-7. Pubmed: 7742981 Echocardiography may allow preoperative selection of appropriately sized aortic homograft valves. This study compared measurement of aortic annulus diameter from the preoperative transthoracic two-dimensional echocardiogram with prosthetic valve annulus diameter in 178 consecutive patients under-going primary aortic valve replacement. Aortic annulus diameter was measured independently from the two-dimensional parasternal long axis view by two experienced observers blinded to the size of valve implanted. Mean annulus diameter from three end-diastolic frames was recorded. Of the 178 patients, 124 (70%) of Observer 1 measurements and 102 (57%) of Observer 2 measurements were within 2mm of valve annulus diameter (p < 0.0001 for both observers). Six percent of Observer 1 measurements and 12% of Observer 2 measurements were more than 4mm away from valve annulus diameter. The echocardiographic prediction of valve size corresponded to actual prosthetic valve annulus diameter in 69 patients (39%) for Observer 1 and 60 patients (34%) for Observer 2. The percentages of echocardiographic measurements within two millimeter of valve annulus diameter were significantly different for the two observers (p < 0.05). The percentages of echocardiographic measurements within two millimeter of valve annulus diameter in 39 patients without significant aortic valve calcification were not significantly different from the remaining 139 patients with calcified valves. The interobserver coefficient of variation was 6.2% and the intraobserver coefficient of variation was 4.3%. Although preoperative measurement of aortic annulus diameter from transthoracic echocardiography approximates prosthetic valve annulus diameter in the majority of patients undergoing primary aortic valve replacement, a significant minority of estimates may be inaccurate, even in the absence of heavy calcification.(ABSTRACT TRUNCATED AT 250 WORDS)1994
Chuttani K, Tischler MD, Pandian NG, Lee RT, Mohanty PK. 1994. Diagnosis of cardiac tamponade after cardiac surgery: relative value of clinical, echocardiographic, and hemodynamic signs. American heart journal. 127(4 Pt 1):913-8. Pubmed: 8154431 Chuttani K, Tischler MD, Pandian NG, Lee RT, Mohanty PK. 1994. Diagnosis of cardiac tamponade after cardiac surgery: relative value of clinical, echocardiographic, and hemodynamic signs. American heart journal. 127(4 Pt 1):913-8. Pubmed: 8154431 Early detection and treatment of cardiac tamponade is crucial in management of patients after cardiac surgery. Because of the atypical features of this condition and paucity of data on relative frequency of different signs, we evaluated the sensitivity of various clinical, echocardiographic, and hemodynamic signs. We retrospectively evaluated the relative frequency of clinical, echocardiographic, and hemodynamic signs in 29 patients with cardiac tamponade after cardiac surgery. In our study 66% had a localized, posterior pericardial effusion, and the other 34% had circumferential pericardial effusion. In the whole group 24% of patients had hypotension, and pulsus paradoxus was noted in 48%, right atrial collapse in 34%, right ventricular diastolic collapse in 27%, left ventricular diastolic collapse in 65%, and left atrial collapse in 13%. Elevation with equalization of pressures was noted in 81% patients. In the patient group with circumferential pericardial effusion and cardiac tamponade 40% patients were hypotensive and 50% patients had pulsus paradoxus. RA collapse was present in 70%, RV diastolic collapse in 70%, and LV diastolic collapse in 20%. Elevated diastolic pressures with equalization of these pressures was present in 71%. In the group with regional pericardial effusion and cardiac tamponade hypotension was present in 16% and pulsus paradoxus in 47%. RA collapse was present in 16%, RV diastolic collapse in 5%, LV diastolic collapse in 89%, and LA collapse in 21% of the patients with regional tamponade. Elevated diastolic pressures with equalization of these pressures was noted in 86% of the patients. Our observations indicate that among patients who have undergone cardiac surgery the presentation of cardiac tamponade is usually atypical.(ABSTRACT TRUNCATED AT 250 WORDS)Loree HM, Tobias BJ, Gibson LJ, Kamm RD, Small DM, Lee RT. 1994. Mechanical properties of model atherosclerotic lesion lipid pools. Arteriosclerosis and thrombosis : a journal of vascular biology. 14(2):230-4. Pubmed: 8305413 Loree HM, Tobias BJ, Gibson LJ, Kamm RD, Small DM, Lee RT. 1994. Mechanical properties of model atherosclerotic lesion lipid pools. Arteriosclerosis and thrombosis : a journal of vascular biology. 14(2):230-4. Pubmed: 8305413 Structural analysis of atherosclerotic coronary arteries has suggested that stress concentrations are associated with plaque rupture and that these stress concentrations are critically dependent on the geometry and mechanical properties of the fibrous cap and lipid pool. Recent clinical trials of lipid-lowering therapy have shown a significant reduction in cardiac events associated with plaque rupture perhaps because of the changing composition of subintimal lipid pools. To test the hypothesis that changes in lipid composition can change the mechanical properties of lipid pools, we measured the dynamic shear moduli of combinations of cholesterol monohydrate crystals, phospholipids, and triglycerides similar to those found in atherosclerotic lesions. Increasing the cholesterol monohydrate concentration from 0% to 50% increased the real component of the dynamic shear modulus (storage modulus or stiffness) by 4.5 times at a frequency of 1 Hz (P < .001). All specimens demonstrated an increase in stiffness with increasing frequencies of stress ranging from 0.1 to 3 Hz. We conclude that the stiffness of model atherosclerotic plaque lipid pools is related to the concentration of cholesterol monohydrate crystals. Because the relative concentration of cholesterol monohydrate increases during early regression of experimental atherosclerosis, the resultant stiffening of the lipid pool may reduce stresses in plaque caps. However, the magnitude of the contribution of changing lipid stiffness to the reduction of cardiac events seen in clinical studies is unclear.Loree HM, Grodzinsky AJ, Park SY, Gibson LJ, Lee RT. 1994. Static circumferential tangential modulus of human atherosclerotic tissue. Journal of biomechanics. 27(2):195-204. Pubmed: 8132688 Loree HM, Grodzinsky AJ, Park SY, Gibson LJ, Lee RT. 1994. Static circumferential tangential modulus of human atherosclerotic tissue. Journal of biomechanics. 27(2):195-204. Pubmed: 8132688 The mechanical properties of atherosclerotic plaque may be of critical importance to the processes of plaque rupture, the most common antecedent of myocardial infarction. To investigate the effects of plaque structure and applied tensile stress on the static circumferential tangential modulus of atherosclerotic plaque, the stress-strain behavior of 26 human aortic intimal plaques was studied. Intimal plaques were collected during routine autopsies of 21 patients from the abdominal (n = 19) and thoracic (n = 2) aorta and were classified by histological analysis as cellular (n = 12), hypocellular (n = 9), and calcified (n = 5). At a physiologic applied circumferential tensile stress of 25 kPa, the tangential moduli of cellular, hypocellular, and calcified specimens were 927 +/- 468 kPa, 2312 +/- 2180 kPa, and 1466 +/- 1284 kPa, respectively. There was a nonsignificant difference in tangential modulus at 25 kPa stress between specimens classified as cellular and hypocellular (p = 0.098), cellular and calcified (p = 0.410), and hypocellular and calcified (p = 0.380). This is in marked contrast to the previously measured radial compressive behavior of plaque tissue, which showed that cellular, hypocellular, and calcified plaques were significantly different in their modulus. In tension, all 26 plaques tested demonstrated a statistically significant increase in tangential modulus with increasing applied circumferential stress. We conclude that the static circumferential tangential modulus of atherosclerotic plaque, unlike its radial compressive modulus, is not significantly affected by the degree of cellularity and calcification determined by histological characterization.(ABSTRACT TRUNCATED AT 250 WORDS)Lee RT, Loree HM, Fishbein MC. 1994. High stress regions in saphenous vein bypass graft atherosclerotic lesions. Journal of the American College of Cardiology. 24(7):1639-44. Pubmed: 7963109 Lee RT, Loree HM, Fishbein MC. 1994. High stress regions in saphenous vein bypass graft atherosclerotic lesions. Journal of the American College of Cardiology. 24(7):1639-44. Pubmed: 7963109 ArraySolomon SD, Kytömaa H, Celi AC, Maas LC, Chou L, Hopkins J, Caguioa E, Lee RT. 1994. Myocardial tissue characterization by autocorrelation of two-dimensional ultrasonic backscatter. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 7(6):631-40. Pubmed: 7840991 Solomon SD, Kytömaa H, Celi AC, Maas LC, Chou L, Hopkins J, Caguioa E, Lee RT. 1994. Myocardial tissue characterization by autocorrelation of two-dimensional ultrasonic backscatter. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 7(6):631-40. Pubmed: 7840991 To evaluate a novel method for determining the spatial distribution of echocardiographic information based on the two-dimensional autocorrelation function, echocardiographic images were obtained from specific regions of interest from 10 healthy volunteers, seven patients with genetically defined hypertrophic cardiomyopathy, and nine patients with pressure-overload hypertrophy. The wavelength of distinct peaks from the two-dimensional autocorrelation of the images was compared between groups of patients and demonstrated a significant decrease in the mean length scale associated with distinct secondary correlation peaks in patients with hypertrophic cardiomyopathy or pressure-overload hypertrophy compared with healthy volunteers (p = 0.0009). With a discriminating wavelength of 3.3 mm, the sensitivity of this technique for detecting abnormal myocardium was 84% with a specificity of 89%. This study suggests that ultrasonic tissue characterization based on the two-dimensional autocorrelation function may have potential for distinguishing normal from abnormal myocardium and provides a rationale for textural approaches to ultrasonic tissue characterization.Fleischmann KE, Goldman L, Robiolio PA, Lee RT, Johnson PA, Cook EF, Lee TH. 1994. Echocardiographic correlates of survival in patients with chest pain. Journal of the American College of Cardiology. 23(6):1390-6. Pubmed: 8176098 Fleischmann KE, Goldman L, Robiolio PA, Lee RT, Johnson PA, Cook EF, Lee TH. 1994. Echocardiographic correlates of survival in patients with chest pain. Journal of the American College of Cardiology. 23(6):1390-6. Pubmed: 8176098 ArrayGriffin BP, Flachskampf FA, Reimold SC, Lee RT, Thomas JD. 1994. Relationship of aortic regurgitant velocity slope and pressure half-time to severity of aortic regurgitation under changing haemodynamic conditions. European heart journal. 15(5):681-5. Pubmed: 8056010 Griffin BP, Flachskampf FA, Reimold SC, Lee RT, Thomas JD. 1994. Relationship of aortic regurgitant velocity slope and pressure half-time to severity of aortic regurgitation under changing haemodynamic conditions. European heart journal. 15(5):681-5. Pubmed: 8056010 The slope and pressure half-time of the aortic regurgitant velocity spectrum have been used as non-invasive markers of regurgitant severity. Recent in vitro and theoretical work, however, has suggested a confounding effect of systemic vascular resistance and left ventricular compliance on these parameters. To study this situation in vivo, we have investigated the determinants of the aortic regurgitant velocity profile in an animal model of aortic regurgitation in which the regurgitation was induced surgically and in which the afterload was varied pharmacologically. Specifically, we examined the relationship of slope and pressure half-time of the aortic regurgitant velocity profile to the severity of aortic regurgitation under varying conditions of afterload using multilinear analysis. Slope varied directly with regurgitant orifice area and inversely with systemic vascular resistance and both left ventricular and aortic compliance (all P < 0.001). Pressure half-time related to these variables in the opposite direction. When the regurgitant orifice was variable in size, slope related directly (P < 0.001) and half-time inversely to the severity of the aortic regurgitation (the clinically expected response). In contrast, when the regurgitant orifice area was constant, slope varied inversely (P < 0.001) and half-time varied directly (P < 0.07) with the severity of the aortic regurgitation. Following nitroprusside infusion, slope tended to increase (P = 0.08) and pressure half-time tended to shorten (P = 0.08) despite a significant reduction in the regurgitant fraction (P = 0.009). Similarly, following dopamine infusion, a significant increase in regurgitant fraction (P = 0.01) was associated with a slight fall in aortic regurgitation slope and a lengthening of the half-time.(ABSTRACT TRUNCATED AT 250 WORDS)Reimold SC, Maier SE, Fleischmann KE, Khatri M, Piwnica-Worms D, Kikinis R, Lee RT. 1994. Dynamic nature of the aortic regurgitant orifice area during diastole in patients with chronic aortic regurgitation. Circulation. 89(5):2085-92. Pubmed: 8181132 Reimold SC, Maier SE, Fleischmann KE, Khatri M, Piwnica-Worms D, Kikinis R, Lee RT. 1994. Dynamic nature of the aortic regurgitant orifice area during diastole in patients with chronic aortic regurgitation. Circulation. 89(5):2085-92. Pubmed: 8181132 ArrayReimold SC, Aranki SF, Caguioa ES, Solomon SD, Birjiniuk V, Cohn LH, Lee RT. 1994. An external aortic root device for decreasing aortic regurgitation: in vitro and in vivo animal studies. Journal of cardiac surgery. 9(3):304-13. Pubmed: 8054725 Reimold SC, Aranki SF, Caguioa ES, Solomon SD, Birjiniuk V, Cohn LH, Lee RT. 1994. An external aortic root device for decreasing aortic regurgitation: in vitro and in vivo animal studies. Journal of cardiac surgery. 9(3):304-13. Pubmed: 8054725 ArrayGoldhaber SZ, Agnelli G, Levine MN. 1994. Reduced dose bolus alteplase vs conventional alteplase infusion for pulmonary embolism thrombolysis. An international multicenter randomized trial. The Bolus Alteplase Pulmonary Embolism Group. Chest. 106(3):718-24. Pubmed: 8082347 Goldhaber SZ, Agnelli G, Levine MN. 1994. Reduced dose bolus alteplase vs conventional alteplase infusion for pulmonary embolism thrombolysis. An international multicenter randomized trial. The Bolus Alteplase Pulmonary Embolism Group. Chest. 106(3):718-24. Pubmed: 8082347 ArrayWolfe MW, Lee RT, Feldstein ML, Parker JA, Come PC, Goldhaber SZ. 1994. Prognostic significance of right ventricular hypokinesis and perfusion lung scan defects in pulmonary embolism. American heart journal. 127(5):1371-5. Pubmed: 8172067 Wolfe MW, Lee RT, Feldstein ML, Parker JA, Come PC, Goldhaber SZ. 1994. Prognostic significance of right ventricular hypokinesis and perfusion lung scan defects in pulmonary embolism. American heart journal. 127(5):1371-5. Pubmed: 8172067 We studied the relation between right ventricular (RV) hypokinesis on echocardiography and defects on the initial perfusion lung scan among 90 hemodynamically stable patients with pulmonary embolism (PE). Of the 90, 38 had qualitative evidence of RV hypokinesis, with a mean RV end-diastolic area significantly larger than those with normal RV wall motion (40.0 +/- 10.2 cm2 vs 20.1 +/- 6.4 cm2; p < 0.001). The degree of the perfusion defect was greater in those patients with baseline RV hypokinesis (54% +/- 16% of the lung nonperfused) than in those patients with normal RV wall motion at baseline (30% +/- 18% nonperfused lung; p < 0.001). Receiver operating characteristic curve analysis showed that a perfusion lung scan defect score of 0.3 (i.e., 30% of the lung nonperfused) had a 92% sensitivity for predicting RV hypokinesis and carried a relative risk for observing RV hypokinesis of 6.8 times greater than among those patients with a perfusion scan score of < 0.3. Considering that all patients with recurrent symptomatic PE were in the subgroup with RV hypokinesis (13% vs 0% for those with normal RV wall motion; p = 0.01), a strategy of performing echocardiography in those patients with a perfusion scan defect score of > or = 0.3 appears to identify patients at increased risk for recurrent PE.Feng Y, Yang JH, Huang H, Kennedy SP, Turi TG, Thompson JF, Libby P, Lee RT. Transcriptional profile of mechanically induced genes in human vascular smooth muscle cells. Circulation research. 85(12):1118-23. Pubmed: 10590237 Feng Y, Yang JH, Huang H, Kennedy SP, Turi TG, Thompson JF, Libby P, Lee RT. Transcriptional profile of mechanically induced genes in human vascular smooth muscle cells. Circulation research. 85(12):1118-23. Pubmed: 10590237 Vascular smooth muscle cells must monitor and respond to their mechanical environment; however, the molecular response of these cells to mechanical stimuli remains incompletely defined. By applying a highly uniform biaxial cyclic strain to cultured cells, we used DNA microarray technology to describe the transcriptional profile of mechanically induced genes in human aortic smooth muscle cells. We first identified vascular endothelial growth factor (VEGF) as a mechanically induced gene in these cells; VEGF served as a positive control for these experiments. We then used a DNA microarray with 5000 genes with putative functions to identify additional mechanically induced genes. Surprisingly, relatively few genes are mechanically induced in human aortic smooth muscle cells. Only 3 transcripts of 5000 were induced >2.5-fold: cyclooxygenase-1, tenascin-C, and plasminogen activator inhibitor-1. Downregulated transcripts included matrix metalloproteinase-1 and thrombomodulin. The transcriptional profile of mechanically induced genes in human aortic smooth muscle cells suggests a response of defense against excessive deformation. These data also demonstrate that in addition to identifying large clusters of genes that respond to a given stimulus, DNA microarray technology may be used to identify a small subset of genes that comprise a highly specific molecular response.