Yien YY, Shi J, Chen C, Cheung JTM, Grillo AS, Shrestha R, Li L, Zhang X, Kafina MD, Kingsley PD, King MJ, Ablain J, Li H, Zon LI, Palis J, Burke MD, Bauer DE, Orkin SH, Koehler CM, Phillips JD, Kaplan J, Ward DM, Lodish HF, Paw BH. 2018. FAM210B is an erythropoietin target and regulates erythroid heme synthesis by controlling mitochondrial iron import and ferrochelatase activity. The Journal of biological chemistry. 293(51):19797-19811. Pubmed: 30366982 DOI:10.1074/jbc.RA118.002742


Erythropoietin (EPO) signaling is critical to many processes essential to terminal erythropoiesis. Despite the centrality of iron metabolism to erythropoiesis, the mechanisms by which EPO regulates iron status are not well-understood. To this end, here we profiled gene expression in EPO-treated 32D pro-B cells and developing fetal liver erythroid cells to identify additional iron regulatory genes. We determined that FAM210B, a mitochondrial inner-membrane protein, is essential for hemoglobinization, proliferation, and enucleation during terminal erythroid maturation. deficiency led to defects in mitochondrial iron uptake, heme synthesis, and iron-sulfur cluster formation. These defects were corrected with a lipid-soluble, small-molecule iron transporter, hinokitiol, in -deficient murine erythroid cells and zebrafish morphants. Genetic complementation experiments revealed that FAM210B is not a mitochondrial iron transporter but is required for adequate mitochondrial iron import to sustain heme synthesis and iron-sulfur cluster formation during erythroid differentiation. FAM210B was also required for maximal ferrochelatase activity in differentiating erythroid cells. We propose that FAM210B functions as an adaptor protein that facilitates the formation of an oligomeric mitochondrial iron transport complex, required for the increase in iron acquisition for heme synthesis during terminal erythropoiesis. Collectively, our results reveal a critical mechanism by which EPO signaling regulates terminal erythropoiesis and iron metabolism.
© 2018 Yien et al.

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The Zon laboratory aims to dissect how assaults to the hematopoietic system cause severe diseases such as leukemias, lymphomas, and anemias. They investigate hematopoietic development and disease using chemical screens, genetic screens, and analysis of novel transgenic lines in zebrafish.

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