Janzen V, Fleming HE, Riedt T, Karlsson G, Riese MJ, Lo Celso C, Reynolds G, Milne CD, Paige CJ, Karlsson S, Woo M, Scadden DT. 2008. Hematopoietic stem cell responsiveness to exogenous signals is limited by caspase-3. Cell stem cell. 2(6):584-94. Pubmed: 18522851 DOI:10.1016/j.stem.2008.03.012


Limited responsiveness to inflammatory cytokines is a feature of adult hematopoietic stem cells and contributes to the relative quiescence and durability of the stem cell population in vivo. Here we report that the executioner Caspase, Caspase-3, unexpectedly participates in that process. Mice deficient in Caspase-3 had increased numbers of immunophenotypic long-term repopulating stem cells in association with multiple functional changes, most prominently cell cycling. Though these changes were cell autonomous, they reflected altered activation by exogenous signals. Caspase-3(-/-) cells exhibited cell type-specific changes in phosphorylated members of the Ras-Raf-MEK-ERK pathway in response to specific cytokines, while notably, members of other pathways, such as pSTAT3, pSTAT5, pAKT, pp38 MAPK, pSmad2, and pSmad3, were unaffected. Caspase-3 contributes to stem cell quiescence, dampening specific signaling events and thereby cell responsiveness to microenvironmental stimuli.

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David Scadden’s laboratory is dedicated to discovering the principles governing blood cell production, with the ultimate goal of guiding the development of therapies for blood disorders and cancer.

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