Baumgartner C, Toifl S, Farlik M, Halbritter F, Scheicher R, Fischer I, Sexl V, Bock C, Baccarini M. An ERK-Dependent Feedback Mechanism Prevents Hematopoietic Stem Cell Exhaustion.
Cell Stem Cell 2018;
22:879-892.e6. [PMID:
29804890 PMCID:
PMC5988582 DOI:
10.1016/j.stem.2018.05.003]
[Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 03/08/2018] [Accepted: 05/04/2018] [Indexed: 11/22/2022]
Abstract
Hematopoietic stem cells (HSCs) sustain hematopoiesis throughout life. HSCs exit dormancy to restore hemostasis in response to stressful events, such as acute blood loss, and must return to a quiescent state to prevent their exhaustion and resulting bone marrow failure. HSC activation is driven in part through the phosphatidylinositol 3-kinase (PI3K)/AKT/mTORC1 signaling pathway, but less is known about the cell-intrinsic pathways that control HSC dormancy. Here, we delineate an ERK-dependent, rate-limiting feedback mechanism that controls HSC fitness and their re-entry into quiescence. We show that the MEK/ERK and PI3K pathways are synchronously activated in HSCs during emergency hematopoiesis and that feedback phosphorylation of MEK1 by activated ERK counterbalances AKT/mTORC1 activation. Genetic or chemical ablation of this feedback loop tilts the balance between HSC dormancy and activation, increasing differentiated cell output and accelerating HSC exhaustion. These results suggest that MEK inhibitors developed for cancer therapy may find additional utility in controlling HSC activation.
MEK/ERK and AKT/mTORC1 are reversibly activated during hematopoiesis
MEK1 prevents HSC exhaustion during stress hematopoiesis
Feedback phosphorylation of MEK1 by ERK limits AKT/mTORC1 activation
ERK-mediated MEK1 phosphorylation returns activated HSCs to quiescence
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