Pivotal role for glycogen synthase kinase–3 in hematopoietic stem cell homeostasis in mice
Jian Huang, … , Stephen G. Emerson, Peter S. Klein
Jian Huang, … , Stephen G. Emerson, Peter S. Klein
Published November 23, 2009
Citation Information: J Clin Invest. 2009;119(12):3519-3529. https://doi.org/10.1172/JCI40572.
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Research Article Hematology

Pivotal role for glycogen synthase kinase–3 in hematopoietic stem cell homeostasis in mice

Abstract

Hematopoietic stem cell (HSC) homeostasis depends on the balance between self renewal and lineage commitment, but what regulates this decision is not well understood. Using loss-of-function approaches in mice, we found that glycogen synthase kinase–3 (Gsk3) plays a pivotal role in controlling the decision between self renewal and differentiation of HSCs. Disruption of Gsk3 in BM transiently expanded phenotypic HSCs in a β-catenin–dependent manner, consistent with a role for Wnt signaling in HSC homeostasis. However, in assays of long-term HSC function, disruption of Gsk3 progressively depleted HSCs through activation of mammalian target of rapamycin (mTOR). This long-term HSC depletion was prevented by mTOR inhibition and exacerbated by β-catenin knockout. Thus, GSK-3 regulated both Wnt and mTOR signaling in mouse HSCs, with these pathways promoting HSC self renewal and lineage commitment, respectively, such that inhibition of Gsk3 in the presence of rapamycin expanded the HSC pool in vivo. These findings identify unexpected functions for GSK-3 in mouse HSC homeostasis, suggest a therapeutic approach to expand HSCs in vivo using currently available medications that target GSK-3 and mTOR, and provide a compelling explanation for the clinically prevalent hematopoietic effects observed in individuals prescribed the GSK-3 inhibitor lithium.

Authors

Jian Huang, Yi Zhang, Alexey Bersenev, W. Timothy O’Brien, Wei Tong, Stephen G. Emerson, Peter S. Klein

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Figure 1

Gsk3 depletion expands HSCs and HPCs in primary transplants.

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Gsk3 depletion expands HSCs and HPCs in primary transplants. (A) Ir...
(A) Irradiated mice were reconstituted with BM after transduction with lentivirus with or without Gsk3-rnai. Peripheral blood was examined 20 weeks after transplantation; numbers within histograms indicate percent GFP+ cells. Shown is 1 representative of 5 similar experiments; similar results were obtained with Gsk3-rnai-C4. (B) GFP+ myeloid cells (Gr1+CD11b+) in peripheral blood for 10 control and 9 Gsk3-rnai-C2 recipients after BM transplantation (BMT; arrow). (C) Immunoblots for GSK-3α/β and β-catenin in BM from primary recipients 16 weeks after transplantation. Data represent independent replicates from 6 control and 6 Gsk3-rnai recipients. (D) Percent GFP+ LSK cells in control and Gsk3-rnai-C2 primary recipients. (E) Absolute number of GFP+ LSK, LSK CD34–Flk2–, and LSK CD34+Flk2– cells. (F) Representative FCM showing GFP+ cells in the HSC-containing LSK fraction (red gate) for control and Gsk3-rnai-C2 primary recipients. (G) Representative FCM using SLAM markers; the difference between control and Gsk3-rnai was significant (P < 0.05). Numbers in F and G indicate percent cells within gates. (H) Colony formation using GFP+ cells plated in methylcellulose with cytokines and scored for CFU-C (see Supplemental Figure 1). Data represent mean colonies per well performed in duplicate groups for 5 mice per construct repeated in 3 separate experiments. *P < 0.05 versus respective control value.