ID2 and HIF-1α collaborate to protect quiescent hematopoietic stem cells from activation, differentiation, and exhaustion
Brad L. Jakubison, … , Kimberly D. Klarmann, Jonathan R. Keller
Brad L. Jakubison, … , Kimberly D. Klarmann, Jonathan R. Keller
Published July 1, 2022
Citation Information: J Clin Invest. 2022;132(13):e152599. https://doi.org/10.1172/JCI152599.
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Research Article Hematology

ID2 and HIF-1α collaborate to protect quiescent hematopoietic stem cells from activation, differentiation, and exhaustion

Abstract

Defining mechanism(s) that maintain tissue stem quiescence is important for improving tissue regeneration, cell therapies, aging, and cancer. We report here that genetic ablation of Id2 in adult hematopoietic stem cells (HSCs) promotes increased HSC activation and differentiation, which results in HSC exhaustion and bone marrow failure over time. Id2Δ/Δ HSCs showed increased cycling, ROS production, mitochondrial activation, ATP production, and DNA damage compared with Id2+/+ HSCs, supporting the conclusion that Id2Δ/Δ HSCs are less quiescent. Mechanistically, HIF-1α expression was decreased in Id2Δ/Δ HSCs, and stabilization of HIF-1α in Id2Δ/Δ HSCs restored HSC quiescence and rescued HSC exhaustion. Inhibitor of DNA binding 2 (ID2) promoted HIF-1α expression by binding to the von Hippel-Lindau (VHL) protein and interfering with proteasomal degradation of HIF-1α. HIF-1α promoted Id2 expression and enforced a positive feedback loop between ID2 and HIF-1α to maintain HSC quiescence. Thus, sustained ID2 expression could protect HSCs during stress and improve HSC expansion for gene editing and cell therapies.

Authors

Brad L. Jakubison, Tanmoy Sarkar, Kristbjorn O. Gudmundsson, Shweta Singh, Lei Sun, Holly M. Morris, Kimberly D. Klarmann, Jonathan R. Keller

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Figure 2

Cell proliferation is increased in Id2Δ/Δ HSCs in vivo.

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Cell proliferation is increased in Id2Δ/Δ HSCs in vivo. (A) Summary of t...
(A) Summary of the procedure to evaluate the proliferation of Id2Δ/Δ and Id2+/+ HSCs and ST-HSCs in vivo, 2 weeks after ablation of Id2. (B) Flow cytometry contour maps of Ki-67 expression in Id2+/+ and Id2Δ/Δ HSCs and ST-HSCs and quantification by cell cycle. (C) Summary of the procedure to measure HSC divisions in R26rtTA/+ TetOP-H2B-GFP Mx1-Cre Id2fl/fl and R26 rtTA/+ TetOP-H2B-GFP Mx1-Cre Id2+/+ mice. Mice were given Dox for 6 weeks, starting 2 weeks after BMT, followed by a 4-week chase; pIpC was administered 1 week before the chase. (D) GFP retention in HSCs after a 4-week chase. (E) Flow cytometry contour maps of Ki-67 expression in ID2hieYFPhi and ID2loeYFPlo HSCs and cell-cycle quantification. (F) Procedure to measure the serial competitive repopulation potential of ID2hieYFPhi or ID2loeYFPlo HSCs. (G) RT-qPCR analysis of Id2 expression in ID2hieYFPhi and ID2loeYFPlo HSCs. (H) Competitive repopulation of ID2hieYFPhi and ID2loeYFPlo HSCs in primary and secondary BMT recipient mice. (I) Total HSCs in secondary BMT recipient mice. In B, D, E, G, and I, data are presented as the mean ± SEM. In H, the center line indicates the median, and the box represents the 25th and 75th percentiles. Comparisons between mean values of 2 groups were evaluated using an unpaired, 1-tailed Student’s t test. *P ≤ 0.05, **P ≤ 0.01, and ***P ≤ 0.001.