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 4

Loss of Id2 increases HSC proliferation and differentiation.

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Loss of Id2 increases HSC proliferation and differentiation. (A) Summary...
(A) Summary of single-cell proliferation assays of FACS-sorted Id2+/+ and Id2Δ/Δ HSCs after 48 hours. (B) Total cells per well (upper panel) and cell area (lower panel) at 10 days. (C) Summary of the method used to analyze BrdU incorporation into Id2+/+and Id2Δ/Δ HSPCs from 5-day Lin– cell expansion cultures. Histogram shows BrdU incorporation into HSCs, total HSCs in culture, and the percentage of BrdU+ HSCs. (D) Procedure to determine HSC self-renewal by NUMB staining. (E) Immunofluorescence analysis of NUMB-stained Id2+/+ and Id2Δ/Δ paired daughter HSCs. Original magnification, 40×. (F) Quantification of HSC doublets (minimum of 22 daughter cell pairs were counted per genotype in 3 separate experiments) following the NUMB assay and the percentage of self-renewed HSCs after a single division. In A, C, and F, data are presented as the mean ± SEM. In A and B, column scatter plots show the mean. 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. SR, self-renewal; AR, asymmetric renewal; SD, symmetric differentiation.