ID2 and HIF-1α collaborate to protect quiescent hematopoietic stem cells from activation, differentiation, and exhaustion
Brad L. Jakubison, Tanmoy Sarkar, Kristbjorn O. Gudmundsson, Shweta Singh, Lei Sun, Holly M. Morris, Kimberly D. Klarmann, Jonathan R. Keller
Brad L. Jakubison, Tanmoy Sarkar, Kristbjorn O. Gudmundsson, Shweta Singh, Lei Sun, Holly M. Morris, Kimberly D. Klarmann, Jonathan R. Keller
View: Text | PDF
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

×

Figure 9

SCF and TPO promote ID2 and HIF-1α expression in a feed-forward loop to maintain HSCs.

Options: View larger image (or click on image) Download as PowerPoint
SCF and TPO promote ID2 and HIF-1α expression in a feed-forward loop to ...
(A) Procedure to analyze HIF-1α and ID2/eYFP expression in maintenance cultures with SCF, TPO, or SCF plus TPO. Quantitation of HSCs (top), HIF-1α expression in HSCs (middle), and ID2/eYFP expression in HSCs after 2 days of culturing (bottom). (B) Procedure to analyze HIF-1α expression in HSPCs in Lin– expansion cultures 5 days after treatment with KC-7F2 (KC). Flow cytometric histogram plots of HIF-1α expression in HSCs (top), total HSCs in culture (middle), and HIF-1α expression in HSCs (bottom). (C) Procedure to evaluate ID2/eYFP expression in HSCs in maintenance cultures of Lin– ID2eYFP cells after 2 days of treatment with KC-7F2 and echinomycin (Ech). Flow cytometric histogram plots below the procedure schema show ID2/eYFP expression in HSCs in control and KC-7F2–treated cultures. Graphs on the right show quantitation of HSCs and ID2/eYFP expression in KC-7F2–treated cultures (top) and quantitation of HSCs and ID2/eYFP expression in echinomycin-treated cultures (bottom). In A–C, data are presented as the mean ± SEM. Comparisons between mean values of 2 groups were evaluated using an unpaired, 1-tailed Student’s t test, and 1-way ANOVA with Dunnett’s correction was used for multiple means testing in A. *P ≤ 0.05, and **P ≤ 0.01, and ***P ≤ 0.001. Ctrl, control.