Transient HIF2A inhibition promotes satellite cell proliferation and muscle regeneration
Liwei Xie, … , Jarrod A. Call, Hang Yin
Liwei Xie, … , Jarrod A. Call, Hang Yin
Published March 13, 2018
Citation Information: J Clin Invest. 2018;128(6):2339-2355. https://doi.org/10.1172/JCI96208.
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Research Article Muscle biology Stem cells

Transient HIF2A inhibition promotes satellite cell proliferation and muscle regeneration

Abstract

The remarkable regeneration capability of skeletal muscle depends on the coordinated proliferation and differentiation of satellite cells (SCs). The self-renewal of SCs is critical for long-term maintenance of muscle regeneration potential. Hypoxia profoundly affects the proliferation, differentiation, and self-renewal of cultured myoblasts. However, the physiological relevance of hypoxia and hypoxia signaling in SCs in vivo remains largely unknown. Here, we demonstrate that SCs are in an intrinsic hypoxic state in vivo and express hypoxia-inducible factor 2A (HIF2A). HIF2A promotes the stemness and long-term homeostatic maintenance of SCs by maintaining their quiescence, increasing their self-renewal, and blocking their myogenic differentiation. HIF2A stabilization in SCs cultured under normoxia augments their engraftment potential in regenerative muscle. Conversely, HIF2A ablation leads to the depletion of SCs and their consequent regenerative failure in the long-term. In contrast, transient pharmacological inhibition of HIF2A accelerates muscle regeneration by increasing SC proliferation and differentiation. Mechanistically, HIF2A induces the quiescence and self-renewal of SCs by binding the promoter of the Spry1 gene and activating Spry1 expression. These findings suggest that HIF2A is a pivotal mediator of hypoxia signaling in SCs and may be therapeutically targeted to improve muscle regeneration.

Authors

Liwei Xie, Amelia Yin, Anna S. Nichenko, Aaron M. Beedle, Jarrod A. Call, Hang Yin

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Figure 7

Transient pharmacological inhibition of HIF2A in CTX-injured muscle promotes SC proliferation and accelerates muscle regeneration.

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Transient pharmacological inhibition of HIF2A in CTX-injured muscle prom...
(A) Timeline of pharmacological inhibition of HIF2A after CTX-induced muscle injury in C57BL/6 mice. (B) Representative images of HIF-c2– or 1% DMSO–treated TA muscles (3 dpi) from C57BL/6 mice (n = 6 mice/group). Immunofluorescence revealed increased Pax7+EdU+ proliferative SCs (arrowheads) and decreased Pax7+EdU– QSCs (circles). Scale bar: 20 μm. (C) Number of EdU+ and EdU– SCs per TA muscle section 3 dpi (n = 6). (D) Number of Pax7+ SCs per TA muscle section 7 dpi, 10 dpi, and 30 dpi (n = 6 or 7). (E) Representative eMyHC and laminin B2 immunofluorescence in HIF-c2– or DMSO-treated TA muscles 7 dpi and 30 dpi (n = 3). Scale bars: 20 μm. (F) Immunoblots showing the expression levels of HIF2A, eMyHC, MyoD, and tubulin in HIF-c2– or DMSO-treated TA muscles 7 dpi (n = 3). (G) Distributions of myofiber cross-sectional areas of HIF-c2– or DMSO-treated TA muscles 30 dpi (n = 3). (H) Maximal torques of uninjured TA muscles and HIF-c2– or DMSO-treated TA muscles 7 dpi (n = 6), 10 dpi (n = 3), and 30 dpi (n = 3). (I) Timeline of pharmacological inhibition of HIF2A after CTX-induced muscle injury in C57BL/6 mice and SC-HIF2AKO mice. (J)Representative Pax7 immunofluorescence images of HIF-c2– or DMSO-treated TA muscles from SC-HIF2AKO mice (n = 6 mice/group) 10 dpi and number of Pax7+ SCs per TA muscle section 7 dpi. Scale bar: 20 um. (K) Representative eMyHC and laminin B2 immunofluorescence images of HIF-c2– or DMSO-treated TA muscles from SC-HIF2AKO (n = 6 mice/group) 7 dpi. Scale bar: 20 μm. *P < 0.05, **P < 0.01, and ***P < 0.005, by 2-sided Student’s t test. Data represent the mean ± SEM.