Hypoxia Inhibits Myogenic Differentiation through p53 Protein-dependent Induction of Bhlhe40 Protein

• Published in: The Journal of biological chemistry 2015-12, Vol.290 (50), p.29707-29716
• Main Authors: Wang, Chao, Liu, Weiyi, Liu, Zuojun, Chen, Long, Liu, Xiaoqi, Kuang, Shihuan
• Format: Article
• Language: English
• Subjects: Animals; basic helix-loop-helix transcription factor (bHLH); Basic Helix-Loop-Helix Transcription Factors - biosynthesis; Basic Helix-Loop-Helix Transcription Factors - genetics; Cell Differentiation; Cells, Cultured; Developmental Biology; differentiation; Gene Knockdown Techniques; Homeodomain Proteins - biosynthesis; Homeodomain Proteins - genetics; hypoxia; Hypoxia - pathology; Mice; muscle regeneration; Muscle, Skeletal - cytology; Muscle, Skeletal - metabolism; Myogenin - metabolism; Oligonucleotide Array Sequence Analysis; p53; Signal Transduction; skeletal muscle; Tumor Suppressor Protein p53 - metabolism; Up-Regulation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M115.688671

Satellite cells are muscle-resident stem cells capable of self-renewal and differentiation to repair injured muscles. However, muscle injury often leads to an ischemic hypoxia environment that impedes satellite cell differentiation and reduces the efficiency of muscle regeneration. Here we performed microarray analyses and identified the basic helix-loop-helix family transcription factor Bhlhe40 as a candidate mediator of the myogenic inhibitory effect of hypoxia. Bhlhe40 is strongly induced by hypoxia in satellite cell-derived primary myoblasts. Overexpression of Bhlhe40 inhibits Myog expression and mimics the effect of hypoxia on myogenesis. Inhibition of Bhlhe40, conversely, up-regulates Myog expression and promotes myogenic differentiation. Importantly, Bhlhe40 knockdown rescues myogenic differentiation under hypoxia. Mechanistically, Bhlhe40 binds to the proximal E-boxes of the Myog promoter and reduces the binding affinity and transcriptional activity of MyoD on Myog. Interestingly, hypoxia induces Bhlhe40 expression independent of HIF1α but through a novel p53-dependent signaling pathway. Our study establishes a crucial role of Bhlhe40 in mediating the repressive effect of hypoxia on myogenic differentiation and suggests that inhibition of Bhlhe40 or p53 may facilitate muscle regeneration after ischemic injuries. Background: Hypoxia inhibits myogenic differentiation, but the underlying mechanisms are not well understood. Results: We used microarray analysis to identify genes and pathways affected by hypoxia. Gain- and loss-of-function studies indicate that Bhlhe40 inhibits myogenic differentiation and that hypoxia up-regulates Bhlhe40 through an HIF1α-independent, p53-dependent mechanism. Conclusion: Hypoxia inhibits myogenesis through p53-dependent induction of Bhlhe40. Significance: Inhibition of Bhlhe40 or p53 may facilitate muscle repair after ischemic injuries.