Muscular dystrophies (MDs) are a group of inherited degenerative muscle disorders characterized by a progressive skeletal muscle wasting. Respiratory impairments and subsequent hypoxemia are encountered in a significant subgroup of patients in almost all MD forms. In response to hypoxic stress, compensatory mechanisms are activated especially through Hypoxia-Inducible Factor 1 α (HIF-1α). In healthy muscle, hypoxia and HIF-1α activation are known to affect oxidative stress balance and metabolism. Recent evidence has also highlighted HIF-1α as a regulator of myogenesis and satellite cell function. However, the impact of HIF-1α pathway modifications in MDs remains to be investigated. Multifactorial pathological mechanisms could lead to HIF-1α activation in patient skeletal muscles. In addition to the genetic defect per se, respiratory failure or blood vessel alterations could modify hypoxia response pathways. Here, we will discuss the current knowledge about the hypoxia response pathway alterations in MDs and address whether such changes could influence MD pathophysiology.

FacioScapuloHumeral Dystrophy (FSHD) is one of the most frequent inherited muscle disorders, and is linked to the inappropriate expression of the DUX4 transcription factor in adult muscles. The deregulated molecular network causing FSHD skeletal muscle dysfunction and pathology is still not well understood. It has been shown that the hypoxia response factor HIF1α is critically disturbed in FSHD and has a major role in DUX4 induced cell death. In this study, we further explore the relationship between DUX4 and HIF1α. We found that the DUX4 and HIF1α link differed according to the stage of myogenic differentiation and was conserved between human and mouse muscle. Finally, we found that HIF1α knock-down in an FSHD mouse model exacerbated DUX4-mediated muscle damages. Our data indicate that the suggested role of HIF1α in DUX4 toxicity is complex and that targeting HIF1α might be challenging in the context of FSHD therapeutic approaches.

FacioScapuloHumeral Dystrophy (FSHD) is one of the most frequent inherited muscle disorders, and is linked to the inappropriate expression of the DUX4 transcription factor in adult muscles. The deregulated molecular network causing FSHD skeletal muscle dysfunction and pathology is still not well understood. It has been shown that the hypoxia response factor HIF1α is critically disturbed in FSHD and has a major role in DUX4 induced cell death. In this study, we further explore the relationship between DUX4 and HIF1α. We found that the DUX4 and HIF1α link differed according to the stage of myogenic differentiation and was conserved between human and mouse muscle. Finally, we found that HIF1α knock-down in an FSHD mouse model exacerbated DUX4-mediated muscle damages. Our data indicate that the suggested role of HIF1α in DUX4 toxicity is complex and that targeting HIF1α might be challenging in the context of FSHD therapeutic approaches.