Nguyen, T. T. H.; Huang, Y. X.; Poliakova, S.; Citu, C.; Mann, E.; Sopariwala, D. H.; Zhao, Z.; Kumar, A.; NARKAR, V. A.

Skeletal muscle regeneration in chronic muscle diseases such as Duchenne Muscular Dystrophy (DMD) has remained clinically unsurmountable. Estrogen-related receptor alpha (ERR) plays a critical role in adult skeletal muscle metabolism and exercise fitness. Whether ERR activation can drive muscle regeneration and mitigation of dystrophy in DMD is not known. We have investigated ERR signaling in pre-clinical models of acute muscle injury and DMD. ERR is induced in differentiating C2C12 myoblast and regenerating muscle. ERR silencing suppressed proliferation and differentiation in C2C12 myoblasts. RNA sequencing revealed that angiogenic factor and proliferation genes were downregulated by ERR knockdown in proliferating cells, whereas oxidative mitochondrial and differentiation regulator genes were downregulated in differentiating cells. In accordance with in vitro findings, transgenic ERR overexpression in rodent skeletal muscle stimulates muscle regeneration after acute BaCl2 injury, which is accompanied by enhanced angiogenesis and mitochondrial biogenesis. Notably, ERR and its angiogenic and metabolic target gene expression is suppressed in muscle stem cells (MuSCs) derived from dystrophic muscles in mdx mice, coinciding with proliferation and differentiation defect in these cells. Loss of ERR and its target gene expression was recapitulated in adult dystrophic mdx muscles. Consequently, muscle specific ERR overexpression in mdx mice restored angiogenic and metabolic gene expression, induced vascular and oxidative remodeling, alleviated baseline muscle damage, and boosted regeneration after BaCl2 injury in dystrophic muscle. Our studies demonstrate a pro-regenerative role of ERR and its deficiency in dystrophic muscles and its MuSCs. ERR restoration could be a therapeutic strategy for DMD through angio-metabolic gene program.