Ryanodine receptor RyR1-mediated elevation of Ca(2+) concentration is required for the late stage of myogenic differentiation and fusion

BACKGROUND: Cytosolic Ca(2+) plays vital roles in myogenesis and muscle development. As a major Ca(2+) release channel of endoplasmic reticulum (ER), ryanodine receptor 1 (RyR1) key mutations are main causes of severe congenital myopathies. The role of RyR1 in myogenic differentiation has attracted intense research interest but remains unclear. RESULTS: In the present study, both RyR1-knockdown myoblasts and CRISPR/Cas9-based RyR1-knockout myoblasts were employed to explore the role of RyR1 in myogenic differentiation, myotube formation as well as the potential mechanism of RyR1-related myopathies. We observed that RyR1 expression was dramatically increased during the late stage of myogenic differentiation, accompanied by significantly elevated cytoplasmic Ca(2+) concentration. Inhibition of RyR1 by siRNA-mediated knockdown or chemical inhibitor, dantrolene, significantly reduced cytosolic Ca(2+) and blocked multinucleated myotube formation. The elevation of cytoplasmic Ca(2+) concentration can effectively relieve myogenic differentiation stagnation by RyR1 inhibition, demonstrating that RyR1 modulates myogenic differentiation via regulation of Ca(2+) release channel. However, RyR1-knockout-induced Ca(2+) leakage led to the severe ER stress and excessive unfolded protein response, and drove myoblasts into apoptosis. CONCLUSIONS: Therefore, we concluded that Ca(2+) release mediated by dramatic increase in RyR1 expression is required for the late stage of myogenic differentiation and fusion. This study contributes to a novel understanding of the role of RyR1 in myogenic differentiation and related congenital myopathies, and provides a potential target for regulation of muscle characteristics and meat quality. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40104-021-00668-x.