FTO-mediated demethylation of GADD45B promotes myogenesis through the activation of p38 MAPK pathway

N6-methyladenosine (m⁶A) modification plays a critical role in mammalian development. However, the role of m⁶A in the skeletal muscle development remains largely unknown. Here, we report a global m⁶A modification pattern of goat skeletal muscle at two key development stages and identified that the m⁶A modification regulated the expression of the growth arrest and DNA damage-inducible 45B (GADD45B) gene, which is involved in myogenic differentiation. We showed that GADD45B expression increased during myoblast differentiation, whereas the downregulation of GADD45B inhibits myogenic differentiation and mitochondrial biogenesis. Moreover, the expression of GADD45B regulates the expression of myogenic regulatory factors and peroxisome proliferator-activated receptor gamma coactivator 1 alpha by activating the p38 mitogen-activated protein kinase (MAPK) pathway. Conversely, the inactivation of p38 MAPK abolished the GADD45B-mediated myogenic differentiation. Furthermore, we found that the knockdown of fat mass and obesity-associated protein (FTO) increases GADD45B m⁶A modification and decreases the stability of GADD45B mRNA, which impairs myogenic differentiation. Our results indicate that the FTO-mediated m⁶A modification in GADD45B mRNA drives skeletal muscle differentiation by activating the p38 MAPK pathway, which provides a molecular mechanism for the regulation of myogenesis via RNA methylation.