Irisin regulates the phosphorylation of glucocorticoid receptor Ser212 and Ser234 and mediates glucocorticoid-induced muscle atrophy in mice.

Glucocorticoid-induced skeletal muscle atrophy severely limits the clinical use of glucocorticoids and occurs in various endocrine and metabolic diseases. However, a detailed understanding of how glucocorticoid receptor (GR) transcriptional responses contribute to muscle atrophy is lacking. Irisin is a myokine induced by exercise and has been shown to exert multiple beneficial effects on muscle mass and metabolism regulation. Here, we show that glucocorticoid genomic effects are the main pathway through which glucocorticoids induce muscle atrophy in mice. Increased GR Ser212 and Ser234 site phosphorylation reduces glucocorticoid-induced muscle atrophy in mice. Irisin ameliorates high-fat diet (HFD) and dexamethasone (Dex)-induced muscle atrophy. Mechanistically, this effect depends on irisin promoting the phosphorylation of ERK and JNK through integrin αVβ5 receptors, which in turn impairs the dephosphorylation of GR Ser212 and Ser234 sites, affecting the GCs genomic effect on the transcription of muscle atrophy-related genes. These findings highlight the genomic effects of GCs as an intervention target to ameliorate GC-induced muscle atrophy and suggest that irisin could be a potential therapeutic target.