Abstract
Obesity may impair muscle function and is sometimes associated with lower muscle mass. However, the internal regulatory mechanism is still unclear. Nur77 has been reported to improve obesity phenotype by regulating glucose and lipid metabolism and inhibiting the production of inflammatory factors and reactive oxygen species. Concurrently, Nur77 also plays an important role in muscle differentiation and development. We aimed to investigate the role of Nur77 in obesity-related lower muscle mass. Our in vivo and in vitro experiments illustrated that the reduction of obesity-related Nur77 accelerated the occurrence of lower muscle mass by interfering with the signaling pathways involved in the regulation of myoprotein synthesis and degradation. We further demonstrated that Nur77 activates the PI3K/Akt pathway by promoting Pten degradation, which enhances the phosphorylation of the Akt/mTOR/p70S6K pathway and inhibits the expression of skeletal muscle-specific E3 ligases (MAFbx/MuRF1). Nur77 induces Pten degradation by increasing the transcription of its specific E3 ligase Syvn1. Our study confirms that Nur77 is a key factor in ameliorating obesity-related lower muscle mass, providing a new therapeutic target and theoretical basis for the treatment of obesity-related lower muscle mass.