Musclin attenuates lipid deposition in hepatocytes through SIRT7/autophagy-mediated suppression of ER stress.

Musclin, an exercise-responsive myokine, has the ability to attenuate inflammation, oxidative stress, and apoptosis in cardiomyocytes under pathogenic conditions. While the potential benefits of musclin in the cardiovascular system have been well documented, its effects on hepatic endoplasmic reticulum (ER) stress and lipid metabolism are not fully understood. The present study showed that musclin treatment reduced lipid accumulation and lipogenic protein expression in primary hepatocytes exposed to palmitate. Palmitate treatment led to an increase in markers of ER stress, which was reversed by musclin treatment. Musclin treatment increased SIRT7 expression and markers of autophagy in a dose-dependent manner. Small interfering (si) RNA of SIRT7 or 3-methyladenine (3 MA) reduced the effects of musclin on lipogenic lipid deposition in hepatocytes under hyperlipidemic conditions. These findings suggest that musclin can suppress palmitate-induced ER stress by upregulating SIRT7 and autophagy signaling, thereby alleviating lipid accumulation in primary hepatocytes. The current study provides a potential therapeutic strategy for the treatment of liver diseases characterized by lipid accumulation and ER stress, such as nonalcoholic fatty liver disease (NAFLD).