RNA analysis of diet-induced sarcopenic obesity in rats.

Obesity has been suggested as a risk factor for sarcopenia. Sarcopenic obesity (SO), as a new category of obesity, is a high-risk geriatric syndrome in elderly individuals. However, knowledge about the molecular pathomechanisms of SO is still sparse. In the present study, starting at 13 months, male Sprague-Dawley (SD) rats were fed a high-fat diet (HFD) and normal diet (ND) for 28 weeks to establish a rodent animal model of SO with an identical protocol, which was further assessed and verified as a successful SO model. Through RNA-seq analysis of gastrocnemius muscle in SO rats, we found that differentially expressed genes (DEGs) and alternative splicing events (ASEs) focused mainly on inflammatory, immune-response, skeletal muscle cell differentiation, fat cell differentiation and antigen processing and presentation. Furthermore, as the core regulation factor of skeletal muscle, the mef2c (myocyte enhancer Factor 2C) gene also has a significant alternative 3' splice site (A3SS) and down-regulated expression in HFD-induced SO. The alternative genes targeted by mef2c identified by GO analysis were enriched in transcript regulation of RNA polymerase II promoter. In conclusion, these explorative findings in aging high-fat-fed rats might serve as a firm starting point for understanding the pathway and mechanism of sarcopenic obesity.