Differential protein metabolism and regeneration in hypertrophic diaphragm and atrophic gastrocnemius muscles in hibernating Daurian ground squirrels

New findings What is the central question of this study? The purpose of this article is to investigate whether diaphragm hypertrophy and gastrocnemius atrophy during hibernation of Daurian ground squirrels involve differential regulation of protein metabolism and regeneration. What is the main finding and its importance? We clarified the differences in protein metabolism and muscle regeneration potential in the diaphragm and gastrocnemius of hibernating ground squirrels, reflecting the different adaptability of muscles. Abstract Whether differences in regulation of protein metabolism and regeneration are involved in the different phenotypic adaptation mechanisms of muscle hypertrophy and atrophy in hibernators? Two fast-type muscles (diaphragm and gastrocnemius) in summer active and hibernating Daurian ground squirrels were selected to detect changes in cross-sectional area (CSA) and protein expression indicative of protein synthesis metabolism (protein expression of P-Akt, P-mTORC1, P-S6K1, and P-4E-BP1), protein degradation metabolism (MuRF1, atrogin-1, calpain-1, calpain-2, calpastatin, desmin, troponin T, Beclin1, and LC3-II), and muscle regeneration (MyoD, myogenin, and myostatin). Results showed the CSA of the diaphragm muscle increased significantly by 26.1%, whereas the CSA of the gastrocnemius muscle decreased significantly by 20.4% in the hibernation group compared with the summer active group. Our study further indicated that increased protein synthesis, decreased protein degradation, and increased muscle regeneration potential contributed to diaphragm muscle hypertrophy, whereas decreased protein synthesis, increased protein degradation, and decreased muscle regeneration potential contributed to gastrocnemius muscle atrophy. In conclusion, the differences in muscle regeneration and regulatory pattern of protein metabolism may contribute to the different adaptive changes observed in the diaphragm and gastrocnemius muscles of ground squirrels. This article is protected by copyright. All rights reserved.