Garcinol Promotes the Formation of Slow-Twitch Muscle Fibers by Inhibiting p300-Dependent Acetylation of PGC-1α
Abstract Background The conversion of skeletal muscle fiber from fast twitch to slow-twitch is crucial for sustained contractile and stretchable events, energy homeostasis, and anti-fatigue ability. The purpose of our study was to explore the mechanism and effects of garcinol on the regulation of skeletal muscle fiber type transformation. Methods Forty 21-day-old male C57/BL6J mice (n = 10/diet) were fed a control diet or a control diet plus garcinol at 100 mg/kg (Low Gar), 300 mg/kg (Mid Gar), or 500 mg/kg (High Gar) for 12 weeks. The tibialis anterior (TA) and soleus muscles were collected for protein and immunoprecipitation analyses. Results Dietary garcinol significantly downregulated (P<0.05) fast MyHC expression and upregulated (P<0.05) slow MyHC expression in the TA and soleus muscles. Garcinol significantly increased (P<0.05) the activity of PGC-1α and markedly decreased (P<0.05) the acetylation of PGC-1α. In vitro and in vivo experiments showed that garcinol decreased (P<0.05) lactate dehydrogenase activity and increased (P<0.05) the activities of malate dehydrogenase and succinic dehydrogenase. In addition, the results of immunostaining C2C12 myotubes showed that garcinol treatment increased (P<0.05) the transformation of glycolytic muscle fiber to oxidative muscle fiber by 45.9%. Garcinol treatment and p300 interference reduced (P<0.05) the expression of fast MyHC but increased (P<0.05) the expression of slow MyHC in vitro. Moreover, the acetylation of PGC-1α was significantly decreased (P<0.05). Conclusion Garcinol promotes the transformation of skeletal muscle fibers from the fast-glycolytic type to the slow-oxidative type through the p300/PGC-1α signaling pathway in C2C12 myotubes.