5'AMP-activated protein kinase (AMPK) is one of longevity-related genes, which promotes health and wellbeing by regulating glucose, lipid, and energy metabolisms. Recently, it has been revealed that AMPK is also associated with regulating skeletal muscle mass. However, the precise mechanism of AMPK-mediated regulation of muscle mass is not fully clarified. In the present study, we examined mechanisms by which AMPK coordinates muscle mass. Wild type mice (WT) and muscle-specific AMPK inactivated mice (AMPK-DN) were used in this experiment, and soleus muscle atrophy was induced by 2-week hindlimb suspension. Soleus muscle atrophy was greater in WT group than AMPK-DN group. In WT group, mRNA of muscleRing finger 1, which promotes protein degradation in muscle, was upregulated, but not in AMPK-DN group. In addition, Akt/mammalian target of rapamycin/p70 s6 kinase pathway, which promotes protein synthesis in muscle, is activated more in AMPKDN group compared with WT group. In conclusion, a longevity-related gene, AMPK negatively regulates skeletal muscle mass through upregulating protein synthesis pathways and downregulating protein degradation pathways.

DESCENTE SPORTS SCIENCE Vol.35/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE