High glucose induces differentiation and adipogenesis in porcine muscle satellite cells via mTOR

摘要

The present study investigated whether the mammalian target of rapamycin (mTOR) signal pathway is involved in the regu-lation of high glucose-induced intramuscular adipogenesis in porcine muscle satellite cells. High glucose (25 mM) dramati-cally increased intracellular lipid accumulation in cells during the 10-day adipogenic differentiation period. The expressions of CCAAT/enhancer binding protein-a (C/EBP-α) and fatty acid synthase (FAS) protein were gradually enhanced during the 10-day duration while mTOR phosphorylation and sterol-regu-latory-element-binding protein (SREBP)-1c protein were in-duced on day 4. Moreover, inhibition of mTOR activity by ra-pamycin resulted in a reduction of SREBP-lc protein expre-ssion and adipogenesis in cells. Collectively, our findings sug-gest that the adipogenic differentiation of porcine muscle satel-lite cells and a succeeding extensive adipogenesis, which is triggered by high glucose, is initiated by the mTOR signal pathway through the activation of SREBP-1c protein. This proc-ess is previously uncharacterized and suggests a cellular mech-anism may be involved in ectopic lipid deposition in skeletal muscle during type 2 diabetes.