Leucine promotes leptin receptor expression in mouse C2C12 myotubes through the mTOR pathway
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Leptin plays a critical role in regulating muscle protein metabolism by binding with leptin receptors in a 1:1 stoichiometry. However, the role for leucine in the regulation of leptin receptor expression in muscle has not been investigated. The present study was conducted to test the hypothesis that leucine regulates leptin receptor levels in C2C12 myotubes. Cells were cultured in the presence of DMEM/F12 medium containing supplemental 0 or 5 mM l-leucine. Leptin receptor expression by C2C12 myotubes peaked at 2 h post-supplementation. Additionally, leucine stimulated leptin receptor expression at both mRNA and protein levels in a dose-dependent manner. Furthermore, leucine enhanced the phosphorylation of mammalian target of rapamycin (mTOR). Addition of rapamycin (an inhibitor of mTOR) to culture medium completely suppressed leucine-induced activation of mTOR and inhibited leucine-stimulated leptin receptor production. These results indicate that leucine affects leptin receptor expression in muscle cells via the mTOR signaling pathway.
KeywordsLeptin receptor Leucine Mouse C2C12 myotubes Mammalian target of rapamycin
This study was financially supported by grants from the National Science Foundation of China (30525029). Special thanks to Professor Malcolm Watford from the Rutgers University and Professor Guoyao Wu from the Texas A&M University for editing the manuscript.
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