Leucine promotes differentiation of porcine myoblasts through the protein kinase B (Akt)/Forkhead box O1 signalling pathway.

Leucine, one of the branched-chain amino acids, is the only amino acid to regulate protein turnover in skeletal muscle. Leucine not only increases muscle protein synthesis, but also decreases muscle protein degradation. It is well documented that leucine plays a positive role in differentiation of murine muscle cells. However, the role of leucine on porcine myoblast differentiation and its mechanism remains unclear. In this study, porcine myoblasts were induced to differentiate with differentiation medium containing different concentrations of leucine, and wortmannin was used to interdict the activity of protein kinase B (Akt). We found that leucine increased the number of myosin heavy chain-positive cells and creatine kinase activity. Moreover, leucine increased the mRNA and protein levels of myogenin and myogenic determining factor (MyoD). In addition, leucine increased the levels of phosphorylated Akt/Akt and phosphorylated Forkhead box O1 (P-FoxO1)/FoxO1, as well as decreased the protein level of FoxO1. However, wortmannin, a specific repressor of PI3K/Akt signalling pathway, attenuated the positive role of leucine on porcine myoblast differentiation. Our results suggest that leucine promotes porcine myoblast differentiation through the Akt/FoxO1 signalling pathway.