A long-lasting vitamin C derivative, ascorbic acid 2-phosphate, increases myogenin gene expression and promotes differentiation in L6 muscle cells.

Hormones and growth factors are important regulators of myogenic cell differentiation, but little is known about the effect of vitamins on muscle differentiation and development. We recently showed that L-ascorbic acid 2-phosphate, a stable form of vitamin C, increased the expression of muscle-specific glucose and ion transporters. We now show the effect of L-ascorbic acid 2-phosphate on the kinetics of myogenin expression at both the mRNA and protein levels during differentiation of L6 muscle cells. At the fully differentiated stage, control and L-ascorbic acid 2-phosphate treated cultures showed the same degree of cell fusion, but L-ascorbic acid 2-phosphate treated myotubes had a larger diameter than control myotubes. During L6 cell differentiation, the amount of both myogenin mRNA and protein reached a maximal level on day 4 before full myotube formation and then declined. L-ascorbic acid 2-phosphate treated cells expressed a higher amount of myogenin at both the mRNA and protein levels on day 4 compared to untreated cultures. Ethyl-3,4-dihydroxybenzoate, an inhibitor of collagen synthesis, prevented expression of myogenin mRNA and protein in both the control and L-ascorbic acid 2-phosphate treated cells. These results demonstrate that vitamin C can promote muscle differentiation likely through the increase of myogenin expression in myogenic cells, which may in turn regulate muscle differentiation in vivo.