Figure 1. The role of Sirt1 in satellite cells proliferation and maturation. The scheme summarizes the effects of increased Sirt1 expression observed in satellite cells and myoblasts on proliferation and myogenesis. In activated satellite cells. Sirt1 inhibits the expression of cell cyle inhibitors and promotes its proliferation. The negative role played by Sirt1 on the myogenic program by direct or indirect interactions with the myogenic factors MyoD and MEF2 suggest a further inhibition of muscle formation.