Myostatin inhibits cell proliferation and protein synthesis in C2C12 muscle cells

Myostatin mutations in mice and cattle are associated with increased muscul arity, suggesting that myostatin is a negative regulator of skeletal muscle mass. To test the hypothesis that myostatin inhibits muscle cell growth, w e examined the effects of recombinant myostatin in mouse skeletal muscle C2 C12 cells. After verification of the expression of cDNA constructs in a cel l-free system and in transfected Chinese hamster ovary cells, the human rec ombinant protein was expressed as the full-length (375-amino acid) myostati n in Drosophila cells (Mst375D), or the 110-amino acid carboxy-terminal pro tein in Escherichia coli (Mst110EC). These proteins were identified by immu noblotting and were purified. Both Mst375D and Mst110EC dose dependently in hibited cell proliferation (cell count and Formazan assay), DNA synthesis ( [H-3] thymidine incorporation), and protein synthesis ([1-C-14] leucine inc orporation) in C2C12 cells. The inhibitory effects of both proteins were gr eater in myotubes than in myoblasts. Neither protein had any significant ef fects on protein degradation or apoptosis. In conclusion, recombinant myost atin proteins inhibit cell proliferation, DNA synthesis, and protein synthe sis in C2C12 muscle cells, suggesting that myostatin may control muscle mas s by inhibiting muscle growth or regeneration.