Electrical stimulation induces AMPK-mediated cell cycle arrest in C2C12 myoblasts

Skeletal muscle is a phenotypically dynamic tissue that responds to alterations in activation which can have an affect on muscle recovery from injury. Using a cell culture model system, electrical stimulation caused 18 and 12 fold increases in protein levels of p27 and p21, respectively. This suggested that electrical stimulation was inducing cell cycle arrest in these cells. Thus, we stimulated proliferating myoblasts and examined the effects on p27 protein levels in these cells. p27 protein levels increased while cyclin E protein levels decreased with time from 1 to 5 days of electrical stimulation suggesting these cells are undergoing cell cycle arrest. Concomitant with these changes was an increase in pAMPK and T198-p27 (a direct AMPK stabilizing phosphorylation site on the p27 protein). Pharmacologic inhibition of AMPK activation using compound C blunted electrical stimulation-induced increases in AMPK activation, T198-p27 and total p27 protein levels. These data suggest that electrical stimulation alters the activity of AMPK in C2C12 myoblasts, resulting in cell cycle arrest.