Unknown

To test this hypothesis, we incubated C2C12 myotubes with 1 μm tomatidine for 1 h. We found that tomatidine increased phosphorylation of a key mTORC1 substrate, S6 kinase (S6K) (Fig. 3A). In addition, tomatidine increased protein synthesis (Fig. 3B) and IGF1 and PGC-1α1 mRNAs (Fig. 3C). To determine if mTORC1 signaling is required for tomatidine-mediated cell growth, we tested the effect of an mTORC1 inhibitor, rapamycin. As expected, rapamycin abolished the effect of tomatidine on S6K phosphorylation (Fig. 3D). Moreover, rapamycin inhibited tomatidine-mediated protein accretion and myotube growth (Fig. 3, E and F). Collectively, these data indicate that tomatidine stimulates muscle cell growth by activating mTORC1 signaling.