Tyrosine phosphorylation regulates mechanical stretch‐induced activation of protein translation initiation in C2C12 myoblasts

Abstract

It has been proposed that mechanically‐induced tension was the critical event for initiating muscle hypertrophy. However, the molecular mechanisms involved in this process are still under investigation. In the present study, effect of mechanical stretch on the protein translation initiation was studied in C2C12 myoblasts. C2C12 cells were plated on fibronectin‐coated silicone elastomer chamber in DMEM containing 10% fetal bovine serum. Cells were grown in CO2 incubator and subjected to 30 min of cyclic stretch (15% uniaxial stretch at a frequency of 1 Hz). Western blot analysis revealed that 30 min of cyclic stretch increased the phosphorylation of p70 S6 kinase (p70S6K), which is a key regulator for translation initiation. Pre‐treatment of cells with broad range tyrosine kinase inhibitor, genistein, completely blocked the stretch‐induced phosphorylation of p70S6K. These results suggest that tyrosine phosphorylation plays a critical role in the activation of protein translation initiation process in response to cyclic stretch. This work is supported by Grant‐in‐Aid for Scientific Research C (20500577 to N.N.) from the Japan Society for the Promotion of Science (JSPS).