Phosphorylation of Eukaryotic Elongation Factor 2 Can Be Regulated by Phosphoinositide 3-Kinase in the Early Stages of Myoblast Differentiation

  • Woo, Joo Hong (Department of Biological Science, College of Natural Sciences, Ajou University) ;
  • Kim, Hye Sun (Department of Biological Science, College of Natural Sciences, Ajou University)
  • Received : 2005.10.07
  • Accepted : 2006.01.01
  • Published : 2006.04.30


We have previously reported that phosphorylation of eukaryotic elongation factor 2 (eEF2) is related to the differentiation of chick embryonic muscle cells in culture. In the present study, we found that eEF2 phosphorylation declined shortly after induction of differentiation of L6 myoblasts, when the cells prepare for terminal differentiation by withdrawing from the cell cycle. This decrease in phosphorylation was prevented by inhibitors of phosphoinositide 3-kinase (PI3-kinase) that strongly inhibit myoblast differentiation. We hypothesized that PI3-kinase plays an important role in myoblast differentiation by regulating eEF2 phosphorylation in the early stages of differentiation. To test this hypothesis, myoblasts were synchronized at in $G_2/M$ and cultured in fresh differentiation medium (DM) or growth medium (GM). In DM the released cells accumulated in $G_0$/$G_1$ while in GM they progressed to S phase. In addition, cyclin D1 was more rapidly degraded in DM than in GM, and eEF2 phosphorylation decreased more. Inhibitors of PI3-kinase increased eEF2 phosphorylation, but PI3-kinase became more activated when eEF2 phosphorylation declined. These results suggest that the regulation of L6 myoblast differentiation by PI3-kinase is related to eEF2 phosphorylation.


Cell Cycle;Eukaryotic Elongation Factor 2(eEF2);LY 294002;Myoblast Differentiation;Phosphoinositide 3-Kinase (PI3-Kinase)


Supported by : Korea Research Foundation


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