Palmitate contributes to insulin resistance through downregulation of the Src-mediated phosphorylation of Akt in C2C12 myotubes

Biosci Biotechnol Biochem. 2012;76(7):1356-61. doi: 10.1271/bbb.120107. Epub 2012 Jul 7.

Abstract

The mechanisms of free fatty acid (FFA)-induced peripheral insulin resistance remain elusive. This study aimed to investigate the effect of palmitate, a saturated fatty acid, on glucose metabolism in C2C12 myotubes, and to explore the underlying mechanisms. In it, palmitate decreased insulin-stimulated glucose uptake and consumption in a dose-dependent manner, and it reduced the insulin-stimulated phosphorylation of Akt at Thr308 and Ser473, but had no effect on the protein expression of PI3K-p85 or the activity of PI3K. Additionally, it inhibited the insulin-stimulated phosphorylation of Src at Tyr416, causing a reduction in the Src-mediated phosphorylation of Akt. Inhibition of Src by PP2 resulted in decreases in insulin-stimulated glucose uptake and phosphorylation of Src at Tyr416 and Akt at Thr308 and Ser473. The findings indicate that palmitate contributes to insulin resistance by inhibiting the Src-mediated phosphorylation of Akt in C2C12 myotubes, and this provides insight into the molecular mechanisms of FFA-induced insulin resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Dose-Response Relationship, Drug
  • Down-Regulation / drug effects
  • Glucose / metabolism
  • Insulin / metabolism
  • Insulin Resistance / genetics*
  • Mice
  • Muscle Fibers, Skeletal / cytology
  • Muscle Fibers, Skeletal / drug effects*
  • Muscle Fibers, Skeletal / metabolism
  • Palmitates / pharmacology*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins pp60(c-src) / antagonists & inhibitors*
  • Proto-Oncogene Proteins pp60(c-src) / genetics
  • Pyrimidines / pharmacology
  • Signal Transduction / drug effects

Substances

  • AG 1879
  • Insulin
  • Palmitates
  • Pyrimidines
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins pp60(c-src)
  • Proto-Oncogene Proteins c-akt
  • Glucose