Class II phosphoinositide 3-kinase is activated by insulin but not by contraction in skeletal muscle

Arch Biochem Biophys. 2001 Dec 15;396(2):244-8. doi: 10.1006/abbi.2001.2587.


While the role of the class IA phosphoinositide 3-kinase (PI 3-kinase) in insulin signaling is well established, little is known about the role of the class II PI 3-kinases. We show that insulin stimulation of intact rat soleus and epitrochlearis muscles causes a 3- to 4-fold increase in the activity of the wortmannin-resistant alpha isoform of the class II PI 3-kinase (PI3K-C2alpha). This activation is rapid and parallels the insulin-induced activation of the class IA PI 3-kinase associated with IRS-1 in these muscles. However, while contraction activated p38 Map kinase, it did not stimulate the activity of the class II PI 3-kinase. Therefore, activation of class II PI 3-kinase is unlikely to provide a mechanism that explains the fact that exercise-induced activation of glucose uptake is not blocked by wortmannin. However, the results suggest that activation of class II PI 3-kinase is likely to play a role in insulin signaling pathways in skeletal muscle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androstadienes / pharmacology
  • Animals
  • Blotting, Western
  • Dose-Response Relationship, Drug
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • Insulin / metabolism*
  • Male
  • Mitogen-Activated Protein Kinases / metabolism
  • Muscle Contraction
  • Muscle, Skeletal / enzymology
  • Phosphatidylinositol 3-Kinases / chemistry*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Precipitin Tests
  • Protein Binding
  • Rats
  • Rats, Wistar
  • Signal Transduction
  • Time Factors
  • Wortmannin
  • p38 Mitogen-Activated Protein Kinases


  • Androstadienes
  • Enzyme Inhibitors
  • Insulin
  • Phosphatidylinositol 3-Kinases
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Wortmannin