Rosiglitazone, insulin treatment, and fasting correct defective activation of protein kinase C-zeta/lambda by insulin in vastus lateralis muscles and adipocytes of diabetic rats

Endocrinology. 2001 Apr;142(4):1595-605. doi: 10.1210/endo.142.4.8066.

Abstract

Atypical protein kinases C (PKCs), zeta and lambda, and protein kinase B (PKB) are thought to function downstream of phosphatidylinositol 3-kinase (PI 3-kinase) and regulate glucose transport during insulin action in skeletal muscle and adipocytes. Insulin-stimulated glucose transport is defective in type II diabetes mellitus, and this defect is ameliorated by thiazolidinediones and lowering of blood glucose by chronic insulin therapy or short-term fasting. Presently, we evaluated the effects of these insulin-sensitizing modalities on the activation of insulin receptor substrate-1 (IRS-1)-dependent PI 3-kinase, PKC-zeta/lambda, and PKB in vastus lateralis skeletal muscles and adipocytes of nondiabetic and Goto-Kakizaki (GK) diabetic rats. Insulin provoked rapid increases in the activity of PI 3-kinase, PKC-zeta/lambda, and PKB in muscles and adipocytes of nondiabetic rats, but increases in IRS-1-dependent PI 3-kinase and PKC-zeta/lambda, but not PKB, activity were substantially diminished in GK muscles and adipocytes. Rosiglitazone treatment for 10-14 days, 10-day insulin treatment, and 60-h fasting reversed defects in PKC-zeta/lambda activation in GK muscles and adipocytes and increased glucose transport in GK adipocytes, without necessarily increasing IRS-1-dependent PI 3-kinase or PKB activation. Our findings suggest that insulin-sensitizing modalities, viz. thiazolidinediones, chronic insulin treatment, and short-term fasting, similarly improve defects in insulin-stimulated glucose transport at least partly by correcting defects in insulin-induced activation of PKC-zeta/lambda.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adipocytes / drug effects
  • Adipocytes / enzymology*
  • Animals
  • Blotting, Western
  • Diabetes Mellitus, Type 2 / genetics
  • Diabetes Mellitus, Type 2 / metabolism
  • Enzyme Activators / pharmacology
  • Fasting / metabolism*
  • Hypoglycemic Agents / pharmacology*
  • Insulin / pharmacology*
  • Isoenzymes
  • Mice
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / enzymology*
  • Phosphatidylinositol 3-Kinases / metabolism
  • Protein Kinase C / metabolism*
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Rats
  • Rats, Wistar
  • Rosiglitazone
  • Thiazoles / pharmacology*
  • Thiazolidinediones*

Substances

  • Enzyme Activators
  • Hypoglycemic Agents
  • Insulin
  • Isoenzymes
  • Proto-Oncogene Proteins
  • Thiazoles
  • Thiazolidinediones
  • Rosiglitazone
  • Phosphatidylinositol 3-Kinases
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Protein Kinase C
  • protein kinase C lambda