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.
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.
Kanoh
Y
Y
J. A. Haley Veterans Hospital Research Service and Department of Internal Medicine, University of South Florida College of Medicine Tampa, Florida 33612, USA.
Bandyopadhyay
G
G
Sajan
M P
MP
Standaert
M L
ML
Farese
R V
RV
D017667:Adipocytes / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D015153:Blotting, Western; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism; D020536:Enzyme Activators / Q000494:pharmacology; D005215:Fasting / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D007527:Isoenzymes; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D000077154:Rosiglitazone; D013844:Thiazoles / Q000494:pharmacology*; D045162:Thiazolidinediones; D000099293:Protein Kinase C-lambda
D020536:Enzyme Activators; D007004:Hypoglycemic Agents; D007328:Insulin; D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D000077154:Rosiglitazone; D013844:Thiazoles; D045162:Thiazolidinediones; D000099293:Protein Kinase C-lambda