Combination of insulinomimetic agents H2O2 and vanadate enhances insulin receptor mediated tyrosine phosphorylation of IRS-1 leading to IRS-1 association with the phosphatidylinositol 3-kinase.
To analyze the mechanism of action of the insulinomimetic agents H2O2, vanadate, and pervanadate (H2O2 and vanadate), CHO cells or CHO cells that overexpress wild-type or mutant insulin receptor and/or the insulin receptor substrate (IRS-1) were used. H2O2 or vanadate treatment alone had little or no effect on tyrosine phosphorylation of cellular proteins; however, pervanadate treatment dramatically enhanced tyrosine phosphorylation of a number of proteins including the insulin receptor and IRS-1. However, the insulin receptor and IRS-1 coimmunoprecipitate from insulin-treated but not from pervanadate-treated cells. Pervanadate-induced tyrosine phosphorylation of the insulin receptor led to an increase in insulin receptor tyrosine kinase activity toward IRS-1 in vivo and IRS-1 peptides in vitro equal to that induced by insulin treatment. Pervanadate-enhanced phosphorylation of IRS-1 led to a fifteenfold increase in IRS-1-associated phosphatidylinositol (PtdIns) 3-kinase activity. However, insulin receptor-associated PtdIns 3-kinase activity from pervanadate-treated cells was not detectable, while insulin receptor-associated PtdIns 3-kinase activity from insulin-treated cells was 20% of the IRS-1-associated activity. Thus, pervanadate but not H2O2 or vanadate alone under these conditions mimics many of insulin actions, but pervanadate treatment does not induce insulin receptor/IRS-1 association.
Wilden
P A
PA
Department of Pharmacology, University of Missouri-Columbia, School of Medicine 65212, USA.
Broadway
D
D
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011972:Receptor, Insulin / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology*
D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D010750:Phosphoproteins; C076715:pervanadate; D014638:Vanadates; D014443:Tyrosine; D006861:Hydrogen Peroxide; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011972:Receptor, Insulin; D017027:Protein Tyrosine Phosphatases