Differential regulation of insulin-stimulated tyrosine phosphorylation of IRS-1 and SHC by Wortmannin in intact cells.
Wortmannin is an inhibitor of phosphatidylinositol (PI) 3'-kinase, a cellular kinase activated by docking to phosphotyrosyl residues of insulin receptor substrate-1 (IRS-1) that can also phosphorylate serine residues on IRS-1 in vitro. After treatment of hepatoma cells with 100 nM wortmannin, the tyrosine phosphorylation of IRS-1 in response to insulin was increased by 38.3 +/- 3.3% while its phosphoserine/threonine content was reduced by 19%. Treatment with 1 microM wortmannin further increased IRS-1 tyrosine phosphorylation to 180% of control, while under these conditions, tyrosine phosphorylation of the IR substrate p52 Shc was reduced to less than 50% of control. Thus, alteration of the serine phosphorylation of IR substrates by a wortmannin-sensitive kinase may regulate post-insulin receptor signaling pathways by differential modulation of their insulin-stimulated tyrosine phosphorylation.
Li
P M
PM
Dorrance H. Hamilton Research Laboratories, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Goldstein
B J
BJ
D000730:Androstadienes / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D007700:Kinetics; D008114:Liver Neoplasms, Experimental; D010710:Phosphates / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors; D019000:Phosphotyrosine / Q000032:analysis / Q000378:metabolism; D051381:Rats; D011972:Receptor, Insulin / Q000302:isolation & purification / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism*; D000077191:Wortmannin
D000730:Androstadienes; D004791:Enzyme Inhibitors; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D010710:Phosphates; D010750:Phosphoproteins; D010769:Phosphothreonine; D010768:Phosphoserine; D019000:Phosphotyrosine; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011972:Receptor, Insulin; D000077191:Wortmannin