title: Angiotensin II impairs the insulin signaling pathway promoting production of nitric oxide by inducing phosphorylation of insulin receptor substrate-1 on Ser312 and Ser616 in human umbilical vein endothelial cells.
abstract: It has been suggested that serine (Ser) phosphorylation of insulin receptor substrate-1 (IRS-1) decreases the ability of IRS-1 to be phosphorylated on tyrosine, thereby attenuating insulin signaling. There is evidence that angiotensin II (AII) may impair insulin signaling to the IRS-1/phosphatydilinositol 3-kinase (PI 3-kinase) pathway by enhancing Ser phosphorylation. Insulin stimulates NO production by a pathway involving IRS-1/PI3-kinase/Akt/endothelial NO synthase (eNOS). We addressed the question of whether AII affects insulin signaling involved in NO production in human umbilical vein endothelial cells and tested the hypothesis that the inhibitory effect of AII on insulin signaling was caused by increased site-specific Ser phosphorylation in IRS-1. Exposure of human umbilical vein endothelial cells to AII resulted in inhibition of insulin-stimulated production of NO. This event was associated with impaired IRS-1 phosphorylation at Tyr612 and Tyr632, two sites essential for engaging the p85 subunit of PI3-kinase, resulting in defective activation of PI 3-kinase, Akt, and eNOS. This inhibitory effect of AII was reversed by the type 1 receptor antagonist losartan. AII increased c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) 1/2 activity, which was associated with a concomitant increase in IRS-1 phosphorylation at Ser312 and Ser616, respectively. Inhibition of JNK and ERK1/2 activity reversed the negative effects of AII on insulin-stimulated NO production. Our data suggest that AII, acting via the type 1 receptor, increases IRS-1 phosphorylation at Ser312 and Ser616 via JNK and ERK1/2, respectively, thus impairing the vasodilator effects of insulin mediated by the IRS-1/PI 3-kinase/Akt/eNOS pathway.
authors.affiliation: Department of Clinical and Experimental Medicine, University Magna Graecia of Catanzaro, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Andreozzi
authors.forename: Emanuela
authors.initials: E
authors.lastname: Laratta
authors.forename: Angela
authors.initials: A
authors.lastname: Sciacqua
authors.forename: Francesco
authors.initials: F
authors.lastname: Perticone
authors.forename: Giorgio
authors.initials: G
authors.lastname: Sesti
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D002478:Cells, Cultured / Q000378:metabolism; D003062:Codon; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000502:physiology*; D055504:Insulin Receptor Substrate Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D019808:Losartan / Q000494:pharmacology; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000032:analysis; D019000:Phosphotyrosine / Q000032:analysis; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014471:Umbilical Veins
chemical_list: D000804:Angiotensin II; D003062:Codon; D016895:Culture Media, Serum-Free; D005947:Glucose; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D019808:Losartan; D048670:MAP Kinase Kinase 4; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D010768:Phosphoserine; D019000:Phosphotyrosine; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D044140:Receptor, Angiotensin, Type 1; C526292:IRS1 protein, human; C496314:NOS3 protein, human; C494918:AKT1 protein, human