title: S-nitrosylation-dependent inactivation of Akt/protein kinase B in insulin resistance.
abstract: Inducible nitric-oxide synthase (iNOS) has been implicated in many human diseases including insulin resistance. However, how iNOS causes or exacerbates insulin resistance remains largely unknown. Protein S-nitrosylation is now recognized as a prototype of a redox-dependent, cGMP-independent signaling component that mediates a variety of actions of nitric oxide (NO). Here we describe the mechanism of inactivation of Akt/protein kinase B (PKB) in NO donor-treated cells and diabetic (db/db) mice. NO donors induced S-nitrosylation and inactivation of Akt/PKB in vitro and in intact cells. The inhibitory effects of NO donor were independent of phosphatidylinositol 3-kinase and cGMP. In contrast, the concomitant presence of oxidative stress accelerated S-nitrosylation and inactivation of Akt/PKB. In vitro denitrosylation with reducing agent reactivated recombinant and cellular Akt/PKB from NO donor-treated cells. Mutated Akt1/PKBalpha (C224S), in which cysteine 224 was substituted by serine, was resistant to NO donor-induced S-nitrosylation and inactivation, indicating that cysteine 224 is a major S-nitrosylation acceptor site. In addition, S-nitrosylation of Akt/PKB was increased in skeletal muscle of diabetic (db/db) mice compared with wild-type mice. These data suggest that S-nitrosylation-mediated inactivation may contribute to the pathogenesis of iNOS- and/or oxidative stress-involved insulin resistance.
authors.affiliation: Department of Anesthesia and Critical Care, Massachusetts General Hospital, Shriners Hospital for Children, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yasukawa
authors.forename: Eriko
authors.initials: E
authors.lastname: Tokunaga
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Ota
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sugita
authors.forename: J A Jeevendra
authors.initials: JA
authors.lastname: Martyn
authors.forename: Masao
authors.initials: M
authors.lastname: Kaneki
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003545:Cysteine / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015151:Immunoblotting; D007333:Insulin Resistance; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000378:metabolism; D009154:Mutation; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism; D018384:Oxidative Stress; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
chemical_list: D003545:Cysteine; D018076:DNA, Complementary; D048049:Extracellular Signal-Regulated MAP Kinases; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D009584:Nitrogen; D010396:Penicillamine; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012694:Serine; C110881:S-nitro-N-acetylpenicillamine; C496317:Nos2 protein, mouse