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: Takashi Yasukawa, Eriko Tokunaga, Hidetaka Ota, Hiroki Sugita, J A Jeevendra Martyn, Masao Kaneki
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 280 Issue 9 Pg. 7511-8 (Mar 04 2005) ISSN: 0021-9258 [Print] United States
• PMID: 15632167 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• DNA, Complementary
• Proto-Oncogene Proteins
• S-nitro-N-acetylpenicillamine
• Nitric Oxide
• Serine
• Nitric Oxide Synthase
• Nitric Oxide Synthase Type II
• Nos2 protein, mouse
• Protein Serine-Threonine Kinases
• Proto-Oncogene Proteins c-akt
• Extracellular Signal-Regulated MAP Kinases
• Penicillamine
• Cysteine
• Nitrogen

Topics

• 3T3 Cells
• Adipocytes (metabolism)
• Animals
• COS Cells
• Cell Line, Tumor
• Cells, Cultured
• Cysteine (chemistry)
• DNA, Complementary (metabolism)
• Diabetes Mellitus, Experimental (metabolism)
• Extracellular Signal-Regulated MAP Kinases (metabolism)
• Immunoblotting
• Insulin Resistance
• Male
• Mice
• Mice, Inbred C57BL
• Mice, Transgenic
• Muscle, Skeletal (metabolism)
• Mutation
• Nitric Oxide (chemistry, metabolism)
• Nitric Oxide Synthase (metabolism)
• Nitric Oxide Synthase Type II
• Nitrogen (chemistry, metabolism)
• Oxidative Stress
• Penicillamine (analogs & derivatives, pharmacology)
• Phosphatidylinositol 3-Kinases (metabolism)
• Protein Serine-Threonine Kinases (physiology)
• Proto-Oncogene Proteins (physiology)
• Proto-Oncogene Proteins c-akt
• Serine (chemistry)
• Signal Transduction
• Time Factors
• Transfection