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Type: Artigo de periódico
Title: Regulation Of Insulin Receptor Substrate-2 Tyrosine Phosphorylation In Animal Models Of Insulin Resistance.
Author: Rojas, Fernanda Alvarez
Hirata, Aparecida Emiko
Saad, Mario J A
Abstract: Insulin induces a wide variety of growth and metabolic responses in many cell types. These actions are initiated by insulin binding to its receptor and involve a series of alternative and complementary pathways created by the multiple substrates of the insulin receptor (insulin receptor substrates [IRSs]). We investigated IRS-1 and IRS-2 tyrosine phosphorylation; their association with phosphatidylinositol-3-OH kinase (PI3-K); and the phosphorylation of Akt, a serine-threonine kinase situated downstream of PI3-K, in liver and muscle of two animal models of insulin resistance: epinephrine- or dexamethasone-treated rats. We used in vivo insulin infusion followed by tissue extraction, immunoprecipitation, and immunoblotting. IRS-1 and IRS-2 protein expression did not change in liver and muscle of the epinephrine- treated rats, but in dexamethasone-treated rats IRS-1 presented an increase in liver and a decrease in muscle tissue. PI3-K and Akt protein expression did not change in liver or muscle of the two animal models of insulin resistance. There was a downregulation in insulin- induced IRS-1 and IRS-2 tyrosine phosphorylation and association with PI3-K in both models of insulin resistance. In parallel, insulin-induced Akt phosphorylation was reduced in both tissues of epinephrine-treated rats, and in liver but not in muscle of dexamethasonetreated rats. The reduction in insulin-induced Akt phosphorylation may help to explain the insulin resistance in liver and muscle of epinephrine-treated rats and in the liver of dexamethasone-treated rats.
Subject: Animals
Disease Models, Animal
Insulin Receptor Substrate Proteins
Insulin Resistance
Intracellular Signaling Peptides And Proteins
Muscle, Skeletal
Phosphatidylinositol 3-kinases
Protein-serine-threonine Kinases
Proto-oncogene Proteins
Proto-oncogene Proteins C-akt
Rats, Wistar
Rights: fechado
Identifier DOI: 10.1385/ENDO:21:2:115
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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