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Type: Artigo de periódico
Title: The cross-talk between angiotensin and insulin differentially affects phosphatidylinositol 3-kinase- and mitogen-activated protein kinase-mediated signaling in rat heart: Implications for insulin resistance
Author: Carvalheira, JBC
Calegari, VC
Zecchin, HG
Nadruz, W
Guimaraes, RB
Ribeiro, EB
Franchini, KG
Velloso, LA
Saad, MJA
Abstract: Insulin and angiotensin II (AngII) may act through overlapping intracellular pathways to promote cardiac myocyte growth. In this report insulin and AngII signaling, through the phosphatidylinositol 3-kinase (PI 3-kinase) and MAPK pathways, were compared in cardiac tissues of control and obese Zucker rats. AngII induced Janus kinase 2 tyrosine phosphorylation and coimmunoprecipitation with insulin receptor substrate 1 (IRS-1) and IRS-2 as well as an increase in tyrosine phosphorylation of IRS and its association with growth factor receptor-binding protein 2. Simultaneous treatment with both hormones led to marked increases in the associations of IRS-1 and -2 with growth factor receptor-binding protein 2 and in the dual phosphorylation of ERK1/2 compared with the administration of AngII or insulin alone. In contrast, an acute inhibition of both basal and insulin-stimulated PI 3-kinase activity was induced by both hormones. Insulin stimulated the phosphorylation of MAPK equally in lean and obese rats. Conversely, insulin-induced phosphorylation of Akt in heart was decreased in obese rats. Pretreatment with losartan did not change insulin-induced activation of ERK1/2 and attenuated the reduction of Akt phosphorylation in the heart of obese rats. Thus, the imbalance between PI 3-kinase-Akt and MAPK signaling pathways in the heart may play a role in the development of cardiovascular abnormalities observed in insulin-resistant states, such as in obese Zucker rats.
Country: EUA
Editor: Endocrine Soc
Rights: embargo
Identifier DOI: 10.1210/en.2003-0788
Date Issue: 2003
Appears in Collections:Unicamp - Artigos e Outros Documentos

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