Document Detail


Amino acids require glucose to enhance, through phosphoinositide-dependent protein kinase 1, the insulin-activated protein kinase B cascade in insulin-resistant rat adipocytes.
MedLine Citation:
PMID:  16550357     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
AIMS/HYPOTHESIS: Amino acids are well known to activate the mammalian target of the rapamycin (mTOR) pathway in synergy with insulin to regulate cell functions. Despite recent important advances, the mTOR signalling pathway is poorly understood. Our previous results revealed a new pathway in which amino acids permit insulin-induced activation of the protein kinase B (PKB)/mTOR pathway in freshly isolated adipocytes when phosphatidylinositol 3-kinase (PI3K) is inhibited. The aim of this study was to further investigate this pathway at the molecular level. METHODS: We studied the effect of amino acids on PKB phosphorylation in different cellular models or in freshly isolated adipocytes incubated in different buffers, after a time course of insulin and amino acids and in the presence of pharmacological inhibitors. To investigate the potential role of amino acids in insulin action, the effect on glucose transport in obese rat adipocytes following a high-fat diet was assessed. RESULTS: Insulin-induced PKB phosphorylation is restored by amino acids in the presence of wortmannin in adipose tissue explants and freshly isolated adipocytes, but not in cultured adipocytes or hepatocytes. Moreover, amino acids require the presence of glucose to phosphorylate PKB and to partially rescue glucose transport in a PI3K-independent manner. The results also suggest that the amino acids act through the phosphoinositide-dependent protein kinase 1. In addition, amino acids were seen to improve insulin-stimulated glucose transport in adipocytes from high-fat-fed rats. CONCLUSIONS/INTERPRETATION: This study suggests that amino acids could enhance adipocyte insulin signalling in pathophysiological situations such as insulin resistance associated with obesity.
Authors:
C Hinault; I Mothe-Satney; N Gautier; E Van Obberghen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-03-21
Journal Detail:
Title:  Diabetologia     Volume:  49     ISSN:  0012-186X     ISO Abbreviation:  Diabetologia     Publication Date:  2006 May 
Date Detail:
Created Date:  2006-04-27     Completed Date:  2006-10-24     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0006777     Medline TA:  Diabetologia     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  1017-26     Citation Subset:  IM    
Affiliation:
INSERM Unit 145, IFR 50, Faculty of Medicine, Avenue de Valombrose, F-06107, Nice, Cedex 2, France.
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MeSH Terms
Descriptor/Qualifier:
1-Phosphatidylinositol 3-Kinase / metabolism*
Adipocytes / drug effects,  enzymology,  physiology
Amino Acids / metabolism*
Androstadienes / pharmacology
Animals
Biological Transport
Deoxyglucose / pharmacokinetics
Glucose / metabolism*,  pharmacology*
Insulin Resistance*
Male
Phosphatidylinositols / metabolism
Phosphorylation
Proto-Oncogene Proteins c-akt / metabolism*
Rats
Rats, Wistar
Chemical
Reg. No./Substance:
0/Amino Acids; 0/Androstadienes; 0/Phosphatidylinositols; 154-17-6/Deoxyglucose; 19545-26-7/wortmannin; 50-99-7/Glucose; EC 2.7.1.137/1-Phosphatidylinositol 3-Kinase; EC 2.7.11.1/Proto-Oncogene Proteins c-akt

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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