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Specific inhibition by hGRB10zeta of insulin-induced glycogen synthase activation: evidence for a novel signaling pathway.

Authors: Mounier, C  Lavoie, L  Dumas, V  Mohammad-Ali, K  Wu, J  Nantel, A  Bergeron, JJ  Thomas, DY  Posner, BI 
Citation: Mounier C, etal., Mol Cell Endocrinol. 2001 Feb 28;173(1-2):15-27.
Pubmed: (View Article at PubMed) PMID:11223174

Grb10 is a member of a family of adapter proteins that binds to tyrosine-phosphorylated receptors including the insulin receptor kinase (IRK). In this study recombinant adenovirus was used to over-express hGrb10zeta, a new Grb10 isoform, in primary rat hepatocytes and the consequences for insulin signaling were evaluated. Over-expression of hGrb10zeta resulted in 50% inhibition of insulin-stimulated IRK autophosphorylation and activation. Analysis of downstream events showed that hGrb10zeta over-expression specifically inhibits insulin-stimulated glycogen synthase (GS) activity and glycogen synthesis without affecting insulin-induced IRS1/2 phosphorylation, PI3-kinase activation, insulin like growth factor binding protein-1 (IGFBP-1) mRNA expression, and ERK1/2 MAP kinase activity. The classical pathway from PI3-kinase through Akt-PKB/GSK-3 leading to GS activation by insulin was also not affected by hGrb10zeta over-expression. These results indicate that hGrb10zeta inhibits a novel and presently unidentified insulin signaling pathway leading to GS activation in liver.


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CRRD Object Information
CRRD ID: 8553640
Created: 2014-05-08
Species: All species
Last Modified: 2014-05-08
Status: ACTIVE


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