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Mol Cell Biol. 2008 Oct;28(20):6314-28. doi: 10.1128/MCB.00763-08. Epub 2008 Aug 11.

Tissue-specific role of glycogen synthase kinase 3beta in glucose homeostasis and insulin action.

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  • 1Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.

Abstract

Dysregulation of the protein kinase glycogen synthase kinase 3 (GSK-3) has been implicated in the development of type 2 diabetes mellitus. GSK-3 protein expression and kinase activity are elevated in diabetes, while selective GSK-3 inhibitors have shown promise as modulators of glucose metabolism and insulin sensitivity. There are two GSK-3 isoforms in mammals, GSK-3alpha and GSK-3beta. Mice engineered to lack GSK-3beta die in late embryogenesis from liver apoptosis, whereas mice engineered to lack GSK-3alpha are viable and exhibit improved insulin sensitivity and hepatic glucose homeostasis. To assess the potential role of GSK-3beta in insulin function, a conditional gene-targeting approach whereby mice in which expression of GSK-3beta was specifically ablated within insulin-sensitive tissues were generated was undertaken. Liver-specific GSK-3beta knockout mice are viable and glucose and insulin tolerant and display "normal" metabolic characteristics and insulin signaling. Mice lacking expression of GSK-3beta in skeletal muscle are also viable but, in contrast to the liver-deleted animals, display improved glucose tolerance that is coupled with enhanced insulin-stimulated glycogen synthase regulation and glycogen deposition. These data indicate that there are not only distinct roles for GSK-3alpha and GSK-3beta within the adult but also tissue-specific phenotypes associated with each of these isoforms.

PMID:
18694957
PMCID:
PMC2577415
DOI:
10.1128/MCB.00763-08
[PubMed - indexed for MEDLINE]
Free PMC Article
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