PMID: 8972717Nov 8, 1996Paper

The inhibitory effect of staurosporine on insulin action is prevented by okadaic acid. Evidence for an important role of serine/threonine phosphorylation in eliciting insulin-like effects

Biochimica Et Biophysica Acta
C M RondinoneU Smith

Abstract

The serine/threonine phosphatase inhibitor, okadaic acid (OA), exerted several insulin-like effects in rat adipose cells and was, in part, synergistic with insulin. OA stimulated glucose transport activity, altered the electrophoretic mobility of IRS-1, increased the phosphorylation of the MAP-kinases ERK 1 and 2 on tyrosine sites, markedly increased MAP kinase activity and also acted synergistically with insulin in activating these enzymes. However, OA did not increase PI 3-kinase activity or the tyrosine phosphorylation of key upstream proteins in insulin's signaling cascade. Staurosporine virtually completely inhibited the insulin-stimulated glucose transport and MAP kinase activation in spite of a maintained high PI 3-kinase activity. In contrast, the effects of OA alone or in the presence of insulin were less, or not at all, affected. These data suggest that OA exerts an insulin-like effect through a serine/threonine-related pathway which is distinct from, but converges with, that of insulin downstream PI 3-kinase and upon which staurosporine exerts an inhibitory effect.

References

Feb 1, 1990·Proceedings of the National Academy of Sciences of the United States of America·J J EganC Londos
Apr 1, 1990·Current Opinion in Cell Biology·S Jaken
Jan 1, 1989·Annual Review of Biochemistry·P Cohen
Apr 6, 1995·Biochemical and Biophysical Research Communications·K KotaniM Kasuga

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