Insulin Transiently Increases Tau Phosphorylation

Involvement of Glycogen Synthase Kinase-3β and Fyn Tyrosine Kinase

Authors


  • Abbreviations used : DTT, dithiothreitol ; GSK-3, glycogen synthase kinase-3 ; HRP, horseradish peroxidase ; IGF-1, insulin-like growth factor-1 ; IRS-1, insulin receptor substrate-1 ; MAP kinase, mitogen-activated protein kinase ; PHF, paired helical filament ; SDS, sodium dodecyl sulfate.

Address correspondence and reprint requests to Dr. G. V. W. Johnson at 1720 7th Ave., South, SC1061, Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294-0017, U.S.A.

Abstract

Abstract : The modulation of tau phosphorylation in response to insulin was examined in human neuroblastoma SH-SY5Y cells. Insulin treatment resulted in a transient increase in tau phosphorylation followed by a decrease in tau phosphorylation that correlated directly with a sequential activation and deactivation of glycogen synthese kinase-3β (GSK-3β). The insulin-induced increase in tau phosphorylation and concurrent activation of GSK-3β was rapid (<2 min) and transient, and was associated with increased tyrosine phosphorylation of GSK-3β. The increase in GSK-3β tyrosine phosphorylation corresponded directly to an increase in the association of Fyn tyrosine kinase with GSK-3β, and Fyn immunoprecipitated from cells treated with insulin for 1 min phosphorylated GSK-3β to a significantly greater extent than Fyn immunoprecipitated from control cells. Subsequent to the increase in GSK-3β activation and tau phosphorylation, treatment of cells with insulin for 60 min resulted in a dephosphorylation of tau and a decrease in GSK-3β activity. Thus, insulin rapidly and transiently activated GSK-3β and modulated tau phosphorylation, alterations that may contribute to neuronal plasticity.

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