Regulation of DARPP-32 dephosphorylation at PKA- and Cdk5-sites by NMDA and AMPA receptors: Distinct roles of calcineurin and protein phosphatase-2A

Academic Article

Abstract

  • Glutamatergic inputs from corticostriatal and thalamostriatal pathways have been shown to modulate dopaminergic signaling in neostriatal neurons. DARPP-32 (dopamine- and cAMP-regulated phosphoprotein of M 32 kDa) is a signal transduction molecule that regulates the efficacy of dopamine signaling in neostriatal neurons. Dopamine signaling is mediated in part through phosphorylation of DARPP-32 at Thr34 by cAMP-dependent protein kinase, and antagonized by phosphorylation of DARPP-32 at Thr75 by cyclin-dependent protein kinase 5. We have now investigated the effects of the ionotropic glutamate NMDA and AMPA receptors on DARPP-32 phosphorylation in neostriatal slices. Activation of NMDA and AMPA receptors decreased the state of phosphorylation of DARPP-32 at Thr34 and Thr75. The decrease in Thr34 phosphorylation was mediated through Ca -dependent activation of the Ca -/calmodulin-dependent phosphatase, calcineurin. In contrast, the decrease in Thr75 phosphorylation was mediated through Ca -dependent activation of dephosphorylation by protein phosphatase-2A. The results provide support for a complex effect of glutamate on dopaminergic signaling through the regulation of dephosphorylation of different sites of DARPP-32 by different protein phosphatases. r 2+ 2+ 2+
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    Author List

  • Nishi A; Bibb JA; Matsuyama S; Hamada M; Higashi H; Nairn AC; Greengard P
  • Start Page

  • 832
  • End Page

  • 841
  • Volume

  • 81
  • Issue

  • 4