Glutamate Counteracts Dopamine/PKA Signaling via Dephosphorylation of DARPP-32 Ser-97 and Alteration of Its Cytonuclear Distribution

J Biol Chem. 2017 Jan 27;292(4):1462-1476. doi: 10.1074/jbc.M116.752402. Epub 2016 Dec 20.

Abstract

The interaction of glutamate and dopamine in the striatum is heavily dependent on signaling pathways that converge on the regulatory protein DARPP-32. The efficacy of dopamine/D1 receptor/PKA signaling is regulated by DARPP-32 phosphorylated at Thr-34 (the PKA site), a process that inhibits protein phosphatase 1 (PP1) and potentiates PKA action. Activation of dopamine/D1 receptor/PKA signaling also leads to dephosphorylation of DARPP-32 at Ser-97 (the CK2 site), leading to localization of phospho-Thr-34 DARPP-32 in the nucleus where it also inhibits PP1. In this study the role of glutamate in the regulation of DARPP-32 phosphorylation at four major sites was further investigated. Experiments using striatal slices revealed that glutamate decreased the phosphorylation states of DARPP-32 at Ser-97 as well as Thr-34, Thr-75, and Ser-130 by activating NMDA or AMPA receptors in both direct and indirect pathway striatal neurons. The effect of glutamate in decreasing Ser-97 phosphorylation was mediated by activation of PP2A. In vitro phosphatase assays indicated that the PP2A/PR72 heterotrimer complex was likely responsible for glutamate/Ca2+-regulated dephosphorylation of DARPP-32 at Ser-97. As a consequence of Ser-97 dephosphorylation, glutamate induced the nuclear localization in cultured striatal neurons of dephospho-Thr-34/dephospho-Ser-97 DARPP-32. It also reduced PKA-dependent DARPP-32 signaling in slices and in vivo Taken together, the results suggest that by inducing dephosphorylation of DARPP-32 at Ser-97 and altering its cytonuclear distribution, glutamate may counteract dopamine/D1 receptor/PKA signaling at multiple cellular levels.

Keywords: CK2; DARPP-32; dopamine; glutamate; nuclear translocation; protein kinase A (PKA); protein phosphatase 2 (PP2A); protein phosphorylation; striatum.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Nucleus / genetics
  • Cell Nucleus / metabolism*
  • Cyclic AMP-Dependent Protein Kinases / genetics
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Dopamine / genetics
  • Dopamine / metabolism*
  • Dopamine and cAMP-Regulated Phosphoprotein 32 / genetics
  • Dopamine and cAMP-Regulated Phosphoprotein 32 / metabolism*
  • Male
  • Mice
  • Phosphorylation / physiology
  • Protein Phosphatase 2 / genetics
  • Protein Phosphatase 2 / metabolism
  • Receptors, Dopamine D1 / genetics
  • Receptors, Dopamine D1 / metabolism*
  • Signal Transduction / physiology*

Substances

  • Dopamine and cAMP-Regulated Phosphoprotein 32
  • Ppp1r1b protein, mouse
  • Receptors, Dopamine D1
  • Cyclic AMP-Dependent Protein Kinases
  • Protein Phosphatase 2
  • Dopamine