title: Regulation of DARPP-32 dephosphorylation at PKA- and Cdk5-sites by NMDA and AMPA receptors: distinct roles of calcineurin and protein phosphatase-2A.
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 (r) 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(2+) -dependent activation of the Ca(2+) -/calmodulin-dependent phosphatase, calcineurin. In contrast, the decrease in Thr75 phosphorylation was mediated through Ca(2+) -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.
authors.affiliation: Department of Physiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan. nishia@med.kurume-u.ac.jp
authors.forename: Akinori
authors.initials: A
authors.lastname: Nishi
authors.forename: James A
authors.initials: JA
authors.lastname: Bibb
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Matsuyama
authors.forename: Miho
authors.initials: M
authors.lastname: Hamada
authors.forename: Hideho
authors.initials: H
authors.lastname: Higashi
authors.forename: Angus C
authors.initials: AC
authors.lastname: Nairn
authors.forename: Paul
authors.initials: P
authors.lastname: Greengard
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000502:physiology; D019703:Calcineurin / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003035:Cobalt / Q000494:pharmacology; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016202:N-Methylaspartate / Q000494:pharmacology; D009419:Nerve Tissue Proteins; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010750:Phosphoproteins / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D054648:Protein Phosphatase 2; D018091:Receptors, AMPA / Q000819:agonists / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000378:metabolism*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
chemical_list: D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D019319:Okadaic Acid; D003035:Cobalt; D016202:N-Methylaspartate; D011189:Potassium Chloride; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D051360:Cyclin-Dependent Kinase 5; D017868:Cyclic AMP-Dependent Protein Kinases; C495906:Cdk5 protein, mouse; D018844:Cyclin-Dependent Kinases; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D002118:Calcium