title: Metabotropic mGlu5 receptors regulate adenosine A2A receptor signaling.
abstract: Dopamine, by activating dopamine D1-type receptors, and adenosine, by activating adenosine A(2A) receptors, stimulate phosphorylation of DARPP-32 (dopamine- and cAMP-regulated phosphoprotein of M(r) 32,000) at Thr-34. In this study, we investigated the effect of metabotropic glutamate (mGlu) receptors on DARPP-32 phosphorylation at Thr-34 in neostriatal slices. A broad-spectrum mGlu receptor agonist, trans-ACPD, and a group I mGlu receptor agonist, DHPG, stimulated DARPP-32 phosphorylation at Thr-34. Studies with mGlu receptor antagonists revealed that the effects of trans-ACPD and DHPG were mediated through activation of mGlu5 receptors. The action of mGlu5 receptors required activation of adenosine A(2A) receptors by endogenous adenosine. Conversely, the action of adenosine A(2A) receptors required activation of mGlu5 receptors by endogenous glutamate. Coactivation of mGlu5 and adenosine A(2A) receptors by exogenous agonists synergistically increased DARPP-32 phosphorylation. mGlu5 receptors did not require activation of dopamine D1-type receptors by endogenous dopamine, nor did dopamine D1-type receptors require activation of mGlu5 receptors by endogenous glutamate. DHPG potentiated the effect of forskolin, but not that of 8-bromo-cAMP, and stimulated DARPP-32 phosphorylation in the presence of the phosphodiesterase inhibitor IBMX, suggesting that mGlu5 receptors stimulate the rate of cAMP formation coupled to adenosine A(2A) receptors. The action of mGlu5 receptors was attenuated by inhibitors of extracellular signal-regulated kinase, but not by inhibitors of phospholipase C, p38, casein kinase 1, or Cdk5. The results demonstrate that mGlu5 receptors potentiate adenosine A(2A)DARPP-32 signaling by stimulating the adenosine A(2A) receptor-mediated formation of cAMP in an extracellular signal-regulated kinase-dependent manner.
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: Feng
authors.initials: F
authors.lastname: Liu
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: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000378:metabolism; D000818:Animals; D047388:Casein Kinases; D000242:Cyclic AMP / Q000378:metabolism; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004305:Dose-Response Relationship, Drug; D015151:Immunoblotting; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009419:Nerve Tissue Proteins; D009474:Neurons / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D043705:Receptor, Adenosine A2A; D064529:Receptor, Metabotropic Glutamate 5; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism* / Q000502:physiology*; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D015398:Signal Transduction; D013912:Threonine / Q000378:metabolism; D013997:Time Factors; D010738:Type C Phospholipases / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D009419:Nerve Tissue Proteins; D010726:Phosphodiesterase Inhibitors; D010750:Phosphoproteins; D043705:Receptor, Adenosine A2A; D064529:Receptor, Metabotropic Glutamate 5; D017447:Receptors, Dopamine D1; D018094:Receptors, Metabotropic Glutamate; D018047:Receptors, Purinergic P1; D015124:8-Bromo Cyclic Adenosine Monophosphate; D013912:Threonine; D000242:Cyclic AMP; D011494:Protein Kinases; D047388:Casein Kinases; D051360:Cyclin-Dependent Kinase 5; C495906:Cdk5 protein, mouse; D018844:Cyclin-Dependent Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D015056:1-Methyl-3-isobutylxanthine