title: Molecular pathways mediating activation by kainate of mitogen-activated protein kinase in oligodendrocyte progenitors.
abstract: Oligodendroglial cells express ionotropic glutamate receptors of alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid hydrobromide (AMPA) and kainate (KA) subtypes. Recently, we reported that AMPA receptor agonists increased 45Ca2+ uptake and phospholipase C (PLC) activity. To further elucidate the intracellular signaling mechanisms, we examined the effects of AMPA and KA on mitogen-activated protein kinase (MAPK). KA caused a time- and concentration-dependent increase in MAPK activity (predominantly the p42mapk or ERK2) and the effect was blocked by 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX), a competitive AMPA/KA receptor antagonist. Furthermore, the noncompetitive antagonists of AMPA receptor GYKI 52466 and LY 303070 prevented the actions of the agonists, indicating that the effect of KA on MAPK activation is mediated through AMPA receptors in oligodendrocyte progenitors. Chelation of extracellular Ca2+ by EDTA or inhibition of PLC with U73122 abolished MAPK activation by KA. In addition, KA-stimulated MAPK activation was reduced by the protein kinase C (PKC) inhibitors, H7 and bisindolylmaleimide, as well as downregulation of PKC by prolonged exposure to phorbol esters. The involvement of PKC in the signal transduction pathways was further supported by the ability of KA to induce translocation of PKC measured by [3H]PDBu binding. Interestingly, a wortmannin-sensitive phosphatidylinositol 3-kinase and a pertussis toxin (PTX)-sensitive G protein form part of the molecular pathways mediating MAPK activation by AMPA receptor. A specific inhibitor of MAPK kinase, PD 098059, blocked MAPK activation and reduced KA-induced c-fos gene expression. All together, these results indicate that MAPK is implicated in the transmission of AMPA signaling to the nucleus and requires extracellular Ca2+, and PLC/PKC activation.
authors: Department of Pharmacology and Therapeutics, McGill University, Room 1321, 3655 Drummond St., Montreal, Quebec, Canada.
authors: H N
authors: HN
authors: Liu
authors: J N
authors: JN
authors: Larocca
authors: G
authors: G
authors: Almazan
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D007211:Indoles / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology*; D008301:Maleimides / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009836:Oligodendroglia / Q000737:chemistry / Q000166:cytology / Q000201:enzymology*; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013234:Stem Cells / Q000737:chemistry / Q000166:cytology / Q000201:enzymology*; D014316:Tritium; D010738:Type C Phospholipases / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D000077191:Wortmannin; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
chemical_list: D000730:Androstadienes; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D005419:Flavonoids; D007211:Indoles; D008301:Maleimides; D016760:Proto-Oncogene Proteins c-fos; D018091:Receptors, AMPA; D010566:Virulence Factors, Bordetella; D014316:Tritium; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; C070515:bisindolylmaleimide I; D007608:Kainic Acid; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium; D000077191:Wortmannin