title: Regulation of MAPK/ERK phosphorylation via ionotropic glutamate receptors in cultured rat striatal neurons.
abstract: Extracellular signals may regulate mitogen-activated protein kinase (MAPK) cascades through a receptor-mediated mechanism. As a signaling superhighway to the nucleus, active Ras-MAPK cascades phosphorylate transcription factors and facilitate gene expression. In cultured rat striatal neurons, the present work systemically examined the linkage between glutamate receptors and the extracellular signal-regulated kinase 1/2 (ERK1/2) subclass of MAPK. We found that glutamate induced a rapid and transient phosphorylation of ERK1/2. Similar responses of ERK1/2 phosphorylation were also induced by the ligands selective for each of three subtypes of ionotropic receptors (NMDA, AMPA and kainate), although not by the subgroup-selective agonists for three subgroups of metabotropic glutamate receptors after 8-9 days in culture. The ERK1/2 phosphorylation induced by all ionotropic receptor agents was dose-, time- and Ca(2+) influx-dependent and occurred in neurons, but not glia. The NMDA-, AMPA- and kainate-induced ERK1/2 phosphorylation was blocked only by the antagonists selective for respective subtypes. The ERK1/2 phosphorylation induced by these agents was also sensitive to the MAPK kinase 1 (MEK1) inhibitor PD98059 and the MEK1/2 inhibitor U0126. In a further attempt to evaluate the role of active ERK1/2 in activating a downstream transcription factor cAMP response element-binding protein (CREB), NMDA, AMPA, and kainate were found to increase CREB phosphorylation. The NMDA- and AMPA/kainate-induced CREB phosphorylation was completely and partially blocked by U0126, respectively. These results revealed a positive linkage between ionotropic glutamate receptors and MEK-sensitive ERK1/2 phosphorylation in striatal neurons. The active ERK1/2 cascade activates the downstream transcription factor CREB to participate in the regulation of gene expression.
authors.affiliation: Department of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, 2411 Holmes Street, Rm. M3-225, Kansas City, Missouri 64108, USA.
authors.forename: Limin
authors.initials: L
authors.lastname: Mao
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Tang
authors.forename: Shazia
authors.initials: S
authors.lastname: Samdani
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Liu
authors.forename: John Q
authors.initials: JQ
authors.lastname: Wang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004622:Embryo, Mammalian; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011247:Pregnancy; D051381:Rats; D018091:Receptors, AMPA / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D020929:Mitogen-Activated Protein Kinase Kinases; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate