title: Group I metabotropic glutamate receptors, mGlu1a and mGlu5a, couple to cyclic AMP response element binding protein (CREB) through a common Ca2+ - and protein kinase C-dependent pathway.
abstract: Coupling of the group I metabotropic glutamate receptors, mGlu1a and mGlu5a, to the cAMP response element binding protein (CREB) has been studied in Chinese hamster ovary cell lines where receptor expression is under the control of an inducible promoter. Both receptors stimulate CREB phosphorylation with similar time courses, and agonist potency was also comparable between the two receptors. Stimulation of cells in Ca(2+)-free medium containing EGTA (100 microm), with or without the additional depletion of intracellular stores, caused marked decreases in agonist-mediated responses in both cell lines. Down-regulation of protein kinase C (PKC) activity by phorbol ester treatment, or treatment with the broad spectrum PKC inhibitor Ro 31-8220, partially attenuated both mGlu1a and mGlu5a receptor-mediated responses. Furthermore, stimulation of cells in the absence of extracellular Ca(2+) following prior PKC down-regulation resulted in additive inhibitory effects. The involvement of extracellular signal-regulated kinases (ERK1/2), Ca(2+)/calmodulin or Ca(2+)/calmodulin-dependent protein kinases was assessed using pharmacological inhibitors. Results indicated that coupling of the group I mGlu receptors to CREB phosphorylation occurs independently of these pathways. Thus, although the [Ca(2+)](i) signatures activated by these mGlu receptors differ, they couple to CREB with comparable potency and recruit similar downstream components to execute CREB phosphorylation.
authors.affiliation: Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, UK.
authors.forename: Helen K
authors.initials: HK
authors.lastname: Warwick
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Nahorski
authors.forename: R A John
authors.initials: RA
authors.lastname: Challiss
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D016257:Fura-2 / Q000031:analogs & derivatives* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D018698:Glutamic Acid / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016318:Quisqualic Acid / Q000494:pharmacology; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013722:Teprotide / Q000494:pharmacology; D013997:Time Factors
chemical_list: D002121:Calcium Channel Blockers; D017362:Cyclic AMP Response Element-Binding Protein; D018690:Excitatory Amino Acid Agonists; D007211:Indoles; D007476:Ionophores; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; C049925:fura-2-am; D005576:Colforsin; D007544:Isopropyl Thiogalactoside; D018698:Glutamic Acid; D015759:Ionomycin; D016318:Quisqualic Acid; D013722:Teprotide; D000242:Cyclic AMP; D037342:Pertussis Toxin; D011493:Protein Kinase C; D002118:Calcium; D016257:Fura-2; C064758:Ro 31-8220