title: Protein kinase Cɛ activity regulates mGluR5 surface expression in the rat nucleus accumbens.
abstract: Type 5 metabotropic glutamate receptors (mGluR5) activate protein kinase C (PKC) via coupling to Gαq/11protein signaling. We have previously demonstrated that the epsilon isoform of PKC (PKCɛ) is a critical downstream target of mGluR5 in regulating behavioral and biochemical responses to alcohol. Recent evidence suggests that PKC-mediated phosphorylation of mGluR5 can lead to receptor desensitization and internalization. We therefore sought to examine the specific involvement of PKCɛ in the regulation of mGluR5 surface expression in the nucleus accumbens (NAc), a key regulator of alcohol-associated behaviors. Coronal brain sections from male Wistar rats were analyzed for either colocalization of mGluR5 and PKCɛ via immunohistochemistry or changes in mGluR5 surface expression and PKCɛ phosphorylation following local application of PKCɛ translocation activator or inhibitor peptides and/or an orthosteric mGluR5 agonist. We observed colocalization of mGluR5 and PKCɛ in the NAc. We also showed that intra-NAc infusion of the PKCɛ translocation inhibitor ɛV1-2 increased mGluR5 surface expression under baseline conditions. Stimulation of mGluR5 with an orthosteric agonist DHPG, dose dependently increased ERK1/2 and PKCɛ phosphorylation as well as mGluR5 internalization in acute NAc slices. Finally, we observed that activation of PKCɛ translocation with Tat-ΨɛRACK peptide mediates agonist-independent mGluR5 internalization, whereas PKCɛ translocation inhibitor ɛV1-2 prevents agonist-dependent internalization of mGluR5 in NAc slice preparations. These findings suggest that the subcellular localization of mGluR5 in the NAc is regulated by PKCɛ under basal and stimulation conditions, which may influence the role of mGluR5-PKCɛ signaling in alcohol-related behaviors. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Psychology Department, University of Florida, Gainesville, Florida.
authors.forename: Marek
authors.initials: M
authors.lastname: Schwendt
authors.affiliation: Psychology Department, Arizona State University, Tempe, Arizona.
authors.forename: M Foster
authors.initials: MF
authors.lastname: Olive
mesh_terms: D000818:Animals; D019921:Biotinylation; D037281:Calnexin / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation; D014176:Protein Biosynthesis / Q000187:drug effects; D051744:Protein Kinase C-epsilon / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D064529:Receptor, Metabotropic Glutamate 5 / Q000378:metabolism*; D050827:Syntaxin 1 / Q000378:metabolism
chemical_list: D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D005229:Fatty Acids, Monounsaturated; D010455:Peptides; D064529:Receptor, Metabotropic Glutamate 5; D050827:Syntaxin 1; D037281:Calnexin; D008734:Methoxyhydroxyphenylglycol; D051744:Protein Kinase C-epsilon; C054211:9-tetradecenoic acid; C010117:3,4-dihydroxyphenylglycol
keywords: ERK1/2; Tat peptide; acute brain slices; membrane trafficking; phosphorylation; surface biotinylation