title: Kappa opioid receptor activation of p38 MAPK is GRK3- and arrestin-dependent in neurons and astrocytes.
abstract: AtT-20 cells expressing the wild-type kappa opioid receptor (KOR) increased phospho-p38 MAPK following treatment with the kappa agonist U50,488. The increase was blocked by the kappa antagonist norbinaltorphimine and not evident in untransfected cells. In contrast, U50,488 treatment of AtT-20 cells expressing KOR having alanine substituted for serine-369 (KSA) did not increase phospho-p38. Phosphorylation of serine 369 in the KOR carboxyl terminus by G-protein receptor kinase 3 (GRK3) was previously shown to be required for receptor desensitization, and the results suggest that p38 MAPK activation by KOR may require arrestin recruitment. This hypothesis was tested by transfecting arrestin3-(R170E), a dominant positive form of arrestin that does not require receptor phosphorylation for activation. AtT-20 cells expressing both KSA and arrestin3-(R170E) responded to U50,488 treatment with an increase in phospho-p38 consistent with the hypothesis. Primary cultured astrocytes (glial fibrillary acidic protein-positive) and neurons (gamma-aminobutyric acid-positive) isolated from mouse striata also responded to U50,488 by increasing phospho-p38 immunolabeling. p38 activation was not evident in either striatal astrocytes or neurons isolated from KOR knock-out mice or GRK3 knock-out mice. Astrocytes pretreated with small interfering RNA for arrestin3 were also unable to activate p38 in response to U50,488 treatment. Furthermore, in striatal neurons, the kappa-mediated phospho-p38 labeling was colocalized with arrestin3. These findings suggest that KOR may activate p38 MAPK in brain by a GRK3 and arrestin-dependent mechanism.
authors.affiliation: Department of Pharmacology, University of Washington, 1959 Pacific Avenue N.E., Seattle, WA 98195, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Bruchas
authors.forename: Tara A
authors.initials: TA
authors.lastname: Macey
authors.forename: Janet D
authors.initials: JD
authors.lastname: Lowe
authors.forename: Charles
authors.initials: C
authors.lastname: Chavkin
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer / Q000494:pharmacology; D018712:Analgesics, Non-Narcotic / Q000494:pharmacology; D000818:Animals; D019390:Arrestins / Q000378:metabolism*; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000166:cytology; D054770:G-Protein-Coupled Receptor Kinase 3; D051379:Mice; D008810:Mice, Inbred C57BL; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017473:Receptors, Opioid, kappa / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D051552:beta-Adrenergic Receptor Kinases / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D018712:Analgesics, Non-Narcotic; D019390:Arrestins; D009292:Narcotic Antagonists; D017473:Receptors, Opioid, kappa; C082333:arrestin3; C051844:norbinaltorphimine; D009271:Naltrexone; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D054770:G-Protein-Coupled Receptor Kinase 3; C517850:GRK3 protein, mouse; C517851:Grk3 protein, rat; D051552:beta-Adrenergic Receptor Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases