title: Agonist-Specific Recruitment of Arrestin Isoforms Differentially Modify Delta Opioid Receptor Function.
abstract: Ligand-specific recruitment of arrestins facilitates functional selectivity of G-protein-coupled receptor signaling. Here, we describe agonist-selective recruitment of different arrestin isoforms to the delta opioid receptor in mice. A high-internalizing delta opioid receptor agonist (SNC80) preferentially recruited arrestin 2 and, in arrestin 2 knock-outs (KOs), we observed a significant increase in the potency of SNC80 to inhibit mechanical hyperalgesia and decreased acute tolerance. In contrast, the low-internalizing delta agonists (ARM390, JNJ20788560) preferentially recruited arrestin 3 with unaltered behavioral effects in arrestin 2 KOs. Surprisingly, arrestin 3 KO revealed an acute tolerance to these low-internalizing agonists, an effect never observed in wild-type animals. Furthermore, we examined delta opioid receptor-Ca(2+)channel coupling in dorsal root ganglia desensitized by ARM390 and the rate of resensitization was correspondingly decreased in arrestin 3 KOs. Live-cell imaging in HEK293 cells revealed that delta opioid receptors are in pre-engaged complexes with arrestin 3 at the cell membrane and that ARM390 strengthens this membrane interaction. The disruption of these complexes in arrestin 3 KOs likely accounts for the altered responses to low-internalizing agonists. Together, our results show agonist-selective recruitment of arrestin isoforms and reveal a novel endogenous role of arrestin 3 as a facilitator of resensitization and an inhibitor of tolerance mechanisms.
  
  
  CONCLUSIONS
  Agonists that bind to the same receptor can produce highly distinct signaling events and arrestins are a major mediator of this ligand bias. Here, we demonstrate that delta opioid receptor agonists differentially recruit arrestin isoforms. We found that the high-internalizing agonist SNC80 preferentially recruits arrestin 2 and knock-out (KO) of this protein results in increased efficacy of SNC80. In contrast, low-internalizing agonists (ARM390 and JNJ20788560) preferentially recruit arrestin 3 and, surprisingly, KO of arrestin 3 produces acute tolerance and impaired receptor resensitization to these agonists. Arrestin 3 is in pre-engaged complexes with the delta opioid receptor at the cell membrane and low-internalizing agonists promote this interaction. This study reveals a novel role for arrestin 3 as a facilitator of receptor resensitization.
authors.affiliation: Semel Institute for Neuropsychiatry and Human Behavior and Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, California 90095, Department of Psychiatry, University of Illinois, Chicago, Illinois 60612, apradhan@psych.uic.edu.
authors.forename: Amynah A
authors.initials: AA
authors.lastname: Pradhan
authors.affiliation: Centre National de la Recherche Scientifique, Unité Mixte de Recherche-5203, Institut de Génomique Fonctionnelle, Montpellier, F-34094, France, INSERM, U1191, Montpellier, F-34094, France, Universités de Montpellier 1 and 2, Unité Mixte de Recherche-5203, Montpellier, F-34094, France, and.
authors.forename: Julie
authors.initials: J
authors.lastname: Perroy
authors.affiliation: Semel Institute for Neuropsychiatry and Human Behavior and Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, California 90095.
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Walwyn
authors.affiliation: Semel Institute for Neuropsychiatry and Human Behavior and Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, California 90095.
authors.forename: Monique L
authors.initials: ML
authors.lastname: Smith
authors.affiliation: Department of Psychiatry, University of Illinois, Chicago, Illinois 60612.
authors.forename: Ana
authors.initials: A
authors.lastname: Vicente-Sanchez
authors.affiliation: Department of Psychiatry, University of Illinois, Chicago, Illinois 60612.
authors.forename: Laura
authors.identifier: http://orcid.org/0000-0003-3755-8801
authors.initials: L
authors.lastname: Segura
authors.affiliation: Semel Institute for Neuropsychiatry and Human Behavior and Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, California 90095.
authors.forename: Alia
authors.initials: A
authors.lastname: Bana
authors.affiliation: Douglas Hospital, McGill University, Verdun, Quebec H4H 1R3, Canada.
authors.forename: Brigitte L
authors.initials: BL
authors.lastname: Kieffer
authors.affiliation: Semel Institute for Neuropsychiatry and Human Behavior and Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, California 90095.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Evans
mesh_terms: D000818:Animals; D019390:Arrestins / Q000378:metabolism*; D001549:Benzamides / Q000008:administration & dosage*; D004361:Drug Tolerance; D005260:Female; D006930:Hyperalgesia / Q000503:physiopathology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D058748:Pain Perception; D010879:Piperazines / Q000008:administration & dosage*; D020033:Protein Isoforms; D017465:Receptors, Opioid, delta / Q000037:antagonists & inhibitors* / Q000378:metabolism*
chemical_list: D019390:Arrestins; D001549:Benzamides; D010879:Piperazines; D020033:Protein Isoforms; D017465:Receptors, Opioid, delta; C088464:4-(alpha-(4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl)-N,N-diethylbenzamide
keywords: DRG; GPCR; arrestin; pain; resensitization; tolerance