title: Role of Src in ligand-specific regulation of delta-opioid receptor desensitization and internalization.
abstract: The opioid receptors are a member of G protein-coupled receptors that mediate physiological effects of endogenous opioid peptides and structurally distinct opioid alkaloids. Although it is well characterized that there is differential receptor desensitization and internalization properties following activation by distinct agonists, the underlying mechanisms remain elusive. We investigated the signaling events of delta-opioid receptor (deltaOR) initiated by two ligands, DPDPE and TIPP. We found that although both ligands inhibited adenylyl cyclase (AC) and activated ERK1/2, only DPDPE induced desensitization and internalization of the deltaOR. We further found that DPDPE, instead of TIPP, could activate GRK2 by phosphorylating the non-receptor tyrosine kinase Src and translocating it to membrane receptors. Activation of GRK2 led to the phosphorylation of serine residues in the C-terminal tail, which facilitates beta-arrestin1/2 membrane translocation. Meanwhile, we also found that DPDPE promoted beta-arrestin1 dephosphorylation in a Src-dependent manner. Thus, DPDPE appears to strengthen beta-arrestin function by dual regulations: promoting beta-arrestin recruitment and increasing beta-arrestin dephosphorylation at the plasma membrane in a Src-dependent manner. All effects initiated by DPDPE could be abolished or suppressed by PP2, an inhibitor of Src. Morphine, which has been previously shown to be unable to desensitize or internalize deltaOR, also behaved as TIPP in failure to utilize Src to regulate deltaOR signaling. These findings point to the existence of agonist-specific utilization of Src to regulate deltaOR signaling and reveal the molecular events by which Src modulates deltaOR responsiveness.
authors.affiliation: State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Min-Hua
authors.initials: MH
authors.lastname: Hong
authors.forename: Chi
authors.initials: C
authors.lastname: Xu
authors.forename: Yu-Jun
authors.initials: YJ
authors.lastname: Wang
authors.forename: Jing-Li
authors.initials: JL
authors.lastname: Ji
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: Tao
authors.forename: Xue-Jun
authors.initials: XJ
authors.lastname: Xu
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Xin
authors.initials: X
authors.lastname: Xie
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Chi
authors.forename: Jing-Gen
authors.initials: JG
authors.lastname: Liu
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D019390:Arrestins / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D020881:Enkephalin, D-Penicillamine (2,5)- / Q000494:pharmacology; D005434:Flow Cytometry; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009020:Morphine / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D017465:Receptors, Opioid, delta / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D044005:Tetrahydroisoquinolines / Q000494:pharmacology; D014162:Transfection; D000071557:beta-Arrestins; D019061:src-Family Kinases / Q000502:physiology*
chemical_list: D000701:Analgesics, Opioid; D019390:Arrestins; D009842:Oligopeptides; D017465:Receptors, Opioid, delta; D044005:Tetrahydroisoquinolines; D000071557:beta-Arrestins; C082263:tyrosyl-1,2,3,4-tetrahydro-3-isoquinolinecarbonyl-phenylalanyl-phenylalanine; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D012694:Serine; D009020:Morphine; D020881:Enkephalin, D-Penicillamine (2,5)-; D019061:src-Family Kinases; D054769:G-Protein-Coupled Receptor Kinase 2; D048052:Mitogen-Activated Protein Kinase 3; D000262:Adenylyl Cyclases