Role of Src in ligand-specific regulation of δ-opioid receptor desensitization and internalization

• Published in: Journal of neurochemistry Vol. 108; no. 1; pp. 102 - 114
• Main Authors: Hong, Min-Hua, Xu, Chi, Wang, Yu-Jun, Ji, Jing-Li, Tao, Yi-Min, Xu, Xue-Jun, Chen, Jie, Xie, Xin, Chi, Zhi-Qiang, Liu, Jing-Gen
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 2009; Blackwell Publishing Ltd; Wiley-Blackwell
• Subjects: Adenylyl Cyclases - metabolism; Analgesics, Opioid - pharmacology; Animals; Arrestins - metabolism; beta-Arrestins; Biological and medical sciences; Cell receptors; Cell structures and functions; CHO Cells; Cricetinae; Cricetulus; desensitization; Dose-Response Relationship, Drug; Enkephalin, D-Penicillamine (2,5)- - pharmacology; Flow Cytometry; Fundamental and applied biological sciences. Psychology; G-Protein-Coupled Receptor Kinase 2 - metabolism; GRK2; Guanosine 5'-O-(3-Thiotriphosphate) - metabolism; internalization; Mitogen-Activated Protein Kinase 3 - metabolism; Molecular and cellular biology; Monoamines receptors (catecholamine, serotonine, histamine, acetylcholine); Morphine - pharmacology; Neuropeptide receptors; Oligopeptides - pharmacology; Protein Binding - drug effects; Protein Transport - drug effects; Receptors, Opioid, delta - metabolism; Serine - metabolism; Signal Transduction - drug effects; Signal Transduction - physiology; Src; src-Family Kinases - physiology; Tetrahydroisoquinolines - pharmacology; Transfection; β-arrestin; δ-opioid receptor; Phosphorylation; Desensitization; Peptides; Src; Opioid receptor; Activation; δ Opioid receptor; Src tyrosine kinase; Signal transduction; Membrane receptor; Endogenous; GRK2; β-arrestin; Internalization; intemalization; δ-opioid receptor; G protein; Biological receptor
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2008.05740.x

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 δ-opioid receptor (δOR) 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 δOR. 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 β-arrestin1/2 membrane translocation. Meanwhile, we also found that DPDPE promoted β-arrestin1 dephosphorylation in a Src-dependent manner. Thus, DPDPE appears to strengthen β-arrestin function by dual regulations: promoting β-arrestin recruitment and increasing β-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 δOR, also behaved as TIPP in failure to utilize Src to regulate δOR signaling. These findings point to the existence of agonist-specific utilization of Src to regulate δOR signaling and reveal the molecular events by which Src modulates δOR responsiveness.