title: Oligomerization of opioid receptors with beta 2-adrenergic receptors: a role in trafficking and mitogen-activated protein kinase activation.
abstract: G-protein-coupled receptors (GPCRs) have recently joined the list of cell surface receptors that dimerize. Dimerization has been shown to alter the ligand-binding, signaling, and trafficking properties of these receptors. Recent studies have shown that GPCRs heterodimerize with closely related members, resulting in the modulation of their function. In this study, we have attempted to determine whether members of GPCR superfamilies that couple to different families of G-proteins can associate and form oligomers. We chose the beta2 adrenergic receptor that couples to stimulatory G-proteins and delta & kappa opioid receptors that couple to inhibitory G-proteins. beta2 and delta receptors undergo robust agonist-mediated endocytosis, whereas kappa receptors do not. We find that when coexpressed, beta2 receptors can form heteromeric complexes with both delta and kappa receptors. This heterooligomerization does not significantly alter the ligand binding or coupling properties of the receptors. However, it affects the trafficking properties of the receptors. For example, we find that delta receptors, when coexpressed with beta2 receptors, undergo isoproterenol-mediated endocytosis. Conversely, beta2 receptors in these cells undergo etorphine-mediated endocytosis. However, beta2 receptors, when coexpressed with kappa receptors, undergo neither opioid- nor isoproterenol-mediated endocytosis. Moreover, these cells exhibit a substantial decrease in the isoproterenol-induced phosphorylation of mitogen-activated protein kinases. Taken together, these results provide direct evidence of heteromerization of GPCRs that couple to different types of G-proteins, which results in the modulation of receptor trafficking and signal transduction.
authors.affiliation: Department of Pharmacology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Jordan
authors.forename: N
authors.initials: N
authors.lastname: Trapaidze
authors.forename: I
authors.initials: I
authors.lastname: Gomes
authors.forename: R
authors.initials: R
authors.lastname: Nivarthi
authors.forename: L A
authors.initials: LA
authors.lastname: Devi
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005048:Etorphine / Q000494:pharmacology; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008024:Ligands; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009294:Narcotics / Q000494:pharmacology; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D021381:Protein Transport / Q000187:drug effects; D011940:Receptor Aggregation; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics / Q000378:metabolism*; D011957:Receptors, Opioid / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D014162:Transfection
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists; D008024:Ligands; D009294:Narcotics; D010714:Phosphatidylethanolamines; D018343:Receptors, Adrenergic, beta-2; D011957:Receptors, Opioid; D011993:Recombinant Fusion Proteins; D005048:Etorphine; C020888:1,2-dielaidoylphosphatidylethanolamine; D000242:Cyclic AMP; D020928:Mitogen-Activated Protein Kinases; D020962:Heterotrimeric GTP-Binding Proteins; D007545:Isoproterenol