title: Allosteric interactions between the oxytocin receptor and the β2-adrenergic receptor in the modulation of ERK1/2 activation are mediated by heterodimerization.
abstract: The oxytocin receptor (OTR) and the β(2)-adrenergic receptor (β(2)AR) are key regulators of uterine contraction. These two receptors are targets of tocolytic agents used to inhibit pre-term labor. Our recent study on the nature of OTR- and β(2)AR-mediated ERK1/2 activation in human hTERT-C3 myometrial cells suggested the presence of an OTR/β(2)AR hetero-oligomeric complex (see companion article). The goal of this study was to investigate potential allosteric interactions between OTR and β(2)AR and establish the nature of the interactions between these receptors in myometrial cells. We found that OTR-mediated ERK1/2 activation was attenuated significantly when cells were pretreated with the β(2)AR agonist isoproterenol or two antagonists, propranolol or timolol. In contrast, pretreatment of cells with a third β(2)AR antagonist, atenolol resulted in an increase in OTR-mediated ERK1/2 activation. Similarly, β(2)AR-mediated ERK1/2 activation was strongly attenuated by pretreatment with the OTR antagonists, atosiban and OTA. Physical interactions between OTR and β(2)AR were demonstrated using co-immunoprecipitation, bioluminescence resonance energy transfer (BRET) and protein-fragment complementation (PCA) assays in HEK 293 cells, the latter experiments indicating the interactions between the two receptors were direct. Our analyses suggest physical interactions between OTR and β(2)AR in the context of a new heterodimer pair lie at the heart of the allosteric effects.
authors.affiliation: Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada.
authors.forename: Paulina K
authors.initials: PK
authors.lastname: Wrzal
authors.forename: Dominic
authors.initials: D
authors.lastname: Devost
authors.forename: Darlaine
authors.initials: D
authors.lastname: Pétrin
authors.forename: Eugénie
authors.initials: E
authors.lastname: Goupil
authors.forename: Christian
authors.initials: C
authors.lastname: Iorio-Morin
authors.forename: Stéphane A
authors.initials: SA
authors.lastname: Laporte
authors.forename: Hans H
authors.initials: HH
authors.lastname: Zingg
authors.forename: Terence E
authors.initials: TE
authors.lastname: Hébert
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology; D058672:Adrenergic beta-2 Receptor Antagonists / Q000494:pharmacology; D000494:Allosteric Regulation; D001262:Atenolol / Q000494:pharmacology; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D047468:Immunoprecipitation; D007545:Isoproterenol / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009215:Myometrium / Q000166:cytology; D010121:Oxytocin / Q000494:pharmacology / Q000502:physiology; D010766:Phosphorylation; D011433:Propranolol / Q000494:pharmacology; D011485:Protein Binding; D055503:Protein Multimerization; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D018045:Receptors, Oxytocin / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013999:Timolol / Q000494:pharmacology; D014668:Vasotocin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D058672:Adrenergic beta-2 Receptor Antagonists; C569600:OXTR protein, human; D018343:Receptors, Adrenergic, beta-2; D018045:Receptors, Oxytocin; D011993:Recombinant Fusion Proteins; C047046:atosiban; D010121:Oxytocin; D001262:Atenolol; D013999:Timolol; D011433:Propranolol; D017868:Cyclic AMP-Dependent Protein Kinases; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D007545:Isoproterenol; D014668:Vasotocin