title: Identification and profiling of novel α1A-adrenoceptor-CXC chemokine receptor 2 heteromer.
abstract: We have provided the first evidence for specific heteromerization between the α(1A)-adrenoceptor (α(1A)AR) and CXC chemokine receptor 2 (CXCR2) in live cells. α(1A)AR and CXCR2 are both expressed in areas such as the stromal smooth muscle layer of the prostate. By utilizing the G protein-coupled receptor (GPCR) heteromer identification technology on the live cell-based bioluminescence resonance energy transfer (BRET) assay platform, our studies in human embryonic kidney 293 cells have identified norepinephrine-dependent β-arrestin recruitment that was in turn dependent upon co-expression of α(1A)AR with CXCR2. These findings have been supported by co-localization observed using confocal microscopy. This norepinephrine-dependent β-arrestin recruitment was inhibited not only by the α(1)AR antagonist Terazosin but also by the CXCR2-specific allosteric inverse agonist SB265610. Furthermore, Labetalol, which is marketed for hypertension as a nonselective β-adrenoceptor antagonist with α(1)AR antagonist properties, was identified as a heteromer-specific-biased agonist exhibiting partial agonism for inositol phosphate production but essentially full agonism for β-arrestin recruitment at the α(1A)AR-CXCR2 heteromer. Finally, bioluminescence resonance energy transfer studies with both receptors tagged suggest that α(1A)AR-CXCR2 heteromerization occurs constitutively and is not modulated by ligand. These findings support the concept of GPCR heteromer complexes exhibiting distinct pharmacology, thereby providing additional mechanisms through which GPCRs can potentially achieve their diverse biological functions. This has important implications for the use and future development of pharmaceuticals targeting these receptors.
authors.affiliation: Laboratory for Molecular Endocrinology-G Protein-Coupled Receptors, Western Australian Institute for Medical Research and Centre for Medical Research, The University of Western Australia, Nedlands, Perth, Western Australia 6009, Australia.
authors.forename: Sanam
authors.initials: S
authors.lastname: Mustafa
authors.forename: Heng B
authors.initials: HB
authors.lastname: See
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Seeber
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Armstrong
authors.forename: Carl W
authors.initials: CW
authors.lastname: White
authors.forename: Sabatino
authors.initials: S
authors.lastname: Ventura
authors.forename: Mohammed Akli
authors.initials: MA
authors.lastname: Ayoub
authors.forename: Kevin D G
authors.initials: KD
authors.lastname: Pfleger
mesh_terms: D058668:Adrenergic alpha-1 Receptor Antagonists / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000494:Allosteric Regulation / Q000502:physiology; D000818:Animals; D019390:Arrestins / Q000378:metabolism; D016466:CHO Cells; D018925:Chemokines / Q000378:metabolism; D006224:Cricetinae; D057809:HEK293 Cells; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D007741:Labetalol / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009638:Norepinephrine / Q000494:pharmacology; D011224:Prazosin / Q000031:analogs & derivatives / Q000494:pharmacology; D011467:Prostate / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D018340:Receptors, Adrenergic, alpha-1 / Q000737:chemistry* / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000378:metabolism; D023063:Receptors, Interleukin-8B / Q000737:chemistry* / Q000378:metabolism; D000071557:beta-Arrestins
chemical_list: D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D019390:Arrestins; D018925:Chemokines; D007295:Inositol Phosphates; D018340:Receptors, Adrenergic, alpha-1; D043562:Receptors, G-Protein-Coupled; D023063:Receptors, Interleukin-8B; D000071557:beta-Arrestins; C450520:seven-transmembrane G-protein-coupled receptor; C041226:Terazosin; D007741:Labetalol; D009638:Norepinephrine; D011224:Prazosin