title: β-Arrestin Recruitment and Biased Agonism at Free Fatty Acid Receptor 1.
abstract: FFAR1/GPR40 is a seven-transmembrane domain receptor (7TMR) expressed in pancreatic β cells and activated by FFAs. Pharmacological activation of GPR40 is a strategy under consideration to increase insulin secretion in type 2 diabetes. GPR40 is known to signal predominantly via the heterotrimeric G proteins Gq/11. However, 7TMRs can also activate functionally distinct G protein-independent signaling via β-arrestins. Further, G protein- and β-arrestin-based signaling can be differentially modulated by different ligands, thus eliciting ligand-specific responses ("biased agonism"). Whether GPR40 engages β-arrestin-dependent mechanisms and is subject to biased agonism is unknown. Using bioluminescence resonance energy transfer-based biosensors for real-time monitoring of cell signaling in living cells, we detected a ligand-induced GPR40-β-arrestin interaction, with the synthetic GPR40 agonist TAK-875 being more effective than palmitate or oleate in recruiting β-arrestins 1 and 2. Conversely, TAK-875 acted as a partial agonist of Gq/11-dependent GPR40 signaling relative to both FFAs. Pharmacological blockade of Gq activity decreased FFA-induced insulin secretion. In contrast, knockdown or genetic ablation of β-arrestin 2 in an insulin-secreting cell line and mouse pancreatic islets, respectively, uniquely attenuated the insulinotropic activity of TAK-875, thus providing functional validation of the biosensor data. Collectively, these data reveal that in addition to coupling to Gq/11, GPR40 is functionally linked to a β-arrestin 2-mediated insulinotropic signaling axis. These observations expose previously unrecognized complexity for GPR40 signal transduction and may guide the development of biased agonists showing improved clinical profile in type 2 diabetes.
authors.affiliation: Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada.
authors.forename: Arturo D
authors.initials: AD
authors.lastname: Mancini
authors.affiliation: Institut de Génomique Fonctionnelle, CNRS UMR 5203, INSERM U661, Universités de Montpellier 1 & 2, 34060 Montpellier, France.
authors.forename: Gyslaine
authors.initials: G
authors.lastname: Bertrand
authors.affiliation: Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Vivot
authors.affiliation: Department of Biochemistry and Molecular Medicine, University of Montreal, Quebec H3C 3J7, Canada.
authors.forename: Éric
authors.initials: É
authors.lastname: Carpentier
authors.affiliation: Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Tremblay
authors.affiliation: Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada.
authors.forename: Julien
authors.initials: J
authors.lastname: Ghislain
authors.affiliation: Department of Biochemistry and Molecular Medicine, University of Montreal, Quebec H3C 3J7, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Bouvier
authors.affiliation: Montreal Diabetes Research Center, Research Center of the University of Montreal Hospital Center (CRCHUM), and Department of Medicine, University of Montreal, Quebec H2X 0A9, Canada; Department of Biochemistry and Molecular Medicine, University of Montreal, Quebec H3C 3J7, Canada. Electronic address: vincent.poitout@umontreal.ca.
authors.forename: Vincent
authors.initials: V
authors.lastname: Poitout
mesh_terms: D000818:Animals; D019390:Arrestins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D001572:Benzofurans / Q000494:pharmacology; D015374:Biosensing Techniques; D045744:Cell Line, Tumor; D004578:Electron Spin Resonance Spectroscopy; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D007328:Insulin / Q000819:agonists / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D019301:Oleic Acid / Q000494:pharmacology; D019308:Palmitic Acid / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D013450:Sulfones / Q000494:pharmacology; D046509:Tissue Culture Techniques; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins
chemical_list: C000605254:ARRB2 protein, human; C000605258:Arrb2 protein, mouse; C000605257:Arrb2 protein, rat; D019390:Arrestins; D001572:Benzofurans; C473035:G-protein-coupled receptor 40, rat; D007328:Insulin; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled; D013450:Sulfones; C557331:TAK-875; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; D019301:Oleic Acid; D019308:Palmitic Acid; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
keywords: FFAR1/GPR40; G protein-coupled receptor (GPCR); Islet of Langerhans; Type 2 diabetes; arrestin; biased agonism; cell signaling; insulin secretion