title: Agonism, Antagonism, and Inverse Agonism Bias at the Ghrelin Receptor Signaling.
abstract: The G protein-coupled receptor GHS-R1a mediates ghrelin-induced growth hormone secretion, food intake, and reward-seeking behaviors. GHS-R1a signals through Gq, Gi/o, G13, and arrestin. Biasing GHS-R1a signaling with specific ligands may lead to the development of more selective drugs to treat obesity or addiction with minimal side effects. To delineate ligand selectivity at GHS-R1a signaling, we analyzed in detail the efficacy of a panel of synthetic ligands activating the different pathways associated with GHS-R1a in HEK293T cells. Besides β-arrestin2 recruitment and ERK1/2 phosphorylation, we monitored activation of a large panel of G protein subtypes using a bioluminescence resonance energy transfer-based assay with G protein-activation biosensors. We first found that unlike full agonists, Gq partial agonists were unable to trigger β-arrestin2 recruitment and ERK1/2 phosphorylation. Using G protein-activation biosensors, we then demonstrated that ghrelin promoted activation of Gq, Gi1, Gi2, Gi3, Goa, Gob, and G13 but not Gs and G12. Besides, we identified some GHS-R1a ligands that preferentially activated Gq and antagonized ghrelin-mediated Gi/Go activation. Finally, we unambiguously demonstrated that in addition to Gq, GHS-R1a also promoted constitutive activation of G13. Importantly, we identified some ligands that were selective inverse agonists toward Gq but not of G13. This demonstrates that bias at GHS-R1a signaling can occur not only with regard to agonism but also to inverse agonism. Our data, combined with other in vivo studies, may facilitate the design of drugs selectively targeting individual signaling pathways to treat only the therapeutically relevant function.
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Céline
authors.initials: C
authors.lastname: M'Kadmi
authors.affiliation: the Institut des Neurosciences de Montpellier, Hôpital Saint-Eloi, 80 Avenue Augustin Fliche, BP 74103, 34091 Montpellier Cedex 05.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Leyris
authors.affiliation: the Institut des Maladies Métaboliques et Cardiovasculaires, INSERM, U1048, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, 31432 Toulouse, France.
authors.forename: Lauriane
authors.initials: L
authors.lastname: Onfroy
authors.affiliation: the Institut des Maladies Métaboliques et Cardiovasculaires, INSERM, U1048, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, 31432 Toulouse, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Galés
authors.affiliation: the Institut des Maladies Métaboliques et Cardiovasculaires, INSERM, U1048, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, 31432 Toulouse, France.
authors.forename: Aude
authors.initials: A
authors.lastname: Saulière
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Didier
authors.initials: D
authors.lastname: Gagne
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Damian
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Sophie
authors.initials: S
authors.lastname: Mary
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Maingot
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Séverine
authors.initials: S
authors.lastname: Denoyelle
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Pascal
authors.initials: P
authors.lastname: Verdié
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Jean-Alain
authors.initials: JA
authors.lastname: Fehrentz
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Jean
authors.initials: J
authors.lastname: Martinez
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Banères
authors.affiliation: Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05,. Electronic address: jacky.marie@univ-montp1.fr.
authors.forename: Jacky
authors.initials: J
authors.lastname: Marie
mesh_terms: D019390:Arrestins / Q000378:metabolism; D015195:Drug Design; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis; D007700:Kinetics; D008024:Ligands; D020935:MAP Kinase Signaling System; D054440:Receptors, Ghrelin / Q000819:agonists* / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D007295:Inositol Phosphates; D008024:Ligands; D054440:Receptors, Ghrelin; D000071557:beta-Arrestins; D019204:GTP-Binding Proteins; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
keywords: G protein; G protein subtypes; G protein-coupled receptor (GPCR); bioluminescence resonance energy transfer (BRET); cell signaling; ghrelin; hormone receptor; signaling bias