title: Structure-Activity Analysis of Biased Agonism at the Human Adenosine A3 Receptor.
abstract: Biased agonism at G protein-coupled receptors (GPCRs) has significant implications for current drug discovery, but molecular determinants that govern ligand bias remain largely unknown. The adenosine A3 GPCR (A3AR) is a potential therapeutic target for various conditions, including cancer, inflammation, and ischemia, but for which biased agonism remains largely unexplored. We now report the generation of bias "fingerprints" for prototypical ribose containing A3AR agonists and rigidified (N)-methanocarba 5'-N-methyluronamide nucleoside derivatives with regard to their ability to mediate different signaling pathways. Relative to the reference prototypical agonist IB-MECA, (N)-methanocarba 5'-N-methyluronamide nucleoside derivatives with significant N(6) or C2 modifications, including elongated aryl-ethynyl groups, exhibited biased agonism. Significant positive correlation was observed between the C2 substituent length (in Å) and bias toward cell survival. Molecular modeling suggests that extended C2 substituents on (N)-methanocarba 5'-N-methyluronamide nucleosides promote a progressive outward shift of the A3AR transmembrane domain 2, which may contribute to the subset of A3AR conformations stabilized on biased agonist binding.
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (J.-A.B., A.T.N.N., K.J.G., A.C., L.T.M); and Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland (S.P., D.K.T., K.A.J).
authors.forename: Jo-Anne
authors.initials: JA
authors.lastname: Baltos
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (J.-A.B., A.T.N.N., K.J.G., A.C., L.T.M); and Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland (S.P., D.K.T., K.A.J).
authors.forename: Silvia
authors.initials: S
authors.lastname: Paoletta
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (J.-A.B., A.T.N.N., K.J.G., A.C., L.T.M); and Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland (S.P., D.K.T., K.A.J).
authors.forename: Anh T N
authors.initials: AT
authors.lastname: Nguyen
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (J.-A.B., A.T.N.N., K.J.G., A.C., L.T.M); and Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland (S.P., D.K.T., K.A.J).
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Gregory
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (J.-A.B., A.T.N.N., K.J.G., A.C., L.T.M); and Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland (S.P., D.K.T., K.A.J).
authors.forename: Dilip K
authors.initials: DK
authors.lastname: Tosh
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (J.-A.B., A.T.N.N., K.J.G., A.C., L.T.M); and Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland (S.P., D.K.T., K.A.J).
authors.forename: Arthur
authors.initials: A
authors.lastname: Christopoulos
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (J.-A.B., A.T.N.N., K.J.G., A.C., L.T.M); and Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland (S.P., D.K.T., K.A.J).
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Jacobson
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (J.-A.B., A.T.N.N., K.J.G., A.C., L.T.M); and Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland (S.P., D.K.T., K.A.J) lauren.may@monash.edu.
authors.forename: Lauren T
authors.initials: LT
authors.lastname: May
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D058909:Adenosine A3 Receptor Agonists / Q000737:chemistry* / Q000494:pharmacology*; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D008024:Ligands; D062105:Molecular Docking Simulation; D043684:Receptor, Adenosine A3 / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D058909:Adenosine A3 Receptor Agonists; D008024:Ligands; D043684:Receptor, Adenosine A3; C084956:N(6)-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine; D000241:Adenosine