title: Identification and pharmacological characterization of multiple allosteric binding sites on the free fatty acid 1 receptor.
abstract: Activation of FFA1 (GPR40), a member of G protein-coupling receptor family A, is mediated by medium- and long-chain fatty acids and leads to amplification of glucose-stimulated insulin secretion, suggesting a potential role for free fatty acid 1 (FFA1) as a target for type 2 diabetes. It was assumed previously that there is a single binding site for fatty acids and synthetic FFA1 agonists. However, using members of two chemical series of partial and full agonists that have been identified, radioligand binding interaction studies revealed that the full agonists do not bind to the same site as the partial agonists but exhibit positive heterotropic cooperativity. Analysis of functional data reveals positive functional cooperativity between the full agonists and partial agonists in various functional assays (in vitro and ex vivo) and also in vivo. Furthermore, the endogenous fatty acid docosahexaenoic acid (DHA) shows negative or neutral cooperativity with members of both series of agonists in binding assays but displays positive cooperativity in functional assays. Another synthetic agonist is allosteric with members of both agonist series, but apparently competitive with DHA. Therefore, there appear to be three allosterically linked binding sites on FFA1 with agonists specific for each of these sites. Activation of free fatty acid 1 receptor (FFAR1) by each of these agonists is differentially affected by mutations of two arginine residues, previously found to be important for FFAR1 binding and activation. These ligands with their high potencies and strong positive functional cooperativity with endogenous fatty acids, demonstrated in vitro and in vivo, have the potential to deliver therapeutic benefits.
authors.affiliation: Amgen Inc, South San Francisco, California 94080, USA.
authors.forename: Daniel C-H
authors.initials: DC
authors.lastname: Lin
authors.forename: Qi
authors.initials: Q
authors.lastname: Guo
authors.forename: Jian
authors.initials: J
authors.lastname: Luo
authors.forename: Jane
authors.initials: J
authors.lastname: Zhang
authors.forename: Kathy
authors.initials: K
authors.lastname: Nguyen
authors.forename: Michael
authors.initials: M
authors.lastname: Chen
authors.forename: Thanh
authors.initials: T
authors.lastname: Tran
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Dransfield
authors.forename: Sean P
authors.initials: SP
authors.lastname: Brown
authors.forename: Jonathan
authors.initials: J
authors.lastname: Houze
authors.forename: Marc
authors.initials: M
authors.lastname: Vimolratana
authors.forename: Xian Yun
authors.initials: XY
authors.lastname: Jiao
authors.forename: Yingcai
authors.initials: Y
authors.lastname: Wang
authors.forename: Nigel J M
authors.initials: NJ
authors.lastname: Birdsall
authors.forename: Gayathri
authors.initials: G
authors.lastname: Swaminath
mesh_terms: D000495:Allosteric Site; D000818:Animals; D001120:Arginine / Q000235:genetics; D001713:Biphenyl Compounds / Q000737:chemistry / Q000494:pharmacology; D002460:Cell Line; D004281:Docosahexaenoic Acids / Q000378:metabolism / Q000494:pharmacology; D054333:Drug Partial Agonism; D004357:Drug Synergism; D005951:Glucose Tolerance Test; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D010666:Phenylpropionates / Q000737:chemistry / Q000494:pharmacology; D011869:Radioligand Assay; D043562:Receptors, G-Protein-Coupled / Q000819:agonists* / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D000480:Alkynes
chemical_list: D001120:Arginine; D001713:Biphenyl Compounds; D004281:Docosahexaenoic Acids; D007004:Hypoglycemic Agents; D007328:Insulin; D010666:Phenylpropionates; D043562:Receptors, G-Protein-Coupled; C578198:3-(4-((2'-fluoro-5'-methoxy-(1,1'-biphenyl)-4-yl)methoxy)phenyl)hex-4-enoic acid; C578199:3-(4-((4'-chloro-2'-ethoxy-(1,1'-biphenyl)-4-yl)methoxy)phenyl)hex-4-ynoic acid; C578200:3-cyclopropyl-3-(3-((2-(5,5-dimethylcyclopent-1-en-1-yl)-2'-fluoro-5'-methoxy-(1,1'-biphenyl)-4-yl)methoxy)phenyl)propanoic acid; C473034:FFAR1 protein, human; C557933:AMG-837; D000480:Alkynes