Defining the Molecular Basis for the First Potent and Selective Orthosteric Agonists of the FFA2 Free Fatty Acid Receptor

Abstract

Background: Understanding the function of FFA2 has been slowed by a lack of selective orthosteric ligands.Results: Residues within FFA2 that dictate the recognition and function of potent and selective orthosteric agonists are described.Conclusion: Key aspects of ligand interaction with the orthosteric binding pocket of FFA2 are defined.Significance: This work will be invaluable in future drug development at the FFA2 receptor.

The Neutrophil Response Induced by an Agonist for Free Fatty Acid Receptor 2 (GPR43) Is Primed by Tumor Necrosis Factor Alpha and by Receptor Uncoupling from the Cytoskeleton but Attenuated by Tissue Recruitment

“…The recently described Cmp1 and CATPB molecules fulfill the requirements in being both fairly potent and receptor selective (17,20). The expression and basic functional characteristics of FFA2R in phagocytic cells were described when the receptor was deorphanized and shown to be predominantly expressed in peripheral blood leukocytes and recognize short-chain free fatty acids (44,45).…”

“…Subsequent dilutions of all peptides and other reagents were made in Krebs-Ringer glucose phosphate buffer (KRG; 120 mM NaCl, 4.9 mM KCl, 1. The FFA2R agonist Cmp1 [3-benzyl-4-(cyclopropyl-(4-(2,5-dichlorophenyl)thiazol-2-yl)amino)-4-oxobutanoic acid] and the antagonist CATPB [(S)-3-(2-(3-chlorophenyl)acetamido)-4-(4-(trifluoromethyl)phenyl) butanoic acid] were synthesized as described previously (17,19,20).…”

“…A molecule identified from the patent literature with reported activity on free fatty acid receptor 2 (FFAR2) was recently characterized as an orthosteric agonist for the human FFAR2/ GPR43 (17), and this compound, Cmp1 (structure shown in Fig. 1A), was used to investigate the basic functions of this receptor in human neutrophils.…”

“…A proper and defined regulatory role for FFA2R in neutrophil function has not been possible to disclose, due to the lack of potent and selective agonists and antagonists. Given the fact that novel selective ligands, both orthosteric FFA2R agonists and antagonists, were recently described (17,18), this situation is now about to change.…”

“…We have determined the basic activation and inhibition properties in relation to human neutrophils of Cmp1 and CATPB (see below), two recently described FFA2R ligands (17,18). The new FFA2R ligands were initially characterized through the desensitization and inhibition profiles of the neutrophil response (transient increase in cytosolic Ca 2ϩ ) to acetate, and we show that Cmp1 is a selective FFA2R agonist and CATPB is a potent antagonist for the same neutrophil receptor.…”