TY - JOUR T1 - Probe-Dependent Negative Allosteric Modulators of the Long-Chain Free Fatty Acid Receptor FFA4 JF - Molecular Pharmacology JO - Mol Pharmacol SP - 630 LP - 641 DO - 10.1124/mol.116.107821 VL - 91 IS - 6 AU - Kenneth R. Watterson AU - Steffen V. F. Hansen AU - Brian D. Hudson AU - Elisa Alvarez-Curto AU - Sheikh Zahir Raihan AU - Carlos M. G. Azevedo AU - Gabriel Martin AU - Julia Dunlop AU - Stephen J. Yarwood AU - Trond Ulven AU - Graeme Milligan Y1 - 2017/06/01 UR - http://molpharm.aspetjournals.org/content/91/6/630.abstract N2 - High-affinity and selective antagonists that are able to block the actions of both endogenous and synthetic agonists of G protein–coupled receptors are integral to analysis of receptor function and to support suggestions of therapeutic potential. Although there is great interest in the potential of free fatty acid receptor 4 (FFA4) as a novel therapeutic target for the treatment of type II diabetes, the broad distribution pattern of this receptor suggests it may play a range of roles beyond glucose homeostasis in different cells and tissues. To date, a single molecule, 4-methyl-N-9H-xanthen-9-yl-benzenesulfonamide (AH-7614), has been described as an FFA4 antagonist; however, its mechanism of antagonism remains unknown. We synthesized AH-7614 and a chemical derivative and demonstrated these to be negative allosteric modulators (NAMs) of FFA4. Although these NAMs did inhibit FFA4 signaling induced by a range of endogenous and synthetic agonists, clear agonist probe dependence in the nature of allosteric modulation was apparent. Although AH-7614 did not antagonize the second long-chain free fatty acid receptor, free fatty acid receptor 1, the simple chemical structure of AH-7614 containing features found in many anticancer drugs suggests that a novel close chemical analog of AH-7614 devoid of FFA4 activity, 4-methyl-N-(9H-xanthen-9-yl)benzamide (TUG-1387), will also provide a useful control compound for future studies assessing FFA4 function. Using TUG-1387 alongside AH-7614, we show that endogenous activation of FFA4 expressed by murine C3H10T1/2 mesenchymal stem cells is required for induced differentiation of these cells toward a more mature, adipocyte-like phenotype. ER -