RT Journal Article SR Electronic T1 High throughput identification and characterization of novel, species-selective GPR35 agonists JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP jpet.112.201798 DO 10.1124/jpet.112.201798 A1 Zaynab Neetoo-Isseljee A1 Amanda E Mackenzie A1 Craig Southern A1 Jeff Jerman A1 Edward G McIver A1 Nicholas Harries A1 Debra L Taylor A1 Graeme Milligan YR 2012 UL http://jpet.aspetjournals.org/content/early/2012/12/21/jpet.112.201798.abstract AB Drugs targeting the orphan receptor, GPR35, have potential therapeutic application in a number of disease areas including: inflammation, metabolic disorders, nociception and cardiovascular disease. Currently available surrogate GPR35 agonists identified from pharmacologically relevant compound libraries have limited utility due to the likelihood of off-target effects in vitro and in vivo and the variable potency that such ligands exhibit across species. We sought to identify and characterize novel GPR35 agonists to facilitate studies aimed at defining the physiological role of GPR35. PathHunter™ β-arrestin recruitment technology was validated as a human GPR35 screening assay and a High Throughput Screen of 100,000 diverse low molecular weight compounds conducted. Confirmed GPR35 agonists from five distinct chemotypes were selected for detailed characterization using both β-arrestin recruitment and G protein-dependent assays and each of the human, mouse and rat GPR35 orthologs. These studies identified 4-{(Z)-[(2Z)-2-(2-fluorobenzylidene)-4-oxo-1,3-thiazolidin-5-ylidene]methyl}benzoic acid (compound 1) as the highest potency, full agonist of human GPR35 yet described. As with certain other GPR35 agonists, compound 1 was markedly selective for human GPR35, but displayed elements of signal bias between β-arrestin-2 and G protein-dependent assays. Compound 1 also displayed competitive behaviour when assessed against the human GPR35 antagonist, ML-145 (2-hydroxy-4-[4-(5Z)-5-[(E)-2-methyl-3-phenylprop-2-enylidene]-4-oxo-2-sulfanylidene-1,3-thiazolidin-3-yl]butanoylamino]benzoic acid). Of the other chemotypes studied, compounds 2 and 3 were selective for the human receptor, but compounds 4 and 5 demonstrated similar activity at human, rat and mouse GPR35 orthologs. Further characterization of these compounds and related analogues is likely to facilitate a better understanding of GPR35 in health and disease.