title: The Orphan Receptor GPR17 Is Unresponsive to Uracil Nucleotides and Cysteinyl Leukotrienes.
abstract: Pairing orphan G protein–coupled receptors (GPCRs) with their cognate endogenous ligands is expected to have a major impact on our understanding of GPCR biology. It follows that the reproducibility of orphan receptor ligand pairs should be of fundamental importance to guide meaningful investigations into the pharmacology and function of individual receptors. GPR17 is an orphan receptor characterized by some as a dualistic uracil nucleotide/cysteinyl leukotriene receptor and by others as inactive toward these stimuli altogether. Whereas regulation of central nervous system myelination by GPR17 is well established, verification of activity of its putative endogenous ligands has proven elusive so far. Herein we report that uracil nucleotides and cysteinyl leukotrienes do not activate human, mouse, or rat GPR17 in various cellular backgrounds, including primary cells, using eight distinct functional assay platforms based on labelfree pathway-unbiased biosensor technologies, as well as canonical second-messenger or biochemical assays. Appraisal of GPR17 activity can neither be accomplished with co-application of both ligand classes, nor with exogenous transfection of partner receptors (nucleotide P2Y12, cysteinyl-leukotriene CysLT1) to reconstitute the elusive pharmacology. Moreover, our study does not support the inhibition of GPR17 by the marketed antiplatelet drugs cangrelor and ticagrelor, previously suggested to antagonize GPR17. Whereas our data do not disagree with a role of GPR17 per se as an orchestrator of central nervous system functions, they challenge the utility of the proposed (ant)agonists as tools to imply direct contribution of GPR17 in complex biologic settings.
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Katharina
authors.initials: K
authors.lastname: Simon
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Nicole
authors.initials: N
authors.lastname: Merten
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Ralf
authors.initials: R
authors.lastname: Schröder
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hennen
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Philip
authors.initials: P
authors.lastname: Preis
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Nina-Katharina
authors.initials: NK
authors.lastname: Schmitt
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Lucas
authors.initials: L
authors.lastname: Peters
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Ramona
authors.initials: R
authors.lastname: Schrage
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Celine
authors.initials: C
authors.lastname: Vermeiren
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Michel
authors.initials: M
authors.lastname: Gillard
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Klaus
authors.initials: K
authors.lastname: Mohr
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.).
authors.forename: Jesus
authors.initials: J
authors.lastname: Gomeza
authors.affiliation: Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology (K.S., N.M., Ral.S., S.H., P.P., N.-K.S, L.P., J.G., E.K.), Research Training Group 1873 (K.S., E.K.), Pharmacology and Toxicology Section, Institute of Pharmacy (Ram.S., K.M.), University of Bonn, Bonn, Germany; UCB Pharma, CNS Research, Braine l'Alleud, Belgium (C.V., M.G.). kostenis@uni-bonn.de.
authors.forename: Evi
authors.initials: E
authors.lastname: Kostenis
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D003545:Cysteine / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D015289:Leukotrienes / Q000494:pharmacology*; D008024:Ligands; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D054852:Small Molecule Libraries / Q000494:pharmacology; D000077486:Ticagrelor; D014500:Uracil Nucleotides / Q000494:pharmacology*
chemical_list: C121670:GPR17 protein, human; C534979:GPR17 protein, mouse; C514731:GPR17 protein, rat; D015289:Leukotrienes; D008024:Ligands; D009419:Nerve Tissue Proteins; D043562:Receptors, G-Protein-Coupled; D054852:Small Molecule Libraries; D014500:Uracil Nucleotides; C112381:cysteinyl-leukotriene; D000249:Adenosine Monophosphate; C117446:cangrelor; D000077486:Ticagrelor; D000241:Adenosine; D003545:Cysteine