title: Pharmacological characterization of a small-molecule agonist for the chemokine receptor CXCR3.
abstract: OBJECTIVE
  The chemokine receptor CXCR3 is a GPCR found predominantly on activated T cells. CXCR3 is activated by three endogenous peptides; CXCL9, CXCL10 and CXCL11. Recently, a small-molecule agonist, VUF10661, has been reported in the literature and synthesized in our laboratory. The aim of the present study was to provide a detailed pharmacological characterization of VUF10661 by comparing its effects with those of CXCL11.
  
  
  METHODS
  Agonistic properties of VUF10661 were assessed in a chemotaxis assay with murine L1.2 cells transiently transfected with cDNA encoding the human CXCR3 receptor and in binding studies, with [(125)I]-CXCL10 and [(125)I]-CXCL11, on membrane preparations from HEK293 cells stably expressing CXCR3. [(35)S]-GTPγS binding was used to determine its potency to induce CXCR3-mediated G protein activation and BRET-based assays to investigate its effects on intracellular cAMP levels and β-arrestin recruitment.
  
  
  RESULTS
  VUF10661 acted as a partial agonist in CXCR3-mediated chemotaxis, bound to CXCR3 in an allosteric fashion in ligand binding assays and activated G(i) proteins with the same efficacy as CXCL11 in the [(35)S]-GTPγS binding and cAMP assay, while it recruited more β-arrestin1 and β-arrestin2 to CXCR3 receptors than the chemokine.
  
  
  CONCLUSIONS
  VUF10661, like CXCL11, activates both G protein-dependent and -independent signalling via the CXCR3 receptor, but probably exerts its effects from an allosteric binding site that is different from that for CXCL11. It could stabilize different receptor and/or β-arrestin conformations leading to differences in functional output. Such ligand-biased signalling might offer interesting options for the therapeutic use of CXCR3 agonists.
authors: Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Faculty of Science, VU University Amsterdam, Amsterdam, the Netherlands.
authors: D J
authors: DJ
authors: Scholten
authors: M
authors: M
authors: Canals
authors: M
authors: M
authors: Wijtmans
authors: S
authors: S
authors: de Munnik
authors: P
authors: P
authors: Nguyen
authors: D
authors: D
authors: Verzijl
authors: I J P
authors: IJ
authors: de Esch
authors: H F
authors: HF
authors: Vischer
authors: M J
authors: MJ
authors: Smit
authors: R
authors: R
authors: Leurs
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D018929:Cell Culture Techniques; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D054357:Chemokine CXCL10 / Q000378:metabolism; D054371:Chemokine CXCL11 / Q000378:metabolism; D002633:Chemotaxis / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D057809:HEK293 Cells; D006801:Humans; D007546:Isoquinolines / Q000737:chemistry / Q000494:pharmacology*; D008024:Ligands; D051379:Mice; D054448:Precursor Cells, B-Lymphoid / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding; D011869:Radioligand Assay; D054367:Receptors, CXCR3 / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000235:genetics; D011956:Receptors, Cell Surface / Q000096:biosynthesis; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology*; D014162:Transfection
chemical_list: C114753:CXCL10 protein, human; C515202:CXCL11 protein, human; C515187:CXCR3 protein, human; D054357:Chemokine CXCL10; D054371:Chemokine CXCL11; D018076:DNA, Complementary; D007546:Isoquinolines; D008024:Ligands; C571745:N-(6-amino-1-(2,2-diphenylethylamino)-1-oxohexan-2-yl)-2-(4-oxo-4-phenylbutanoyl)-1,2,3,4-tetrahydroisoquinoline-3-carboxamide; D054367:Receptors, CXCR3; D011956:Receptors, Cell Surface; D054852:Small Molecule Libraries; D000242:Cyclic AMP