Pharmacological characterization of a small-molecule agonist for the chemokine receptor CXCR3

Br J Pharmacol. 2012 Jun;166(3):898-911. doi: 10.1111/j.1476-5381.2011.01648.x.


Background and purpose: 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.

Experimental approach: 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.

Key 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 and implications: 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.

MeSH terms

  • Allosteric Regulation
  • Animals
  • Cell Culture Techniques
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Chemokine CXCL10 / metabolism
  • Chemokine CXCL11 / metabolism
  • Chemotaxis / drug effects
  • Cyclic AMP / metabolism
  • DNA, Complementary / genetics
  • Dose-Response Relationship, Drug
  • HEK293 Cells
  • Humans
  • Isoquinolines / chemistry
  • Isoquinolines / pharmacology*
  • Ligands
  • Mice
  • Precursor Cells, B-Lymphoid / cytology
  • Precursor Cells, B-Lymphoid / drug effects
  • Precursor Cells, B-Lymphoid / metabolism
  • Protein Binding
  • Radioligand Assay
  • Receptors, CXCR3 / agonists*
  • Receptors, CXCR3 / antagonists & inhibitors
  • Receptors, CXCR3 / genetics
  • Receptors, Cell Surface / biosynthesis
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology*
  • Transfection


  • CXCL10 protein, human
  • CXCL11 protein, human
  • CXCR3 protein, human
  • Chemokine CXCL10
  • Chemokine CXCL11
  • DNA, Complementary
  • Isoquinolines
  • Ligands
  • N-(6-amino-1-(2,2-diphenylethylamino)-1-oxohexan-2-yl)-2-(4-oxo-4-phenylbutanoyl)-1,2,3,4-tetrahydroisoquinoline-3-carboxamide
  • Receptors, CXCR3
  • Receptors, Cell Surface
  • Small Molecule Libraries
  • Cyclic AMP