Internalization of the chemokine receptor CCR4 can be evoked by orthosteric and allosteric receptor antagonists

Laura Ajram, Malcolm Begg, Robert Slack, Jenni Cryan, David Hall, Simon Hodgson, Alison Ford, Ashley Barnes, Dawid Swieboda, Aurelie Mousnier, Roberto Solari

Research output: Contribution to journalArticle

31 Citations (Scopus)
237 Downloads (Pure)

Abstract

The chemokine receptor CCR4 has at least two natural agonist ligands, MDC (CCL22) and TARC (CCL17) which bind to the same orthosteric site with a similar affinity. Both ligands are known to evoke chemotaxis of CCR4-bearing T cells and also elicit CCR4 receptor internalization. A series of small molecule allosteric antagonists have been described which displace the agonist ligand, and inhibit chemotaxis. The aim of this study was to determine which cellular coupling pathways are involved in internalization, and if antagonists binding to the CCR4 receptor could themselves evoke receptor internalization. CCL22 binding coupled CCR4 efficiently to β-arrestin and stimulated GTPγS binding however CCL17 did not couple to β-arrestin and only partially stimulated GTPγS binding. CCL22 potently induced internalization of almost all cell surface CCR4, while CCL17 showed only weak effects. We describe four small molecule antagonists that were demonstrated to bind to two distinct allosteric sites on the CCR4 receptor, and while both classes inhibited agonist ligand binding and chemotaxis, one of the allosteric sites also evoked receptor internalization. Furthermore, we also characterize an N-terminally truncated version of CCL22 which acts as a competitive antagonist at the orthosteric site, and surprisingly also evokes receptor internalization without demonstrating any agonist activity. Collectively this study demonstrates that orthosteric and allosteric antagonists of the CCR4 receptor are capable of evoking receptor internalization, providing a novel strategy for drug discovery against this class of target.

Original languageEnglish
Pages (from-to)75-85
Number of pages11
JournalEuropean Journal of Pharmacology
Volume729
Early online date15 Feb 2014
DOIs
Publication statusPublished - 15 Apr 2014
Externally publishedYes

Keywords

  • Allosteric Regulation
  • Animals
  • Basophils
  • CHO Cells
  • Cells, Cultured
  • Chemokine CCL17
  • Chemokine CCL22
  • Chemotaxis
  • Cricetinae
  • Cricetulus
  • Dose-Response Relationship, Drug
  • Endocytosis
  • Humans
  • Receptors, CCR4

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