Role of CXCR3 carboxyl terminus and third intracellular loop in receptor-mediated migration, adhesion and internalization in response to CXCL11

Blood. 2006 May 15;107(10):3821-31. doi: 10.1182/blood-2004-01-0214. Epub 2005 Dec 20.

Abstract

The chemokine receptor CXCR3 is predominantly expressed on activated T and natural killer (NK) cells. CXCR3 and its ligands, CXCL11, CXCL10, and CXCL9, play a major role in T-helper 1 (Th1)-dependent inflammatory responses. CXCL11 is the most dominant physiological inducer of adhesion, migration, and internalization of CXCR3. To study the role of CXCR3 carboxyl-terminus and the third intracellular (3i) loop in chemokine-mediated migration, adhesion, and CXCR3 internalization, we generated CXCR3 receptors mutated in their distal (Ser-Thr domain) or proximal (trileucine domain) membrane carboxyl terminus, and/or the third intracellular loop. We found that migration of CXCR3-expressing HEK 293 cells toward CXCL11 was pertussis toxin-dependent and required the membrane proximal carboxyl terminus of CXCR3. Internalization induced by CXCL11 and protein kinase C (PKC) activation was also regulated by the membrane proximal carboxyl terminus; however, only CXCL11-induced internalization required the LLL motif of this region. Internalization and Ca(2+) flux induced by CXCL11 were independent of the 3i loop S245, whereas migration at high CXCL11 concentrations, integrin-dependent adhesion, and actin polymerization were S245 dependent. Our findings indicate that CXCL11-dependent CXCR3 internalization and cell migration are regulated by the CXCR3 membrane proximal carboxyl terminus, whereas adhesion is regulated by the 3i loop S245. Thus, distinct conformational changes induced by a given CXCR3 ligand trigger different downstream effectors of adhesion, motility, and CXCR3 desensitization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Biological Transport
  • Calcium / metabolism
  • Calcium Signaling
  • Cell Adhesion / physiology*
  • Cell Line
  • Cell Movement / physiology*
  • Chemokine CXCL11
  • Chemokines, CXC / physiology*
  • DNA Primers
  • Fibronectins / physiology
  • Gene Transfer Techniques
  • Humans
  • Kidney
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Plasmids
  • Receptors, CXCR3
  • Receptors, Chemokine / chemistry
  • Receptors, Chemokine / genetics
  • Receptors, Chemokine / physiology*
  • Recombinant Proteins / metabolism
  • Transfection
  • Vascular Cell Adhesion Molecule-1 / physiology

Substances

  • CXCL11 protein, human
  • CXCR3 protein, human
  • Chemokine CXCL11
  • Chemokines, CXC
  • DNA Primers
  • Fibronectins
  • Receptors, CXCR3
  • Receptors, Chemokine
  • Recombinant Proteins
  • Vascular Cell Adhesion Molecule-1
  • Calcium