EBI2 regulates CXCL13-mediated responses by heterodimerization with CXCR5

FASEB J. 2012 Dec;26(12):4841-54. doi: 10.1096/fj.12-208876. Epub 2012 Aug 22.


B-cell movement into lymphoid follicles depends on the expression of the chemokine receptor CXCR5 and the recently reported Epstein-Barr virus-induced receptor 2 (EBI2). In cooperation with CXCR5, EBI2 helps to position activated B cells in the follicle, although the mechanism is poorly understood. Using human HEK293T cells and fluorescence resonance energy transfer (FRET) techniques, we demonstrate that CXCR5 and EBI2 form homo- and heterodimers. EBI2 expression modulated CXCR5 homodimeric complexes, as indicated by the FRET(50) value (CXCR5 homodimer, 0.9851±0.0784; CXCR5 homodimer+EBI2, 1.7320±0.4905; P<0.05). HEK293T cells expressing CXCR5/EBI2 and primary activated murine B cells both down-modulated CXCR5-mediated responses, such as Ca(2+) flux, cell migration, and MAPK activation; this modulation did not occur when primary B cells were obtained from EBI2(-/-) mice. The mechanism involves a reduction in binding affinity of the ligand (CXCL13) for CXCR5 (K(D): 5.05×10(-8) M for CXCR5 alone vs. 1.49×10(-7) M for CXCR5/EBI2) and in the efficacy (E(max)) of G-protein activation in CXCR5/EBI2-coexpressing cells (42.33±4.3%; P<0.05). These findings identify CXCR5/EBI2 heterodimers as functional units that contribute to the plasticity of CXCL13-mediated B-cell responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • B-Lymphocytes / metabolism
  • Binding, Competitive
  • Blotting, Western
  • Cell Movement
  • Cells, Cultured
  • Chemokine CXCL13 / genetics
  • Chemokine CXCL13 / metabolism*
  • Fluorescence Resonance Energy Transfer
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
  • HEK293 Cells
  • Humans
  • Kinetics
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Protein Multimerization
  • Radioligand Assay
  • Receptors, CXCR5 / chemistry
  • Receptors, CXCR5 / genetics
  • Receptors, CXCR5 / metabolism*
  • Receptors, G-Protein-Coupled / chemistry
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism*
  • Transfection


  • CXCR5 protein, human
  • Chemokine CXCL13
  • GPR183 protein, human
  • Luminescent Proteins
  • Receptors, CXCR5
  • Receptors, G-Protein-Coupled
  • Guanosine 5'-O-(3-Thiotriphosphate)