Binding and functional properties of recombinant and endogenous CXCR3 chemokine receptors.
IP10 and MIG are two members of the CXC branch of the chemokine superfamily whose expression is dramatically up-regulated by interferon (IFN)-gamma. The proteins act largely on natural killer (NK)-cells and activated T-cells and have been implicated in mediating some of the effects of IFN-gamma and lipopolysaccharides (LPSs), as well as T-cell-dependent anti-tumor responses. Recently both chemokines have been shown to be functional agonists of the same G-protein-coupled receptor, CXCR3. We now report the pharmacological characterization of CXCR3 and find that, when heterologously expressed, CXCR3 binds IP10 and MIG with Ki values of 0.14 and 4.9 nM, respectively. The receptor has very modest affinity for SDF-1alpha and little or no affinity for other CXC-chemokines. The properties of the endogenous receptor expressed on activated T-cells are similar. Surprisingly, several CC-chemokines, particularly eotaxin and MCP-4, also compete with moderate affinity for the binding of IP10 to CXCR3. Eotaxin does not activate CXCR3 but, in CXCR3-transfected cells, can block IP10-mediated receptor activation. Eotaxin, therefore, may be a natural CXCR3 antagonist.
Weng
Y
Y
Department of Immunology Research, Merck Research Laboratories, Rahway, New Jersey 07065, USA.
Siciliano
S J
SJ
Waldburger
K E
KE
Sirotina-Meisher
A
A
Staruch
M J
MJ
Daugherty
B L
BL
Gould
S L
SL
Springer
M S
MS
DeMartino
J A
JA
D000818:Animals; D016466:CHO Cells; D054413:Chemokine CCL11; D018946:Chemokine CCL5 / Q000378:metabolism; D054410:Chemokine CCL7; D054357:Chemokine CXCL10; D054370:Chemokine CXCL9; D019742:Chemokines, CC; D019743:Chemokines, CXC / Q000378:metabolism; D002631:Chemotactic Factors, Eosinophil / Q000378:metabolism; D003001:Cloning, Molecular; D006224:Cricetinae; D016207:Cytokines / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007371:Interferon-gamma / Q000494:pharmacology; D008213:Lymphocyte Activation; D018945:Monocyte Chemoattractant Proteins / Q000378:metabolism; D011485:Protein Binding; D054367:Receptors, CXCR3; D019707:Receptors, Chemokine / Q000378:metabolism*; D018121:Receptors, Cytokine / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D015854:Up-Regulation
C515456:CCL11 protein, human; C099677:CCL13 protein, human; C515450:CCL7 protein, human; C080810:CXCL9 protein, human; C515187:CXCR3 protein, human; D054413:Chemokine CCL11; D018946:Chemokine CCL5; D054410:Chemokine CCL7; D054357:Chemokine CXCL10; D054370:Chemokine CXCL9; D019742:Chemokines, CC; D019743:Chemokines, CXC; D002631:Chemotactic Factors, Eosinophil; D016207:Cytokines; C104577:IP10-Mig receptor; D036341:Intercellular Signaling Peptides and Proteins; D018945:Monocyte Chemoattractant Proteins; D054367:Receptors, CXCR3; D019707:Receptors, Chemokine; D018121:Receptors, Cytokine; D011994:Recombinant Proteins; D007371:Interferon-gamma