Characterization and species distribution of high affinity GTP-coupled receptors for human rantes and monocyte chemoattractant protein 1.
Equilibrium binding studies with recombinant human chemoattractant cytokines Rantes and monocyte chemoattractant protein 1 (MCP-1) on monocytic THP-1 cells have allowed the functional identification of two distinct receptors for C-C chemokines. One is a novel oligospecific receptor with high affinity for Rantes (50% maximal inhibitory concentration [IC50], 0.68 nM) and low affinity (IC50, 35 nM) for MCP-1, while the other is the previously described specific receptor for MCP-1 (IC50, 0.5 nM). Receptor affinity for Rantes is enhanced on preparation of isolated membranes with a 12-fold decrease in receptor Kd. The basis of this enhancement is not understood. The Rantes receptor appears to be G protein linked, as binding activity is abolished by guanosine 5'-O-(3-thiotriphosphate) (IC50, 7.3 nM). In contrast to the consequences of MCP-1 binding, we were unable to demonstrate ligand-dependent calcium fluxes on binding of Rantes to human monocytes or THP-1 cells. The binding of Rantes and MCP-1 to mononuclear cells from dog, rabbit, and rat were tested. While high affinity binding could be demonstrated in dog and rabbit, differences in ligand-induced Ca2+ fluxes could be shown between species. This suggests that receptor-ligand interactions and receptor coupling is best examined with autologous receptors and cytokine.
Van Riper
G
G
Department of Biochemical and Molecular Pathology, Merck Research Laboratories, Rahway, New Jersey 07065.
Siciliano
S
S
Fischer
P A
PA
Meurer
R
R
Springer
M S
MS
Rosen
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D018932:Chemokine CCL2; D018946:Chemokine CCL5; D002630:Chemotactic Factors / Q000378:metabolism*; D004285:Dogs; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006801:Humans; D008222:Lymphokines / Q000378:metabolism*; D009000:Monocytes / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D011485:Protein Binding; D011817:Rabbits; D051381:Rats; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000378:metabolism; D013045:Species Specificity
D018932:Chemokine CCL2; D018946:Chemokine CCL5; D002630:Chemotactic Factors; D008222:Lymphokines; D011956:Receptors, Cell Surface; D006160:Guanosine Triphosphate; D002118:Calcium