CYTOKINE INDUCTION OF MONOCYTE CHEMOATTRACTANT PROTEIN-1 GENE-EXPRESSION IN HUMAN ENDOTHELIAL-CELLS DEPENDS ON THE COOPERATIVE ACTION OF NF-KAPPA-B AND AP-1

Chemokines are potent mediators of cell migration and activation and t herefore play an essential role in early events of inflammation. In co njunction with cell adhesion molecules, chemokines help to localize ce lls to a specific site and enhance the inflammatory reaction at the si te. Clinically elevated levels of che mokines have been found in a var iety of inflammatory diseases. The prototype C-C chemokine is monocyte chemoattractant protein-1 (MCP-1) which is synthesized by a variety o f cell types including endothelial cells in response to a variety of s timuli. MCP-1 is a major chemoattractant for monocytes, T lymphocytes, and basophils. In the present study, we investigated the factors invo lved in cytokine-induced MCP-1 gene expression in human endothelial ce lls. We present evidence that the nuclear factor (NF)-kappa B-like bin ding site and the AP-1 binding site located 90 and 68 base pairs upstr eam of the transcriptional start site, respectively, are required for maximal induction of the human MCP-1 promoter by interleukin-(IL)-1 be ta. Site-directed mutagenesis or deletion of the NF-kappa B-like site decreased the cytokine-induced activity of the promoter. Site-directed mutagenesis of the AP-1 binding site also decreased the cytokine-indu ced activity of the promoter. We show that the NF-kappa B-like site lo cated at -90 in the MCP-1 promoter binds to the p50/p65 heterodimer of the NF-kappa B/Rel family in IL-1 beta-stimulated human endothelial c ells. Overexpression of p65 results in the transactivation of the MCP- 1 promoter as well. The data presented in this study suggest that cyto kine-induced MCP-1 gene expression in human endothelial cells depends on the cooperative action of NF-kappa B and AP-1.