Identification of a functional NF-kappa B site in the platelet endothelialcell adhesion molecule-1 promoter

Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a type I transme mbrane adhesion protein of 130 kDa that belongs to a subgroup of the Ig gen e superfamily, characterized by the presence of immunoreceptor tyrosine-bas ed inhibitory motifs, PECAM-1 is expressed in circulating platelets, monocy tes, neutrophils, a selective subgroup of T cells, and in endothelial cells , where it is preferentially located at intercellular junctions and partici pates in leukocyte transmigratory processes. The identification of two cons ensus NF-kappa B sites within the PECAM-1 promoter led us to analyze their possible involvement in the PECAM-1 expression regulated by inflammatory; s timuli. We found that surface expression and promoter activity of PECAM-1 i n myeloid cells are regulated by modulators of NF-kappa B, including TNF-al pha, PMA, and pyrrolidine dithiocarbamate, Mobility shifts assays identifie d a specific NF-kappa B-binding element at +110/+120, whose mutation abolis hed the basal promoter activity of PECAM-1 and decreased NF-kappa B-depende nt responses of the PECAM-1 gene promoter. Furthermore, cotransfection expe riments with an expression vector encoding the p65 subunit of NF-kappa B sh owed transactivation of the PECAM-1 promoter. These results demonstrate tha t NF-kappa B can regulate the transcriptional activity of PECAM-1.