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

Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a type I transmembrane adhesion protein of 130 kDa that belongs to a subgroup of the Ig gene superfamily, characterized by the presence of immunoreceptor tyrosine-based inhibitory motifs. PECAM-1 is expressed in circulating platelets, monocytes, neutrophils, a selective subgroup of T cells, and in endothelial cells, where it is preferentially located at intercellular junctions and participates in leukocyte transmigratory processes. The identification of two consensus NF-kappa B sites within the PECAM-1 promoter led us to analyze their possible involvement in the PECAM-1 expression regulated by inflammatory stimuli. We found that surface expression and promoter activity of PECAM-1 in myeloid cells are regulated by modulators of NF-kappa B, including TNF-alpha, PMA, and pyrrolidine dithiocarbamate. Mobility shifts assays identified a specific NF-kappa B-binding element at +110/+120, whose mutation abolished the basal promoter activity of PECAM-1 and decreased NF-kappa B-dependent responses of the PECAM-1 gene promoter. Furthermore, cotransfection experiments with an expression vector encoding the p65 subunit of NF-kappa B showed transactivation of the PECAM-1 promoter. These results demonstrate that NF-kappa B can regulate the transcriptional activity of PECAM-1.