Regulation of the Tissue Factor Promoter in Endothelial Cells

Tissue factor is up-regulated on endothelial cells and monocytes in response to cytokines and endotoxin and is the main trigger of the extrinsic pathway of the coagulation cascade. We have isolated the porcine tissue factor gene and studied the regulation of the promoter, which has not been investigated previously in endothelial cells. Comparison of the promoter sequences with the respective human and murine genes reveals short stretches of homology, which encompass potential binding sites for AP-1, NFκB, and Sp1 transcription factors. Using DNase I footprinting, we detect binding of nuclear factors to these promoter elements. Transfection experiments demonstrate that a 300-base pair fragment containing the conserved elements can mediate induced transcription and that the NFκB-like element is essential. In accordance, electrophoretic mobility shift assays show a strong increase in the binding of factors to the NFκB-like site following induction. We further provide evidence that RelA (p65), c-Rel, and possibly novel polypeptides bind to the tissue factor NFκB element. In addition, we show constitutive binding of members of the Fos/Jun and Sp1 families to the AP-1 and Sp1 sites, respectively. We propose a concerted action of AP-1-, NFκB-, and Sp1-like factors in transcription from the tissue factor promoter in endothelial cells. Tissue factor is up-regulated on endothelial cells and monocytes in response to cytokines and endotoxin and is the main trigger of the extrinsic pathway of the coagulation cascade. We have isolated the porcine tissue factor gene and studied the regulation of the promoter, which has not been investigated previously in endothelial cells. Comparison of the promoter sequences with the respective human and murine genes reveals short stretches of homology, which encompass potential binding sites for AP-1, NFκB, and Sp1 transcription factors. Using DNase I footprinting, we detect binding of nuclear factors to these promoter elements. Transfection experiments demonstrate that a 300-base pair fragment containing the conserved elements can mediate induced transcription and that the NFκB-like element is essential. In accordance, electrophoretic mobility shift assays show a strong increase in the binding of factors to the NFκB-like site following induction. We further provide evidence that RelA (p65), c-Rel, and possibly novel polypeptides bind to the tissue factor NFκB element. In addition, we show constitutive binding of members of the Fos/Jun and Sp1 families to the AP-1 and Sp1 sites, respectively. We propose a concerted action of AP-1-, NFκB-, and Sp1-like factors in transcription from the tissue factor promoter in endothelial cells.