Thrombin Stimulation of Vascular Adhesion Molecule-1 in Endothelial Cells Is Mediated by Protein Kinase C (PKC)-δ-NF-κB and PKC-ζ-GATA Signaling Pathways

Abstract

We recently demonstrated that thrombin induces the expression of vascular adhesion molecule-1 (VCAM-1) in endothelial cells by an NF-B-and GATA-dependent mechanism. In the present study, we describe the signaling pathways that mediate this response. Thrombin stimulation of the VCAM-1 gene and promoter in human umbilical vein endothelial cells was inhibited by preincubation with the phosphatidylinositol 3-kinase inhibitor, LY294002, the protein kinase C (PKC)-␦ inhibitor, rottlerin, a PKC-peptide inhibitor, or by overexpression of dominant negative (DN)-PKC-. In electrophoretic mobility shift assays, thrombin-mediated induction of NF-B p65 binding to two NF-B motifs in the upstream promoter region of VCAM-1 was blocked by LY294002 and rottlerin, whereas the inducible binding of GATA-2 to a tandem GATA motif was inhibited by LY294002 and the PKC-peptide inhibitor. In co-transfection assays, thrombin stimulation of a minimal promoter containing multimerized VCAM-1 NF-B sites was inhibited by DN-PKC-␦ but not DN-PKC-. In contrast, thrombin-mediated transactivation of a minimal promoter containing tandem VCAM-1 GATA motifs was inhibited by DN-PKC-but not DN-PKC-␦. Finally, thrombin failed to induce VCAM-1 expression in vascular smooth muscle cells. Taken together, these data suggest that the endothelial cell-specific effect of thrombin on VCAM-1 expression involves the coordinate activity of PKC-␦-NF-B and PKC--GATA signaling pathways. Vascular adhesion molecule-1 (VCAM-1)1 is a 110-kDa cell surface glycoprotein that is expressed in cytokine-activated endothelial cells (1). The VCAM-1 promoter, originally cloned and characterized in cultured endothelial cells (2), represents a potentially valuable tool for dissecting the molecular mechanisms of endothelial cell activation. Several studies have demonstrated the importance of two tandem NF-B elements located at position Ϫ77 and Ϫ63, relative to the transcriptional start site, in transducing the response to inflammatory mediators (2-4). Other studies have provided evidence for the role of co-stimulators in mediating cytokine response, including Sp1 (5), activating protein-1 (6), and interferon regulatory factor-1 (7).In a recent report, we showed that the incubation of endothelial cells with thrombin or the PAR-1 agonist, thrombin receptor activation peptide (TRAP), resulted in increased VCAM-1 mRNA levels and VCAM-1 promoter activity (8). Not surprisingly, a mutation of the tandem NF-B motif blocked the response to thrombin. Moreover, in electrophoretic mobility shift assays, thrombin induced the binding of p65 homodimers to the two adjacent NF-B sites in the VCAM-1 promoter. A more interesting finding was that a mutation of a tandem GATA motif (located at Ϫ244 and Ϫ259) also attenuated the thrombin response. Consistent with these results, thrombin treatment resulted in increased binding of GATA-2 to the VCAM-1 promoter. These data suggested that thrombin-mediated induction of VCAM-1 involves the coordinate activity of NF-B p65 and GATA-2 and raised new questions as to...

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Critical Role for GATA3 in Mediating Tie2 Expression and Function in Large Vessel Endothelial Cells

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Protein Kinase Cδ Mediates Lysophosphatidic Acid-induced NF-κB Activation and Interleukin-8 Secretion in Human Bronchial Epithelial Cells

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