TNF induction of jagged-1 in endothelial cells is NFκB-dependent

Abstract

TNF-α is a potent proinflammatory cytokine that induces endothelial cell (EC) adhesion molecules. In addition, TNF promotes angiogenesis by inducing an EC tip cell phenotype and the expression of jagged-1, a ligand for the notch pathway. Notch signaling is critical for vascular patterning and helps to restrict the proliferation of tip cells. Here we demonstrate that TNF induction of jagged-1 in human EC is rapid and dependent upon signaling through TNFR1, but not TNFR2. A luciferase reporter construct carrying 3.7 kb of 5′ promoter sequence from the human gene was responsive to both TNF and overexpression of NFκB pathway components. TNF-induced promoter activation was blocked by treatment with an NFκB inhibitor or co-expression of dominant-negative IKKβ. Mutations in a putative NFκB-binding site at − 3.0 kb, which is conserved across multiple species, resulted in a loss of responsiveness to TNF and NFκB. Electromobility shift and chromatin immunoprecipitation assays revealed binding of both p50 and p65 to the promoter in response to TNF treatment. Full promoter activity also depends on an AP-1 site at − 2.0 kb. These results indicate that canonical NFκB signaling is required for TNF induction of the notch ligand jagged-1 in EC.