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Delta-like 4 (Dll4), a membrane-bound ligand for Notch1 and Notch4, is selectively expressed in the developing endothelium and in some tumor endothelium, and it is induced by vascular endothelial growth factor (VEGF)-A and hypoxia. Gene targeting studies have shown that Dll4 is required for normal embryonic vascular remodeling, but the mechanisms underlying Dll4 regulatory functions are currently not defined. In this study, we generated primary human endothelial cells that overexpress Dll4 protein to study Dll4 function and mechanism of action. Human umbilical vein endothelial cells retrovirally transduced with Dll4 displayed reduced proliferative and migratory responses selectively to VEGF-A. Expression of VEGF receptor-2, the principal signaling receptor for VEGF-A in endothelial cells, and coreceptor neuropilin-1 was significantly decreased in Dll4-transduced endothelial cells. Consistent with Dll4 signaling through Notch, expression of HEY2, one of the transcription factors that mediates Notch function, was significantly induced in Dll4-overexpressing endothelial cells. The gamma-secretase inhibitor L-685458 significantly reconstituted endothelial cell proliferation inhibited by immobilized extracellular Dll4 and reconstituted VEGFR2 expression in Dll4-overexpressing endothelial cells. These results identify the Notch ligand Dll4 as a selective inhibitor of VEGF-A biologic activities down-regulating 2 VEGF receptors expressed on endothelial cells and raise the possibility that Dll4 may be exploited therapeutically to modulate angiogenesis.

Original publication

DOI

10.1182/blood-2005-03-1000

Type

Journal article

Journal

Blood

Publication Date

01/02/2006

Volume

107

Pages

931 - 939

Keywords

Amyloid Precursor Protein Secretases, Aspartic Acid Endopeptidases, Basic Helix-Loop-Helix Transcription Factors, Blood Proteins, Carbamates, Cells, Cultured, Dipeptides, Endopeptidases, Endothelial Cells, Enzyme Inhibitors, Humans, Intercellular Signaling Peptides and Proteins, Ligands, Neovascularization, Physiologic, Protein Binding, Proto-Oncogene Proteins, Receptor, Notch1, Receptor, Notch4, Receptors, Notch, Repressor Proteins, Transfection, Umbilical Veins, Up-Regulation, Vascular Endothelial Growth Factor A, Vascular Endothelial Growth Factor Receptor-2