title: Notch activation during endothelial cell network formation in vitro targets the basic HLH transcription factor HESR-1 and downregulates VEGFR-2/KDR expression.
abstract: Angiogenesis is essential for normal homeostasis, wound healing, and tumor growth and involves a switch in endothelial cell (EC) phenotype from quiescence to migration, proliferation and network formation, and back to quiescence. The notch signaling pathway is critically involved in cell fate decisions during development, and mice deficient in several notch/notch ligand genes have vascular phenotypes. Here we show that notch signaling is activated during EC capillary-like network formation in vitro and that EC express transcripts for notch 1, notch 4, the notch ligand delta 4, and the putative notch processing enzymes ADAM-10 and presenilin. Expression of dominant negative notch blocks network formation; however, constitutively active notch (NICD) does not induce morphologic changes. Furthermore, both EC network formation and expression of activated notch 1 or notch 4 induce expression of the bHLH transcription factor HESR-1 and downregulate the known HESR-1 target VEGFR-2 (KDR). Notch-mediated reduction in VEGFR-2 expression results in decreased EC proliferation in response to VEGF but not bFGF. These data suggest that HESR-1 may be involved in the phenotypic changes that characterize the progression from EC proliferation and migration to network formation and quiescence.
authors.affiliation: Dept of Molecular Biology and Biochemistry, University of California-Irvine, Irvine, CA 92627-3900, USA.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Taylor
authors.forename: April M
authors.initials: AM
authors.lastname: Henderson
authors.forename: Christopher C W
authors.initials: CC
authors.lastname: Hughes
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins; D002455:Cell Division; D002465:Cell Movement; D002478:Cells, Cultured; D015536:Down-Regulation; D029721:Drosophila Proteins; D004727:Endothelium / Q000166:cytology*; D004730:Endothelium, Vascular / Q000166:cytology; D006801:Humans; D019476:Insect Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009389:Neovascularization, Pathologic; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D000074562:Receptor, Notch4; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014157:Transcription Factors; D014162:Transfection; D014471:Umbilical Veins / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D000074562:Receptor, Notch4; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; D014157:Transcription Factors; D040301:Vascular Endothelial Growth Factor Receptor-2; C120390:Hey protein, Drosophila; C106075:NOTCH4 protein, human