Angiopoietin-1 and its receptor tie-2 participate in the regulation of capillary-like tubule formation and survival of endothelial cells

Andrew J. Hayes, Wei Qun Huang, Jamie Mallah, Dajun Yang, Marc E. Lippman, Lu Yuan Li

Research output: Contribution to journalArticlepeer-review

159 Scopus citations

Abstract

Angiopoietin-1 (Ang-1) and its receptor Tie-2, a transmembrane tyrosine kinase uniquely expressed by endothelial cells, are shown by null mutation studies to be essential to developmental angiogenesis. The phenotypic abnormalities in these knockout animals suggest that Tie-2 signaling is necessary for the maintenance and expansion of the primitive capillary network. We present in vitro evidence indicating that the Ang-1/Tie-2 system participates in the regulation of capillary tubule formation and is necessary for the survival of confluent endothelial cells. Although recombinant Ang-1, which induces Tie-2 phosphorylation, has no effect on the proliferation of endothelial cells, treatment of confluent adult bovine aortic endothelial cells (ABAE) cells grown on collagen gels with Ang-1 (100 ng/ml) causes the cells to migrate into the collagen gel and form capillary-like tubules. The tubule-forming effect of Ang-1 is similar to the effect caused by FGF-2. A soluble form of the Tie-2 extracellular domain, in fivefold molar excess, blocks Ang-1-induced tubule formation. Specific elimination of Tie-2 protein expression in cultured ABAE cells as a result of transfection with an antisense oligonucleotide causes cell death in a dose-dependent manner (IC50 = 50 nM). The antisense treatment has no effect on cells that do not express Tie-2. Cells treated with antisense oligonucleotide show a sixfold increase in the rate of apoptosis as assessed by in situ end labeling of fragmented DNA. These findings are consistent with the view that Ang-1/Tie-2 signaling is essential for both angiogenesis and endothelial cell survival.

Original languageEnglish (US)
Pages (from-to)224-237
Number of pages14
JournalMicrovascular Research
Volume58
Issue number3
DOIs
StatePublished - Nov 1999

Keywords

  • Angiogenesis
  • Angiopoietin-1, Tie-2
  • Endothelial cell

ASJC Scopus subject areas

  • Biochemistry
  • Cardiology and Cardiovascular Medicine

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