Alternatively spliced tissue factor induces angiogenesis through integrin ligation

Proc Natl Acad Sci U S A. 2009 Nov 17;106(46):19497-502. doi: 10.1073/pnas.0905325106. Epub 2009 Oct 29.

Abstract

The initiator of coagulation, full-length tissue factor (flTF), in complex with factor VIIa, influences angiogenesis through PAR-2. Recently, an alternatively spliced variant of TF (asTF) was discovered, in which part of the TF extracellular domain, the transmembrane, and cytoplasmic domains are replaced by a unique C terminus. Subcutaneous tumors produced by asTF-secreting cells revealed increased angiogenesis, but it remained unclear if and how angiogenesis is regulated by asTF. Here, we show that asTF enhances angiogenesis in matrigel plugs in mice, whereas a soluble form of flTF only modestly enhances angiogenesis. asTF dose-dependently upregulates angiogenesis ex vivo independent of either PAR-2 or VIIa. Rather, asTF was found to ligate integrins, resulting in downstream signaling. asTF-alphaVbeta3 integrin interaction induces endothelial cell migration, whereas asTF-dependent formation of capillaries in vitro is dependent on alpha6beta1 integrin. Finally, asTF-dependent aortic sprouting is sensitive to beta1 and beta3 integrin blockade and a TF-antibody that disrupts asTF-integrin interaction. We conclude that asTF, unlike flTF, does not affect angiogenesis via PAR-dependent pathways but relies on integrin ligation. These findings indicate that asTF may serve as a target to prevent pathological angiogenesis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Alternative Splicing*
  • Animals
  • Aorta / growth & development
  • Aorta / metabolism
  • Capillaries / growth & development
  • Capillaries / metabolism
  • Cell Movement
  • Endothelium, Vascular / metabolism
  • Factor V / metabolism
  • Integrin alpha6beta1 / metabolism*
  • Integrin alphaVbeta3 / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Neovascularization, Pathologic / genetics*
  • Receptor, PAR-2 / metabolism
  • Thromboplastin / genetics*

Substances

  • Integrin alpha6beta1
  • Integrin alphaVbeta3
  • Receptor, PAR-2
  • Factor V
  • Thromboplastin