title: Alternatively spliced tissue factor induces angiogenesis through integrin ligation.
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.
authors.affiliation: The Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
authors.forename: Y W
authors.initials: YW
authors.lastname: van den Berg
authors.forename: L G
authors.initials: LG
authors.lastname: van den Hengel
authors.forename: H R
authors.initials: HR
authors.lastname: Myers
authors.forename: O
authors.initials: O
authors.lastname: Ayachi
authors.forename: E
authors.initials: E
authors.lastname: Jordanova
authors.forename: W
authors.initials: W
authors.lastname: Ruf
authors.forename: C A
authors.initials: CA
authors.lastname: Spek
authors.forename: P H
authors.initials: PH
authors.lastname: Reitsma
authors.forename: V Y
authors.initials: VY
authors.lastname: Bogdanov
authors.forename: H H
authors.initials: HH
authors.lastname: Versteeg
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001011:Aorta / Q000254:growth & development / Q000378:metabolism; D002196:Capillaries / Q000254:growth & development / Q000378:metabolism; D002465:Cell Movement; D004730:Endothelium, Vascular / Q000378:metabolism; D005165:Factor V / Q000378:metabolism; D039121:Integrin alpha6beta1 / Q000378:metabolism*; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000235:genetics*; D044464:Receptor, PAR-2 / Q000378:metabolism; D013925:Thromboplastin / Q000235:genetics*
chemical_list: D039121:Integrin alpha6beta1; D039302:Integrin alphaVbeta3; D044464:Receptor, PAR-2; D005165:Factor V; D013925:Thromboplastin