van den Berg Y W, van den Hengel L G, Myers H R, Ayachi O, Jordanova E, Ruf W, Spek C A, Reitsma P H, Bogdanov V Y, Versteeg H H
The Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
Proc Natl Acad Sci U S A. 2009 Nov 17;106(46):19497-502. doi: 10.1073/pnas.0905325106. Epub 2009 Oct 29.
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.
凝血起始因子全长组织因子（flTF）与因子VIIa形成复合物，通过蛋白酶激活受体-2（PAR-2）影响血管生成。最近，发现了组织因子（TF）的一种选择性剪接变体（asTF），其中TF细胞外结构域的一部分、跨膜结构域和细胞质结构域被一个独特的C末端所取代。由分泌asTF的细胞产生的皮下肿瘤显示血管生成增加，但asTF是否以及如何调节血管生成仍不清楚。在此，我们表明asTF可增强小鼠基质胶塞中的血管生成，而可溶性形式的flTF仅适度增强血管生成。asTF在体外剂量依赖性地上调血管生成，且不依赖于PAR-2或VIIa。相反，发现asTF可与整合素结合，导致下游信号传导。asTF与αVβ3整合素的相互作用诱导内皮细胞迁移，而asTF依赖的体外毛细血管形成则依赖于α6β1整合素。最后，asTF依赖的主动脉芽生对β1和β3整合素阻断以及破坏asTF-整合素相互作用的TF抗体敏感。我们得出结论，与flTF不同，asTF不通过PAR依赖途径影响血管生成，而是依赖于整合素结合。这些发现表明asTF可能作为预防病理性血管生成的靶点。
