Laboratory for Thrombosis Research, Katholieke Universiteit Leuven Campus Kortrijk, B-8500 Kortrijk, Belgium.
J Biol Chem. 2011 Oct 21;286(42):36361-7. doi: 10.1074/jbc.M111.271890. Epub 2011 Sep 6.
Platelet-decorated von Willebrand factor (VWF) strings anchored to the endothelial surface are rapidly cleaved by ADAMTS13. Individual VWF string characteristics such as number, location, and auxiliary features of the ADAMTS13 cleavage sites were explored here using imaging and computing software. By following changes in VWF string length, we demonstrated that VWF strings are cleaved multiple times, successively shortening string length in the function of time and generating fragments ranging in size from 5 to over 100 μm. These are larger than generally observed in normal plasma, indicating that further proteolysis takes place in circulation. Interestingly, in 89% of all cleavage events, VWF strings elongate precisely at the cleavage site before ADAMTS13 proteolysis. These local elongations are a general characteristic of VWF strings, independent of the presence of ADAMTS13. Furthermore, large elongations, ranging in size from 1.4 to 40 μm, occur at different sites in space and time. In conclusion, ADAMTS13-mediated proteolysis of VWF strings under flow is preceded by large elongations of the string at the cleavage site. These elongations may lead to the simultaneous exposure of many exosites, thereby facilitating ADAMTS13-mediated cleavage.
血小板修饰的血管性血友病因子 (VWF) 串被 ADAMTS13 迅速切割，固定在血管内皮表面。在此，我们使用成像和计算软件探索了 ADAMTS13 切割位点的个体 VWF 串特征，如数量、位置和辅助特征。通过跟踪 VWF 串长度的变化，我们证明 VWF 串被多次切割，随着时间的推移连续缩短串的长度，并产生大小从 5 到 100μm 以上的片段。这些片段比在正常血浆中通常观察到的要大，表明在循环中进一步发生蛋白水解。有趣的是，在所有切割事件中的 89%中，VWF 串在 ADAMTS13 蛋白水解之前在切割位点精确伸长。这些局部伸长是 VWF 串的一般特征，与 ADAMTS13 的存在无关。此外，在不同的空间和时间点还会发生大小从 1.4μm 到 40μm 的大伸长。总之，在流动条件下，ADAMTS13 介导的 VWF 串蛋白水解之前，在切割位点处会发生大的伸长。这些伸长可能导致许多外显子同时暴露，从而促进 ADAMTS13 介导的切割。
