Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA.
Department of Bioengineering, Lehigh University, Bethlehem, Pennsylvania, USA.
J Thromb Haemost. 2022 Nov;20(11):2686-2696. doi: 10.1111/jth.15837. Epub 2022 Aug 29.
Von Willebrand factor (VWF) is a multimeric plasma protein that bridges the gap between vessel injury and platelet capture at high shear rates. Under high shear or tension, VWF can become activated upon the unfolding of its autoinhibitory module (AIM). AIM unfolding exposes the A1 domain, allowing for binding to platelet glycoprotein (GP)Ibα to initiate primary hemostasis. The characteristics of the AIM and its inhibitory properties within mouse VWF are unknown.
To determine and characterize the autoinhibitory properties of mouse VWF.
Recombinant mouse VWF A1 fragments containing or lacking the flanking regions around the A1 domain were generated. We tested the ability of these fragments to bind to human or mouse GPIbα and platelets. We compared the unfolding of mouse AIM-A1 to human AIM-A1 by single-molecule force spectroscopy.
Recombinant mouse AIM-A1 binds with higher affinity to GPIbα than its human counterpart. Recombinant mouse proteins lacking part of the AIM show increased binding to GPIbα. Activated A1 fragments lacking the AIM can effectively agglutinate platelets across the species barrier. Using single-molecule force spectroscopy, we determined that the mouse AIM unfolds under forces similar to the human AIM. Additionally, the human AIM paired with mouse A1 largely recapitulates the behavior of human AIM-A1.
Our results suggest that the regulation of VWF-GPIbα binding has been specifically tuned to work optimally in different rheological architectures. Differences in the AIM sequence may contribute to the difference in VWF shear response between human and mice.
血管性血友病因子（VWF）是一种多聚体血浆蛋白，可在高剪切率下桥接血管损伤和血小板捕获之间的间隙。在高剪切或张力下，VWF 的自动抑制模块（AIM）展开时可以被激活。AIM 展开暴露 A1 结构域，允许与血小板糖蛋白（GP）Ibα结合，启动初级止血。鼠 VWF 中 AIM 的特性及其抑制特性尚不清楚。
确定并表征鼠 VWF 的自动抑制特性。
生成了含有或缺乏 A1 结构域侧翼区的重组鼠 VWF A1 片段。我们测试了这些片段与人和鼠 GPIbα 和血小板结合的能力。我们通过单分子力谱比较了鼠 AIM-A1 和人 AIM-A1 的展开情况。
重组鼠 AIM-A1 与 GPIbα 的结合亲和力高于其对应的人 AIM-A1。缺乏 AIM 的部分的重组鼠蛋白显示出与 GPIbα 结合增加。缺乏 AIM 的激活 A1 片段可以有效地跨越物种屏障聚集血小板。通过单分子力谱，我们确定鼠 AIM 在与人类 AIM 相似的力下展开。此外，与人 A1 配对的人 AIM 在很大程度上再现了人 AIM-A1 的行为。
我们的结果表明，VWF-GPIbα 结合的调节已被专门调整为在不同的流变学结构中最佳工作。AIM 序列的差异可能导致人与鼠 VWF 剪切反应的差异。
