Mechanisms of interactions between von Willebrand factor and its binding partners

摘要 血管性血友病因子(VWF)在血液中有两个主要作用。一种是促进血小板黏附和 聚集，其中一个关键步骤是激活VWFA1结构域，使其与血小板蛋白GPIBα结合 流。另一种是防止凝血因子VIII(FVIII)的降解，这对纤维蛋白凝块很重要。 队形。干扰这些结合相互作用的VWF突变可导致血栓形成或von Willebrand 疾病。这个项目的目标是确定控制vwf之间相互作用的分子机制。 及其结合伙伴GPIBα和Fviii。 关于VWF与GPIB、α和FVIII相互作用的几个问题仍然存在。已经没有一个 VWFA1结构域如何激活以与GPIBα结合的一致模型。目前还不清楚是什么以及如何进行的。 构象变化实际上发生在A1激活过程中。迄今为止，VWF多聚体之间的相互作用 而FVIII主要是使用原装VWF制剂进行研究。FVIII如何与单个VWF多聚体结合 是未知的。在静脉输液治疗出血性疾病时，输液中更多的游离FVIII与 FVIII具有较高的免疫原性风险，但其机制尚不清楚。 在本项目中，我们将结合单分子生物物理和超分辨率成像方法进行研究 目标有以下几点。(1)了解VWF A1与GPIBα结合的流动诱导激活。(2)解剖VWF- FVIII结合模式及其对血液中FVIII的保护作用。这项研究将为 VWF如何与GPIBα和FVIII结合的机制，并为治疗开发提供了新的见解 治疗血栓性或出血性疾病。

SUMMARY Von Willebrand factor (VWF) has two major roles in blood. One is to facilitate platelet adhesion and aggregation, in which a critical step is to activate the VWF A1 domain to bind with platelet protein GPIbα under flow. The other is to protect coagulation factor VIII (FVIII) from degradation, which is important for fibrin clot formation. Mutations in VWF interfering with these binding interactions can cause thrombosis or von Willebrand disease. The goal of this project is to determine molecular mechanisms governing the interactions between VWF and its binding partners GPIbα and FVIII. Several questions regarding VWF interactions with GPIbα and FVIII persist. There has not been a consistent model for how VWF A1 domain is activated to bind with GPIbα. It still remains unclear which and how conformational changes actually happen during A1 activation. To date, the interaction between VWF multimer and FVIII has been studied primarily using bulk VWF preparations. How FVIII binds to individual VWF multimers is unknown. In intravenous infusion treatment for bleeding disorders, more free FVIII in the infusion is linked to higher risk of FVIII immunogenicity, but the mechanisms remain unclear. In this project, we will combine single molecule biophysics and super resolution imaging methods to study the following aims. (1) Understand flow-induced activation of VWF A1 binding with GPIbα. (2) Dissect the VWF- FVIII binding mode and its role in protecting FVIII in blood. This study will provide direct evidence for the mechanisms of how VWF binds with GPIbα and FVIII, and provide new insights into therapeutic development to treat thrombotic or bleeding disorders.