Biophysical Analysis of GPIb-VWF Interaction

描述(申请人提供)：这项建议的目的是阐明调节血小板与损伤部位破裂的血管壁的黏附的分子和生物物理机制。研究的焦点是血小板膜糖蛋白Ib(GPIB)与血浆蛋白von Willebrand因子(VWF)的相互作用，后者与内皮下细胞外基质上的胶原结合。GPIB-VWF相互作用介导了多步黏附和信号级联反应的初始步骤，包括血小板与破裂血管表面的捆绑和滚动(或移位)。调节这个最初的粘连过程是至关重要的：粘连不足不能止血以维持止血。过度粘连会导致血栓形成。我们的假设是，最初的血小板黏附是由血流的生物物理参数与GPIB-VWF相互作用的特定动力学和力学性质相互作用调节的。GPIB和VWF的突变，例如在各种类型的von Willebrand病(VWD)患者中自然发生的突变，会改变这些动力学和力学特性以及生物物理参数对它们的调节，从而改变血小板的粘附性，导致血栓或出血性疾病。利用实验、计算和理论相结合的方法，这一假说将在三个综合的具体目标上得到验证：1)通过生物物理参数量化GPIB-VWF相互作用的调节；2)通过结构变化确定GPIB-VWF相互作用的调节；3)通过分子动力学模拟研究GPIB-VWF相互作用。这项综合而系统的研究将阐明GPIB-VWF相互作用的动力学和力学特性如何满足在循环机械压力环境中血小板黏附于血管壁的生物物理要求。破译分子结构如何决定这些性质以及生物物理参数对它们的调节将为血管生理学和病理学提供关键的见解。因此，这些数据可能为抑制血栓形成过程中病理性血小板黏附和/或干预出血障碍提供新的治疗方法。 我们建议阐明调节血小板膜糖蛋白Ib(GPIB)与蛋白质von Willebrand因子分子相互作用的生物物理机制，以介导血小板与损伤部位破裂的血管壁的黏附。这一调节是至关重要的，因为粘合不足不能止血以维持止血，但粘合过多会导致血栓形成。这些数据可能为抑制血栓形成过程中病理性血小板黏附和/或干预出血性疾病von Willebrand病提供新的治疗方法。

DESCRIPTION (provided by applicant): The objective of this proposal is to elucidate the molecular and biophysical mechanisms that regulate platelet adhesion to disrupted vessel wall at sites of injury. The focus is the interaction of the platelet glycoprotein Ib (GPIb) with plasma protein von Willebrand factor (VWF) that is bound to collagen on subendothelial extracellular matrix. The GPIb-VWF interaction mediates the initial step of the multistep adhesion and signaling cascade, which includes platelet tethering to and rolling (or translocating) on disrupted vascular surfaces. Regulation of this initial adhesion process is crucial: Insufficient adhesion cannot stop bleeding to maintain hemostasis. Excessive adhesion results in thrombosis. Our hypothesis is that initial platelet adhesion is regulated by the interplay of biophysical parameters of the blood flow with specific kinetic and mechanical properties of the GPIb-VWF interaction. Mutations in GPIb and VWF, such as those naturally occurring in patients with various types of von Willebrand diseases (VWD), alter these kinetic and mechanical properties as well as their regulation by biophysical parameters, thereby changing platelet adhesion and resulting in thrombotic or bleeding disorders. Using combined experimental, computational, and theoretical approaches, this hypothesis will be tested in three integrated specific aims: 1) Quantify the regulation of GPIb-VWF interaction by biophysical parameters, 2) Determine the regulation of GPIb-VWF interaction by structural variations, and 3) Investigate GPIb-VWF interaction by molecular dynamics simulations. This integrated and systematic study will clarify how the kinetic and mechanical properties of GPIb-VWF interaction fulfill the biophysical requirements for platelets to adhere to blood vessel wall in the mechanically stressful environment of the circulation. Decoding how molecular structure determines these properties and their regulation by biophysical parameters will provide key insights into vascular physiology and pathology. As a result, the data may offer new therapeutic approaches to inhibiting pathological platelet adhesion during thrombosis and/or intervention to the bleeding disorder. We propose to elucidate the biophysical mechanisms that regulate the molecular interaction of the platelet glycoprotein Ib (GPIb) with protein von Willebrand factor, which mediates platelet adhesion to disrupted vessel wall at sites of injury. This regulation is crucial because insufficient adhesion cannot stop bleeding to maintain hemostasis but excessive adhesion results in thrombosis. The data may offer new therapeutic approaches to inhibiting pathological platelet adhesion during thrombosis and/or intervention to the bleeding disorder von Willebrand diseases.