Regulation of von Willebrand Factor - platelet binding by Force and Interdomain I

描述（由申请人提供）：动脉血栓形成发生在高流体流动的条件下，由血小板通过其受体糖蛋白Ib （GPIb）通过A1结构域与称为血管性血友病因子（VWF）的血浆蛋白结合介导。这个过程通常是下调的，以防止自发粘连和血栓形成，但被高剪切应力激活。这项工作将验证GPIb与A1的结合被VWF内的邻近结构域或侧翼区域下调，从而使VWF表现出结构域间的自抑制。它还将验证高剪切应力相关的机械力通过将这些调节区域拉离A1结构域来激活血小板结合以减轻自身抑制的假设。最后一个有待检验的假设是，增加血小板与VWF自发结合的条件，包括2B型血管性血友病，是通过破坏正常的域间自抑制来实现的。通过克隆VWF的不同区域，确定可溶性和表面固定化分子的粘附行为，可以鉴定VWF中的调控结构域和元件。机械力和剪切应力对这种调节的影响将在分子定向固定后使用原子力显微镜和微流体来确定。

DESCRIPTION (provided by applicant): Arterial thrombosis occurs in conditions of high fluid flow and is mediated by the binding of platelets via their receptor Glycoprotein Ib (GPIb) to the plasma protein called von Willebrand Factor (VWF) via the A1 domain. This process is normally down-regulated to prevent spontaneous adhesion and thrombosis, but is activated by high shear stress. The proposed work will test the hypothesis that binding of GPIb to A1 is down-regulated by the neighboring domains or flanking regions within VWF, so that VWF displays interdomain auto-inhibition. It will also test the hypothesis that mechanical force associated with high shear stress activates platelet binding by pulling these regulatory regions away from the A1 domain to relieve the auto- inhibition. The final hypothesis to be tested is that conditions that increase the spontaneous binding of platelets to VWF, including type 2B von Willebrand disease, do so by damaging the normal interdomain auto-inhibition. Regulatory domains and elements within VWF will be identified by cloning different regions of VWF and determining the adhesive behavior of both soluble and surface-immoblized molecules. The effect of mechanical force and shear stress on this regulation will be determined using an atomic force microscope and microfluidics after immobilizing the molecules in an oriented fashion. PUBLIC HEALTH RELEVANCE: Thrombosis prevents bleeding at the site of damaged blood vessels but can also lead to heart attacks or strokes, the leading causes of death in cardiovascular disease. Current treatments for cardiovascular disease often cause excessive bleeding, while treatments for bleeding disorders can cause thrombotic disorders. To develop new therapies without these fundamental trade- offs, we need to better understand how the thrombotic process is regulated in the body.