VW Factor Cleaving Prostease and Thrombotic Diseases

描述(申请人提供)：血栓性血小板减少性紫癜(UP)是一种血栓性微血管病态疾病，与血浆中解聚von Willebrand因子的蛋白酶活性缺乏有关。家族性TIP是由这种蛋白酶的遗传缺陷引起的，而获得性UP是由该酶的自身抗体的存在引起的。该酶被命名为vWF裂解酶(VWFCP)，是一种金属蛋白酶，特异性地裂解vWF亚基P2区的Tyr1 605-METI606键。对VWFCP进行了纯化和部分测序，并克隆了VWFCP的cDNA。VWFCP是ADAMTS金属蛋白水解酶家族的成员之一，含有结构基序，如去整合素、富含半胱氨酸的和血栓反应蛋白-1基序，这些基序是该家族的定义特征。在这一应用中，我们建议(1)研究VWFCP的结构和功能关系，并比较VWFCP与其自然存在的变体的生化性质，这些变体是通过选择性mRNA剪接合成的；(2)开发替代底物，改进用于定量检测VWFCP活性、血浆中VWFCP抗原水平和抗VWFCP自身抗体效价的方法。这些研究将更好地了解这种金属蛋白酶如何调节vWF的功能，并在血栓形成和早期止血之间保持微妙的平衡。这一认识将为设计治疗家族性和获得性UP的替代方法提供基础。

DESCRIPTION (provided by applicant): Thrombotic thrombocytopenic purpura (UP) is a thrombotic microangiopathic disorder that is associated with a deficiency of a protease activity that depolymerizes von Willebrand factor in plasma. Familial TIP is caused by a genetic deficiency of this protease, whereas acquired UP is caused by the presence of autoantibodies to the protease. This protease, which has been named vWF cleaving protease (VWFCP), is a metalloprotease and specifically cleaves the Tyrl 605-MetI 606 bond in the P2 domain of the vWF subunit. VWFCP has been purified to homogeneity, partially sequenced, and its cDNA has been cloned. VWFCP is a member of the ADAMTS family of metalloproteases and contains structural motifs such as disintegrin, Cys-rich, and thrombospondin-1 motifs, which are the defining characteristics of this family. In this application, we propose to (1) study the structure and function relationship of VWFCP, and compare the biochemical properties of VWFCP to its naturally occurring variant forms, which are synthesized as a result of alternative mRNA splicing; (2) develop alternative substrates, improved assays for the quantitative measurement of VWFCP activity, the level of VWFCP antigen in plasma, and the titer of autoantibodies to VWFCP. These studies would provide a better understanding of how this metalloprotease regulates the function of vWF and keeps a delicate balance between thrombosis and primary hemostasis. This understanding would provide a basis for devising alternative methods for treating familial and acquired UP.