A novel platelet inhibitor from bloodfeeding hookworms

描述（由申请方提供）：血栓栓塞性疾病是发达国家发病率和死亡率的主要原因。 由于血小板在血栓形成的活化和传播中起着关键作用，因此它们是新的抗血栓药物的重要靶点。 从吸血钩虫（Ancylostoma caninum）中分离出一种有效的人类血小板功能抑制剂。 这种新的蛋白质是第一种天然存在的化合物，显示出阻断血小板整合素GPIIb/IIIa和GPIa/IIa的结合，分别是纤维蛋白原和胶原蛋白的细胞表面受体。 该I期STTR资助申请的目的是纯化毫克量的活性重组钩虫血小板抑制剂（rHPI），适用于体内和体外试验。 将使用全血小板聚集和粘附试验表征rHPI。 此外，定量实验将测量rHPI阻断胶原蛋白和纤维蛋白原与其各自整联蛋白受体相互作用的能力。 与各种肽的竞争实验将描绘HPI结合位点，并进一步表征其分子作用机制。 最后，将产生rHPI的截短变体，以确定具有保留的抗血小板活性的最小蛋白质结构域。 长期目标是开发rHPI作为治疗人类血栓性疾病的治疗剂。

DESCRIPTION (provided by applicant): Thromboembolic disease is a major cause of morbidity and mortality in the developed world. Because platelets play a critical role in the activation and propagation of thrombosis, they represent important targets for new anti-thrombotic drugs. A potent inhibitor of human platelet function has been isolated from the bloodfeeding hookworm, Ancylostoma caninum. This novel protein is the first naturally occurring compound shown to block the binding of platelet integrins GPIIb/IIIa and GPIa/IIa, the cell surface receptors for fibrinogen and collagen, respectively. The objective of this Phase I STTR grant application is to purify milligram quantities of active recombinant hookworm platelet inhibitor (rHPI) suitable for testing in vivo and in vitro. The rHPI will be characterized using whole platelet assays of aggregation and adhesion. In addition, quantitative experiments will measure the ability of rHPI to block the interaction of collagen and fibrinogen with their respective integrin receptors. Competition experiments with various peptides will delineate HPI binding sites and further characterize its molecular mechanism of action. Lastly, truncated variants of rHPI will be produced in order to determine the smallest protein domain with preserved antiplatelet activity. The long-term objective is to develop rHPI as a therapeutic agent for the treatment of thrombotic disorders in humans.