The Biochemistry and Physiology of Platelet TFPI

描述（由申请人提供）：组织因子途径抑制剂（TFPI）是启动血液凝固的组织因子/维拉因子（TF/维拉）催化复合物的主要抑制剂。因此，TFPI是一种有效的抗凝血蛋白。在动脉粥样硬化和癌症等疾病中，血管系统内的TF数量增加，从而产生血管内血栓，从而导致心脏病发作、中风和肺栓塞等常见和严重的疾病。我们提出的研究的长期目标是了解巨核细胞产生并在活化血小板表面表达的TFPI在控制血管内TF活性中的作用。我们假设血小板TFPI的最佳定位和集中是为了在不断增长的血凝块中下调TF活性。因此，它可以防止血栓的形成，从而完全阻塞血管，产生严重的、可能致命的疾病。这一假设基于以下几点：1)血液中循环的TF是血栓形成和生长的主要因素；2) TFPI是唯一的TF生理抑制剂；3)血小板是血栓形成的主要细胞成分；4)肌动蛋白和TFPI在活化血小板内共定位；5)血小板TFPI缺乏的小鼠在肝脏和大脑中有大量的纤维蛋白沉积，而血小板TFPI缺乏的小鼠则没有。这里提出的实验将确定1)TFPI在静止血小板内的细胞内位置；2) TFPI转移到活化血小板表面的生化机制；3)血小板TFPI在体内TFPI缺乏小鼠模型中的生理功能。这是我5年职业发展计划的一部分。职业发展计划包括血液学、小鼠病理学和胚胎发生方面的额外培训。与威斯康星血液中心血液研究所（BRI）和威斯康星医学院的基础科学家的持续互动将提供1)接触在血液学，凝血和病理学领域具有专业知识的经验丰富的研究人员，2)小鼠模型的生产和评估，3)使用体外和体内系统研究凝血，4)通过血液研究所赞助的访问系列讲座，接触到国际和国内知名的科学家。这些机会将为Maroney博士过渡到独立资助的研究者提供额外的支持和指导。

DESCRIPTION (provided by applicant): Tissue factor pathway inhibitor (TFPI) is the major inhibitor of the tissue factor/factor Vila (TF/Vlla) catalytic complex that initiates blood coagulation. Therefore, TFPI is a potent anticoagulant protein. The amount of TF within the vasculature system increases in diseases such as atherosclerosis and cancer producing intravascular thrombosis that can result in common and severe diseases such as heart attack, stroke and pulmonary embolism. The long term goal of our proposed studies is to understand the role of TFPI produced by megakaryocytes and expressed on the surface of activated platelets in controlling intravascular TF activity. We hypothesize that platelet TFPI is optimally located and concentrated in order to down-regulate TF activity within a growing blood clot. Thereby, it prevents the formation of blood clots that totally occlude the blood vessel and produce severe, potentially lethal, disease. This hypothesis is based on the following: 1) circulating TF in the blood is a major contributor to clot formation and growth; 2) TFPI is the only physiological inhibitor of TF; 3) platelets are the major cellular component of clot formation; 4) actin and TFPI co-localize within activated platelets; and 5) mice deficient in platelet TFPI have substantial amounts of fibrin deposition in their liver and brain that is not present in mice with platelet TFPI. The experiments proposed here will determine 1) the intracellular location of TFPI within quiescent platelets; 2) the biochemical mechanism(s) for transfer of TFPI to the surface of activated platelets; and 3) the physiological function(s) of platelet TFPI in an in vivo mouse model of TFPI deficiency. This proposal is part of a career development plan spanning 5 years. The career development plan includes additional training in the discipline of hematology, mouse pathology and embryogenesis. Continuous interactions with basic scientists at the Blood Research Institute (BRI) of the Blood Center of Wisconsin and the Medical College of Wisconsin will provide 1) access to experienced investigators with expertise in the areas of hematology, coagulation, and pathology, 2) production and evaluation of mouse models, 3) use of in vitro and in vivo systems to study coagulation, and 4) access to internationally and nationally recognized scientists through the visiting lecture series sponsored by the Blood Research Institute. These opportunities will provide additional support and mentoring as Dr. Maroney transitions to an independently funded investigator. RELEVANCE (Seeinstructions): This proposal is relevant to public health as it investigates the role platelet TFPI plays in the down-regulation of the clot forming activities of platelets. Investigation of these mechanisms will enhance our understanding of how platelets can form clots to prevent severe bleeding while controlling clot growth to prevent vessel occlusion that can result in stroke or heart attack or other potentially lethal diseases. (End of Abstract)