Small GTPases in the biology of platelets and megakaryocytes

血小板和巨核细胞生物学中的小 GTP 酶

• 批准号: 10577770
• 负责人: Wolfgang Bergmeier
• 金额: $ 84.21万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-21 至 2026-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10577770
• 关键词: Adhesions; Biochemical; Biological; Biological Assay; Biology; Biosensor; Blood; Blood Cells; Blood Coagulation Disorders; Blood Platelets; Blood Vessels; Bone Marrow; Cardiovascular system; Cells; Clinical Research; Deep Vein Thrombosis; Development; Diagnosis; Disease; Funding; Future; Goals; Grant; Guanosine Triphosphate Phosphohydrolases; Hemorrhage; Hemostatic Agents; Hemostatic function; Human; In Vitro; Inflammation; Inherited; Life; Megakaryocytes; Molecular; Molecular Profiling; Monitor; Monomeric GTP-Binding Proteins; Mus; Myocardial Infarction; National Heart, Lung, and Blood Institute; Pathology; Pathway interactions; Peripheral; Phagocytes; Platelet Activation; Platelet Count measurement; Prevention approach; Process; Production; Proliferating; Regulation; Risk; Role; Signal Transduction; Thrombocytopenia; Thrombosis; Venous Thrombosis; Work; improved; inhibitor; inter-individual variation; mouse model; novel; novel strategies; optogenetics; personalized approach; platelet function; platelet homeostasis; podoplanin; preservation; rho; shear stress; thrombotic complications; tool; transfusion medicine

ABSTRACT Mammalian platelets are small anucleate blood cells specialized to continuously monitor and preserve the integrity of the cardiovascular system (hemostasis). They are produced by megakaryocytes (MKs) in the bone marrow and released into blood, where they circulate for ten days in humans and five days in mice until they get cleared by phagocytes. Platelet homeostasis, i.e. the establishment of a defined peripheral platelet count, requires tight regulation of both platelet production and clearance. To fulfill their hemostatic function, platelets depend on a very sensitive signaling machinery that facilitates platelet adhesion under shear stress. This high sensitivity, however, poses a risk for unwanted platelet activation that can lead to platelet clearance and/or thrombosis. The overarching goal of our work is to achieve a better understanding of the molecular mechanisms regulating MK development and platelet reactivity, with a specific focus on the role of small GTPases in these processes. This R35 OIA application is an extension to three funded NHLBI R01 grants: Small GTPases in Megakaryocyte Biology; Rap1 Signaling in Platelet Homeostasis and Vascular Hemostasis; Spatial Regulation of Platelet Activation by Podoplanin-Clec2 Signaling. Our MK studies utilize unique biosensors to establish a molecular signature of small GTPase activity (both Rho and Rap GTPases) during the final stages of development, including the transition from proliferation to proplatelet formation. Once established, we will establish proof-of-principle that precisely targeted perturbation of GTPase activity by optogenetic tools is a viable strategy to optimize in vitro platelet production, a hot topic in Transfusion Medicine. Our platelet work focuses more specifically on the role of Rap GTPases as master regulators of cellular activation and hemostatic plug formation. We have utilized unique mouse models to establish the importance and the key regulators of Rap1 signaling during platelet activation. Furthermore, we have shown that Rap1 activity has to be tightly balanced both in quiescent, circulating and in hemostatically active platelets, and that disturbance of this pathway leads to bleeding or thrombocytopenia/ thrombosis. In ongoing and future work, we will expand on our cell biological and biochemical/-physical studies to provide a comprehensive understanding of how Rap signaling controls platelet function, how it is regulated, and if/ how it contributes to other patho-physiological processes such as vascular integrity in development/ inflammation and venous thrombosis. We will use our unique biochemical assays to screen for inhibitors of Rap signaling. Our clinical studies will investigate if Rap1 signaling is altered in various pathologies, and whether there is interindividual variability in this pathway in healthy and diseased subjects? Together, these studies are expected to lead to novel strategies for the diagnosis and management of some inherited and acquired thrombocytopenias and bleeding disorders, and to a more personalized approach to anti-platelet therapy.

抽象的 哺乳动物血小板是小的无核细胞，专门用于连续监测和保留 心血管系统（止血）的完整性。它们是由骨头中的巨核细胞（MK）产生的 骨髓并释放成血液，在那里他们在人类中循环十天，在小鼠中五天直到他们 被吞噬细胞清除。血小板稳态，即建立定义的周围血小板计数， 需要严格调节血小板的产生和清除率。为了实现其止血功能，血小板 取决于非常敏感的信号传导机制，该机制促进剪切应力下的血小板粘附。这个高 然而，敏感性构成了不需要的血小板激活的风险，可能导致血小板间隙和/或 血栓形成。我们工作的总体目标是更好地了解分子 调节MK发育和血小板反应性的机制，特别关注小的作用 这些过程中的GTPases。此R35 OIA应用程序是三个资助的NHLBI R01赠款的扩展： 巨核细胞生物学中的小gtpase；血小板稳态和血管止血的RAP1信号传导； podoplanin-clec2信号传导对血小板激活的空间调节。我们的MK研究利用独特 生物传感器建立小GTPase活性（RHO和RAP GTPases）的分子特征 发展的最后阶段，包括从增殖到预言形成的过渡。一次 建立的，我们将建立原理证明，以确切针对GTPase活性的扰动 光遗传学工具是优化体外血小板生产的可行策略，这是输血中的热门话题 药品。我们的血小板工作更具体地关注RAP GTPases作为主要监管机构的作用 细胞激活和止血塞形成。我们利用独特的鼠标模型来建立 在血小板激活过程中RAP1信号传导的重要性和关键调节剂。此外，我们已经显示 Rap1活性在静止，循环和止血活性血小板中必须保持紧密平衡， 这种途径的干扰导致出血或血小板减少症/血栓形成。在持续和未来 工作，我们将扩展我们的细胞生物学和生化/物理研究，以提供全面的 了解说唱信号如何控制血小板功能，调节其如何调节以及它如何贡献 其他病情生理过程，例如发育/炎症中的血管完整性和静脉 血栓形成。我们将使用独特的生化测定法来筛选说唱信号的抑制剂。我们的临床 研究将调查RAP1信号是否在各种病理中发生改变，以及个人之间是否有个体 在健康和患病受试者中，这种途径的可变性？总之，这些研究将导致 诊断和管理某些遗传和获得的血小板减少症和管理的新型策略 出血性疾病，并采用更个性化的抗血小板治疗方法。