Defining the Role of TREM-Like Transcript-1 in Platelet Aggregation

描述(由申请人提供)：心血管疾病(CVD)仍然是我们死亡和发病的最大原因。虽然有几种原因，但血小板血栓的形成和纤溶在这些心血管疾病的各个方面的发生和发展中起着核心作用。因此，了解导致血小板激活调节崩溃的线索是很重要的。我的长期目标是识别和了解与正常血小板功能相关的关键分子成分，并随后开发急性冠脉综合征患者的治疗方法。我们发现了在小鼠和人类中发现的类似于转录-1或TLT-1的血小板表面受体，称为在髓系细胞中表达的触发受体(TREM)。TLT-1含量丰富，专用于血小板和巨核细胞，并在凝血酶或脂多糖刺激下从α颗粒上调至血小板表面。在血小板活化后，在血清中发现TLT-1的可溶性片段。这些结果表明，TLT-1在止血和/或血栓形成中起着独特的作用。使用针对TLT-1的单链抗体片段(ScFv)，我们能够阻断凝血酶介导的血小板聚集和延迟凝块回缩，提示TLT-1增强凝血酶介导的聚集，是一种促血栓形成分子。血小板的凝块回缩是通过CD41/CD61与其配体纤维蛋白(原)的相互作用来调节的。因此，凝块回缩的延迟可能与CD41/CD61或其配体纤维蛋白(原)相互作用。 这个项目将解决TLT-1作为CD41/CD61次要的聚集受体的假设，其功能是增强CD41/CD61的激活和随后的血小板聚集。因此，TLT-1在动脉粥样硬化斑块的形成和生长中起着早期作用。为了验证这一假设，我们提出了三个特定的目标，以解决TLT-1参与血小板激活的机制，并在体内检测TLT-1的功能。 目的1：研究TLT-1在血栓回缩中的作用。 目的2：鉴定与TLT-1胞浆结构域相互作用的蛋白质。 目的：阐明TLT-1的作用机制，探讨TLT-1在体内CVD发病机制中的作用。 我们对TLT-1及其在血栓形成和止血中的潜在作用的发现和初步表征使我们的实验室处于一个独特的位置来详细研究这种相互作用。

DESCRIPTION (provided by applicant): Cardiovascular disease (CVD) remains our largest cause of mortality and morbidity. Although there are several causes, platelet thrombus formation and fibrinolysis play a central role in the initiation and progression of various facets of these CVDs. Therefore, it is important to understand the cues that cause the breakdown of the regulation of platelet activation. It is my long-term goal to identify and understand the key molecular components involved in proper platelet function and subsequently to develop treatments for patients with acute coronary syndromes. We discovered the platelet surface receptor called "triggering receptor expressed in myeloid cells" (TREM) like transcript-1 or TLT-1 that is found in mice and humans. TLT-1 is abundant, specific to platelets and megakaryocytes, and up-regulated from the alpha-granules upon stimulation with thrombin or LPS to the platelet surface. After platelet activation, a TLT-1 soluble fragment is found in serum. These results suggest that TLT-1 plays a unique role in hemostasis and/or thrombosis. Using single chain antibody fragments (scFv) specific to TLT-1, we are able block thrombin-mediated platelet aggregation and delay clot retraction, suggesting that TLT-1 enhances thrombin-mediated aggregation and is a pro-thrombotic molecule. Clot retraction in platelets is mediated by the CD41/CD61 interaction with its ligand fibrin(ogen). Therefore, the delay in clot retraction implies a possible interaction with CD41/CD61 or its ligand, fibrin(ogen). This project will address the hypothesis that TLT-1 functions as an aggregation receptor secondary to CD41/CD61 whose function is to potentiate the activation of CD41/CD61 and subsequent platelet aggregation. Consequently, TLT-1 plays an early role in the formation and growth of an atherosclerotic plaque. To test this hypothesis, we propose three specific aims that address the mechanisms of TLT-1 involvement in platelet activation and examine TLT-1 function in vivo. Aim 1: To characterize TLT-1 involvement in clot retraction. Aim 2: Identify proteins that interact with the TLT-1 cytoplasmic domain. Aim 3: To elucidate the mechanisms of TLT-1 function and evaluate TLT-1 involvement in the advancement of CVD in an in vivo model. Our discovery and initial characterization of the TLT-1 and its potential role in thrombosis and hemostasis places our laboratory in a unique position to examine this interaction in detail.