Fibrin(ogen) Structure and Interactions

说明(申请人提供)：纤维蛋白原是一种多功能血浆蛋白，转化为纤维蛋白后，通过与不同蛋白质和细胞类型的相互作用，有助于止血和其他生理和病理过程。在这些过程中，炎症在心血管疾病的病理生理学中起着关键作用。白细胞从循环到炎症部位的募集是炎症反应中不可或缺的一部分，而白细胞的内皮迁移是这种募集的关键步骤。大量数据表明，纤维蛋白原参与了这一过程。根据提出的假设，纤维蛋白原或其降解产物通过分别与内皮细胞受体ICAM-1或VE-钙粘蛋白相互作用，将白细胞连接到内皮细胞，从而诱导白细胞迁移。我们最近发现，纤维蛋白N结构域与内皮细胞上的另一种受体--极低密度脂蛋白受体(VLDLR)相互作用，这种相互作用也促进白细胞迁移。基于这一发现和一些初步数据，我们假设纤维蛋白通过与VLDLR的相互作用促进白细胞的跨内皮细胞迁移，这种纤维蛋白诱导的VLDLR依赖的白细胞迁移可以被针对这种相互作用的特定抑制剂调节。本申请的主要目标是检验这一假设。这将通过以下具体目标来实现。第一个目的是通过研究纤维蛋白在这一过程中的作用，进一步证明纤维蛋白-VLDLR相互作用促进白细胞迁移。第二个目标是建立 通过重组技术绘制互补结合部位的图谱，并利用生化和生物物理方法表征它们之间的相互作用，从而揭示这种相互作用的分子机制。第三个目标是在已有知识的基础上开发这种相互作用的新型特异性抑制剂，并使用活体小鼠模型测试其抗炎特性和心脏保护作用。这项拟议的研究将阐明纤维蛋白依赖炎症的分子机制，并可能导致治疗炎症相关心血管疾病的新疗法，包括心肌缺血再灌注损伤。

DESCRIPTION (provided by applicant): Fibrinogen is a multifunctional plasma protein that after conversion into fibrin contributes to hemostasis and other physiological and pathological processes through its interaction with different proteins and cell types. Among these processes is inflammation, which plays a pivotal role in the pathophysiology of cardiovascular diseases. Recruitment of leukocytes from the circulation to sites of inflammation is an integral part of the inflammatory response and transendothelial migration of leukocytes is a key step in such recruitment. Numerous data indicate that fibrinogen is involved in this process. According to the proposed hypotheses, fibrinogen or its degradation products induce leukocyte transmigration by bridging leukocytes to the endothelium through the interaction with the endothelial receptors ICAM-1 or VE-cadherin, respectively. We have recently discovered that fibrin ¿N-domains interact with the VLDL receptor (VLDLR), another receptor on endothelial cells, and this interaction also promotes leukocyte transmigration. Based on this discovery and some preliminary data, we hypothesize that fibrin promotes transendothelial migration of leukocytes through its interaction with VLDLR and such fibrin-induced VLDLR-dependent leukocyte transmigration can be modulated by specific inhibitors targeting this interaction. The major goal of the present application is to test this hypothesis. This will be accomplished in the following specific aims. The first aim is to further prove that fibrin-VLDLR interaction promotes leukocyte transmigration by studying the effect of fibrin on this process. The second aim is to establish the molecular mechanism of this interaction by mapping the complementary binding sites using recombinant techniques and characterizing the interaction between them using biochemical and biophysical methods. The third aim is to develop novel specific inhibitors of this interaction based on knowledge obtained and test their anti-inflammatory properties and cardioprotective effect using in vivo mouse models. The proposed study will clarify the molecular mechanisms of fibrin-dependent inflammation and may result in novel therapeutics for treatment of inflammation-related cardiovascular diseases including myocardial ischemia-reperfusion injury.