血小板内皮聚集受体1调控血管稳态作用机制研究

Endothelial cells play critical roles in maintaining blood vessel homeostasis and regulating vascular injury repair process. Platelets, as one of direct effectors of endothelial damage have important roles in maintaining the integrity of vascular endothelium, involving in vascular physiologic injury repair, but enhancing chronic inflammation caused vascular injury. Platelet aggregation endothelial receptor 1 (PEAR1) is highly expressed in endothelial cells and platelets. The unknown platelet surface ligand binds to the PEAR1 extracellular EMI domain, and initiates platelet activation. Clinical studies have verified PEAR1 single nucleotide polymorphisms closely correlate with platelet aggregation and vascular function. Our preliminary data showed that platelet-mediated inhibition of endothelial cell tube formation is dependent on PEAR1 in vitro. Therefore, PEAR1 is supposed an important regulator of endothelial cell function and mediator of platelet and endothelial cell interaction. The project presented here will find the PEAR1 ligand and study the roles and mechanisms of PEAR1 involving in vascular function, platelet activation and release, using PEAR1 knockout mice, vascular injury and repair models, and biochemistry and cell biology techniques. The results derived from this project may provide a new approach to target on PEAR1 for treatment of cardiovascular diseases.

血管内皮细胞在维持血管健康稳态以及损伤修复中发挥至关重要作用。血小板作为血管内皮损伤直接效应细胞，在维持血管内皮完整、参与血管生理性损伤修复，加剧慢性炎症引起的血管内皮损伤等血管病理生理过程发挥重要作用。血小板内皮聚集受体1（PEAR1）高表达于内皮细胞和血小板，血小板表面未知配体能够结合PEAR1胞外EMI结构域并介导血小板活化信号。临床研究证实PEAR1单核苷酸多态性与血小板聚集能力以及血管功能有着密切的关系。我们前期体外研究发现血小板抑制内皮细胞成管能力是由PEAR1所介导的，因而我们认为PEAR1是调控内皮细胞功能和介导血小板与内皮细胞相互作用的重要受体。本项目将利用PEAR1基因敲除小鼠，多种血管损伤、修复模型，以及生化和细胞生物学技术，围绕寻找PEAR1配体，研究PEAR1在血管内皮功能和血小板活化、释放中的作用机制展开研究，为以PEAR1为靶的心血管疾病的治疗提供理论依据。

内皮细胞在维持血管稳态和调节血管损伤修复过程中发挥着关键作用。血小板作为内皮损伤的直接效应细胞之一，在维持血管内皮完整性和参与血管损伤修复都起到重要作用；但是血小板也具有增强血管慢性炎症损伤等病理作用。血小板内皮聚集受体1（pear1）在血小板和内皮细胞中高表达，其表达升高被认为与心血管疾病发生发展具有相关性。在本项目研究中，我们发现pear1在血管形成过程中可以从内皮细胞细胞核转移至细胞膜。pear1抗体能够活化pear1受体并能破坏人脐静脉内皮细胞成管能力。pear1激活能够显著降低β-catenin蛋白水平，从而破坏内皮细胞细胞连接。pear1缺失只是轻微影响血小板聚集和分泌，但可明显抑制LPS诱导的血管渗漏，因此，pear1是调节血小板与内皮细胞相互作用的重要受体。以pear1为靶是心血管疾病治疗的新手段。除此之外，我们还研究发现囊泡分拣蛋白33B（vps33b）是一种血小板α颗粒形成和血小板衍生血管调节活性因子包装与释放的关键调控分子，vps33b也在干细胞外泌体生成和分泌中起着至关重要的作用。我们还发现，血小板p38α是调节血小板活化关键应激激酶，抑制血小板p38α可以大大改善急性STEMI患者的临床预后。