血小板内皮细胞黏附分子-1的结构研究

Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a cell surface receptor. It is a commonly used endothelial cell marker and widely applied to the imaging of the lining of blood vessels. PECAM-1's function is not restricted to its adhesive properties, but also intimately involved in mediating signal transduction. PECAM-1 involves in many important physiological processes, such as maintaining the integrity of the lining of blood vessels, especially, playing an important role in immune cell escaping from blood vessels. The homotypic interaction is the important basis of maintaining the integrity of the blood vessels, and is regulated by interaction with different heterotypic ligands. However, these functional regulation have not fully understood yet. In addition, structural details for PECAM-1 extracellular domain and its complex with ligands remain unknown. In this project, we plan to utilize X-ray crystallography, in combination with other biochemical or biophysics assays, to study the structure of PECAM-1 and its complex with ligands. The study will provide detailed structural information for the understanding of molecular mechanism about homotypic and heterotypic interactions and will provide critical molecular insights into PECAM-1 functions.

本项青年科学基金申请项目的研究目标为血小板内皮细胞黏附分子-1（PECAM-1），该分子是血管内皮细胞的标志物，并广泛应用于血管内壁的成像，它是一种具有细胞粘附及信号传导功能的细胞表面受体，维持了血管内壁的完整性，特别是在免疫细胞血管外逃逸过程中起重要作用。PECAM-1同源二聚化是其维持血管完整性的重要基础，二聚化受到不同配体的调控，对PECAM-1生理功能的发挥具有重要意义。但关于PECAM-1的许多作用机制尚不甚明确，而且迄今为止，尚无PECAM-1胞外结构域或其与配体结合的结构信息。本项目拟采用X-射线晶体衍射技术为主要研究手段，结合其他生物化学和生物物理方法开展PECAM-1胞外结构域以及其与配体复合物的结构研究，通过结构信息解释PECAM-1同源二聚化以及其与配体结合的分子机制，从分子水平上阐明PECAM-1发挥作用的机理。

血小板内皮细胞黏附分子-1（Platelet–endothelial-celladhesionmolecule 1，PECAM-1）又名endoCAM或CD31，是一种具有细胞粘附及信号传导功能的细胞表面受体，它是一种具有细胞粘附及信号传导功能的细胞表面受体，维持了血管内壁的完整性，特别是在免疫细胞血管外逃逸过程中起重要作用。PECAM-1同源二聚化是其维持血管完整性的重要基础，二聚化受到不同配体的调控，对PECAM-1生理功能的发挥具有重要意义。但关于PECAM-1的许多作用机制尚不甚明确，而且迄今为止，尚无PECAM-1胞外结构域或其与配体结合的结构信息。在本项目中，我们采用S2系统表达纯化了PECAM-1胞外结构域蛋白（sPECAM-1）以及sPECAM-1 D1-D2和sPECAM-1 D1-D3片段蛋白，并筛选得到了sPECAM-1的结晶。使用小角度X射线散射技术（SAXS）解析了PECAM-1在溶液中的结构，此结构显示D1结构域在PECAM-1二聚化方面发挥着关键的作用。并基于此项目，我们完善了果蝇S2 胚胎细胞表达体系，成功获得了Endo180等蛋白的晶体及其晶体结构。