可溶性去唾液酸糖蛋白受体（s-ASGPR）清除糖蛋白配体的作用机制研究

去唾液酸糖蛋白受体（ASGPR）可特异性识别清除糖链末端为半乳糖或N-乙酰半乳糖胺残基的糖蛋白，对维持血液循环系统中糖蛋白稳态具有重要作用。前期研究显示血液中存在的可溶性ASGPR （s-ASGPR）可能迅速结合游离配体糖蛋白并将其输送至肝脏细胞进行代谢。本课题将以s-ASGPR为研究对象，通过体外受体-配体和细胞-配体结合测试、内吞实验、蛋白纯化和晶体结构解析等，研究s-ASGPR清除其配体糖蛋白的作用机制，包括：明确s-ASGPR与游离配体的结合作用；阐明其所输送配体进入肝细胞的转运机制和它随后的代谢途径；确定m-ASGPR在该转运过程中的作用；解析ASGPR异构体的三维结构，为明确各自的作用和特性提供基础。以上结果将确定s-ASGPR在血液循环系统中的配体结合作用和肝脏靶向输送性质，有助于进一步阐明ASGPR生物学作用和特性，并为基于ASGPR的肝脏靶向给药研究提供新的可能和思路。

The asialoglycoprotein receptor (ASGPR), which can specifically recognize and bind with asialoglycoproteins with terminal galactose- (Gal-) and N-acetylgalactosamine (N-GalNAc) residues, is very critical for maintaining homeostasis of glycoproteins in blood. Previous results showed that the soluble ASGPR (s-ASGPR) can quickly bind with the ligands and then transport them to the liver. In this project, the work mainly focuses on s-ASGPR and the ELISA, SPR, fluorescent microscope, ligand uptake assay, protein purification and structural analysis will be performed. This project will clarify the mechanism of s-ASGPR clearing asialoglycoproteins including: 1) To determine the binding of s-ASGPR with the ligand proteins; 2) To clarify the transport mechanism s-ASGPR/ligand into hepatic cells and the metabolism fate of s-ASGPR; 3) To study the role of m-ASGPR on the ligand transport by s-ASGPR; 4) To analyze the crystal structures of ASGPR variants to better understand their biological activity. It can be demonstrated that s-ASGPR can quickly bind with the ligands in blood and possesses the liver-targeting transport activity, which will be helpful to further clarify the biological role of ASGPR and provide novel strategy for the development of ASGPR-based liver targeting delivery systems.