尿酸盐转运体URAT1的N-糖基化修饰在高尿酸血症中的作用及机制研究

尿酸盐转运体URAT1是治疗高尿酸血症的重要药物靶点。研究表明，高尿酸血症患者肾脏URAT1的细胞膜表达量升高，尿酸排泄分数减少，进一步加重高尿酸血症的病情，而对此现象的机制研究尚不完善。申请人的前期研究发现URAT1是具有三个潜在N-糖基化位点的糖蛋白，而糖基化修饰对膜蛋白在细胞膜上的表达具有重要调节作用。因此，本课题拟通过定点突变分析确认URAT1的糖基化位点，以蛋白的膜表达量、溶酶体降解情况以及细胞尿酸转运功能为主要指标，研究URAT1的糖基化修饰在高尿酸血症中对URAT1蛋白的调节作用。通过建立高尿酸血症的小鼠模型、细胞模型，采用凝集素pull-down等技术找到对URAT1具有关键调节作用的糖基组成。本课题研究将完善高尿酸血症中URAT1的调节机制，为高尿酸血症的治疗提供十分有价值的理论基础，并首次以糖基化修饰的角度给以URAT1蛋白靶向治疗高尿酸血症的药物设计提供新思路。

Urate transporter URAT1 is a key target in hyperuricemia treatment. It was reported that in hyperuricemia kidneys, URAT1 membrane expression was increased and uric acid excretion fraction was decreased, resulting in even severer hyperuricemia. Yet the mechanism of this phenomenon is still not clear. In our previous studies, we found that URAT1 has three potential N-glycosylation sites, and N-glycosylation plays very important role in regulating membrane expression of membrane proteins. Therefore, in this study, we will first analyze and confirm the glycosylation sites of URAT1 through site-directed mutagenesis. Then we will investigate the effect of N-glycosylation modification on URAT1 regulation in hyperuricemia, by assessing URAT1 membrane expression, lysosome degradation and oocytes uric acid transport. Finally, by establishing hyperuricemia model in mice and cells, using lectin pull-down assay etc., we intend to find a key glycan, which is most responsible for URAT1 regulation in hyperuricemia. This study will refine the mechanism of URAT1 regulation in hyperuricemia, provide valuable theoretical basis for hyperuricemia treatment, and for the first time, provide a new strategy for anti-hyperuricemia drug design targeting URAT1 in a glycosylation modification point of view.