自噬受体蛋白NDP52、TAX1BP1和Optineurin的结构和功能研究

Autophagy is a tightly regulated lysosome-dependent intracellular catabolic process involving degradation of protein aggregates, dysfunctional organelles and invading pathogens to adapt to multiple cellular stresses and to maintain cellular homeostasis. Autophagy receptors are adaptor proteins, which play essential roles in selective autophagy processes by sequestering the degrading cargoes and subsequently linking them to the autophagic machinery. A large number of human diseases including inflammation and neurodegenerative diseases are associated with the dysfunction or deficiency of autophagy receptors. The recent explosion of interest in autophagy has prompted tremendous progresses in the study of autophagy receptors. However, the detailed underlying molecular principles governing the functions of autophagy receptors and the pathogenic mechanisms of numerous disease-associated gene mutations of autophagy receptors are still largely unclear. In this research proposal, we focus on three important autophagy receptors, NDP52, TAX1BP1 and Optineurin. By using multidisciplinary approaches including structure biology, biochemistry and cell biology methods, we want to systemically characterize the structures and functions of these three autophagy receptors, thereby to elucidate some unknown molecular mechanisms related to these autophagy receptors as well as to provide mechanistic insights into disease-associated mutations of these autophagy receptors. Meanwhile, we also want to modify and improve autophagy receptors or develop potential bioactive small molecules to mimic some functions of autophagy receptors for future autophagy research and for the medical treatment of relevant human diseases.

细胞自噬是细胞体内一种高度受调控的，利用溶酶体来清除蛋白聚集体、受损细胞器、入侵病原体等成分以应对内外界细胞压力和维持自身动态平衡的重要分解代谢过程。自噬受体蛋白是一类在选择性自噬过程中发挥着举足轻重作用的衔接蛋白，它可以作为一个桥联蛋白把底物与自噬体联系起来，从而介导目标底物的选择性自噬过程。众多人类疾病，如炎症、神经退行性疾病，均与自噬受体蛋白的功能异常相关。近年来针对自噬受体蛋白的研究取得了长足的进展，但是许多重要的深层次作用机制以及基因变异所引起疾病的致病机理一直没有得到很好地阐述。本申请课题针对NDP52、TAX1BP1和Optineurin三个自噬受体蛋白，采用结构生物学、细胞生物学等方法来系统性地研究和阐明这三个自噬受体蛋白的结构与功能的关系，从而来揭示相关未知的分子机制和致病机理。同时也将尝试通过改造自噬受体蛋白或开发自噬受体模拟分子用于自噬相关领域的研究和潜在的疾病治疗。

选择性细胞自噬在调节哺乳动物细胞内稳态和众多的生理过程中发挥着举足轻重的作用。NDP52、TAX1BP1和Optineurin是哺乳动物细胞内三个重要的、可结合泛素的自噬受体蛋白，在选择性自噬降解入侵病原体和受损线粒体过程中扮演着重要的角色。同时，自噬受体蛋白Optineurin的基因变异与青光眼和渐冻人症等神经退行性疾病相关联。本项目综合采用结构生物学（X射线晶体学和核磁共振）、生物化学、细胞生物学等方法系统地研究了自噬受体蛋白NDP52、TAX1BP1和Optineurin的结构与功能之间的关系以及相关基因突变引起人类疾病的致病机制。项目执行期间，取得了良好的研究成果，共解析了10个新颖蛋白及其复合物的结构，发表标注受项目资助的高水平学术论文6篇，其中包括1篇Nature Communications、3篇Autophagy、1篇PNAS、1篇Journal of Molecular Biology。项目取得的研究结果不仅从结构角度首次阐明了NDP52、TAX1BP1、Optineurin识别泛素蛋白，Optineurin结合TBK1，NAP1结合TBK1，NDP52和TAX1BP1通过其SKICH结构域结合NAP1蛋白，Myosin6结合Tom1的分子机制，而且从原子水平揭示了4个Optineurin和TBK1的基因突变导致神经退行性疾病的潜在致病机理，并为将来评估相关疾病的基因诊断和治疗相关疾病提供了重要的科学基础。