基于短肽聚集结构的蛋白错折叠毒性机理的研究

蛋白质在细胞表面形成淀粉样沉积是一些退行性疾病的主要特征。大量的证据表明蛋白早期形成的寡聚体而不是成熟的淀粉样纤维是产生细胞毒性的主要种类，也是所有淀粉质疾病的致病元素。但是，由于蛋白寡聚中间体寿命很短，常规方法很难检测到，所以对蛋白的毒性寡聚体的结构和形貌及细胞毒性机理知之甚少。基于由实验证据支持的蛋白毒性寡聚体的形成机理与蛋白质序列无关的假设，本项目拟选取不同长度和性质的短肽制备不同结构和形态的寡聚体，用各种谱学、影像学和生物物理方法研究其结构和形貌、与不同组成脂质体（如含有胆固醇的脂质体）的相互作用及对磷脂膜和细胞膜的影响。研究中短肽的采用延长了寡聚体的稳定时间，使寡聚中间体的研究成为可能。期望通过本项目的研究能够找出对膜有破坏作用的肽寡聚体在聚集结构和形态上的主要特性，不同膜成分对肽寡聚体的形成和膜-肽相互作用的调节作用。本研究项目对揭示蛋白错折叠的细胞毒性机理具有重要的科学意义。

Amyloid diposit of proteins at membrane surface is a characteristic feature of degenerative diseases. Multiple lines of evidence indicate that the early formed oligomers rather than the matured amyloid fibrils are the main cytotoxic species and a common pathogenic element of amyloid diseases. However, the details of the oligomeric structure and morphology of the amyloid proteins and the mechanism underlying the cytotoxicity induced by the amyloid protein aggregation are poorly understood due to a short lifetime of the oligomeric intermediates and the difficulty in the measurement of the oligomers using a conventional method. On the basis of the hypothesis that the formation mechnism of the toxic protein oligomers is independent of the protein sequence, we will use a series of short peptides with different lengths and properties to prepare different structures and morphologies of oligomers, and study their structures and morphologies, the interactions with different compositions of liposomes and their effects on the membrane integration by using various spectroscopic, imaging and biophysical methods. The use of short peptides replacing for the longer sequence of proteins/polypeptides increases the stability of oligomers, making the study of oligomeric intermediates possible. We hope that we can gain insight into the common features of the membrane-disruptive oligomers in the structure and morphology, and the roles of some membrane components in regulating the formation of the oligomers and the peptide-membrane interactions through this research project. This project is significant for understanding the mechanism of the cytotoxicity induced by the protein misfolding.