Biophysical study of lipid rafts and their role in amyloid fibril formation

淀粉样原纤维是由蛋白质组成的不溶性分子聚集体。尽管淀粉样蛋白形成蛋白的天然结构存在差异，但它们形成相似的淀粉样蛋白原纤维，而不管它们来源于何种蛋白质。斑块形成的分子机制（这是纤维的集合），以及引发这一过程的原因，目前尚不清楚。虽然纤维斑块的形成与体内生物膜有关，但大多数关于纤维形成的研究都是在溶液相中进行的，其中考虑的是“仅蛋白质”模型。脂筏存在于细胞膜上，是细胞组织的一个主要方面，是细胞与周围环境通讯的中心。因此，脂筏可能在淀粉样纤维的形成及其与细胞的相互作用机制中起重要作用。这项研究将探讨脂筏的性质和功能，并阐明其在淀粉样纤维形成的分子机制、能量学和动力学中的作用。由于它们的尺寸很小（纳米），解决这些问题是一项艰巨的任务，需要高度先进的显微技术。单肽分子之间的相互作用，导致淀粉样蛋白原纤维的形成和肽与脂质膜的相互作用将通过原子力显微镜，新型调频开尔文探针力显微镜和原子力光谱法进行研究。随着周围环境（包括脂质组成、胆固醇或抑制剂的存在）的改变，将研究原子尺度上的相互作用力。这些新方法将允许脂筏的性质与它们与原纤维形成蛋白和聚集体的相互作用有关。这项研究的结果将提供分子水平的洞察淀粉样蛋白原纤维形成的基本机制中存在的脂质模板，和小的中间有毒聚集体模型膜的行动。这些知识对于开发淀粉样蛋白原纤维形成的更复杂模型以及膜异质性在此过程中的作用至关重要，并将有助于促进淀粉样蛋白相关疾病治疗的发展。

Amyloid fibrils are insoluble molecular aggregates composed of proteins. Despite of the differences in native structures of amyloid forming proteins, they form similar amyloid fibrils irrespective of the protein from which they originate. The molecular mechanism of the formation of plaques (which are collections of fibrils), and the reason for initiation of this process, are currently unknown. Although fibril plaque formation is associated with biological membranes in vivo, most of research on fibrillogenesis has been performed in a solution phase, in which "only protein" model is considered. Lipid rafts, which are present in cell membrane, are a major aspect of cell organization and central to the communication of cells with their environs. Therefore lipid rafts may play an important role in the mechanism of amyloid fibril formation and the interaction of fibrils with the cell. The proposed research will investigate the nature and functions of lipid rafts and elucidating their role in the molecular mechanism, energetics, and kinetics of amyloid fibril formation. Because of their small (nanometer) size, solving these problems is a demanding undertaking requiring highly advanced microscopic techniques. The interaction between single peptide molecules that results in amyloid fibril formation and interaction of peptides with the lipid membrane will be investigated by atomic force microscopy, novel frequency modulation Kelvin probe force microscopy and atomic force spectroscopy. Forces of interaction at an atomic scale will be studied as the surrounding environment (including lipid composition, the presence of cholesterol or inhibitors) is modified. These new approaches will allow the nature of lipid rafts to be related to their interaction with fibril forming proteins and aggregates. The outcome of this study will provide molecular level insight into the fundamental mechanisms of amyloid fibril formation in the presence of lipid templates, and action of small intermediate toxic aggregates on model membranes. This knowledge is essential to develop a more sophisticated model for amyloid fibril formation and the role of membrane heterogeneity in this process and will help to facilitate the development of therapies for amyloid-related diseases.