Insight into pathological self assembly using alpha-helical mimetics

描述（由申请人提供）：本提案的主要目标是设计小分子化合物，其靶向新鉴定的与II型糖尿病中胰岛素分泌2细胞活力直接相关的蛋白质结构。胰岛淀粉样多肽（IAPP）是一种由37个氨基酸残基组成的肽类激素，由内分泌胰腺的2-细胞与胰岛素共同分泌。IAPP属于一类易于聚集的蛋白质，其包括来自阿尔茨海默病的A2，其中野生型蛋白质前体不可逆地形成/折叠成2片层丰富的纤维状淀粉样蛋白斑块。2型糖尿病2细胞死亡的起源知之甚少。与大多数淀粉样疾病一样，与病理学相关的是淀粉样蛋白沉积的存在，而不是程度。相反，组装反应的中间产物与细胞死亡有关。重要的是，这种细胞毒性是由膜结合蛋白结构的形成介导的。在IAPP的情况下，这是非常有趣的，因为尽管成熟淀粉样蛋白的2-片层性质，膜结合状态是1-螺旋。该提议所追求的总体假设是，淀粉样蛋白生成前状态的基于小分子结构的靶向将能够阐明IAPP诱导的细胞毒性的机制。这些努力将在分子水平上提供IAPP寡聚化的新描述，并为创造改善2-细胞死亡的先导化合物提供合理的设计途径。我们同时追求的目标包括在合成化学，细胞和结构生物学方面的协同努力。重要的是，我们将通过合成旨在模拟1-螺旋的一个边缘的表面呈现的小分子来靶向IAPP的1-螺旋中间体。将开发细胞方法来评估IAPP的毒性和定位。衍射，核磁共振和计算方法将用于阐明原子分辨率的替代低聚状态，并为小分子合成提供基于结构的指导。

DESCRIPTION (provided by applicant): The primary goal of this proposal is the design of small molecule compounds which target newly identified protein structures with direct relevance to insulin secreting 2-cell viability in type II diabetes. Islet amyloid polypeptide (IAPP) is a 37-residue peptide hormone, which is co-secreted with insulin by the 2-cells of the endocrine pancreas. IAPP belongs to a class of aggregation prone proteins, which includes A2 from Alzheimer's, in which a wild-type protein precursor irreversibly forms/folds into 2-sheet rich fibrillar amyloid plaques. The origin of 2-cell death in type II diabetes is poorly understood. Like most amyloid diseases, it is the presence, rather than the extent, of amyloid deposition that is correlated with pathology. Instead, it is the intermediates of the assembly reaction that have been implicated in cell death. Importantly, this cytotoxicity is mediated by the formation of membrane bound protein structures. In the case of IAPP, this is highly intriguing since, despite the 2-sheet nature of mature amyloid, membrane bound states are 1-helical. The overall hypothesis pursued by this proposal is that small-molecule, structure based targeting of pre-amyloidogenic states will enable elucidation of the mechanism of IAPP induced cytotoxicity. These efforts will provide novel descriptions of IAPP oligomerization at a molecular level, and provide a rational design path for the creation of lead compounds that ameliorate 2-cell death. Our concurrently pursued aims include synergistic efforts in synthetic chemistry, cell and structural biology. Importantly, we will target the 1-helical intermediates of IAPP by synthesizing small molecules designed to mimic the surface presentation of one edge of an 1-helix. Cellular methods will be developed to assess toxicity and localization of IAPP. Diffraction, NMR and computational methods will be employed to elucidate the alternative oligomeric states at atomic resolution and to provide structure based guidance for small molecule synthesis.