Elucidating the mechanism of amyloid-beta's pathological aggregation

描述（由申请人提供）：阿尔茨海默病（AD）是最常见的神经退行性疾病，是一种导致认知功能进行性丧失的年龄依赖性疾病。在美国，它影响着400多万人，因此是影响老年人生活质量的一个高度相关的因素。该疾病的症状与AD患者大脑中瞬时形成的可溶性淀粉样蛋白（Aβ）聚集体的存在密切相关。由于阿尔茨海默病与公共卫生的相关性，人们对了解阿尔茨海默病的分子机制和治疗该病有很大的兴趣。然而，在其病理聚集过程中形成的a β可溶性中间体的短暂性对用于研究生物分子的传统技术提出了巨大的挑战。尽管在研究这些分子方面取得了进展，例如通过轻微的化学修饰来增加其稳定性，但尚不清楚这些研究中观察到的分子行为是否与Aβ在人体内的行为完全相关。在Frydman实验室，技术已经发展到可以快速表征与其行为（结构和动力学）相关的生物分子的特征。我们建议使用这些技术，一套超快核磁共振实验，研究a β的结构和动力学，因为它经历了聚集。超快TOCSY和STD-TOCSY实验将用于探测Aβ单体和低聚物在聚集过程中的相互作用。系统的扩散动力学将通过超快DOSY实验来探测，该实验根据与它们所属的化学位点相关的流体动力学半径分离共振。进一步的功能研究也将从位点解析的纵向弛豫测量中获得，它揭示了分子片段的迁移性，从而揭示了它们的聚合程度。这项研究旨在揭示a β折叠单体状态的详细结构信息，这被认为在a β聚集的细胞核形成中起着至关重要的作用。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD), the most common neurodegenerative disorder, is an age-dependent disorder resulting in progressive loss of cognitive function. It affects more than 4 million people in the United States and is therefore a highly relevant factor in the elderly's quality of life. The symptoms of the disease strongly correlate with the presence of transiently formed and soluble aggregates of amyloid-beta (Aβ) in the brains of AD patients. Because of the relevance Alzheimer's to public health, there is substantial interest in understanding the molecular mechanism of AD and treating the disease. Nevertheless, the short-lived nature of the Aβ soluble intermediates formed during the course of its pathological aggregation presents a formidable challenge to the traditional techniques used for the investigation of biological molecules. Although progress has been made in studying these molecules, by making slight chemical modifications that increase their stability, for example, it is not known whether the molecular behavior observed in these studies is completely relevant to the behavior of Aβ in humans. In the Frydman lab techniques have been developed that allow the fast characterization of features of biological molecules relevant to thei behavior (structure and dynamics). We propose to use these techniques, a suite of ultrafast NMR experiments, to investigate the structure and dynamics of Aβ as it undergoes aggregation. Ultrafast TOCSY and STD-TOCSY experiments will be used to probe the interaction between Aβ monomers and oligomers during the aggregation process. The diffusive dynamics of the system will be probed by ultrafast DOSY experiments, which separates resonances according to the hydrodynamic radii associated with the chemical sites to which they belong. Further functional insights will also be gained from site-resolved longitudinal relaxation measurements, which reveal the mobility of molecular fragments-and hence their degree of polymerization. This proposal aims to uncover detailed structural information about Aβ's folded monomeric state, which is believed to play a crucial role in the formation of a nucleus for Aβ's aggregation. In aqueous solution, folded conformers of Aβ undergo conformational exchange with its random coil state. Using the innovative selective dynamic recoupling (SDR) technique that I have developed, the chemical shifts of folded Aβ conformers will be revealed, which can be used to probe their structures. The in vivo behavior of Aβ in a cellular environment is believed to play a significant role in its pathology. I plan to uncover detailed information on the intracellular behavior of Aβ by performing NMR experiments in living Xenopus laevis oocytes.