Membrane interaction and disruption by the Alzheimer's amyloid-beta peptide

摘要 阿尔茨海默病(AD)是一种神经退行性疾病，目前影响着500多万人 美国人。AD的特征是记忆力下降，认知功能丧失，最终导致智力下降 脑部肿块。疾病状态可能与淀粉样前体蛋白裂解成更小的 片段-淀粉样多肽称为淀粉样蛋白-β(Aβ)。事实上，淀粉样蛋白纤维的形成 Aβ的两个最常见的同种异型，Aβ1-40和Aβ1-42，以前被认为与疾病病理有关； 然而，越来越多的证据表明，错误折叠的中间体是导致细胞死亡的原因。 阿尔茨海默病的大脑。关于β如何引起毒性，有许多理论，包括产生游离 自由基，与金属离子的相互作用，细胞表面受体的激活，以及细胞膜的破坏 正直。β与细胞膜的相互作用尤其显著，因为它具有脂类-Aβ的能力 相互作用加速纤维的形成，促进离子通道样孔的形成，并导致 脂膜碎裂。在理解和刻画错折的形成过程中 Aβ在溶液中的中间体是非常重要的(并且是持续的)，Aβ多肽与 膜一直难以捉摸，也一直备受争议。围绕β膜研究的数据缺乏在很大程度上是 由于在存在脂质的情况下进行生化和生物物理研究存在困难， 尽管分子动力学模拟已经获得了许多洞察力，这些模拟提供了强有力的基础 用于实验研究。为了确定膜相关毒性的模式，仍有一个 需要进一步表征Aβ与脂膜的相互作用，确定这些相互作用是如何 驱动膜破裂，并定义在膜存在时形成的结构。因此，我们 建议通过以下目的来研究β的膜相互作用：1)β的特性 脂膜存在下的错误折叠和聚集；2)原子拆分结构测定 用固体核磁共振波谱分析膜环境中的β。除了各种生物物理 实验，溶液和固体核磁共振技术和分子动力学模拟的结合 将用于成功实现拟议研究的目标。从以下方面获得高分辨率见解 拟议中的研究将指导药物的开发，以阻止神经元死亡。虽然建议的 研究的重点是Aβ，其结果将对其他淀粉样蛋白相关疾病具有重要意义，例如 帕金森氏症和II型糖尿病有相似的蛋白质病变。

Abstract Alzheimer's disease (AD) is a neurodegenerative condition that currently affects more than 5 million Americans. AD is characterized by decreasing memory, loss of cognitive function and an eventual reduction in brain mass. The disease state can be linked to the cleavage of the amyloid precursor protein into smaller fragments - amyloidogenic peptides known as amyloid-β (Aβ). In fact, the formation of amyloid fibrils of the two most common alloforms of Aβ, Aβ1-40 and Aβ1-42, had previously been associated with disease pathology; however, mounting evidence points to misfolded intermediates being responsible for cell death in the Alzheimer's brain. There are a number of theories as to how Aβ elicits toxicity including the generation of free radicals, interaction with metal ions, activation of cell surface receptors, and the disruption of cell membrane integrity. The interaction of Aβ with the cellular membrane is especially significant given the ability of lipid- Aβ interactions to accelerate fibril formation, facilitate the formation of ion channel-like pores, and cause the fragmentation of the lipid membrane. While understanding and characterizing the formation of misfolded intermediates of Aβ in solution is very important (and ongoing), the interaction of Aβ peptides with the membrane has remained elusive and controversial. A lack of data surrounding Aβ-membrane studies is largely due to the difficulties associated with carrying out biochemical and biophysical studies in the presence of lipids, although much insight has been gained by molecular dynamics simulations which have provided a strong basis for experimental studies. In order to determine the mode of membrane-associated toxicity, there remains a need to further characterize the interactions of Aβ with the lipid membrane, determine how these interactions drive membrane disruption, and define the structures formed in the presence of the membrane. Therefore, we propose to investigate the membrane interaction of Aβ through the following aims: 1) Characterization of Aβ misfolding and aggregation in the presence of lipid membranes; 2) Atomistic resolution structure determination of Aβ in a membrane environment by solid-state NMR spectroscopy. In addition to a variety of biophysical experiments, a combination of solution and solid-state NMR techniques and molecular dynamics simulations will be used to successfully accomplish the goals of the proposed study. High-resolution insights gained from the proposed studies will guide the development of drugs to stop the neuronal death. Although the proposed study is focused on Aβ, the outcome will be of importance to other amyloid-linked diseases such as Parkinson's disease and Type II diabetes which have similar proteinopathies.