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，目前影响超过500万人 美国人AD的特征在于记忆力下降、认知功能丧失和最终的认知功能降低。 脑组织这种疾病状态可能与淀粉样前体蛋白裂解成较小的蛋白质有关。 片段-淀粉样蛋白生成肽，称为淀粉样蛋白-β（Aβ）。事实上，淀粉样蛋白纤维的形成， Aβ的两种最常见的异型体，Aβ1-40和Aβ1-42，先前与疾病病理学相关; 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。 老年痴呆症的大脑关于Aβ如何增强毒性有许多理论，包括产生游离的 自由基、与金属离子的相互作用、细胞表面受体的活化和细胞膜的破坏 完整考虑到脂质- Aβ的能力，Aβ与细胞膜的相互作用尤其重要。 相互作用，以加速原纤维形成，促进离子通道样孔的形成，并导致细胞内的细胞分裂。 脂质膜的碎裂。在理解和描述错误折叠的形成的同时， 溶液中Aβ的中间体非常重要（并且正在进行），Aβ肽与 膜仍然是难以捉摸和有争议的。缺乏关于Aβ膜研究的数据， 由于在脂质存在下进行生物化学和生物物理学研究的困难， 尽管通过分子动力学模拟已经获得了许多见解， 用于实验研究。为了确定膜相关毒性的模式，仍然存在一个 需要进一步表征Aβ与脂质膜的相互作用，确定这些相互作用如何 驱动膜破裂，并限定在膜存在下形成的结构。所以我们 本文拟从以下几个方面来研究Aβ的膜相互作用：1）Aβ的表征 在脂质膜存在下的错误折叠和聚集; 2）原子分辨率结构测定 通过固态NMR光谱法测定膜环境中的Aβ。除了各种生物物理 实验，结合溶液和固态NMR技术和分子动力学模拟 将用于成功实现拟议研究的目标。高分辨率的见解， 这项研究将指导开发阻止神经元死亡的药物。虽然拟议 这项研究的重点是Aβ，其结果将对其他淀粉样蛋白相关疾病，如 帕金森病和II型糖尿病，它们具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.