The structural basis of apoE4's role in Alzheimer's Disease

描述(申请人提供)：载脂蛋白E(ApoE)是一种299个氨基酸(~34kD)的蛋白质，在脂质运输和代谢中起核心作用。与apoE3和apoE2不同，apoE4是阿尔茨海默病(AD)的公认危险因素。然而，这些异构体特异性效应的分子基础在很大程度上是未知的，最重要的是，还没有从结构和功能方面进行系统的探索。大部分注意力都集中在载脂蛋白E对大脑中A？肽加工的影响上。 明确的目标。 目的1：确定载脂蛋白E4中β结构的起始。 目的2：研究载脂蛋白E亚型与Aβ多肽的相互作用。 这些目标将阐明实现对apoE4如何参与AD和一般神经变性的机械性理解所需的最重要的细节。在我们(包括合作者)在功能系统方面的专业知识的指导下，我们拥有独特的经验和技术，通过应用最有可能揭示AD中apoE异构体效应的基础的结构生物学工具来解决这个问题。这些工具包括荧光光谱、电子显微镜、表面等离子体共振和FTIR光谱，尽管我们的主要方法将利用位置定向自旋标记的电子顺磁(EPR)光谱。 意义重大。由于EPR能够报告溶液中样品的局部结构和空间关系，这项工作可能转化为筛选药物候选的有效工具。可能的方法包括使用自旋标记的侧链来评估β-链阻断剂，这些阻断剂旨在针对已识别的结构域或带电的化学伴侣，稳定载脂蛋白E内的不稳定区域。由于apoE3也可能经历不稳定的构象，尽管频率要低得多，这种治疗也可能有助于减缓E3携带者的AD进展。

DESCRIPTION (provided by applicant): Apolipoprotein E (apoE) is a 299 amino acid (~34 kD) protein that plays a central role in lipid transport and metabolism. Unlike apoE3 and apoE2, apoE4 is an established risk factor for Alzheimer's disease (AD). However, the molecular basis of these isoform-specific effects is largely unknown and, most importantly, has not been explored systematically in terms of structure and function. Most attention has been focused on the influence of apoE on A¿ peptide processing in the brain. Specific Aims. Aim 1: Identify the initiation of beta structure in apoE4. Aim 2: Characterize the interaction of apoE isoforms with the A¿ peptide. These aims will illuminate the most important details needed for achieving a mechanistic understanding of how apoE4 participates in AD and neurodegeneration in general. Guided by our (including collaborators) expertise on the functional system, we have the experience and technology to uniquely contribute to this problem by applying the structural biology tools most likely to uncover the basis for the apoE isoform effect in AD. These tools include fluorescence spectroscopy, electron microscopy, surface plasmon resonance, and FTIR spectroscopy, though our primary method will utilize electron paramagnetic (EPR) spectroscopy of site-directed spin labels. Significance. Because of the ability of EPR to report on local structure and spatial relationships from the sample in solution, this work may translate into an effective tool for drug candidate screening. Possibilities include use of spin-labeled side chains to evaluate beta-strand blockers designed to target an identified domain or charged chemical chaperones that stabilize a labile region within apoE. Since apoE3 may also experience destabilized conformations, though at a much lower frequency, such treatments may be helpful in slowing the progression of AD in E3 carriers as well.