REGULATION OF APOE METABOLISM BY APOE RECEPTORS AND AB IN NEURONS

在关于载脂蛋白E和载脂蛋白E受体在神经元中的作用的许多关键问题中，载脂蛋白E受体介导的神经元对载脂蛋白E的代谢是否具有异构体特异性。解决这个问题的唯一方法是产生在CMS中发现的不同形式的载脂蛋白，并检查它们与大脑中表达的每个载脂蛋白受体的相互作用。我们认为apoE亚型和AB42影响apoE受体介导的神经元对apoE的代谢。我们将在以下特定目标中阐述这一假说，阐明以下变量对载脂蛋白E代谢的几个关键成分的影响：(I)与其他常见来源的载脂蛋白E相比，胶质细胞载脂蛋白E亚型的独特性质；(Ii)神经元特异性载脂蛋白E受体；以及(Iii)寡聚和纤维状载脂蛋白42。 具体目标1：评估载脂蛋白E来源、载脂蛋白E亚型和A|342对载脂蛋白E与脑结合的影响 载脂蛋白E受体。 特异性目标2：研究载脂蛋白E亚型、载脂蛋白E受体和载脂蛋白42对代谢和循环的影响 体外培养的神经元对载脂蛋白E的影响。 目的3：研究apoE异构体、apoE受体和Ap42在体外对apoE的神经元内转运、神经元内AP积聚和神经元活力的影响。 我们的具体假设是apoE来源、apoE异构体和Ap42影响apoE与神经元表达的apoE受体的结合(目标1)，apoE受体介导的神经元中apoE4的代谢，特别是循环，与APOE2或E3相比受损(目标2)，以及apoE4的改变运输促进神经元内Ap42的积累，损害神经元的活力(目标3)。这些预测为我们的关键观察提供了潜在的细胞基础，即apoE4和寡聚体Ap42共同作用降低神经元活性，这一效果需要apoE受体。明确人载脂蛋白E亚型和载脂蛋白42对载脂蛋白E受体介导的神经元载脂蛋白E代谢、神经元内AP积累和神经元存活率的影响对于鉴定载脂蛋白E亚型的特定功能是至关重要的，最终 影响阿尔茨海默病相关的神经元丢失。这一建议还可以促进基于细胞的 基于对这些通路的调控，筛选出一种独特的AD治疗方法。

Among a number of critical questions that remain unanswered about the role of apoE and apoE receptors in neurons is whether the apoE receptor-mediated metabolism of apoE by neurons is isoform-specific. The only way to address this question is to generate the forms of apoE-lipoproteins found in the CMS and examine their interactions with each apoE receptor expressed in the brain. We propose that apoE isoforms and AB42 affect the apoE receptor-mediated metabolism of apoE by neurons. We will address this hypothesis in the following Specific Aims, elucidating the effects of the following variables on several key components of apoE metabolism: (i) the unique properties of glial-apoE isoforms, as compared to other common sources of apoE, (ii) neuron-specific apoE receptors, and (iii) oligomeric and fibrillar Ap42. Specific Aim 1: Evaluate the effects of apoE source, apoE isoform and A|342 on the binding of apoE to brain apoE receptors. Specific Aim 2: Examine the effects of apoE isoform, apoE receptor and Ap42 on metabolism and recycling of apoE by neurons in vitro. Specific Aim 3: Determine the effects of apoE isoform, apoE receptor, and Ap42 on intraneuronal trafficking of apoE, intraneuronal Ap accumulation and neuronal viability in vitro. Our specific hypotheses are that apoE source, apoE isoform and Ap42 influence apoE binding to apoE receptors expressed by neurons (Aim 1), that apoE receptor-mediated metabolism, specifically recycling, of apoE4 in neurons is impaired compared to apoE2 or E3 (Aim 2), and that altered trafficking of apoE4 facilitates intraneuronal Ap42 accumulation, compromising neuronal viability (Aim 3). These predictions provide a potential cellular basis for our key observation that apoE4 and oligomeric Ap42 act together to reduce neuronal viability, an effect that requires apoE receptors. Defining the effects of human apoE isoforms and Ap42 on apoE receptor-mediated metabolism of apoE by neurons, intraneuronal Ap accumulation and neuronal viability is essential to identifying apoE isoform-specific functions that ultimately effect the neuronal loss associated with AD. This proposal may also facilitate the development of a cellbased screening assay to identify a unique AD therapeutic based on modulating these pathways.