REGULATION OF APOE METABOLISM BY APOE RECEPTORS AND AB IN NEURONS

关于apoE和apoE受体在神经元中的作用的许多关键问题中仍然没有答案的是apoE受体介导的apoE通过神经元的代谢是否是同种型特异性的。解决这个问题的唯一方法是产生CMS中发现的apoE-脂蛋白的形式，并检查它们与大脑中表达的每个apoE受体的相互作用。我们建议，apoE亚型和AB 42影响apoE受体介导的apoE神经元代谢。我们将在以下具体目标中阐述这一假设，阐明以下变量对apoE代谢几个关键组分的影响：（i）与apoE的其他常见来源相比，胶质apoE亚型的独特性质，（ii）神经元特异性apoE受体，以及（iii）寡聚体和纤维状Ap 42。 具体目标1：评价apoE来源、apoE亚型和A| 342关于apoE与脑的结合 apoE受体 具体目标2：检测apoE亚型、apoE受体和Ap 42对代谢和再循环的影响 apoE的表达。 具体目标3：确定apoE亚型、apoE受体和Ap 42对apoE神经元内运输、神经元内Ap蓄积和体外神经元活力的影响。 我们的具体假设是apoE来源、apoE亚型和Ap 42影响apoE与神经元表达的apoE受体的结合（Aim 1），apoE受体介导的apoE 4在神经元中的代谢（特别是再循环）与apoE 2或E3相比受损（Aim 2），apoE 4的改变的运输促进了Ap 42在神经元内的积累，损害了神经元的活力（Aim 3）。这些预测为我们的关键观察提供了潜在的细胞基础，即apoE 4和寡聚Ap 42共同作用以降低神经元活力，这种作用需要apoE受体。确定人apoE亚型和Ap 42对apoE受体介导的apoE神经元代谢、神经元内Ap蓄积和神经元活力的影响对于鉴定apoE亚型特异性功能至关重要， 影响与AD相关的神经元损失。这一建议也可能促进基于细胞的 筛选测定以鉴定基于调节这些途径的独特AD治疗剂。

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.