The role of APOE locus genes regulation in Alzheimer's disease

描述(由申请人提供)： 阿尔茨海默病(AD)是导致老年人痴呆症的最常见原因。据估计，到2010年，将有510万65岁或以上的美国人患上阿尔茨海默病，而且随着老龄化人口预计在未来25年内翻一番，阿尔茨海默病患者的数量将继续大幅增加。退伍军人事务部(VA)医疗保健系统为大量老龄化人口提供服务，由于老龄化与AD风险增加相关，预计面临AD风险的老年退伍军人数量正在以惊人的速度增加；因此，非常需要治疗或预防AD的补救措施。到目前为止，唯一公认的迟发性阿尔茨海默病(LOAD)的易感因素是载脂蛋白E基因(APOE)。APOE e4等位基因与疾病密切相关，它以剂量依赖的方式影响负荷状态和发病年龄。然而，E4本身并不是造成负荷的必要条件或充分条件。因此，人们推测，其他遗传、表观遗传或环境因素也是合成载脂蛋白e4效应以发展负荷所必需的。一些证据，包括我们自己的工作，表明在载脂蛋白E基因座上存在多种影响负荷风险的遗传因素，而e4可能在载脂蛋白E基因的转录调控中具有生物学功能。拟议的研究将探索遗传和生物学证据，以证明APOE e4具有增强/沉默活性。这种活性可以改变APOE基因座上多个基因的表达谱，并且在功能上与负载风险相关。我们的短期目标是确定e4相关APOE基因调控在LOAD中的作用。我们的长期目标是准确定义APOE地区的负荷引发机制，从而改进负荷的预测、预防和干预策略。我们的假设是，apoE e4在转录调控中具有很强的作用，并且e4的负效应可能不仅与apoE蛋白结构和功能的改变有关，而且还与apoE基因表达的变化有关。拟议中的实验专门旨在验证这一假设。我们研究的具体目标将调查这一总体范式的组成部分。目的1研究载脂蛋白E e2/e3/e4等位基因在载脂蛋白E及其邻近基因转录调控中的作用。我们将使用荧光素酶报告基因的构建和分析来研究人类细胞系中的转录活性。目的2将构建APOE核心区染色体相分离的单倍型，确定LOAD风险较高或较低的单倍型，并确定与LOAD相关的关键遗传变异。这些单倍型将促进负载风险的单倍型-表型与目标1中确定的转录活性的单倍型关联。目标3将在细胞模型和AD/对照死后脑中验证APOE基因座对基因调控的单倍型效应。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is the most common cause of dementia among the elderly. It is estimated that 5.1 million Americans aged 65 or older will develop AD by the year 2010, and the number of people with AD will continue to increase significantly, as the aging population is expected to double over the next 25 years. The Veterans Affairs (VA) health care system serves a large aging population, and because aging is associated with an increased risk of AD, the projected number of aging Veterans at risk for AD is increasing at a dramatic pace; thus, there is a great need for remedies that treat or prevent AD. To date, the only well established susceptibility factor for late-onset Alzheimer's disease (LOAD) is the apolipoprotein E gene (APOE). APOE e4 allele, which is strongly associated with the disease, affects LOAD status and age-at-onset in a dose-dependent manner. However, e4 alone is not necessary or sufficient to cause LOAD. It has therefore been postulated that other genetic, epigenetic, or environmental factors are necessary to compound the APOE e4 effect to develop LOAD. Several lines of evidence, including our own work, suggests the presence of multiple LOAD risk- influencing genetic factors in the APOE locus, and e4 may have a biological function in transcriptional regulation of APOE-locus genes. The proposed studies will explore genetic and biological evidence to demonstrate that APOE e4 has enhancer/silencer activity. This activity can alter the expression profiles of multiple genes in the APOE locus and is functionally relevant for the risk of LOAD. Our short-term goal is to determine the role of e4-related APOE-locus gene regulation in LOAD. Our long-term goal is to precisely define LOAD-causative mechanisms in the APOE region, thereby yielding improved prediction, prevention, and intervention strategies for LOAD. Our hypothesis is that APOE e4 has a strong effect in transcriptional regulation, and that the adverse effects of the e4 in LOAD may be related not only to alterations in apoE protein structure and function but also to changes in the expression of APOE-locus genes. The proposed experiments are specifically aimed at testing this hypothesis. The specific aims of our study will investigate the components of this overall paradigm. Aim 1 will investigate the role of APOE e2/e3/ e4 alleles in the transcriptional regulation of APOE and its adjacent genes. We will use the luciferase reporter gene constructs and assays to study the transcriptional activities in human cell lines. Aim 2 will construct the chromosome-phase-separated haplotypes of the APOE core region, determine the higher- or the lower-risk haplotypes of LOAD, and identify critical LOAD-associated genetic variants. These haplotypes will facilitate haplotype-phenotype correlations of LOAD risk with the transcriptional activities identified in Aim 1. Aim 3 will validate haplotype effects of APOE locus on genes regulation in cellular models and in AD/control postmortem brain.