Regulation of Presenilin Genes

描述（由申请人提供）：本项目的目的是验证早老素（PS）和PS相互作用蛋白基因的失调与阿尔茨海默病（AD）病理有关的假设。两个同源早老素基因PS1和PS2的错义突变是家族性早发性阿尔茨海默病（AD）的主要原因。这些基因在最常见的晚发性阿尔茨海默病中的作用仍有待阐明。ps参与了几种蛋白质的蛋白水解裂解，例如。淀粉样前体蛋白（APP）被认为是导致AD的分子级联机制的关键因素。ad相关的突变增强了这种裂解，而PS1和PS2活性的消除抑制了APP底物的内蛋白水解。因此，可以想象，PSs表达的改变会调节AD的病理。我们的初步数据表明，缺氧是调控PS和PS相互作用蛋白基因的重要因素。这些数据有力地表明，PS2在缺氧/高氧条件下是高度诱导的，并且PS2中调控DNA元件（IRF2/CREBB）的改变增加了启动子区域对AD相关应激调节因子的易感性。我们还发现了一个新的早老素同源蛋白家族和缺乏功能域的高调控早老素亚型。我们假设PSs的活性受1)转录因子调节，包括自然发生的DNA变异和应激调节的DNA元件；2)转录后因子，包括ps样蛋白异构体，被认为具有显性的负面影响。本研究的目的是阐明在转录和翻译后水平上调控早老素的分子因子。我们将1)确定导致AD的新分子遗传因素（基因单倍型）；2)分离出动态调控PSs的新型转录和剪接增强/抑制元件；3)阐明新鉴定的PS同源蛋白在PS蛋白加工或表达调控中的作用。我们提出了一种趋同的方法，通过这种方法，对AD患者的遗传分析将伴随着体外基因变异的系统发育和功能分析。为了实现这些目标，将进行遗传关联分析方法、启动子活性定量评估的分子分析、哺乳动物细胞中的蛋白质加工、外显子捕获和ps介导的蛋白质水解的细胞分析。这些目标的实现将阐明阿尔茨海默病的分子遗传和表观遗传机制。这些研究将有助于确定调节阿尔茨海默病主要原因的分子因子，并最终为阿尔茨海默病的预防和合理治疗制定新的策略。

DESCRIPTION (provided by applicant): The objective of this project is to test the hypothesis that deregulation of genes for presenilins (PSs) and PS- interacting proteins contributes to Alzheimer's disease (AD) pathology. Missense-mutations in two homologous presenilin genes, PS1 and PS2, are the major cause of familial early onset Alzheimer's disease (AD). The role of these genes in the most common, the late-onsetAD, remains to be elucidated. PSs are involved in the proteolytic cleavage of several proteins, eg., amyloid precursor protein (APP), that is thought to be critical factor in molecular cascade mechanisms leading to AD. AD-associated mutations enhance this cleavage, while the abolishment of PS1 and PS2 activity inhibits the endoproteolysis of APP substrate. It is conceivable, then, that alteration of expression of PSs modulate AD pathology. Our preliminary data suggest hypoxia is an important factor in regulation of genes for PSs and PS- interacting proteins. The data strongly suggest that PS2 is highly inducible by hypoxia/hyperoxia conditions and that alteration of regulatory DNA elements (IRF2/CREBB) in PS2 increases the susceptibility of the promoter region to stress-regulated factors associated with AD. We also identified a novel family of presenilin-homologous proteins and highly regulated presenilin isoforms lacking functional domains. We hypothesize that activity of PSs is modulated by 1) transcriptional factors, including naturally-occurring DNA variations and stress-regulated DNA elements; and 2) post-transcriptional factors, including PS-like protein isoforms with putative dominant negative effects. The goal of this proposal is to elucidate molecular factors that regulate presenilins on transcriptional and posttranslational levels. We will 1) identify novel-molecular-genetic factors (gene haplotypes) contributing to AD; 2) isolate novel transcription and splicing enhancer/repressor elements that dynamically regulate PSs; 3) elucidate the role of newly identified PS-homologous proteins in modulation of processing or expression of PS proteins. We present a convergent approach with which the genetic analysis of AD patients will be accompanied by phylogenic and functional analysis of the gene variations in vitro. To achieve these goals, methods of genetic association analysis, molecular assays for quantitative evaluation of promoter activities, and protein processing in mammalian cells, cellular assays for exon trapping and PS-mediated proteolysis will be undertaken. The accomplishment of these goals will clarify molecular-genetic and epigenetic mechanisms of AD. These studies will contribute to identification of molecular factors regulating the primary causes of AD, and ultimately, to the development of new strategies for prevention and rational therapy of Alzheimer's disease.