The Role of Cholesterol in Alzheimer's Disease

胆固醇在阿尔茨海默病中的作用

• 批准号: 6988322
• 负责人: ALISON M GOATE
• 金额: $ 4.03万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6988322
• 关键词: Alzheimer' s disease; Bosnia-Hercegovina; CHO cells; amyloid proteins; apolipoprotein E; aspartic endopeptidases; biotechnology; cholesterol; chromosome aberrations; endocytosis; enzyme activity; family genetics; genetic screening; genetic susceptibility; genotype; homeostasis; immunoprecipitation; intracellular transport; linkage disequilibriums; molecular pathology; pathologic process; presenilin; protein metabolism; quantitative trait loci; single nucleotide polymorphism; western blottings

DESCRIPTION (provided by applicant): There is growing interest in the potential contribution of cholesterol to the pathogenesis of Alzheimer's disease (AD). Treatment with cholesterol-lowering statins appears to lower the risk of developing AD. Furthermore, Abeta production has been directly associated with cholesterol-rich domains (lipid rafts) and cholesterol levels have been shown to modulate APR processing and Abeta generation. The link between cholesterol and Abeta has recently been revealed in Niemann Pick Type C (NPC) diseases as well as AD. Deficiency in NPC1 protein causes intracellular accumulation of unesterified cholesterol in late endosomal/lysosomal compartments that is accompanied by a significant increase in Abeta production and a shift in presenilin 1 (PS1) localization to early/late endosomes. Contradictory results were reported on whether changes in cholesterol content may directly affect gamma-secretase cleavage of APP. The goal of this project is to elucidate the mechanisms by which cholesterol affects APP metabolism. We hypothesize that cholesterol modulates APP processing in a similar manner in wild-type and NPC1 knock-out cells. We also hypothesize that cholesterol levels regulate intracellular trafficking of APP, BACE1 and PS1, three key players in the pathogenesis of Alzheimer's disease. We speculate that cholesterol-dependent association with lipid rafts of the three proteins regulates their endocytosis and thus generation of Abeta. In addition, we hypothesize that levels of cholesterol and/or apolipoprotein E (apoE) modulate APP processing directly regulating gamma-secretase activity. To analyze the parallels between cholesterol and APP processing in wild-type and NPC1-/- cells we will test whether an increase or a decrease in cholesterol levels modulates APP metabolism in a similar manner. Comparing cellular localization and association with lipid rafts of APP, BACE1 and PS1 in wt and in NPC1 Knock out cells under sterol-starved and sterol-fed conditions we will elucidate whether the cholesterol-effect on aberrant APP processing is mediated via specific subcellular or lipid raft compartment(s). To test whether gamma-secretase activity per se can be regulated by cholesterol and/or apoE levels we will perform in vitro gamma-assay. If gamma-secretase activity is regulated by cholesterol levels and/or apoE we will test whether this feature is specific for gamma-cleavage of APP or is common among other gamma-secretase substrates (e.g. Notch 1). This research will be done primarily in Croatia at the Rudjer Boskovic Institute in collaboration with Dr. Silva Hecimovic as an extension of NIH grant #R01AG016208. Through these studies we will elucidate the molecular mechanisms of cholesterol action in Alzheimer's disease. Finding the molecular link(s) between cholesterol and AD is important both for treating Alzheimer's disease as well as for understanding normal APP function.

描述（由申请人提供）：人们对胆固醇对阿尔茨海默病（AD）发病机制的潜在贡献越来越感兴趣。使用降低胆固醇的他汀类药物治疗似乎可以降低患 AD 的风险。此外，Abeta 的产生与富含胆固醇的结构域（脂筏）直接相关，并且胆固醇水平已被证明可以调节 APR 加工和 Abeta 的产生。最近在尼曼匹克 C 型 (NPC) 疾病以及 AD 中揭示了胆固醇和 Abeta 之间的联系。 NPC1 蛋白的缺乏会导致细胞内未酯化胆固醇在晚期内体/溶酶体区室中积累，并伴随着 Abeta 产量的显着增加以及早老素 1 (PS1) 定位到早期/晚期内体的转变。关于胆固醇含量的变化是否可能直接影响 APP 的 γ-分泌酶裂解，报道了相互矛盾的结果。该项目的目标是阐明胆固醇影响 APP 代谢的机制。我们假设胆固醇在野生型和 NPC1 敲除细胞中以类似的方式调节 APP 加工。我们还假设胆固醇水平调节 APP、BACE1 和 PS1（阿尔茨海默病发病机制中的三个关键角色）的细胞内运输。我们推测这三种蛋白与脂筏的胆固醇依赖性关联调节它们的内吞作用，从而调节 Abeta 的产生。此外，我们假设胆固醇和/或载脂蛋白 E (apoE) 的水平调节 APP 加工，直接调节 γ 分泌酶活性。为了分析野生型和 NPC1-/- 细胞中胆固醇和 APP 加工之间的相似性，我们将测试胆固醇水平的增加或减少是否以类似的方式调节 APP 代谢。比较 APP、BACE1 和 PS1 在 wt 和 NPC1 中的细胞定位和与脂质筏的关联。在甾醇饥饿和甾醇喂养条件下敲除细胞，我们将阐明胆固醇对异常 APP 加工的影响是否是通过特定的亚细胞或脂质介导的筏舱。为了测试γ-分泌酶活性本身是否可以通过胆固醇和/或apoE水平来调节，我们将进行体外γ-测定。如果 γ-分泌酶活性受胆固醇水平和/或 apoE 调节，我们将测试该特征是否是 APP γ-裂解所特有的，还是在其他 γ-分泌酶底物（例如 Notch 1）中常见。这项研究将主要在克罗地亚的 Rudjer Boskovic 研究所与 Silva Hecimovic 博士合作进行，作为 NIH 拨款 #R01AG016208 的延伸。通过这些研究，我们将阐明胆固醇在阿尔茨海默病中作用的分子机制。寻找胆固醇和 AD 之间的分子联系对于治疗阿尔茨海默病以及了解正常的 APP 功能都很重要。