ACAT inhibitors regulate palmitoylated APP and Abeta production

描述（由申请人提供）：胆固醇途径中的酶已成为预防和治疗阿尔茨海默病（AD）的有效药物靶点。尽管他汀类药物在细胞和动物模型中降低了β -淀粉样蛋白（A?），但迄今为止，在阿尔茨海默病的III期临床试验中，结果令人失望。一种名为酰基辅酶A的胆固醇修饰酶：胆固醇酰基转移酶（ACAT）正成为阿尔茨海默病和动脉粥样硬化治疗的一个令人兴奋的靶点。所有三种现有的ACAT抑制剂，在细胞和AD小鼠模型中敲低ACAT可降低A？生产。我们最近在理解ACAT抑制降低A？的水平。具体来说，我们发现淀粉样蛋白前体蛋白（APP）在棕榈酰化过程中通过添加脂肪酸进行修饰。我们能够证明APP的棕榈酰化受到ACAT活性的高度调节。此外，我们还发现了一系列新的ACAT抑制剂。本应用的总体目标是阐明ACAT抑制剂在AD中的确切作用机制和治疗效果，特别关注我们的新化合物。为此，我们建议采用细胞生物学和体内动物模型的综合方法。我们将鉴定APP的棕榈酰化酶，并询问ACAT抑制剂是否会影响其表达或定位。我们还将研究棕榈酰化APP是如何产生A？以及ACAT抑制剂如何特异性地减少这一过程。最后，我们将测试我们的新型ACAT抑制剂在AD动物模型中的治疗潜力，以及ACAT抑制剂如何在体内调节棕榈酰化APP。总的来说，这些实验的目的是为进一步开发ACAT抑制剂作为AD和心血管疾病的治疗策略提供必要的机制和体内数据。

DESCRIPTION (provided by applicant): Enzymes in the cholesterol pathway have emerged as effective drug targets for the prevention and treatment of Alzheimer's disease (AD). Although statins reduced beta-amyloid (A?) in cells and animal models, so far yielded disappointing results in phase III clinical trials for AD. A cholesterol-modifying enzyme named acyl-coenzyme A: cholesterol acyltransferase (ACAT) is becoming an exciting target for AD therapy and atherosclerosis. All three classes of existing ACAT inhibitors, knockdown of ACAT in cells and in AD mouse models reduce A? production. We have recently made considerable progress toward understanding the mechanism by which ACAT inhibition decreases A? levels. Specifically, we have found that the amyloid precursor protein (APP) is modified by the addition of a fatty acid in a process called palmitoylation. We were able to show that palmitoylation of APP is highly regulated by ACAT activity. In addition, we have identified a series of novel ACAT inhibitors. The overarching goal of this application is to elucidate the precise mechanism of action and therapeutic efficacy of ACAT inhibitors in AD, with particular focus on our novel compounds. To this end, we propose to use an integrated approach of cell biology and in vivo animal models. We will identify the palmitoylating enzyme of APP and ask whether ACAT inhibitors affect its expression or localization. We will also study how palmitoylated APP gives rise to A? and how ACAT inhibitors specifically reduce this process. Lastly, we will test the therapeutic potential of our novel ACAT inhibitors in animal models of AD and how ACAT inhibition regulates palmitoylated APP in vivo. Collectively, the goal of these experiments is to provide the necessary mechanistic and in vivo data for further development of ACAT inhibitors as a therapeutic strategy for AD and perhaps cardiovascular disease. PUBLIC HEALTH RELEVANCE: Cholesterol-based Ab-lowering agents are emerging as attractive therapeutic strategies for AD. This proposal directly tests the mechanism of established and novel ACAT inhibitors in reducing beta-amyloid levels in neurons and AD animal models. These studies will greatly facilitate the understanding and development of cholesterol-based therapies for the prevention and treatment of Alzheimer's disease and perhaps cardiovascular disease.