Mechanisms of Cholinesterase Inhibitors on Beta-amyloid

阿尔茨海默病（AD）的特点是胆碱能神经元的严重丧失和淀粉样肽（Abeta）的沉积。三种FDA批准的治疗阿尔茨海默病的药物（他林、多奈哌齐和利伐他明）属于胆碱酯酶抑制剂（ChEI）的范畴，其作用原理是增加大脑中乙酰胆碱的供应，乙酰胆碱是阿尔茨海默病中缺乏的一种神经交流化学物质。这些药物被批准用于治疗轻度至中度阿尔茨海默病，但在更晚期的阿尔茨海默病中可能没有那么有用。我们的目标是研究ChEI药物对淀粉样蛋白生成途径的作用机制，该途径将β -淀粉样蛋白前体蛋白（APP）加工成潜在的神经毒性β。该研究具有重要意义，因为越来越多的证据表明Abeta在AD的发病机制中起着重要作用。这一建议是基于我们的发现，用某些ChEIs（如他克林和phenserine）处理培养细胞，可显著降低分泌的APP （sAPP）和Abeta的水平，可能有助于减缓AD的进展并改善认知。值得注意的是，减少Abeta的机制并没有增加已知的替代加工途径，因此可能损害较小。我们感兴趣的是确定ChEIs阻断β分泌的机制，以利用β降低特性开发新的治疗剂。规范目标：具体目标是：1。目的：研究乙酰-ChEI （AChEI）和丁基-ChEI （BchEI）对sAPP和β水平的影响。为了检查其作用的特异性，将测试i) AchEI（例如，pheneserine） ii)BChEI（例如，cymserine）和iii)他汀衍生物化合物（例如，velnacrine）的作用，以确定降低Abeta的结构方面。探讨ChEIs对APP代谢的影响。ChEIs对1)FAD-APP突变细胞系中APP加工和2)APP羧基截断片段命运的影响将被测试。3. 确定药物的可能靶点。ChEIs对转基因AD小鼠模型中i) app -切割酶（BACE）， ii) 5' -非翻译区和iii)抑制β水平的影响。我们将机械地选择与che酶的外周变构结合域，或与酯和阴离子结合域（phenserine和cymserine）相互作用的chei，并在APP/PS1双转基因小鼠中进行测试。这些结果将表明chei对APP加工的独特影响，这与它们对酶的选择性无关。我们将进一步研究这一特性，以最大限度地发挥它们在减少淀粉样蛋白沉积方面的潜在作用，并利用它们来设计更好的治疗阿尔茨海默病的药物。

Alzheimer's disease (AD) is characterized by the severe loss of cholinergic neurons and depositions of amyloid beta peptide (Abeta). Three FDA- approved drugs (tacrine, donepezil and rivastigmine) for treating AD subjects belong to the category of cholinesterase (ChE) inhibitor (ChEI), which works by increasing the brain's supply of acetylcholine, a nerve communication chemical that is deficient in AD. These drugs are approved for treatment of mild to moderate AD and may not be as useful in more advanced stages. Our goal is to study the mechanism of ChEI drugs on amyloidogenic pathways that process beta-amyloid precursor protein (APP) to potentially neurotoxic Abeta. Such study is significant as there is increasing evidence that Abeta plays an important role in AD pathogenesis. This proposal is based on our discovery that treating cultured cells with certain ChEIs, such as tacrine and phenserine, significantly reduced levels of secreted APP (sAPP) and Abeta and may serve to slow the progression of AD as well as improve cognition. Notably, the mechanism of reduction of Abeta did not increase known alternative processing pathways and may therefore be less damaging. We are interested in identification of the mechanisms by which ChEIs block Abeta secretion to take advantage of the Abeta lowering property in developing novel therapeutic agents. SPEC. AIMS: The specific aims are: 1. To study the effects of acetyl- ChEI (AChEI) and butyrl-ChEI (BchEI) on sAPP and Abeta levels. To examine the specificity of their actions, effects of i) AchEI (e.g., pheneserine) ii)BChEI (e.g. cymserine), and iii) compounds that are tacrine-derivatives (e.g. velnacrine) will be tested to identify structural aspects that lower Abeta. 2. To investigate the role of ChEIs on APP metabolism. Effects of ChEIs on i)APP processing in FAD-APP mutant cell lines and ii) the fate of APP carboxyl-truncated fragments will be tested. 3. To determine the possible targets of the drugs. Effects of ChEIs on the i) APP-cleaving enzyme (BACE), ii) 5' -untranslated region and iii) inhibition of Abeta levels in transgenic mice model of AD. We will mechanically select ChEIs that interact with the peripheral allosteric binding domain of ChEenzyme, or with the esteractic and anionic binding domains (phenserine and cymserine) and test it in APP/PS1 double transgenic mice. These results will indicate a unique effect of ChEIs on APP processing, which is independent of their selectivity for the enzyme. This property will be further investigated to maximize their potential effects in decreasing amyloid depositions, and which can be utilized to design better drugs for the treatment of AD.