Cell Biology of Presenilin 1 and Associated Proteins

描述（由申请人提供）： β-淀粉样肽（AB）的脑沉积是阿尔茨海默病的病理标志之一。AB是通过BACE 1和g-分泌酶对淀粉样前体蛋白（APP）的连续蛋白水解产生的。G-分泌酶是一种多聚体蛋白复合物，由四个主要亚基组成，即PS1（或PS2）、nicastrin、PEN 2和APH-1，以及包括CD 147和p23（也称为TMP 21）在内的一些调节亚基。PS1被认为是G-分泌酶复合物的催化亚基。G-分泌酶的四个核心亚基的翻译后成熟和稳定性是相互调节的，它们中的每一个都是功能酶活性所不可缺少的。另一方面，减少CD 147或p23的表达增加AB生产，这表明这些蛋白质负调节G-分泌酶加工APP。P23调节G-分泌酶裂解APP的具体机制仍未确定。在这个建议中概述的研究解决的功能p23在运输和g-分泌酶加工的APP在培养的细胞和小鼠脑中。具体地说，我们建议阐明p23和g-分泌酶亚基之间的功能相互作用，使我们可以更好地了解机制，p23负调节AB生产。我们将定义的结构域必不可少的p23的APP贩运和AB生产的影响，并研究p23调制AB沉积使用p23转基因小鼠和p23条件性基因敲除小鼠。最后，我们将详细研究p23在APP分泌和内吞运输中的作用，并研究高尔基体形态与AB产生之间的关系。我们的研究使用生物化学，分子和细胞生物学技术的组合，以实现以下具体目标。目的1：研究p23与G-分泌酶的相互作用。目的2：探讨p23对小鼠脑内AB产生和沉积的调控。目的3：探讨p23功能与APP运输和G-分泌酶加工的关系。我们的研究解决了分子阿尔茨海默病发病机制的核心问题。我们试图研究一个新的方面的g-分泌酶调节p23的影响AB生产。我们的研究有可能揭示APP运输和AB生产的p23调控的重要见解，并可能导致基于p23的新的治疗策略的发展，旨在通过选择性灭活APP加工中的g-分泌酶功能来减少AB负担。 公共卫生相关性：阿尔茨海默病（AD）是老年痴呆症的主要原因，影响超过50%的80岁以上的人口;目前有510万美国人患有这种毁灭性的疾病。AD患者以及老年人在大脑中积累β-淀粉样肽作为沉积物，称为老年斑。利用培养细胞、转基因小鼠和条件性基因敲除小鼠作为实验模型，我们研究了一种称为p23的蛋白在调节β-淀粉样蛋白产生和沉积中的功能。我们的研究对于开发旨在减少大脑中β-淀粉样蛋白负担的新型合理AD治疗方法至关重要。

DESCRIPTION (provided by applicant): Cerebral deposition of beta-amyloid peptides (AB) is one of the pathological hallmarks of Alzheimer's disease. AB is generated by sequential proteolysis of amyloid precursor protein (APP) by BACE1 and g-secretase. g-secretase is a multimeric protein complex made of four main subunits, namely PS1 (or PS2), nicastrin, PEN2 and APH-1, and a few regulatory subunits including CD147 and p23 (also referred to asTMP21). PS1 is thought to function as the catalytic subunit of g-secretase complex. Post-translational maturation and stability of the four core subunits of g-secretase are mutually regulated, and each of them is indispensable for functional enzyme activity. On the other hand, diminution of CD147 or p23 expression increases AB production, suggesting that these proteins negatively regulate g-secretase processing of APP. The specific mechanisms by which p23 modulates g-secretase cleavage of APP remain undetermined. Studies outlined in this proposal address the function of p23 in trafficking and g-secretase processing of APP in cultured cells and in mouse brains Specifically, we propose to elucidate the functional interaction between p23 and g-secretase subunits so that we can better understand the mechanisms by which p23 negatively regulates AB production. We will define the structural domains essential for p23's influence on APP trafficking and AB production, and investigate p23 modulation of AB deposition using p23 transgenic mice and p23 conditional knockout mice. Finally, we will investigate the details on p23's role in secretory and endocytic trafficking of APP and examine the relationship between Golgi morphology and AB production. Our investigation uses a combination of biochemical, molecular and cell biology techniques to accomplish the following specific aims. Aim 1: To study the functional interaction between p23 and g-secretase. Aim 2: To investigate p23 regulation of AB production and deposition in mouse brain. Aim 3: To determine the mechanisms linking p23 function with APP trafficking and g-secretase processing. Our studies address issues that are central to molecular Alzheimer's disease pathogenesis. We seek to investigate a novel aspect of g-secretase modulation by p23 that impacts on AB production. Our studies have the potential to uncover significant insights on p23 regulation of APP trafficking and AB production, and may lead to the development of p23-based novel therapeutic strategies aimed reducing AB burden by selective inactivation of g-secretase function in APP processing. PUBLIC HEALTH RELEVANCE: Alzheimer's disease (AD) is the major cause of dementia in the elderly, afflicting more than 50% of the population over 80 years of age; presently 5.1 million Americans suffer from this devastating disorder. AD patients as well as aged individuals accumulate beta-amyloid peptides as deposits in brain, called senile plaques. Using cultured cells, transgenic mice, and conditional knockout mice as experimental models we investigate the function a protein called p23 in regulating beta-amyloid production and deposition. Our studies will be critical to develop novel rational AD therapeutics aimed at reducing beta-amyloid burden in the brain.