Cell Biology of Presenilin 1 and Associated Proteins

描述（由申请人提供）：β -淀粉样肽（ABeta）的脑沉积是阿尔茨海默病的病理标志之一。AB是由BACE1和γ -分泌酶对淀粉样蛋白前体蛋白（APP）进行顺序蛋白水解而产生的。γ -secretase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、PEN2和APH-1，以及一些调节亚基包括CD147和p23（也称为asTMP21）。PS1被认为是γ -分泌酶复合物的催化亚基。γ -分泌酶四个核心亚基的翻译后成熟和稳定性是相互调控的，它们都是功能酶活性不可或缺的组成部分。另一方面，CD147或p23表达的减少会增加AB的产生，这表明这些蛋白负向调节APP的γ -分泌酶加工。p23调节APP的γ -分泌酶切割的具体机制尚不确定。本研究概述了p23在培养细胞和小鼠脑内APP运输和γ -分泌酶加工中的功能，我们建议阐明p23与γ -分泌酶亚基之间的功能相互作用，以便我们更好地了解p23负性调节β产生的机制。我们将定义p23对APP运输和ABeta产生影响所必需的结构域，并使用p23转基因小鼠和p23条件敲除小鼠研究p23对ABeta沉积的调节。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产生的关系。我们的研究结合了生物化学、分子和细胞生物学技术来实现以下具体目标。目的1：研究p23与γ -分泌酶的功能相互作用。目的2：探讨p23对小鼠脑内β -生成和沉积的调控作用。目的3：确定p23功能与APP转运和γ -分泌酶加工之间的联系机制。我们的研究解决了阿尔茨海默病分子发病机制的核心问题。我们试图研究p23对β产生影响的γ -分泌酶调节的一个新方面。我们的研究有可能揭示p23调控APP运输和ABeta产生的重要见解，并可能导致基于p23的新型治疗策略的发展，旨在通过选择性失活APP加工中的γ分泌酶功能来减少ABeta负担。

DESCRIPTION (provided by applicant): Cerebral deposition of beta-amyloid peptides (ABeta) is one of the pathological hallmarks of Alzheimer's disease. AB is generated by sequential proteolysis of amyloid precursor protein (APP) by BACE1 and gamma-secretase. gamma-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 gamma-secretase complex. Post-translational maturation and stability of the four core subunits of gamma-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 gamma-secretase processing of APP. The specific mechanisms by which p23 modulates gamma-secretase cleavage of APP remain undetermined. Studies outlined in this proposal address the function of p23 in trafficking and gamma-secretase processing of APP in cultured cells and in mouse brains Specifically, we propose to elucidate the functional interaction between p23 and gamma-secretase subunits so that we can better understand the mechanisms by which p23 negatively regulates ABeta production. We will define the structural domains essential for p23's influence on APP trafficking and ABeta production, and investigate p23 modulation of ABeta 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 gamma-secretase. Aim 2: To investigate p23 regulation of ABeta production and deposition in mouse brain. Aim 3: To determine the mechanisms linking p23 function with APP trafficking and gamma-secretase processing. Our studies address issues that are central to molecular Alzheimer's disease pathogenesis. We seek to investigate a novel aspect of gamma-secretase modulation by p23 that impacts on ABeta production. Our studies have the potential to uncover significant insights on p23 regulation of APP trafficking and ABeta production, and may lead to the development of p23-based novel therapeutic strategies aimed reducing ABeta burden by selective inactivation of gamma-secretase function in APP processing.