Alzheimers Disease Mechanism & Experimental Therapeutic

阿尔茨海默病发病机制

• 批准号: 7413266
• 负责人: PHILIP C WONG
• 金额: $ 96.61万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-05-15 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7413266
• 关键词: Alzheimers; Disease; Mechanism; Experimental; Therapeutic

DESCRIPTION (provided by applicant): Alzheimer's disease (AD), the most common cause of dementia of the elderly, is a progressive neurodegenerative disorder characterized by the deposition of amyloid-beta (Abeta) and neurofibrillary tangles in the brain. Endoproteolytic cleavages of APP by beta-and gamma-secretases result in the generation of Abeta peptides. The exciting discoveries of beta-secretase and components of the gamma-secretase complex over the past several years provided opportunities to examine the physiological roles of BACE1 and Nicastrin (NCT) and to evaluate these proteins as therapeutic targets for AD. We created BACE1 null mice and demonstrated that BACE1 is the principal beta-secretase necessary to cleave APR to generate Abeta. In addition, we generated NCT null (NCT-/-) mice and NCT-/- cells and established that NCT is an integral member of the gamma-secretase complex. Taking advantage of our multidisciplinary group of talented investigators, we plan to extend our beta and gamma-secretase program to address several key issues outlined in the following Aims: 1) To determine whether deficits in synaptic functions or cognitive performance occur in BACE1-/-, BACE2-/-, or BACE1-/-;BACE2-/- mice; 2) To develop a conditional tet-inducible BACE1 transgenic model to prospectively address the reversibility of Abeta induced abnormalities and the capacity of the brain to repair itself; 3) To determine whether Abeta burden can be reduced in brains of mutant PS1;APP mice by genetically modulating the levels of BACE1 and/or components of the gamma-secretase complex; 4) To test the hypothesis that Aph-1 and NCT are required to regulate the stability of each other to form a stable pre-complex for assembly of PS and Pen-2. In such a model, we suggest that the three mammalian Aph-1 homologues (Aph-1aL, Aph-1aS and Aph-1b) define a set of six distinct functional gamma-secretase complexes; 5) To determine physiological role of NCT during post-natal development, maturation, and aging outside the central nervous system, NCT transgenic mice will be generated, characterized and crossbred to NCT-/- mice to complement the developmental defects in NCT-/- mice, and 6) To determine the roles of Aph-1a and Aph-1b by generation and characterization of mice and cells deficient in these components of the gamma-secretase complex. In concert, the Projects in this proposal are designed not only to examine the roles of BACE1, BACE2, and components of the gamma-secretase complex, but also allow a critical evaluation of these proteins as therapeutic targets in efforts to ameliorate Abeta amyloidosis in individuals with AD. PROJECT 1 P.I.: Donald L. Price, M.D. Title: BACE1 and BACE2 in Cognition and Models of Aa Amyloidosis Description (provided by applicant) With the discovery of BACE1 as the a-secretase involved in the generation of a-amyloid (Aa) peptides in Alzheimer's disease (AD), we embarked on a series of studies to examine the functional roles of this transmembrane aspartyl protease. We have provided evidence to support our hypothesis that the distributions and levels of BACE1 and BACE2, along with APR, are key determinants of selective vulnerability of brain to Aa amyloidosis. Importantly, deletion of BACE1 abolished Aa deposition and prevented cognitive deficits occurring in brains of mutant APP;PS1 mice. Although BACE1 null mice do not exhibit overt developmental abnormalities, our recent studies show that these animals do manifest alterations in performance on tests of cognition and emotion. The goal of Project 1 is to assess the functional roles of BACE1 and BACE2 and to evaluate critically BACE1 as a high priority therapeutic target for treatment of AD. Thus, studies in Aim 1 are designed to examine whether deficits in synaptic functions or cognitive/behavioral abnormalities occur in BACE1-l-, BACE2-l-, or BACE1-l- , BACE2-l- mice. In Aim 2, we plan to examine the link between abnormal accumulations of Aa peptides and synaptic abnormalities occurring in APPswe;PSl?E9 mice. These studies are critical for Aim 3, which are designed to assess the degree of reversibility/recovery following experimental reductions of BACE1 at different stages of Aa amyloidosis and degeneration. We anticipate that novel mechanism-based treatments such as BACE1 inhibitors will become available in the future, and it is therefore important to prospectively address the issues of the reversibility of Aa induced abnormalities and the capacity of the brain to repair itself. Investigations in Aim 3 are designed to determine to what extent Aa deposition and associated abnormalities can be reversed following reduction of BACE1 activity at various times after the initiation of Aa deposition. Taken together, results from these studies will provide important information regarding the physiological roles of BACE1 and BACE2 and allow a critical evaluation of BACE1 as a therapeutic target in efforts to reduce Aa burden in individuals with AD. Furthermore, these studies provide important information regarding potential mechanism based toxicities associated with anti-BACE1 therapy in humans that should be carefully monitored in clinical trials in the future.

描述(由申请人提供)： 阿尔茨海默病(AD)是导致老年人痴呆的最常见原因，是一种进行性神经退行性疾病，其特征是大脑中淀粉样β蛋白(Abeta)和神经原纤维缠结的沉积。β-和γ-分泌酶对APP的内切作用导致Abeta多肽的产生。在过去的几年中，对β-分泌酶和γ-分泌酶复合体成分的令人兴奋的发现为研究BACE1和尼古丁(NCT)的生理作用以及评估这些蛋白质作为治疗AD的靶点提供了机会。我们创造了BACE1缺失的小鼠，并证明了BACE1是裂解APR产生Abeta所必需的主要β-分泌酶。此外，我们还产生了NCT空(NCT-/-)小鼠和NCT-/-细胞，并确定NCT是伽马分泌酶复合体的一个组成部分。利用我们的多学科有才华的研究小组，我们计划扩大我们的β-和伽马分泌酶计划，以解决以下目标中概述的几个关键问题：1)确定BACE1-/-、BACE2-/-或BACE1-/-小鼠是否存在突触功能或认知能力缺陷；2)开发一个条件性可诱导的BACE1转基因模型，以前瞻性地解决Abeta诱导的异常的可逆性和大脑自我修复的能力；3)确定是否可以减轻突变型PS1的大脑Abeta负担；通过基因调控BACE1和/或γ-分泌酶复合体的水平；4)检验APH-1和NCT相互调节彼此的稳定性以形成稳定的PS和Pen-2组装前复合体的假设。在这样的模型中，我们建议三种哺乳动物的APH-1同源物(APH-1AL、APH-1AS和APH-1b)定义一套六种不同的功能伽马分泌酶复合体：5)为了确定NCT在出生后发育、成熟和中枢神经系统外衰老过程中的生理作用，我们将建立NCT转基因小鼠，并将其鉴定为NCT-/-小鼠，以弥补NCT-/-小鼠的发育缺陷；6)通过对缺乏这些伽玛分泌酶复合体的小鼠和细胞的生成和鉴定来确定APH-1a和APH-1b的作用。总之，这项提案中的项目不仅旨在研究BACE1、BACE2和伽马分泌酶复合体的组成部分，而且还允许对这些蛋白质作为治疗靶点进行关键评估，以努力改善AD患者的Abeta淀粉样变性。 项目1 P.I.：唐纳德·L·普莱斯，医学博士 BACE1和BACE2在AA淀粉样变性的认知和模型中的作用 描述(由申请人提供) 随着BACE1作为参与阿尔茨海默病(AD)中α-淀粉样蛋白(AA)合成的α-分泌酶的发现，我们开始了一系列的研究，以探讨这种跨膜天冬氨酸蛋白酶的功能作用。我们已经提供了证据支持我们的假设，即BACE1和BACE2的分布和水平以及APR是大脑选择性易感性AA淀粉样变性的关键决定因素。重要的是，BACE1的缺失消除了AA的沉积，并防止了突变型APP；PS1小鼠大脑中发生认知障碍。虽然BACE1基因缺失的小鼠没有表现出明显的发育异常，但我们最近的研究表明，这些动物在认知和情绪测试中的表现确实发生了变化。项目1的目标是评估BACE1和BACE2的功能作用，并严格评估BACE1作为AD治疗的高优先级治疗靶点。因此，目标1的研究旨在检查BACE1-L、BACE2-L或BACE1-L、BACE2-L-小鼠是否存在突触功能缺陷或认知/行为异常。在目标2中，我们计划检查在APPswe；PSL？E9小鼠中AA多肽的异常积累和突触异常之间的联系。这些研究对AIM 3至关重要，AIM 3旨在评估在AA淀粉样变性和变性的不同阶段BACE1实验减少后的可逆性/恢复程度。我们预计，未来将有新的基于机制的治疗方法，如BACE1抑制剂，因此，前瞻性地解决AA诱导的异常的可逆性和大脑自我修复能力的问题是重要的。AIM 3中的调查旨在确定在AA沉积开始后不同时间BACE1活性降低后，AA沉积及其相关异常可以在多大程度上逆转。综上所述，这些研究的结果将提供关于BACE1和BACE2的生理作用的重要信息，并允许对BACE1作为努力减轻AD患者AA负担的治疗靶点进行关键评估。此外，这些研究提供了与人类抗BACE1治疗相关的潜在机制毒性的重要信息，这些毒性应在未来的临床试验中仔细监测。