Alzheimers Disease Mechanism & Experimental Therapeutic

阿尔茨海默病发病机制

• 批准号: 7066534
• 负责人: PHILIP C WONG
• 金额: $ 96.27万
• 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/7066534
• 关键词: Alzheimer' s disease; amyloid proteins; aspartic endopeptidases; protein localization

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蛋白 (Abeta) 和神经原纤维缠结的沉积。 β 和 γ 分泌酶对 APP 进行内蛋白水解裂解，从而产生 Abeta 肽。过去几年，β-分泌酶和 γ-分泌酶复合物成分的令人兴奋的发现为研究 BACE1 和 Nicastrin (NCT) 的生理作用以及评估这些蛋白质作为 AD 治疗靶点提供了机会。我们创建了 BACE1 缺失小鼠，并证明 BACE1 是裂解 APR 生成 Abeta 所必需的主要 β 分泌酶。此外，我们还生成了NCT无效（NCT-/-）小鼠和N​​CT-/-细胞，并确定NCT是γ-分泌酶复合物的一个组成部分。利用我们的多学科才华横溢的研究人员小组，我们计划扩展我们的 β 和 γ 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-/-;BACE2-/- 小鼠是否存在突触功能或认知能力缺陷； 2) 开发有条件的tet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) 确定是否可以通过基因调节 BACE1 和/或 γ-分泌酶复合物成分的水平来减少突变型 PS1;APP 小鼠大脑中的 Abeta 负荷； 4) 检验Aph-1和NCT需要调节彼此的稳定性以形成稳定的预复合物以组装PS和Pen-2的假设。在这样的模型中，我们建议三种哺乳动物 Aph-1 同源物（Aph-1aL、Aph-1aS 和 Aph-1b）定义了一组六种不同的功能性 γ 分泌酶复合物； 5) 为了确定 NCT 在中枢神经系统之外的出生后发育、成熟和衰老过程中的生理作用，将生成、表征 NCT 转基因小鼠，并将其与 NCT-/- 小鼠杂交，以补充 NCT-/- 小鼠的发育缺陷，以及 6) 通过生成和表征缺乏这些成分的小鼠和细胞来确定 Aph-1a 和 Aph-1b 的作用。 γ-分泌酶复合物。总之，该提案中的项目不仅旨在检查 BACE1、BACE2 和 γ-分泌酶复合物成分的作用，而且还允许对这些蛋白质作为治疗靶标进行严格评估，以改善 AD 个体的 Abeta 淀粉样变性。 项目1 PI：Donald L. Price，医学博士 标题：BACE1 和 BACE2 在 Aa 淀粉样变性认知和模型中的作用 描述（由申请人提供） 随着发现 BACE1 作为参与阿尔茨海默病 (AD) 中 a-淀粉样 (Aa) 肽生成的 α-分泌酶，我们开展了一系列研究来检验这种跨膜天冬氨酰蛋白酶的功能作用。我们提供了证据来支持我们的假设，即 BACE1 和 BACE2 的分布和水平以及 APR 是大脑选择性易受 Aa 淀粉样变性影响的关键决定因素。重要的是，BACE1 的缺失消除了 Aa 沉积，并防止了突变 APP;PS1 小鼠大脑中发生的认知缺陷。尽管 BACE1 缺失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感测试中的表现确实出现了变化。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 治疗的高度优先治疗靶点。因此，目标1中的研究旨在检查BACE1-1-、BACE2-1-或BACE1-1-、BACE2-1-小鼠中是否发生突触功能缺陷或认知/行为异常。在目标 2 中，我们计划检查 APPswe;PSl?E9 小鼠中 Aa 肽的异常积累与突触异常之间的联系。这些研究对于目标 3 至关重要，目标 3 旨在评估在 Aa 淀粉样变性和变性的不同阶段实验性减少 BACE1 后的可逆性/恢复程度。我们预计未来将出现基于机制的新型治疗方法，例如 BACE1 抑制剂，因此前瞻性地解决 Aa 诱导异常的可逆性和大脑自我修复能力的问题非常重要。目标 3 的研究旨在确定在 Aa 沉积开始后的不同时间 BACE1 活性降低后，Aa 沉积和相关异常可以在多大程度上逆转。总而言之，这些研究的结果将提供有关 BACE1 和 BACE2 生理作用的重要信息，并允许对 BACE1 作为治疗靶点进行严格评估，以努力减少 AD 患者的 Aa 负担。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，应在未来的临床试验中仔细监测。