Elucidating the contribution of amyloidogenic APP processing to AD-relevant impaired synaptic protein turnover

阐明淀粉样蛋白生成 APP 加工对 AD 相关突触蛋白周转受损的影响

• 批准号: 10538032
• 负责人: Nalini Rao
• 金额: $ 4.68万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10538032
• 关键词: Address; Affect; Alzheimer' s Disease; Alzheimer' s disease brain; Alzheimer' s disease pathology; Alzheimer' s disease patient; Amyloid beta-42; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Animals; Antibodies; Antiepileptic Agents; Axon; Biological Assay; Brain; Critical Pathways; Dementia; Disease; Endocytosis; Endosomes; Etiology; Event; Functional disorder; Goals; Human; Impairment; In Vitro; Knock-in; Knock-in Mouse; Label; Lead; Levetiracetam; Mass Spectrum Analysis; Measures; Metabolic; Microfluidic Microchips; Modeling; Molecular; Mus; Mutation; Neurodegenerative Disorders; Neurofibrillary Tangles; Neurons; Pathogenicity; Pathologic; Pathology; Pathway interactions; Peptides; Periodicity; Persons; Phenotype; Physiologic pulse; Play; Pre-Clinical Model; Presynaptic Terminals; Prevalence; Process; Production; Proteins; Proteome; Proteomics; Reporter; Research; Role; Site; Synapses; Synaptic Vesicles; System; Techniques; Testing; Therapeutic; Tissues; Ubiquitin; Ubiquitination; Work; amyloid pathology; amyloid precursor protein processing; base; biochemical tools; clinically relevant; diagnostic tool; hyperphosphorylated tau; in vitro Model; in vivo; mouse model; multicatalytic endopeptidase complex; neuronal cell body; novel; overexpression; prevent; protein aggregation; protein degradation; protein misfolding; protein transport; proteostasis; small molecule; stable isotope; tau Proteins; tool; uptake; vesicle transport

Project Summary Alzheimer’s disease (AD) is a debilitating neurodegenerative disease and the most prevalent form of dementia. AD is pathologically characterized by two misfolded and aggregated proteins: amyloid-beta peptides (Aβ42) and hyperphosphorylated tau. Although Aβ42 accumulation, produced amyloidogenic processing of the amyloid precursor protein (APP), is one of the earliest pathological events, the initial trigger in proteostasis imbalance remains unknown. To investigate proteostasis impairments in AD, our research utilizes metabolic pulse-chase (pc) labeling with stable isotopes in combination with quantitative mass spectrometry (MS) based proteomic analysis. Using this strategy with the recently developed APP knock-in (App KI) mouse models of amyloid pathology, we discovered that axon terminals are selective sites of impaired protein degradation, specifically synaptic vesicle (SV) and SV-associated proteins. This alteration occurred before plaque pathology or elevated Aβ42 levels. This is important as it suggests we have identified the earliest synaptic impairment in protein turnover that occurs before amyloid pathology. Additionally, I recently discovered that targeting SVs with small molecule antiepileptic drug levetiracetam in App KI mice mitigated AD pathology by decreasing Aβ42 accumulation via alteration of amyloidogenic processing of APP. The goal of my proposed project is to uncover the mechanism for impaired synaptic proteostasis in models of preclinical amyloid pathology that may underlie the initial trigger in the cascade of pathologies seen in AD. One mechanism for turnover at the presynapse is thought to rely on the ubiquitin-proteasome system (UPS) marking proteins for transport out of the axon terminal to the soma for degradation. The central hypothesis of my proposal is that amyloidogenic processing of APP leads to a deficit to this key process resulting in an impairment in axon terminal protein turnover. To address if disrupting this process impairs axon terminal proteostasis, I propose the following aims. First, I will investigate in vivo if the UPS is disrupted in App KI brains using previously pc-ed tissue and advanced MS techniques for isolation and quantification of ubiquitinated proteins. Second, I will determine if disruptions in SV transport result from amyloidogenic processing of APP and if this leads to mislocalization of APP in vitro and finally will confirm these findings in human neurons derived from AD patients. Taken all together, this proposed project will determine the initial mechanisms of AD-relevant protein degradation impairments, crucial to determining the cause of protein accumulation in AD which currently remains unknown.

项目摘要 阿尔茨海默氏病（AD）是一种使人衰弱的神经退行性疾病，是最普遍的形式 痴呆症。 AD在病理上以两种错误折叠和聚集的蛋白质为特征： 淀粉样蛋白粉红辣椒（Aβ42）和高磷酸化的tau。尽管Aβ42积累，但 淀粉样前体蛋白（APP）产生的淀粉样蛋白生成加工是最早的 病理事件，蛋白质抑制失衡的初始触发因素仍然未知。调查 AD中的蛋白质症损伤，我们的研究利用了与 稳定的同位素与定量质谱（MS）蛋白质组学结合使用 分析。使用该策略与最近开发的应用程序敲入（APP KI）鼠标模型的模型 淀粉样病理学，我们发现轴突末端是蛋白质受损的选择性位点 降解，特别是突触囊泡（SV）和SV相关蛋白。这种改变 发生在斑块病理或Aβ42升高之前发生。这很重要，因为它暗示了我们 已经确定了在淀粉样蛋白之前发生的蛋白质周转中最早的突触障碍 病理。此外，我最近发现，针对小分子抗癫痫的靶向SV App Ki小鼠中的药物左环乙酰胺通过通过减少Aβ42的积累来减轻AD病理 APP的淀粉样生成处理的改变。我提议的项目的目的是发现 临床前淀粉样病理模型中突触蛋白抑制性受损的机制，可能 基于AD中看到的一系列病理级联的最初触发因素。一种营业额的一种机制 在肿瘤前被认为依靠泛素 - 蛋白酶体系统（UPS）标记蛋白 从轴突末端运输到躯干以进行降解。我的中心假设 提案是，应用程序的淀粉样蛋白生成处理可导致对此关键过程的辩护 在轴突末端蛋白周转率中受损。解决该过程是否破坏 轴突末端proteostasis，我提出以下目的。首先，我将在体内调查 使用先前的PC-ED组织和高级MS技术在App Ki大脑中破坏 泛素化蛋白的分离和定量。其次，我将确定SV中的干扰是否 运输是由APP的淀粉样蛋白生成处理以及APP的错误定位的运输 在体外，最终将确认来自AD患者的人类神经元中的这些发现。拍摄 总之，这个提议的项目将确定与AD相关蛋白的初始机制 降解障碍，对于确定AD中蛋白质积累的原因至关重要 目前仍然未知。