Autophagic Clearance of Aberrant Tau: Biochemical and Therapeutic Implications

异常 Tau 蛋白的自噬清除：生化和治疗意义

基本信息

批准号：
8204248
负责人：
Karen Duff
金额：
$ 42.11万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-07-01 至 2016-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8204248
关键词：
Address Animal Model Attenuated Autophagocytosis Autophagosome Axon Axonal Transport Biochemical Cell Death Cell model Cells Degradation Pathway Development Disease Disease Progression Drug Delivery Systems Enhancers Equilibrium Event Excision Failure Functional disorder Genetic Human In Vitro Label Libraries Lysosomes Microfluidics Molecular Bank Molecular Chaperones Mus Neurodegenerative Disorders Neurofibrillary Tangles Neurons Organelles Outcome Measure Pathology Pathway interactions Patients Pharmaceutical Preparations Phenotype Play Proteins Quality Control Reporter Role Staging System Tauopathies Testing Therapeutic Therapeutic Intervention Tissues Transgenes Ubiquitin United States National Institutes of Health Vacuole Vesicle chemical genetics drug candidate end stage disease human Huntingtin protein human tissue hyperphosphorylated tau in vivo insight mouse model multicatalytic endopeptidase complex novel protein aggregate protein misfolding synuclein tau Proteins tau aggregation tau mutation trafficking

项目摘要

DESCRIPTION (provided by applicant): Intracellular inclusions of misfolded proteins are the hallmark of many neurodegenerative diseases. Dysfunction of either of the two proteolytic pathways involved in clearing abnormal or obsolete cellular proteins, the ubiquitin-proteasome system (UPS) and the autophagic-lysosomal system (A-LS) may underlie the development of the disease. Macroautophagy (autophagy), a major degradative pathway of the lysosomal system, plays a significant role in the removal of organelles and protein aggregates that are too large, or that cannot be unfolded by chaperone proteins and that are consequently unable to be degraded by the UPS. An equilibrium exists between autophagosome formation and clearance by lysosomes, and uncompromised vesicular trafficking, heterotypic organelle fusion and lysosomal function are critical for the terminal stages of autophagosomal degradation. The A-LS has been shown to play an important role in the clearance of misfolded, aggregate-prone proteins such as ?-synuclein and huntingtin. In general, we hypothesize that the UPS is upregulated to clear misfolded tau species early during the disease, but the system becomes overwhelmed as larger aggregates of tau accumulate. We envisage that the A-LS is then upregulated in an effort to compensate for the lost UPS activity and to clear the aggregates but ultimately both systems fail resulting in accelerated pathology and decline. The relationship between the accumulation of tau, the interplay between the UPS and A-LS, and the effect of relevant pharmacologic manipulations on outcome measures of relevance to human tauopathy will be assessed in three specific aims. Aim 1 will examine the interplay between the UPS, AL-S and tau accumulation in human tissue from patients with 4R tauopathies and will compare to two mouse models of 4R tauopathy that have been modified to express an autophagic marker. The mouse models will allow us to manipulate components of the autophagic pathways to further study the interplay with the UPS, with specific examination of what happens to specific ubiquitinated forms of proteins to confirm the significance of autophagic sufficiency in tauopathy progression in vivo. Aim 2 will use primary neurons from the aforementioned animal models to test the impact of dysfunction in a particular pathway (abnormal transport of autophagic vacuoles leading to failure of autophagic flux) and its impact on tauopathy, and whether compounds that activate A-LS or reduce the levels of hyperphosphorylated tau ameliorate the pathological phenotype. Aim 3 will identify if compounds identified by NCGC/NIH (National Chemical and Genetic Center) using the MLPCN (Molecular Library Probes Center Network) to reduce huntingtin aggregates and cell death are viable autophagic enhancers that can be used to treat tauopathy. Cumulatively, these studies will add insight into the relationship between clearance pathways, how and when they fail, and the impact of drugs that target autophagy as a therapeutic intervention for the tauopathies PUBLIC HEALTH RELEVANCE: Several neurodegenerative diseases known collectively as the tauopathies include, as part of the pathology, intracellular inclusions known as neurofibrillary tangles. Although we do not know how tangles form, or exactly what type of tau (misfolded, hyperphosphorylated, oligomeric or aggregated tau) causes the cell to become dysfunctional, but it is likely that clearing abnormal, misfolded tau proteins will attenuate disease progression and possibly cure, or stabilize the disease. Studies proposed aim to understand better how pathological tau is removed from the cell through either of the two clearance pathways - the ubiquitin-proteasome clearance pathway, or the autophagic clearance pathway. Using mouse models of tauopathy, we will examine how and when these systems fail; their relationship to each other, the consequence of abnormal cellular transport function; and whether novel drug candidates that enhance autophagic clearance are efficacious in a mouse model of tauopathy.

描述（由申请人提供）：错误折叠蛋白质的细胞内内含物是许多神经退行性疾病的标志。涉及清除异常或废弃细胞蛋白的两条蛋白水解途径（泛素蛋白酶体系统（UPS）和自噬溶酶体系统（A-LS））的功能障碍可能是该疾病发生的基础。巨自噬（autophagy）是溶酶体系统的主要降解途径，在去除太大的细胞器和蛋白质聚集体或不能被伴侣蛋白展开并因此无法被 UPS 降解的细胞器和蛋白质聚集体中发挥着重要作用。自噬体形成和溶酶体清除之间存在平衡，不受损害的囊泡运输、异型细胞器融合和溶酶体功能对于自噬体降解的末期至关重要。 A-LS 已被证明在清除错误折叠、易于聚集的蛋白质（如 β-突触核蛋白和亨廷顿蛋白）方面发挥着重要作用。一般来说，我们假设 UPS 在疾病早期被上调以清除错误折叠的 tau 物种，但随着更大的 tau 聚集体的积累，该系统变得不堪重负。我们设想 A-LS 随后会上调，以补偿 UPS 活动的损失并清除总量，但最终两个系统都会失败，导致加速病理和衰退。 tau 蛋白积累之间的关系、UPS 和 A-LS 之间的相互作用以及相关药理操作对人类 tau 蛋白病相关结果测量的影响将在三个具体目标中进行评估。目标 1 将检查 4R tau 蛋白病患者人体组织中 UPS、AL-S 和 tau 蛋白积累之间的相互作用，并将与经过修饰以表达自噬标记的两种 4R tau 蛋白病小鼠模型进行比较。小鼠模型将使我们能够操纵自噬途径的组成部分，以进一步研究与 UPS 的相互作用，具体检查特定泛素化形式的蛋白质发生的情况，以确认自噬充分性在体内 tau 病进展中的重要性。目标 2 将使用来自上述动物模型的原代神经元来测试特定途径中功能障碍的影响（自噬泡异常运输导致自噬流失败）及其对 tau 蛋白病的影响，以及是否有化合物激活 A-LS 或减少过度磷酸化的 tau 蛋白水平可改善病理表型。目标 3 将确定 NCGC/NIH（国家化学和遗传中心）使用 MLPCN（分子图书馆探针中心网络）鉴定的用于减少亨廷顿蛋白聚集和细胞死亡的化合物是否是可用于治疗 tau 蛋白病的可行自噬增强剂。总而言之，这些研究将深入了解清除途径之间的关系、它们如何以及何时失败，以及针对自噬作为 tau蛋白病治疗干预的药物的影响公共健康相关性：几种统称为 tau 蛋白病的神经退行性疾病包括称为神经原纤维缠结的细胞内包涵体，作为病理学的一部分。尽管我们不知道缠结是如何形成的，也不知道到底是什么类型的 tau（错误折叠、过度磷酸化、寡聚或聚集的 tau）会导致细胞功能障碍，但清除异常、错误折叠的 tau 蛋白很可能会减轻疾病进展并可能治愈疾病，或稳定病情。研究提出的目的是更好地了解病理性 tau 蛋白如何通过两种清除途径（泛素蛋白酶体清除途径或自噬清除途径）从细胞中清除。使用tau蛋白病小鼠模型，我们将检查这些系统如何以及何时失效；它们之间的关系是细胞运输功能异常的结果；以及增强自噬清除的新候选药物是否对小鼠 tau 蛋白病模型有效。