Chemical Probes and Chaperone-Accelerated Turnover of Tau

化学探针和分子伴侣加速 Tau 蛋白的周转

• 批准号: 8519207
• 负责人: Jason E Gestwicki
• 金额: $ 19.38万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8519207
• 关键词: Alzheimer' s Disease; Animal Model; Appearance; BAG1 gene; Binding; Binding Proteins; Biology; Cell model; Cells; Chemicals; Co-Immunoprecipitations; Collaborations; Complex; Critical Pathways; Decision Making; Disease; Drug Targeting; Equilibrium; Event; Excision; Future; Goals; Heat shock proteins; Homeostasis; Impaired cognition; In Vitro; Individual; Knowledge; Laboratories; Link; Mass Spectrum Analysis; Mediating; Microtubules; Modeling; Molecular; Molecular Chaperones; Neurodegenerative Disorders; Neurons; Pathway interactions; Patients; Peptides; Phosphorylation; Post-Translational Protein Processing; Process; Proteins; Quality Control; Recruitment Activity; Resistance; Staging; System; Tauopathies; Testing; Time; Triage; Ubiquitin; Variant; Work; base; design; in vitro Model; infancy; inhibitor/antagonist; innovation; insight; multicatalytic endopeptidase complex; neuron loss; peptidomimetics; programs; protein complex; research study; tau Proteins; tau aggregation; tau mutation; tool; ubiquitin-protein ligase

DESCRIPTION (provided by applicant): Tau is a microtubule-binding protein that intrinsically disordered and abundantly expressed in neurons. Certain post-translationally modified forms of tau, such as hyper-phosphorylated and proteolyzed fragments, have been found to accumulate in more than fifteen neurodegenerative disorders, including Alzheimer's disease (AD). These "abnormal" tau variants are particularly prone to aggregation and their accumulation leads to proteotoxicity, neuron loss and cognitive impairment. Thus, strategies for accelerating the removal of abnormal tau are expected to protect against tauopathies. Cellular protein quality control (PQC) pathways, including molecular chaperones, have been shown to regulate tau homeostasis by controlling its post-translational modification, binding to microtubules and its turnover. However, the molecular details of this process are not yet clear. How do the chaperones distinguish between normal tau and aggregation-prone tau? Which chaperones and co-chaperones are critical for the triage decisions? What molecular events are critical during the earliest stages of tau degradation? The major goal of this project is to understand how the molecular chaperones and other components of PQC make the decision to degrade tau and its variants. Preliminary evidence suggests that the heat shock protein Hsp70 and Hsp90, in combination with some of their associated co-chaperones, detect the appearance of aggregation-prone tau and then make triage decisions to remove these proteins. Based on these studies, we hypothesize that a specific combination of chaperones and co-chaperones bind tau, distinguish between variants and then enact degradation programs. Towards probing that model, we propose two specific aims: (1) perform co-immunoprecipitation and mass spectrometry studies on normal, cycling tau and tau that has been acutely targeted for proteasomal degradation to identify proteins that are specifically associated with the degradation fate and (2) test whether specific Hsp40 co-chaperones selectively recruit Hsp70 to aggregation-prone tau variants. These studies are timely because they make use of new chemical probes that trigger the rapid (~ 10 min) and dramatic (~80%) degradation of tau by the ubiquitin-proteosome pathway. The Gestwicki laboratory has spent the past five years developing, characterizing and optimizing this suite of compounds and, together with the Dickey group, we have shown their activity in cellular and animal models of tauopathy. We propose that, because of their unusually rapid activities, these chemical probes will permit, for the first time, insight into the very earliest stages of the "decision" to degrade tau. Thus, we expect these aims will provide insight into how chaperone complexes discriminate between tau variants and how protein quality control components shuttle abnormal tau for degradation. The long-term goal of this work is to find new ways of treating AD and other tauopathies by understanding the critical pathways that control tau turnover.

描述（由申请人提供）：Tau是一种微管结合蛋白，其本质上是无序的并且在神经元中大量表达。已经发现某些tau的后修饰形式，如过度磷酸化和蛋白水解片段，在超过15种神经退行性疾病中积累，包括阿尔茨海默病（AD）。这些“异常”tau变体特别容易聚集，并且它们的积累导致蛋白毒性、神经元损失和认知障碍。因此，用于加速异常tau的去除的策略预期可防止tau蛋白病。包括分子伴侣在内的细胞蛋白质质量控制（PQC）途径已被证明通过控制其翻译后修饰、与微管的结合及其周转来调节tau稳态。然而，这一过程的分子细节尚不清楚。分子伴侣如何区分正常的tau蛋白和聚集倾向的tau蛋白？哪些监护人和共同监护人对分诊决定至关重要？在tau蛋白降解的最早阶段，哪些分子事件是关键的？该项目的主要目标是了解分子伴侣和PQC的其他组分如何决定降解tau及其变体。初步证据表明，热休克蛋白Hsp 70和Hsp 90与它们的一些相关的辅助分子伴侣结合，检测到易于聚集的tau蛋白的出现，然后做出分类决定以去除这些蛋白质。基于这些研究，我们假设分子伴侣和辅助分子伴侣的特定组合结合tau，区分变体，然后制定降解程序。为了探索该模型，我们提出了两个具体的目标：（1）对正常的循环tau蛋白和被蛋白酶体降解的tau蛋白进行免疫共沉淀和质谱研究，以鉴定与降解命运特异性相关的蛋白质，以及（2）测试特定的Hsp 40共分子伴侣是否选择性地将Hsp 70招募到易于聚集的tau变体。这些研究是及时的，因为它们利用了新的化学探针，通过泛素-蛋白体途径触发tau的快速（~ 10分钟）和戏剧性（~80%）降解。Gestwicki实验室在过去的五年里一直在开发、表征和优化这套化合物，并与Dickey小组一起，在tau蛋白病的细胞和动物模型中展示了它们的活性。我们认为，由于它们异常迅速的活动，这些化学探针将允许，首先， 时间，洞察降解tau的“决定”的最早阶段。因此，我们期望这些 aims将提供深入了解伴侣蛋白复合物如何区分tau变体以及蛋白质质量控制组分如何穿梭异常tau以进行降解。这项工作的长期目标是通过了解控制tau转换的关键途径来寻找治疗AD和其他tau蛋白病的新方法。