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。某些翻译后修饰形式的 tau 蛋白，例如过度磷酸化和蛋白水解片段，被发现在超过 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 蛋白变体特别容易聚集，它们的积累会导致蛋白质毒性、神经元损失和认知障碍。因此，加速去除异常 tau 蛋白的策略有望预防 tau 蛋白病。细胞蛋白质质量控​​制 (PQC) 途径（包括分子伴侣）已被证明可以通过控制 tau 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 tau 蛋白和易于聚集的 tau 蛋白？哪些陪伴人员和辅助陪伴人员对于分诊决策至关重要？在 tau 降解的最早阶段，哪些分子事件至关重要？该项目的主要目标是了解 PQC 的分子伴侣和其他成分如何决定降解 tau 及其变体。初步证据表明，热休克蛋白 Hsp70 和 Hsp90 与一些相关的共伴侣结合，检测易于聚集的 tau 蛋白的出现，然后做出分类决定以去除这些蛋白。基于这些研究，我们假设伴侣和辅助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目标：（1）对正常、循环的 tau 蛋白和被蛋白酶体降解敏锐靶向的 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 Hsp40 共伴侣是否选择性地将 Hsp70 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-蛋白酶体途径触发 tau 蛋白的快速（约 10 分钟）和剧烈（约 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。我们建议，由于它们异常快速的活性，这些化学探针将首先允许 时间，深入了解降解 tau 蛋白“决定”的最早阶段。因此，我们期望这些 目标将深入了解伴侣复合物如何区分 tau 变体，以及蛋白质质量控​​制成分如何穿梭异常 tau 进行降解。这项工作的长期目标是通过了解控制 tau 蛋白转换的关键途径，找到治疗 AD 和其他 tau 蛋白病的新方法。