Mechanism of VCP interaction and processing of neurodegenerative tau fibrils

VCP相互作用和神经退行性tau原纤维加工的机制

• 批准号: 10463018
• 负责人: Benjamin Creekmore
• 金额: $ 5.18万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10463018
• 关键词: 26S proteasome; ATP phosphohydrolase; Affect; Alzheimer' s Disease; Autophagocytosis; Autopsy; Binding; Binding Proteins; Brain; Cell physiology; Cells; Clinical; Complex; Cryo-electron tomography; Cryoelectron Microscopy; Data; Dementia; Development; Disease; Disease Progression; Drug Targeting; Equilibrium; Excision; Fluorescence; Functional disorder; Goals; Homeostasis; Hybrids; Image; Impaired cognition; In Vitro; Individual; Label; Light; Link; Mediating; Membrane; Methods; Microscopy; Mitochondria; Modeling; Molecular Conformation; Mutation; Nerve Degeneration; Neurodegenerative Disorders; Pathology; Patients; Play; Protein Region; Proteins; Proteome; Recombinants; Regulation; Role; Structure; Tauopathies; Testing; Therapeutic; Time; Ubiquitin; Ubiquitination; cofactor; corticobasal degeneration; insight; link protein; monomer; mutant; neurotoxicity; particle; protein complex; protein function; proteostasis; reaction rate; stoichiometry; tau Proteins; tau aggregation; tau interaction; trafficking; valosin containing protein mutation; valosin-containing protein

Project Summary The goal of this proposal is to study the structure and dynamics of the interaction of the AAA+ ATPase, valosin-containing protein (VCP) with disease-relevant tau fibrils to determine VCP-mediated disease progression and therapeutic potential. Alzheimer's Disease (AD) and Corticobasal degeneration (CBD) are 2 of more than 20 “tauopathies” characterized by different forms of fibrillar tau aggregates. The degree of tau pathology on autopsy correlates with cognitive decline, yet the mechanism of neurotoxicity, disease development, and disease progression in tauopathies remains to be elucidated. Diseases of aggregation indicate a dysfunction in proteostasis – the regulation and balance of the proteome. VCP plays an essential role in proteostasis by removing proteins from complexes, membranes, and aggregates such as those formed by fibrillar tau, thus pointing to VCP as an important player in proteostatic dysfunction and as a potential drug target for tauopathies. VCP has a variety of cofactors that enable it to perform an array of vital cellular. Ufd1 and Npl4 cofactors (UN) together specifically enable VCP to recognize poly-ubiquitinated substrates. AD tau fibrils have high rates of ubiquitination, likely because cells have marked these fibrils for removal by proteins such as VCP. Additionally, mutations within VCP are linked to neurodegenerative disease. A hypoactive VCP mutation first described by the Edward Lee lab clinically presents as dementia and has been shown to promote tau fibril pathology. The hypoactive VCP mutation is thought to reduce VCP function causing the accumulation of tau fibrils, leading to neurodegenerative disease. However, a similar mechanism of VCP inadequately clearing tau fibrils may be present in cases of sporadic tauopathies. VCP/UN, mutant or wild-type, may also get stuck on tau fibrils (possibly due to fibrils' high stability) and be unable to break down the fibril or be released, reducing effective VCP function by trapping it on the fibril. This has been seen with a similar AAA+ ATPase in the 26S proteasome and neurodegenerative aggregates. I propose that for productive disaggregase activity VCP/UN binds unstructured ubiquitin at either end of tau fibrils then pulls off one tau monomer at a time. I also propose the mechanism of action will not change but the stoichiometry and rate of reaction will change between tau fibrils due to differences in fibril structure and ubiquitination. To test this model, in Aim 1 I will structurally characterize how VCP/UN interacts with brain- derived AD and CBD tau fibrils. Structurally understanding how VCP/UN interacts with tau fibrils will help elucidate the protein regions that are crucial to VCP/UN function, and knowing how this interaction changes with fibril type will help understand the generalizability of the VCP/UN fibril interaction. In Aim 2, I will characterize the dynamics of the VCP/UN-tau interaction. Understanding the dynamics of VCP/UN interaction with these fibrils will further elucidate the mechanism of VCP/UN in relation to disease-relevant tau fibrils.

项目概要 该提案的目标是研究 AAA+ ATPase 相互作用的结构和动力学， 含缬洛新蛋白 (VCP) 和疾病相关 tau 原纤维以确定 VCP 介导的疾病 阿尔茨海默病（AD）和皮质基底节变性（CBD）是其中的两种。 超过 20 种以不同形式的纤维状 tau 蛋白聚集为特征的“tau蛋白病”。 尸检病理学与认知能力下降相关，但神经毒性、疾病的机制 tau蛋白病的发生和疾病进展仍有待阐明。 表明蛋白质稳态功能障碍——VCP 的调节和平衡至关重要。 通过从复合物、膜和聚集体（例如形成的聚集体）中去除蛋白质，在蛋白质稳态中发挥作用 纤维状 tau 蛋白，因此表明 VCP 是蛋白质抑制功能障碍的重要参与者，也是一种潜在的药物 tau蛋白病的目标。 VCP 具有多种辅助因子，使其能够执行一系列重要的细胞功能。 辅助因子 (UN) 共同使 VCP 能够识别 AD tau 原纤维具有的多聚泛素化底物。 高泛素化率，可能是因为细胞标记了这些原纤维，以便通过 VCP 等蛋白质去除。 此外，VCP 内的突变首先与神经退行性疾病相关。 Edward Lee 实验室描述的临床表现为痴呆症，并已被证明会促进 tau 纤维的形成 病理学上，VCP 突变被认为会降低 VCP 功能，导致 tau 蛋白积聚。 然而，VCP 的类似机制不足以清除 tau 蛋白。 原纤维可能存在于散发性 tau蛋白病（突变型或野生型）中，也可能被卡住。 tau 原纤维（可能是由于原纤维的高稳定性）并且无法分解原纤维或被释放，从而减少 通过将其捕获在原纤维上来发挥有效的 VCP 功能 这已在 26S 中的类似 AAA+ ATP 酶中观察到。 蛋白酶体和神经退行性聚集体。 我建议，为了实现高效的解聚酶活性，VCP/UN 在两端结合非结构化泛素。 然后，tau 原纤维一次脱落一个 tau 单体，我还认为作用机制不会改变，但会发生变化。 由于原纤维结构和结构的差异，tau 原纤维之间的化学计量和反应速率会发生变化。 为了测试这个模型，在目标 1 中，我将从结构上描述 VCP/UN 如何与大脑相互作用。 衍生的 AD 和 CBD tau 原纤维在结构上了解 VCP/UN 如何与 tau 原纤维相互作用将有所帮助。 阐明对 VCP/UN 功能至关重要的蛋白质区域，并了解这种相互作用如何变化 纤维类型将有助于理解 VCP/UN 纤维相互作用的普遍性。在目标 2 中，我将。 描述 VCP/UN-tau 相互作用的动态特征 了解 VCP/UN 相互作用的动态。 对这些原纤维的研究将进一步阐明 VCP/UN 与疾病相关 tau 原纤维相关的机制。