The role of cell death pathways in mediating neuronal loss during the earliest stages of Alzheimer disease

摘要 本K 01提案的目的是为我提供必要的指导培训，使我成为一名 独立研究员研究细胞死亡途径的作用，介导个体的神经元损失 阿尔茨海默病（AD）。神经元死亡是AD的一个重要特征，也是认知障碍的最佳相关因素 和痴呆症，神经系统缠结（NFT）病理是第二大风险因素。目前未知 哪些机制促进早期AD中的神经元死亡或这些机制如何与NFT联系。研究 AD死后的大脑已经证明了半胱天冬酶介导的细胞死亡途径的激活，以及 泛素-蛋白酶体（UPS）介导的蛋白水解的破坏。本建议的总体目标是 研究半胱天冬酶、缺陷型UPS介导的tau蛋白抑制和NFT病理学之间的相互作用， 介导人脑干的两个核中的AD神经元损失，显示出对NFT的最早脆弱性： 中缝背核（DRN）和蓝斑（LC）。我们将利用一个独特的收集，以及- 在AD各阶段表征人脑，特别是富含早期AD脑样品， 人源性神经元培养模型，用于半胱天冬酶激活、tau蛋白的机制的后续研究 毒性和细胞死亡。我的中心假设是，AD中的神经元功能障碍和随后的死亡是 介导的半胱天冬酶切割的tau和有缺陷的UPS tau清除之间的不平衡。我来测试一下 通过追求以下具体目标的假设：（1）确定caspase之间的关系 激活，半胱天冬酶切割的tau蛋白和神经元死亡的进展阶段的AD（2）检查的作用， 半胱天冬酶、UPS和辅助分子伴侣CHIP（Hsc 70相互作用蛋白的C末端）在 介导AD进展阶段的神经元死亡和NFT病理。(3)确定的作用 caspase激活、泛素-蛋白酶体系统和CHIP介导神经元死亡和tau蛋白 病理学与患者来源的神经元细胞培养物。这一提议意义重大，因为它将产生一个 细胞死亡机制和蛋白酶体系统在介导早期 AD中的神经元死亡和NFT。这一建议是创新的，因为针对早期细胞死亡的干预措施 AD中的通路将促进新的生物标志物和治疗靶点的开发。UCSF和 格莱斯顿研究所是我所提议的培训的理想环境，因为他们提供了出色的研究 设施，培训资源和优秀的导师在我们的科学界随时可用。 完成拟议的研究和职业发展活动将为R 01的发展提供信息 建议对AD中活性细胞死亡标志物的分子谱进行独立研究 使用蛋白质组学分析。我们的研究结果可以为预防疾病的修订模型的实验策略提供信息。 在认知改变出现之前，预防AD的发病，从而减少经济和社会负担， 伴随着AD。

ABSTRACT The purpose of this K01 proposal is to provide me with the necessary mentored training to become an independent investigator studying the role of cell death pathways that mediate neuronal loss in individuals with Alzheimer's disease (AD). Neuronal death is a key feature of AD and the best correlate of cognitive impairment and dementia, with neurofibrillary tangle (NFT) pathology being the next-best risk factor. It is currently unknown which mechanisms promote neuronal death in early AD or how these are linked to NFTs. Studies in postmortem AD brains have demonstrated the activation of caspase-mediated cell death pathways, as well as disruption of ubiquitin-proteasome (UPS)-mediated proteolysis. The overall objective of this proposal is to study the interplay between caspases, defective UPS-mediated tau proteostasis and NFT pathology in mediating AD neuronal loss in two nuclei of the human brainstem showing the earliest vulnerability to NFTs: the dorsal raphe nucleus (DRN) and locus ceruleus (LC). We will make use of a unique collection of well- characterized human brains across the AD stages, specifically enriched with early AD brain samples, and a human-derived neuronal culture model for follow-up studies on the mechanisms of caspase activation, tau toxicity and cell death. My central hypothesis is that neuronal dysfunction and subsequent death in AD is mediated by an imbalance between caspase-cleaved tau and defective UPS tau clearance. I will test this hypothesis by pursuing the following specific aims: (1) Determine the relationship between caspase activation, caspase-cleaved tau and neuronal death in progressive stages of AD (2) Examine the role of caspases, the UPS and the co-chaperone CHIP (C terminus of the Hsc70-interacting protein) in mediating neuronal death and NFT pathology in progressive stages of AD. (3) Determine the role of caspase activation, the ubiquitin-proteasome system and CHIP in mediating neuronal death and tau pathology to patient-derived neuronal cell culture. This proposal is significant because it will generate a precise map of the interaction between cell death mechanisms and the proteasome system in mediating early neuronal death and NFTs in AD. This proposal is innovative because interventions targeting early cell death pathways in AD will promote the development of novel biomarkers and therapeutic targets. UCSF and the Gladstone Institute are ideal environments for my proposed training as they provide outstanding research facilities, training resources and excellent mentorship readily available within our scientific community. Completion of the proposed research and career development activities will inform the development of an R01 proposal for conducting independent research on the molecular profiles of the active cell death markers in AD using proteomic analyses. Our findings could inform experimental strategies on revised models for preventing AD pathogenesis before the cognitive changes appear, thus decreasing the economic and societal burden that accompanies AD.