IMPACTS OF GLIAL LIPID DROPLETS ON OXIDATIVE STRESS AND NEURODEGENERATION IN ALZHEIMER'S DISEASE

项目摘要 目前，约570万美国人患有阿尔茨海默病（AD），这对美国人来说是一个巨大的负担。 社会和我们的医疗体系。尽管长期以来人们都知道AD涉及异常的 Aβ42斑块和神经纤维缠结（NFT;由过度磷酸化的Tau组成）a的蓄积 对AD的成功治疗还有待确定。成功的治疗方法可能涉及识别 AD风险患者和疾病发作前的早期干预。积累的数据支持早期事件， 可能导致AD发作的因素包括活性氧（ROS）的异常上调， 脂质代谢失调。这些特征似乎是不相关的，直到我们最近发现 升高神经元内的ROS会诱导过氧化脂质的形成，这些脂质从神经元转移到神经元。 神经元到周围的胶质细胞。在神经胶质细胞内，这些脂质形成LD，并可能被分解。抑制这种 过程驱动ROS诱导的神经毒性。在慢性神经元ROS期间，胶质细胞变得充斥着LD， 死亡，留下脆弱的神经元。这种途径在苍蝇和小鼠中是保守的，并有支持性的人类数据。 目前，我们正在揭示胶质LD形成在AD中的潜在作用。果蝇的初步数据 GWAS定义为AD风险因子的基因汇聚到神经胶质LD形成途径。 ABCA转运蛋白ABCA 1和ABCA 7在应激神经元中是胶质LD形成所必需的，可能是 过氧化脂质的输出。此外，四个基因-LRP 1，PICALM，CD 2AP和AP 2A 2-在神经胶质中是必需的， 可能是为了摄取过氧化脂质。我们还发现，疾病基因Tau在神经胶质细胞中是必需的， LD形成。最后，初步和已发表的数据支持，破坏胶质LD的形成可能会驱动 细胞外Aβ42积聚、NFT形成和疾病。总的来说，我们假设胶质LD的形成 是一个早期事件，减弱了健康大脑中升高的ROS， 在AD中有缺陷。基于我们目前的数据，我们将定义胶质LD形成的潜在贡献 ROS诱导的神经变性、不溶性Aβ42积聚和NFT形成的缺陷。目标1将调查 AD风险基因和AD相关变异体在ROS升高时参与胶质LD形成 神经元使用新的人源化苍蝇模型。目的2将重点放在Tau作为胶质LD的潜在介质 在新的和已建立的果蝇模型中形成，定义人Tau亚型和突变的不同影响， 以及评估神经胶质LD形成中的缺陷是否可有助于Tau的磷酸化/聚集。最后， 目标3将探索哺乳动物系统中果蝇的定义机制。一开始，一只老鼠 神经元：胶质细胞共培养模型，可以测量从应激神经元到胶质细胞的脂质转移及其 将使用累积到神经胶质LD中来测试AD风险基因和Tau是否可以介导该过程。此外，本发明还 将对死后AD组织进行病理学研究，以确定LD 存在和疾病特征（例如Aβ42斑块、NFT、疾病严重程度和存在AD风险变体）。

PROJECT SUMMARY Currently, ~5.7 million Americans live with Alzheimer’s disease (AD), representing a significant burden on society and our healthcare system. Despite long-standing knowledge that AD involves the aberrant accumulation of Aβ42-plaques and neurofibrillary tangles (NFT; composed of hyperphosphorylated Tau) a successful treatment for AD has yet to be defined. Successful therapies will likely involve the identification of AD-risk patients and early intervention prior to disease onset. Accumulating data support that early events that may contribute to AD-onset include the abnormal upregulation of reactive oxygen species (ROS) and dysregulation of lipid metabolism. These features were seemingly disconnected until we recently discovered that elevating ROS within neurons induces the formation of peroxidated lipids, which are transferred from the neurons to surrounding glia. Within glia, these lipids form LD and are, presumably, resolved. Inhibiting this process drives ROS-induced neurotoxicity. During chronic neuronal ROS, glia become overrun with LD and die, leaving the neurons vulnerable. This pathway is conserved in flies and mice, with supportive human data. Currently, we are uncovering the potential role of glial LD formation in AD. Preliminary data in Drosophila demonstrate that genes defined as risk factors for AD by GWAS converge onto the glial LD formation pathway. ABCA transporters, ABCA1 and ABCA7, are required in stressed neurons for glial LD formation, likely for the export of peroxidated lipids. Further, four genes – LRP1, PICALM, CD2AP, and AP2A2 – are required in glia, likely for the uptake of peroxidated lipids. We also found that the disease gene, Tau, is required within glia for LD formation. Last, preliminary and published data support that disrupting glial LD formation may drive extracellular Aβ42 accumulation, NFT formation, and disease. Overall, we hypothesize that glial LD formation is an early event that attenuates elevated ROS in healthy brains and this process becomes prematurely defective in AD. Building upon our current data, we will define potential contributions of glial LD formation defects on ROS-induced neurodegeneration, insoluble Aβ42 buildup, and NFT formation. Aim 1 will investigate AD-risk genes and AD-associated variants for involvement in glial LD formation during elevated ROS in neurons using novel humanized fly models. Aim 2 will focus on Tau as a potential mediator of glial LD formation in novel and established fly models, defining differing impacts of human Tau isoforms and mutations, and assessing if defects in glial LD formation can contribute to the phosphorylation/ aggregation of Tau. Last, Aim 3 will explore defined mechanisms from flies in mammalian systems. Initially, an established rat neuron:glia co-culture model that can measure lipid transfer from stressed neurons to glia and their accumulation into glial LD will be used to test if AD-risk genes and Tau can mediate this process. Further, pathological studies will be performed on post-mortem AD tissue to determine correlations between LD presence and disease features (e.g. Aβ42-plaques, NFT, disease severity, and presence of AD-risk variants).