Astrocytic and microglial apoE in aging and AD

项目总结(APOE U19：项目3) 载脂蛋白E(ApoE)是晚发性阿尔茨海默病(AD)的主要遗传决定因素 与常见的APOE3等位基因相比，增加了风险，APOE2具有保护性。我们基于团队的工作 将研究一种新的ApoE级联假说(ACH)，它将揭示疾病机制和 为AD的未来治疗策略提供信息。在这里，项目3试图阐明不同的亚型 星形胶质细胞和小胶质细胞载脂蛋白E表现出不同的生化特性，影响其功能、聚集和 淀粉样蛋白-β(A-β)在衰老和AD发展过程中的代谢。除了星形胶质细胞，小胶质细胞 随着年龄的增长，在AD发病机制中，分泌丰富的脂化载脂蛋白E。与疾病相关的 小胶质细胞(DAM)在APOE不同AD小鼠模型中表现出保守的转录特征 是中枢枢纽基因之一。有趣的是，激活的小胶质细胞已经被证明可以诱导神经毒性。 (A1样)反应性星形胶质细胞在AD中的表达。然而，关于载脂蛋白E亚型介导的小胶质细胞- 星形胶质细胞的相互作用影响大脑功能和淀粉样蛋白病理。为了解决这些问题，我们有 建立了人APOE2、APOE3或APOE4基因特异表达的新型可诱导小鼠模型 表达于星形胶质细胞或小胶质细胞。在目标1中，我们将分析星形细胞或小胶质细胞载脂蛋白E的作用 衰老过程中认知功能、脂代谢、神经炎症和血管完整性的异构体。在AIM 2，我们将确定星形细胞或小胶质细胞载脂蛋白E亚型对脑功能、神经炎症和 淀粉样蛋白病理的发展。在目标3中，我们将确定载脂蛋白E亚型在星形胶质细胞中的作用- 衰老和淀粉样蛋白背景下小胶质细胞的相互作用及其与脑血管系统的关系 病理学。使用独特的小鼠模型和创新技术(即体内双光子成像和体内 ，我们将全面研究神经胶质细胞中的载脂蛋白E亚型如何对大脑认知做出贡献。 和淀粉样变性病理。更重要的是，将采用多学科方法，通过与 其他项目/核心：1)来自我们的鼠标模型的apoE粒子的属性将由项目1进行分析 和B核心；2)载脂蛋白E含量和AD相关流体生物标志物将通过D核心进行测量；3) 淀粉样蛋白病理和神经元炎症将通过Core C进行检查；4)我们的 可诱导的载脂蛋白E小鼠模型将使用多种组学方法(即蛋白质组学，代谢组学， 脂质组学和单细胞RNA测序)，结果通过核心F，G；5与人类研究相关联) 我们的数据可以与项目2和项目4的研究相比较，以进一步阐明细胞类型特异性的影响； 6)小鼠模型的发现可以用人iPSC来源的小胶质细胞/星形胶质细胞进一步验证 通过多学科团队和协同的专业知识和资源，我们将 共同了解衰老相关疾病和AD中载脂蛋白E相关的疾病机制。

PROJECT SUMMARY (APOE U19: Project 3) Apolipoprotein E (apoE) is a major genetic determinant of late-onset Alzheimer’s disease (AD) with APOE4 increases the risk and APOE2 being protective compared with common APOE3 allele. Our team-based work will investigate a novel ApoE Cascade Hypothesis (ACH) which will shed light on the disease mechanisms and inform future therapeutic strategies for AD. Here, Project 3 seeks to elucidate whether different isoforms of astrocytic and microglial apoE exhibit different biochemical properties that impact its function, aggregation, and the metabolism of amyloid-β (Aβ) during aging and AD development. In addition to astrocytes, microglia secrete abundant lipidated apoE with aging and in the context of AD pathogenesis. The disease-associated microglia (DAM) exhibit a conserved transcriptional signature across different AD mouse models with APOE being one of the central hub genes. Interestingly, activated microglia have been shown to induce neurotoxic (A1-like) reactive astrocytes in AD. However, little is known about whether apoE isoform-mediated microglia- astrocyte interaction affects brain functions and amyloid pathologies. To address these questions, we have generated novel inducible mouse models in which human APOE2, APOE3, or APOE4 gene is specifically expressed in astrocytes or microglia. In Aim 1, we will analyze the effects of astrocytic or microglial apoE isoforms on cognitive function, lipid metabolism, neuroinflammation, and vascular integrity during aging. In Aim 2, we will define the impacts of astrocytic or microglial apoE isoforms on brain function, neuroinflammation, and the development of amyloid pathology. In Aim 3, we will determine the role of apoE isoforms in astrocyte- microglia interaction and their association with cerebrovasculature during aging and in the context of amyloid pathology. Using unique mouse models and innovative technologies (ie., in vivo 2-photon imaging and in vivo microdialysis), we will comprehensively investigate how apoE isoforms in glia cells contribute to brain cognition and amyloid pathology. More importantly, multi-disciplinary approaches will be employed by interacting with other projects/cores: 1) The properties of apoE particles from our mouse models will be analyzed by Project 1 and Core B; 2) ApoE amounts and AD-related fluid biomarkers will be measured through Core D; 3) The amyloid pathologies and neuroninflammation will be examined by Core C; 4) The molecular phenotypes of our inducible apoE mouse models will be examined using multi-omics approaches (ie., proteomics, metabolomics, lipidomics and single cell RNA sequencing), with results correlating with human studies through Cores F, G; 5) Our data can be compared with studies from Projects 2 and 4 to further elucidate the cell type-specific effects; and 6) Findings from mouse models can be further validated using human iPSC-derived microglia/astrocyte models in Core E. Through multidisciplinary team with synergized expertise and resources, we will collaboratively understand the apoE-associated disease mechanisms in aging-related conditions and AD.