Project 1: Differential Roles of ApoE Isoforms in Neural Network Dysfunction of Alzheimer's Disease

项目1 -摘要 阿尔茨海默病（AD）的复杂性和多因素性对机制提出了独特的挑战。 研究和开发疗法。虽然AD的三大致病因素-淀粉样β肽， tau和载脂蛋白E4（apoE 4）-已经作为AD发病机制中的独立实体被广泛研究， 针对个体AD相关途径（如Ab产生或清除）的努力在人类中基本上失败， 审判新出现的证据有力地表明，AD是年龄依赖性神经网络的结果 主要影响认知的大脑区域功能障碍，可能是通过多种 致病因素因此，迫切需要在一个特定的时间内鉴定新的机制和治疗靶点。 神经网络水平和多个致病因素之间的相互作用的背景下，这一重点 提议 APOE 4编码人类apoE的三种主要亚型之一，是主要的遗传风险因素 AD，并以基因剂量依赖性方式降低发病年龄。在大多数临床研究中，APOE 4携带者 占AD病例的60-75%，突出了APOE 4在AD发病机制中的重要性。另一方面，在一项研究中， 许多临床和人群研究表明，编码最稀有的apoE亚型的APOE 2是一种强保护性的蛋白质， AD的遗传因素AD的病理学标志是形成神经元缠结（NFT）， 高度磷酸化的不溶性tau蛋白，包含3R和4 R tau亚型。在细胞培养和小鼠 模型中，apoE亚型具有tau依赖性差异效应，tau具有apoE亚型依赖性效应， 提示在AD发病机制中的相互作用。然而，几乎所有这些关于apoE亚型和tau蛋白的研究， 我的结论是基于小鼠tau蛋白，它几乎完全以4 R tau蛋白的形式存在，或者基于突变的人类tau蛋白， tau蛋白，它与额颞叶痴呆症有关，但与AD无关。在项目1中，我们建议确定细胞- apoE亚型在年龄依赖性神经网络功能障碍和行为障碍中的类型特异性差异作用 在野生型（WT）人tau（3R和4 R tau同种型）的背景下，在AD的新型小鼠模型中， 在目的1中，我们将确定apoE亚型在神经网络功能障碍和行为障碍中的不同作用， 缺陷，使用apoE同种型floxed敲入（APOEfE 2/fE 2 [fE 2]、APOEfE 3/fE 3 [fE 3]和APOEfE 4/fE 4 [fE 4]）小鼠 在不同年龄表达WT人tau（MAPT敲入或TAUWT）。在目标2中，我们将确定细胞类型- apoE亚型在神经网络功能障碍和行为缺陷中的特异性差异作用， 表达细胞类型特异性Cre重组酶（神经元特异性重组酶）的fE 2/TAUWT、fE 3/TAUWT和fE 4/TAUWT小鼠 Cresyn 1、星形胶质细胞特异性CreGFAP和小胶质细胞特异性CreCx 3cr 1），以删除细胞中的APOE等位基因。 特定类型的方式。该项目的研究以及该项目的其他三个项目的研究 项目赠款，将产生新的见解多因素发病机制的AD，并可能确定神经网络- 基于apoE亚型依赖性和细胞类型特异性疗法的靶点，以治疗或预防AD。

PROJECT 1 – SUMMARY The complexity and multifactorial nature of Alzheimer’s disease (AD) pose unique challenges for mechanistic studies and developing therapies. Although the three major pathogenic factors of AD—amyloid-beta peptides, tau, and apolipoprotein E4 (apoE4)—have been extensively studied as independent entities in AD pathogenesis, efforts to target individual AD-related pathways, such as Ab production or clearance, have largely failed in human trials. Emerging evidence strongly suggests that AD is a consequence of age-dependent neural network dysfunction in brain regions that mostly affect cognition, likely through the interactive effects of multiple pathogenic factors. Thus, there is a pressing need to identify novel mechanisms and therapeutic targets, at a neural network level and in the context of interactions between multiple pathogenic factors—the focus of this proposal. APOE4, which encodes one of the three major isoforms of apoE in humans, is the major genetic risk factor for AD and lowers the age of onset in a gene dose-dependent manner. In most clinical studies, APOE4 carriers account for 60–75% of AD cases, highlighting the importance of APOE4 in AD pathogenesis. On the other hand, many clinical and population studies show that APOE2, encoding the rarest apoE isoform, is a strongly protective genetic factor in AD. A pathological hallmark of AD is the formation of neurofibrillary tangles (NFTs) consisting of hyperphosphorylated, insoluble tau, containing both 3R and 4R tau isoforms. In cell cultures and mouse models, apoE isoforms have tau-dependent differential effects, and tau has apoE isoform-dependent effects, suggesting interactive roles in AD pathogenesis. However, almost all of these studies of apoE isoforms and tau drew conclusions based either on mouse tau, which is present almost exclusively as 4R tau, or on mutant human tau, which is associated with frontotemporal dementia but not AD. In Project 1, we propose to determine cell- type-specific, differential roles of apoE isoforms in age-dependent neural network dysfunction and behavioral deficits, in the context of wildtype (WT) human tau (both 3R and 4R tau isoforms), in novel mouse models of AD. In Aim 1, we will determine differential roles of apoE isoforms in neural network dysfunction and behavioral deficits, using apoE-isoform-floxed knock-in (APOEfE2/fE2 [fE2], APOEfE3/fE3 [fE3], and APOEfE4/fE4 [fE4]) mice expressing WT human tau (MAPT knock-in or TAUWT) at different ages. In Aim 2, we will determine cell-type- specific, differential roles of apoE isoforms in neural network dysfunction and behavioral deficits, using fE2/TAUWT, fE3/TAUWT, and fE4/TAUWT mice expressing cell-type-specific Cre recombinase (neuron-specific Cresyn1, astrocyte-specific CreGFAP, and microglia-specific CreCx3cr1) in order to delete the APOE allele in a cell- type-specific manner. The studies in this project, together with those of the three other projects of this program project grant, will yield new insights into the multifactorial pathogenesis of AD and may identify neural network- based targets for apoE isoform–dependent and cell type-specific therapies to treat or prevent AD.