Genetic models of sporadic Alzheimers Disease in the marmoset

摘要 这个项目的长期目标是开发、表征和验证转基因绒猴 散发性阿尔茨海默病（AD）的模型，将作为研究分子和细胞的工具， 疾病机制，并确定治疗目标。AD是痴呆症最常见的原因， 大多数病例（~95%）似乎是散发性的，这是由以下因素之间的复杂相互作用引起的： 多种基因变异和环境因素。已经开发了许多AD模型（例如，mice）; 这些模型主要集中在家族性AD， 了解AD，但他们未能概括分子，细胞，行为和认知的全谱 在AD中观察到的病理学，并且当试图将发现转化为人类时， 临床试验几条证据表明，绒猴可能有效地弥合小鼠之间的差距 和人类的基础和转化神经科学研究。首先，绒猴和人类 相似的大脑结构、认知/社会行为、新陈代谢和免疫功能。第二、 与其他灵长类动物相比，绒猴寿命短，体型小，繁殖能力强。 最后，基因编辑工具现在可用于生成各种类型的转基因绒猴。 载脂蛋白E（APOE）是迟发性、散发性AD最强的危险因素，也会增加年龄， 单基因家族性AD与女性AD发病率相关风险。有三个APOE等位基因， 具有赋予风险增加的APOE*ε4等位基因和赋予风险降低的APOE*ε2等位基因的人 相对于常见的APOE*ε3等位基因。APOE亚型差异调节淀粉样β（Aβ）依赖性 和Aβ非依赖性途径影响脑内稳态，包括tau介导的神经变性， 小胶质细胞炎症、脂质转运、突触完整性、葡萄糖代谢和脑血管功能。 这三种APOE等位基因在位置112和114的半胱氨酸（C）和精氨酸（R）氨基酸方面不同。 158（APOE 2中的C112/C158; APOE 3中的C112/R158;和APOE 4中的R112/R158）。若干条证据 证明R61对APOE 4介导的AD风险至关重要。绒猴APOE（mAPOE）是由一个 一个等位基因，含有R112和R158的等价物，但缺乏关键的R61等价物（它含有T 相反，这表明它的行为与人类APOE 3相似。为了验证这一假设，mAPOE T61 R突变蛋白 以测试对小胶质细胞中脂多糖诱导的炎症反应的影响。 与野生型mAPOE相比，mAPOE T61 R变体导致更稳健的应答。类似的结果 当使用人APOE 4时，发现（APOE 4> APOE 3）。综合来看，这些初步结果 表明mAPOE T61 R在功能上等同于人APOE 4。此外，几对CRISPR 已经鉴定了用于产生APOE无效突变的gRNA。研究APOE在 将产生并表征绒猴、APOE缺失和T61 R突变绒猴中的散发性AD。

Abstract The long-term goal of this project is to develop, characterize, and validate genetically modified marmoset models of sporadic Alzheimer's Disease (AD) that will serve as tools for investigating molecular and cellular disease mechanisms, and for identifying therapeutic targets. AD is the most common cause of dementia, with the majority of cases (~95%) appearing to be sporadic, which is caused by complex interactions between multiple gene variants and environmental factors. Numerous models of AD have been developed (e.g., mice); these models are primarily focused on familial forms of AD and have enabled significant progress toward understanding AD, but they fail to recapitulate the full spectrum of molecular, cellular, behavioral, and cognitive pathologies observed in AD and provide poor predictive value when trying to translate findings to human clinical trials. Several lines of evidence suggest that marmosets may effectively bridge the gap between mice and humans for both basic and translational neuroscience research. First, marmosets and humans have very similar brain structures, cognitive/social behavioral repertoires, metabolism, and immune functions. Second, compared to other primates, marmosets have short lifespan, small body size, and high reproductive power. Finally, gene editing tools are now available to generate various types of genetically modified marmosets. Apolipoprotein E (APOE) is the strongest risk factor for late-onset, sporadic AD and also increases the age- dependent risk of monogenic familial AD and incidence of AD in women. There are three APOE alleles in humans with the APOE*ε4 allele conferring increased risk and the APOE*ε2 allele conferring decreased risk relative to the common APOE*ε3 allele. APOE isoforms differentially modulate both amyloid-β (Aβ)-dependent and Aβ-independent pathways to affect brain homeostasis, including tau-mediated neurodegeneration, microglial inflammation, lipid transport, synaptic integrity, glucose metabolism and cerebrovascular function. These three APOE alleles differ with regard to cysteine (C) and arginine (R) amino acids at positions 112 and 158 (C112/C158 in APOE2; C112/R158 in APOE3; and R112/R158 in APOE4). Several lines of evidence demonstrate that R61 is critical for APOE4-mediated AD risk. Marmoset APOE (mAPOE) is encoded by a single allele and contains the equivalent of R112 and R158, but lacks the critical R61 equivalent (it contains T instead), suggesting that it behaves like human APOE3. To test this hypothesis, mAPOE T61R mutant protein was generated to test the effect on inflammatory responses induced by lipopolysaccharides in microglial cells. The mAPOE T61R variant resulted in a more robust response compared to wild type mAPOE. Similar results were found when human APOE4 was used (APOE4>APOE3). Taken together, these preliminary results indicate that mAPOE T61R is functionally equivalent to human APOE4. Further, several pairs of CRISPR gRNAs for generating an APOE null mutation have been identified. To investigate the role of APOE in sporadic AD in the marmoset, APOE null and T61R mutant marmosets will be generated and characterized.