Alzheimer Mouse Model for Intraneuronal Amyloid-Beta Oligomer Biology

描述（由申请人提供）： 最近，很多注意力转向了所谓的“寡聚”形式的淀粉样β肽（A？）作为阿尔茨海默病痴呆症的可能关键介质的研究。我们选择利用Dutch A？形成寡聚体的倾向，通过在Thy 1启动子上过表达Dutch APP（Thy 1-Dutch APPE 693 Q转基因小鼠系），创建神经源性A？寡聚体的生化病理学、神经病理学和行为病理学的转基因小鼠模型。在这些Thy 1-Dutch APPE 693 Q小鼠的初步表征中，我们观察到了年龄依赖性认知下降和一些可量化的神经病理学变化。然而，在我们的手中，Thy 1-APPE 693 Q小鼠在其寿命期间从未发生任何类型的实质淀粉样蛋白沉积;然而，免疫可检测的A？寡聚体积累，并且这些寡聚体似乎定位于神经元内体-溶酶体系统。为了生成A？在组织病理学方面，我们将Thy 1- Dutch APPE 693 Q小鼠与缺乏外显子9的家族性阿尔茨海默病突变体早老素（PS19）杂交。PS1的这种致病突变形式提高了A42的水平，从而导致双基因小鼠中形成斑块（这些小鼠被命名为Thy 1-Dutch APPE 693 Q x PS1 9双基因小鼠）。然而，虽然突变型PS1导致斑块形成，但淀粉样蛋白斑块的出现对认知能力下降的时间进程或初始严重程度没有明显影响。 总之，我们注意到：（1）单个荷兰APP转基因和双基因PS/APP小鼠中神经元内APP/A？衍生物的蓄积;（2）荷兰CAA的蓄积。对于该MERIT应用，我们建议根据性别和在其寿命期间的不同年龄对单个荷兰APP转基因和双基因PS/APP小鼠进行定量表征，使用（a）在Morris水迷宫和空间学习和记忆的抑制性回避模型中评估行为表现;（B）定量APP、1和2 CTF、A <$40、A <$42、A <$44和A <$46的脑水平。寡聚体和突触素;（c）APP-A？样免疫反应性的亚细胞定位，包括荷兰CAA;（d）定量形态测定，以确定海马神经元群体的完整性并估计神经元内A？负荷。 受寡聚体损害且从不发展淀粉样蛋白斑块的小鼠品系的可用性将极大地促进在寻找用于治疗阿尔茨海默病的抗寡聚体药物中构建体内功效筛选。 公共卫生相关性： 大多数活着的二战老兵（1983年估计超过1000万）现在已经超过85岁，其中一半可能患有阿尔茨海默病。伊拉克自由行动/持久自由行动的退伍军人具有创伤后脑损伤（TBI）痴呆的高发病率和患病率（Lew等人，2008年）。遗传学的进步使阿尔茨海默氏症基因的发现和阿尔茨海默氏症病理学小鼠模型的建立成为可能。基因指向蛋白质变体的方向，称为寡聚体（Klyubin等人，2008; Shankar等人，2008），并且我们正在寻求测试寡聚体的水平是否与行为病理学的严重性相关。如果得到证实，那么这些形成寡聚体的小鼠模型对于开发抗寡聚体药物将是重要的，这些药物可用于治疗、延迟或预防与阿尔茨海默氏症和/或TBI后痴呆相关的痴呆。

DESCRIPTION (provided by applicant): Recently, much attention has turned to the study of so-called "oligomeric" forms of the amyloid beta peptide (A¿) as possible key mediators of dementia in Alzheimer's disease. We have chosen to exploit the propensity of Dutch A¿ to form oligomers is order to create a transgenic mouse model of the biochemical pathology, neuropathology, and behavioral pathology of neuronally-derived A¿ oligomers by overexpressing Dutch APP on the Thy1 promoter (Thy1-Dutch APPE693Q transgenic mouse line). In preliminary characterization of these Thy1-Dutch APPE693Q mice, we have observed aging-dependent cognitive decline and a number of quantifiable neuropathological changes. However, in our hands, Thy1-APPE693Q mice never develop parenchymal amyloid deposits of any sort during their lifespan; however, immunodetectable A¿ oligomers accumulate, and these oligomers appear to be localized to the neuronal endosomal-lysosomal system. In order to generate A¿ histopathology, we have crossed the Thy1- Dutch APPE693Q mice with familial Alzheimer's mutant presenilin lacking exon 9 (PS1 9). This pathogenic mutant form of PS1 elevates levels of A¿42, thereby causing plaques to form in bigenic mice (these mice are designated Thy1-Dutch APPE693Q x PS1 9 bigenics). However, while the mutant PS1 causes plaques to form, the appearance of amyloid plaques has no obvious effect on the time course or initial severity of cognitive decline. In summary, we observe: (1) accumulation of intraneuronal APP/A¿ derivatives in single Dutch APP transgenic and bigenic PS/APP mice; and (2) accumulation of Dutch CAA. For this MERIT application, we propose to perform quantitative characterization of single Dutch APP transgenic and bigenic PS/APP mice, according to gender and at various ages over their lifespans, using (a) Assessment of behavioral performance in the Morris water maze and inhibitory avoidance models of spatial learning and memory; (b) Quantification of brain levels of APP, 1 and 2 CTFs, A¿40, A¿42, A¿ oligomers, and synaptophysin; (c) Subcellular localization of APP-A¿-like immunoreactivity, including Dutch CAA; (d) Quantitative morphometry to determine integrity of hippocampal neuronal populations and to estimate intraneuronal A¿ burden. The availability of lines of mice that are impaired by oligomers and never develop amyloid plaques would greatly facilitate the construction of in vivo efficacy screens in the search for anti- oligomer drugs for the treatment of Alzheimer's disease. PUBLIC HEALTH RELEVANCE: Most living veterans of World War II (estimated to be over 10 million in 1983) are now over 85 years old, and half of those veterans are probably suffering from Alzheimer's disease. Veterans of Operation Iraqi Freedom/Operation Enduring Freedom have a high incidence and prevalence of post traumatic brain injury (TBI) dementia (Lew et al., 2008). Advances in genetics have enabled the discovery of Alzheimer's genes and the creation of mouse models of Alzheimer's pathology. Genes point the way to protein variants, called oligomers (Klyubin et al., 2008; Shankar et al., 2008), and we are seeking to test whether levels of oligomers correlate with severity of behavioral pathology. If confirmed, then these mouse models that form oligomers will be important for the development of anti-oligomer drugs that could be useful in treating, delaying, or preventing the dementia associated with Alzheimer's and/or post-TBI dementia.