Alzheimer Mouse Model for Intraneuronal Amyloid-Beta Oligomer Biology

描述(由申请人提供)： 最近，许多注意力转向了所谓的“低聚”形式的淀粉样β多肽(A？)的研究，这些研究可能是阿尔茨海默病中痴呆的关键介质。我们选择利用荷兰A？形成寡聚体的倾向，通过在Thy1启动子(Thy1-荷兰APPE693Q转基因小鼠系)上过表达荷兰APP来创建一个研究神经源性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Thy1-荷兰APPE693Q小鼠的初步特征中，我们观察到了与年龄相关的认知能力下降和一些可量化的神经病理变化。然而，在我们的手中，Thy1-APPE693Q小鼠在其一生中从未出现任何类型的实质淀粉样沉积；然而，免疫可检测到的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。为了产生A？组织病理学，我们将Thy1-荷兰APPE693Q小鼠与家族性阿尔茨海默病突变体早老素缺失外显子9(PS1.9)杂交。PS1的这种致病突变形式提高了A？42的水平，从而导致双基因小鼠形成斑块(这些小鼠被命名为Thy1-Dutch APPE693Q x PS1.9 Bigenics)。然而，虽然突变的PS1会导致斑块的形成，但淀粉样斑块的出现对认知能力下降的时间进程或最初的严重程度没有明显的影响。综上所述，我们观察到：(1)在单一的荷兰APP转基因小鼠和双基因PS/APP小鼠中，神经元内APP/A衍生物的积累；(2)荷兰CAA的积累。为了实现这一优点，我们提议根据性别和不同年龄对单个荷兰APP转基因小鼠和双基因PS/APP小鼠的寿命进行定量鉴定，方法包括：(A)评估在Morris水迷宫中的行为表现和空间学习和记忆的抑制回避模型；(B)量化大脑中APP、1和2个CTF、A？40、A？42、A？寡聚体和突触素的水平；(C)APP-A？样免疫反应活性的亚细胞定位，包括荷兰CAA；(D)定量形态计量学，以确定海马神经元群体的完整性和估计神经元内A？负担。获得受低聚物损害且从不形成淀粉样斑块的小鼠品系，将极大地促进体内有效性筛选的构建，以寻找治疗阿尔茨海默病的抗低聚物药物。 公共卫生相关性： 大多数活着的二战退伍军人(1983年估计超过1000万人)现在都超过85岁了，其中一半可能患有阿尔茨海默氏症。参加伊拉克自由行动/持久自由行动的退伍军人创伤后脑损伤痴呆症的发病率和流行率很高(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的小鼠模型的建立成为可能。基因指向了蛋白质变体，称为寡聚体(Klyubin等人，2008；Shankar等人，2008)，我们正在寻求测试寡聚体的水平是否与行为病理的严重程度相关。如果得到证实，那么这些形成低聚物的小鼠模型将对开发抗低聚物药物具有重要意义，这些药物可能有助于治疗、延迟或预防与阿尔茨海默氏症和/或脑外伤后痴呆相关的痴呆。

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.