The amyloid cascade in a novel mouse model of Alzheimer's disease

阿尔茨海默病的神经病理学特征是不溶性淀粉样蛋白的存在 在脑和血管系统中的沉积，异常磷酸化的神经元内积累， 以及聚集形式的tau、微管结合蛋白和神经元损失。虽然确切的机制 产生这些病理变化的原因尚不清楚，淀粉样蛋白级联假说指出， 构成淀粉样蛋白沉积物的肽（Ass）是疾病过程的原因。尽管多次 支持性研究，AD动物模型和AD患者之间的差异仍然是研究的障碍。 完全接受Ass作为AD的主要致病因子。通过改变老鼠大脑中的一氧化氮， 产生了一种新的小鼠模型，提供了独特的见解，小鼠与人类的差异。我们的双基因 AD小鼠模型增加了鼠一氧化氮合酶2（NOS 2）上人Ass的表达 有着出众的背景。所得的表型高度地使人联想到在患有糖尿病的人类中观察到的病理学。 AD包括高水平的Ass肽、tau过度磷酸化、tau再分布和tau聚集， 神经元缺失和行为缺陷。APPSw/N 0 S2-/-小鼠的主要优点是形成 tau病理学与正常的、未突变的tau和存在显著的神经元损失有关。因此，我们的模型 提供了一个独特的机会，充分测试淀粉样蛋白级联假说在体内条件下的慢性 疾病第一个目标将通过测量APPSw/NOS 2-/-小鼠脑中的病理级联反应来证实。 在特定年龄的APPSw/N 0 S2-/-小鼠脑中的Ass、tau病理学、神经元损失以及记忆和学习。 为了确定Ass肽在级联反应中的直接因果作用，我们提出a）降低Ass水平， 和B）通过被动免疫增加NOS 2-/-小鼠脑中的Ass水平 使用海马内注射Ass肽混合物的小鼠。第二个目标是研究NOS 2的作用。 我们提出a）使用小干扰RNA（shNOS 2）的慢病毒递送来减少脑iNOS蛋白 慢病毒）B）以测试NOS 2和NO替代改变由Ass. 第三个目标将检查NO的作用的可能机制，半胱天冬酶活性的调节。

The neuropathological features of Alzheimer's disease are characterized by the presence of insoluble amyloid deposits in the brain and cerebrovasculature, the intra-neuronal accumulation of abnormally phosphorylated and aggregated forms of tau, a microtubule binding protein and neuronal loss. Although the exact mechanisms producing these pathological changes remain unknown, the amyloid cascade hypothesis states that the peptides (Ass) that make up amyloid deposits are the cause of the disease process. Despite numerous supportive studies, discrepancies between animal models of AD and humans with AD remain an obstacle for full acceptance of Ass as the primary causal agent for AD. By altering the nitric oxide in mouse brain, we have generated a novel mouse model that provides unique insights into mouse-human differences. Our bigenic mouse models of AD increase the expression of human Ass on a murine nitric oxide synthase 2 (NOS2) knockout background. The resulting phenotype is highly reminiscent of the pathology observed in humans with AD including high levels of Ass peptides, tau hyperphosphorylation, tau redistribution and tau aggregation, neuronal loss and behavioral deficits. A primary advantage of the APPSw/NOS2-/- mouse is the formation of tau pathology from normal, not mutated tau AND the presence of significant neuronal loss. Thus, our model provides a unique opportunity to fully test the amyloid cascade hypothesis in vivo under conditions of chronic disease. The first aim will confirm a pathological cascade in the APPSw/NOS2-/- mouse brain by measuring Ass, tau pathology, neuronal loss and memory and learning in the APPSw/NOS2-/- mice brains at specific ages. To establish a direct, causal role for Ass peptides in the cascade, we propose a) to reduce Ass levels in the brains of APPSw/NOS2-/- mice by passive immunization and b) to increase Ass levels in the brains of NOS2-/- mice using intrahippocampal injection of Ass peptide mixtures. The second aim will examine the role of NOS2. We propose a) to reduce brain iNOS protein using lentivirus delivery of small interfering RNA (shNOS2 lentivirus) b) to test the ability of NOS2 and NO replacement to alter the pathological cascade mediated by Ass. The third aim will examine a likely mechanism of NO's action, the regulation of caspase activity.