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

描述（由申请人提供）：阿尔茨海默病的神经病理学特征的特征在于脑和血管系统中存在不溶性淀粉样蛋白沉积物、tau的异常磷酸化和聚集形式的神经元内积累、微管结合蛋白和神经元损失。虽然产生这些病理变化的确切机制仍然未知，淀粉样蛋白级联假说指出，肽（A？）淀粉样蛋白沉积物是疾病过程的原因。尽管有许多支持性研究，AD动物模型和AD人类之间的差异仍然是完全接受A？作为AD的主要致病因素。通过改变小鼠大脑中的一氧化氮，我们已经产生了一种新的小鼠模型，为小鼠与人类的差异提供了独特的见解。我们的双基因小鼠模型的AD增加人类A？小鼠一氧化氮合酶2（NOS2）敲除背景。由此产生的表型是高度联想到的病理学观察到的人类与AD，包括高水平的A？肽、tau过度磷酸化、tau再分布和tau聚集、神经元损失和行为缺陷。APPSw/N0S2-/-小鼠的主要优点是从正常而非突变的tau形成tau病理学，并且存在显著的神经元损失。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慢性疾病的条件下。第一个目的是通过测量A？来确认APPSw/NOS 2-/-小鼠脑中的病理级联反应，在特定年龄的APPSw/N0S2-/-小鼠脑中的tau病理学、神经元损失以及记忆和学习。建立一个直接的，因果关系的作用，为A？肽的级联，我们建议a）减少A？通过被动免疫在APPSw/NOS 2-/-小鼠脑中的水平，和B）增加A？NOS 2-/-小鼠海马内注射A？肽混合物。第二个目标是研究NOS2的作用。我们提出a）使用小干扰RNA的慢病毒递送（shNOS 2慢病毒）来减少脑iNOS蛋白B）以测试NOS 2和NO替代改变由A？介导的病理级联的能力。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。公共卫生相关性：该项目将研究淀粉样前体蛋白衍生的A β肽在产生与慢性神经退行性疾病（如阿尔茨海默病）相关的神经病理学中的作用。所使用的方法将涉及潜在治疗价值的新型小鼠模型的产生，并将提供一个有用的工具，以充分研究在临床前阶段的治疗。

DESCRIPTION (provided by applicant): 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 (A?) 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 A? 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 A? 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 A? 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 A?, tau pathology, neuronal loss and memory and learning in the APPSw/NOS2-/- mice brains at specific ages. To establish a direct, causal role for A? peptides in the cascade, we propose a) to reduce A? levels in the brains of APPSw/NOS2-/- mice by passive immunization and b) to increase A? levels in the brains of NOS2-/- mice using intrahippocampal injection of A? 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 A?. The third aim will examine a likely mechanism of NO's action, the regulation of caspase activity. PUBLIC HEALTH RELEVANCE: This project will examine the role of A beta peptides derived from the amyloid precursor protein in generating the neuropathology associated with chronic neurodegenerative diseases such as Alzheimer's disease. The method used will involve the generation of a novel mouse model for potential therapeutic value and will provide a useful to tool to fully investigate therapeutics in the pre-clinical stage.