The Subcellular Neuropathology of Alzheimer's Disease

描述（由申请人提供）：阿尔茨海默病（AD）的特征是大脑中13-淀粉样肽（AI3）的积累。AI3是通过13-淀粉样蛋白前体蛋白（APP）的调控裂解在细胞内产生的。我们建议在携带家族性AD （FAD）突变的转基因小鼠中研究AI3肽定位和随着年龄增长积累的亚细胞位点，以及这如何引发AD斑块病理。我们最近发现Al342定位于多泡体（MVBs），特别是在正常小鼠和AD转基因小鼠，以及大鼠和人脑中的AD易感锥体神经元中，但不存在于APP敲除小鼠的大脑中。由于我们之前的免疫组织化学研究表明，阿尔茨海默病发生在神经元内的AI342积累，我们建议使用免疫电镜和亚细胞分离方法，研究AI3斑块形成过程中AD转基因小鼠的脑组织，以证明AI340和AI342以及各种APP片段的数量和亚细胞分布的变化，以及远端神经元突和突触的变化。我们计划评估AI3肽的数量和亚细胞分布在不同年龄之前和时间，当斑块沉积已知发生在特定转基因AD小鼠研究；表达FAD瑞典670/671突变人类APP的Tg2576小鼠通常在大约11至13月龄时出现AI3斑块。此外，我们计划在培养的原代神经元中研究与mvb相关的AI3库的神经生物学和调控，并探讨神经元MVBs在衰老和AD发病过程中的变化。我们假设，随着MVBs外膜老化，AI342的积累和潜在聚集可能会干扰神经元过程中重要货物分子的正常运输。更好地了解发生在AD发病机制中的大脑神经元内的细胞和分子事件可能对开发更有效的基于分子的阿尔茨海默病治疗策略很重要。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) is characterized by the accumulation of 13-amyloid peptides (AI3) in the brain. AI3 is generated intracellularly by the regulated cleavage of the 13-amyloid precursor protein (APP). We propose to study the subcellular site(s) where AI3 peptides localize and accumulate with aging, and how this may initiate AD plaque pathology, in transgenic mice carrying familial AD (FAD) mutations. We have recently found that Al342 localizes to multivesicular bodies (MVBs) especially within AD-vulnerable pyramidal neurons in both normal and AD transgenic mouse, and in rat and human brain, but not in APP knockout mouse brain. Since our previous immunohistochemical studies suggested that intraneuronal AI342 accumulation occurs with Alzheimer's disease, we propose to study brain tissue from AD transgenic mice in the process of developing AI3 plaques for evidence of changes in the amount and subcellular distribution of AI340 and AI342 and various APP fragments, also in distal neuronal processes and synapses, using immuno-electron microscopy and subcellular fractionation methods. We plan to assess the amount and subcellular distribution of AI3 peptides at various ages prior and during the time when plaque deposition is known to occur in the specific transgenic AD mice under study; Tg2576 mice expressing the FAD Swedish 670/671 mutant human APP generally develop AI3 plaques at approximately 11 to 13 months of age. In addition, we propose to study the neurobiology and regulation of this MVB-associated pool of AI3 in cultured primary neurons, and to investigate for changes in neuronal MVBs with aging and AD pathogenesis. We hypothesize that accumulation, and potentially aggregation, of AI342 with aging on the outer membrane of MVBs may interfere with the normal transport of vital cargo molecules within neuronal processes. A better understanding of the cellular and molecular events occurring within neurons of the brain involved in AD pathogenesis may be important for the development of more effective molecular based treatment strategies for Alzheimer's disease.