The Subcellular Neuropathology of Alzheimer's Disease

描述（由申请人提供）：阿尔茨海默病（AD）的特征在于13-淀粉样肽（AI 3）在脑中的积累。AI 3通过13-淀粉样前体蛋白（APP）的调节切割在细胞内产生。我们建议在携带家族性AD（FAD）突变的转基因小鼠中研究AI 3肽随衰老而定位和积累的亚细胞位点，以及这可能如何启动AD斑块病理学。我们最近发现，Al 342定位于多泡体（MVB），特别是在AD-脆弱的锥体神经元在正常和AD转基因小鼠，大鼠和人脑，但不是在APP敲除小鼠脑。由于我们以前的免疫组织化学研究表明，神经元内AI 342积累发生与阿尔茨海默病，我们建议研究AD转基因小鼠的脑组织在发展AI 3斑块的过程中，AI 340和AI 342以及各种APP片段的数量和亚细胞分布的变化，以及在远端神经元突起和突触中的变化，使用免疫电子显微镜和亚细胞分级分离方法。我们计划评估在研究中的特定转基因AD小鼠中已知发生斑块沉积之前和期间不同年龄段的AI 3肽的量和亚细胞分布;表达FAD Swedish 670/671突变体人APP的Tg 2576小鼠通常在约11至13月龄时形成AI 3斑块。此外，我们建议在培养的原代神经元中研究这种MVB相关的AI 3库的神经生物学和调节，并调查神经元MVB随衰老和AD发病机制的变化。我们推测，随着年龄的增长，AI 342在MVB外膜上的积累和潜在的聚集可能会干扰神经元过程中重要货物分子的正常转运。更好地了解AD发病机制中涉及的脑神经元内发生的细胞和分子事件对于开发更有效的基于分子的阿尔茨海默病治疗策略可能是重要的。

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.