The Subcellular Neuropathology of Alzheimer's Disease

描述(申请人提供)：阿尔茨海默病(AD)的特征是13-淀粉样多肽(AI3)在大脑中积聚。AI3是由13-淀粉样前体蛋白(APP)的调节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肽随年龄增长而定位和积累的亚细胞位置(S)，以及这可能如何引发AD斑块病理。我们最近发现Al342定位于多囊泡小体，特别是在正常和AD转基因小鼠的易感AD锥体神经元中，以及在大鼠和人脑中，但不在APP基因敲除小鼠的脑中。由于我们之前的免疫组织化学研究表明，阿尔茨海默病患者AI342在神经元内积聚，因此我们建议使用免疫电子显微镜和亚细胞分离方法，研究AD转基因小鼠在形成AI3斑块的过程中，AI340和AI342以及各种APP片段的数量和亚细胞分布以及在远端神经元突起和突触中的数量和分布的变化。我们计划评估AI3多肽在不同年龄之前和在已知在特定的转基因AD小鼠中发生斑块沉积的时间段的数量和亚细胞分布；表达FAD瑞典670/671突变人APP的Tg2576小鼠通常在大约11到13个月大的时候形成AI3斑块。此外，我们建议在培养的原代神经元中研究这种与MVB相关的AI3池的神经生物学和调控，并探讨神经元MVB在衰老和AD发病机制中的变化。我们假设，随着年龄的增长，AI342在MVB外膜上的积累和潜在聚集可能会干扰重要货物分子在神经元突起内的正常运输。更好地了解参与AD发病机制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.