Novel nuclear and intracellular pathology in early AD

描述（由申请人提供）：该提案旨在改变我们对阿尔茨海默病的原因和机制的理解。阿尔茨海默病是最严重和经济上最重要的疾病之一，对其没有疾病改善疗法。AD治疗开发的问题是AD发病机制尚未得到普遍理解。人类遗传学暗示APP及其蛋白水解加工和淀粉样蛋白A的产生？肽作为介质的发病机制，但人体临床试验针对分泌的A？或去除斑块的方法几乎没有效果，或者实际上加速了认知能力的下降。最近的试验γ分泌酶抑制剂，防止分泌A？报道说，接受治疗的患者在认知方面比对照组差，这表明我们对疾病机制的理解是有缺陷的或不完整的。该提案的目标是鉴定和表征蛋白质， 聚集在细胞核内和周围的蛋白质片段，对原纤维特异性 单克隆抗体M78。我们将测试的假设，APP及其淀粉样蛋白的片段错误折叠和聚集成不溶性物种之前，他们的蛋白水解转化为A？并积累细胞内由于固有的电阻聚集的A？蛋白质水解。在初步研究中，我们已经发现了一种新的淀粉样纤维免疫反应性和周围的核使用纤维特异性单克隆抗体，M78，它承认一个不连续的A？表位在A？纤维我们的研究表明，M78免疫反应共定位与细胞内核周APP和早期细胞外斑块阶段的AD显着的认知功能障碍之前，在中间时间的发病机制在3xTg-Ad小鼠。一些核M78免疫反应共定位与APP和A？如APP和A？特异性抗体表明M78免疫反应性可能代表错误折叠、聚集的APP或APP片段积累为"细胞内淀粉样蛋白"。在3xTg-AD小鼠中，M78阳性噬斑在未用6E10或4G8染色的较晚时间积累，表明该单克隆抗体也鉴定了独特类型的噬斑。我们还观察到，神经炎斑块中M78和APP免疫反应性的相同空间分布与用荧光染料DAPI可视化的DNA共定位，所述荧光染料DAPI位于神经炎斑块的中心核心中，在"营养不良神经突"中被APP免疫反应性的晕圈包围。总之，我们的观察结果表明，以前未确定的核相关的细胞内途径淀粉样蛋白的发病机制和斑块的生物发生在AD。如果这种新的发病机制是AD的关键事件，它将极大地改变我们对这种疾病的思考方式，重新集中资源用于治疗开发，并使早期临床试验能够改变疾病的进程。

DESCRIPTION (provided by applicant): This proposal seeks to transform our understanding of the causes and mechanisms of Alzheimer's disease. Alzheimer's disease is one of the most serious and economically important diseases for which there is no disease modifying therapy. The problem for therapeutic development in AD is that there is no commonly understood mechanism for AD pathogenesis. Human genetics implicates the APP and its proteolytic processing and the production of the amyloid A? peptide as a mediator of pathogenesis, but human clinical trials targeting the secretion of A? or the removal of plaques have demonstrated little or no effectiveness or have actually accelerated cognitive decline. Recent trials of gamma secretase inhibitors that prevent the secretion of A? reported that treated patients were cognitively worse than controls, suggesting that out understanding of the disease mechanisms is flawed or incomplete. The goal of this proposal is to identify and characterize the proteins and protein fragments that accumulate in and around the nuclei that are reactive to the fibril specific monoclonal antibody M78. We will test the hypothesis that APP and its amyloidogenic fragments misfold and aggregate into insoluble species prior to their proteolytic conversion to A? and accumulate intracellularly due to the intrinsic resistance of the aggregated A? domain to proteolysis. In preliminary studies we have discovered a novel amyloid fibril immunoreactivity in and around nuclei using a fibril specific monoclonal antibody, M78, which recognizes a discontinuous A? epitope in A? fibrils. Our studies suggest that M78 immunoreactivity colocalizes with both intracellular perinuclear APP and early extracellular plaque stages of AD prior to significant cognitive dysfunction and at intermediate times of pathogenesis in 3xTg-Ad mice. Some of the nuclear M78 immunoreactivity colocalizes with APP and A? as visualized with APP and A? specific antibodies suggesting that M78 immunoreactivity may represent misfolded, aggregated APP or APP fragments accumulating as "intracellular amyloid". In 3xTg-AD mice, M78 positive plaques accumulate at later times that are not stained with 6E10 or 4G8, suggesting that a unique type of plaque is also identified by this monoclonal antibody. We also observed that the same spatial distribution of M78 and APP immunoreactivity in neuritic plaques is colocalized with DNA visualized with the fluorescent dye DAPI located in the central core of the neuritic plaque surrounded by a halo of APP immunoreactivity in "dystrophic neurites". Together, our observations suggest a previously unidentified nuclear related intracellular pathway for amyloid pathogenesis and plaque biogenesis in AD. If this novel pathogenesis is a key event in AD, it will dramatically change our way of thinking about this disease, refocus the resources for therapeutic development and enable early clinical trials to alter the course of the disease.