Novel nuclear and intracellular pathology in early AD

描述(由申请人提供)：这项建议旨在改变我们对阿尔茨海默病的病因和机制的理解。阿尔茨海默病是最严重和经济上最重要的疾病之一，目前还没有疾病修饰疗法。阿尔茨海默病治疗发展面临的问题是，人们对阿尔茨海默病的发病机制没有普遍的了解。人类遗传学与APP及其蛋白分解过程和淀粉样蛋白A？多肽作为致病机制的中介物，但针对A？或者去除斑块几乎或没有效果，或者实际上加速了认知能力的下降。最近的伽马分泌酶抑制剂的试验可以阻止A？报道称，接受治疗的患者认知能力比对照组更差，这表明我们对疾病机制的了解是有缺陷的或不完整的。这项提议的目标是鉴定和表征蛋白质和 聚集在核内和核周围的蛋白质片段，这些蛋白质片段对特定的纤维起反应 单抗M78。我们将检验这一假设，即APP及其淀粉样变原片段在蛋白质分解转化为A？之前错误折叠并聚集成不可溶物种。由于聚集态A？结构域到蛋白水解酶。在初步研究中，我们发现了一种新的淀粉样原纤维免疫反应性，它位于细胞核内及其周围，使用纤维特异性单抗M78，它识别不连续的A？A中的表位？纤维。我们的研究表明，在3xTg-Ad小鼠显著认知功能障碍之前和发病中期，M78免疫反应与AD的细胞内APP和早期细胞外斑块共同定位。部分M78核免疫反应与APP和A？与APP和A的可视化效果一样？提示M78免疫反应性的特异性抗体可能代表错误折叠、聚集的APP或APP片段积聚成“细胞内淀粉样蛋白”。在3xTg-AD小鼠中，M78阳性斑块在以后的时间内积聚，而不是6E10或4G8染色，这表明该单抗也识别了一种独特的斑块类型。我们还观察到M78和APP在神经炎斑块中的空间分布相同，与DNA共同定位于位于神经炎斑块中央核心的荧光染料DAPI，周围是APP免疫反应的光晕。综上所述，我们的观察表明，在AD的淀粉样蛋白发病机制和斑块生物发生中，有一条先前未知的核相关细胞内途径。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维方式，重新集中治疗开发的资源，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.