The Secretory Chaperone 7B2 as an Endogenous Regulator of Amyloid Pathology

描述（由申请人提供）：阿尔茨海默病（AD）影响了520万65岁以上的美国人，随着美国人口的普遍老龄化，这一数字预计会增加。虽然在过去十年中，在确定被认为与认知功能丧失有关的淀粉样蛋白物种的毒性作用方面取得了显著进展，但关于淀粉样斑块的发病机制仍有许多有待了解的地方。最近的数据支持这样一种观点，即伴侣蛋白，即控制折叠内稳态的蛋白质，以多种方式促进适当的神经元功能。我们的实验室最近表明，7B2，一种小分泌的神经元蛋白，与阿尔茨海默病人和阿尔茨海默病小鼠组织中的脑淀粉样斑块有关。这些数据得到了五项独立生物信息学研究的支持，表明该蛋白代表了神经退行性疾病的潜在CSF生物标志物。虽然存在于分泌途径而不是细胞质中，但7B2表现出许多类似于小热休克蛋白伴侣蛋白的生化特性。与热休克伴侣蛋白家族的成员α结晶蛋白一样，7B2在体外试验中可以有效阻断β淀粉样蛋白1-42的纤颤，也可以阻断添加到Neuro 2A细胞培养中的β淀粉样蛋白的细胞毒性。目前R21的提议是在一个已知的阿尔茨海默氏症小鼠模型中测试大脑7B2水平可以控制淀粉样斑块沉积的程度并影响认知的假设。我们建议将7B2过表达或过低表达的现有小鼠品系与APP/PS1阿尔茨海默病模型小鼠杂交。认知能力将在6个月和12个月大时在莫里斯水迷宫中进行评估。对各基因型6只动物的皮层和海马切片进行斑块病理学定量分析；同时测定7B2免疫反应性。淀粉样蛋白寡聚化状态将在单独的动物大脑中使用化学和离心分离，然后用ELISA检测，并与基因型相关。总的来说，这些实验构成了我们假设的直接检验，即7B2水平与淀粉样蛋白斑块和低聚物形成负相关。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) affects 5.2 million Americans over 65, a number expected to increase along with the general aging of the US population. While remarkable progress has been made in the last decade in defining the toxic effects of the amyloid species thought to be involved in loss of cognitive function, much remains to be learned regarding amyloid plaque pathogenesis. Recent data support the idea that chaperones, proteins which control folding homeostasis, contribute to proper neuronal function in a variety of ways. Our laboratory has recently shown that 7B2, a small secreted neuronal protein, is associated with brain amyloid plaques in tissues from both AD humans and from mouse AD models. These data are supported by five independent bioinformatics studies indicating that this protein represents a potential CSF biomarker for neurodegenerative disease. Although present in the secretory pathway and not the cytosol, 7B2 exhibits many biochemical characteristics similar to those of small heat shock protein chaperones. Like alpha crystallin, a member of the heat shock chaperone family, 7B2 can potently block the fibrillation of beta amyloid 1-42 in in vitro tests, and also blocks the cytotoxicity of beta amyloid added to Neuro 2A cell cultures. The current R21 proposal is to test the hypothesis that brain 7B2 levels can control the extent of amyloid plaque deposition and affect cognition in a known mouse model of Alzheimer's. We propose to cross existing mouse strains that either over- or underexpress 7B2 with the APP/PS1 Alzheimer's disease model mouse. Cognitive abilities will be assessed at 6 and 12 months of age in a Morris water maze. Plaque pathology will be quantitated in cortical and hippocampal slices in 6 animals of each genotype; 7B2 immunoreactivity will be measured in concert. Amyloid oligomerization state will be examined in brains of separate animals using chemical and centrifugal separation followed by ELISA and also correlated with genotype. Collectively, these experiments constitute a direct test of our hypothesis that 7B2 levels are negatively correlated with amyloid plaque and oligomer formation.