Identifying and understanding the role of repeat RNAs and RAN proteins in Alzheimer's disease

项目总结/摘要（30行文本）： 阿尔茨海默病是痴呆症中最常见的一种，其特征是认知能力下降和受损 行为和功能的能力。美国约有580万人受到 阿尔茨海默病（AD），预计到2050年这一数字将增加两倍。淀粉样蛋白的突变 已知前体蛋白（APP）和早老素（PSEN 1和PSEN 2）引起家族性早发性AD， APOE 4变异体是一种众所周知的疾病危险因素，其遗传贡献大多数为晚发性 AD病例尚不清楚。此外，虽然Aβ斑块和过度磷酸化tau蛋白的积累是 Aβ斑块和tau蛋白缠结被认为是AD病例的标志性特征，但不能完全解释AD的临床表现。 特征和异质性。C9 orf 72 GGGGCC六核苷酸的鉴定 重复扩张是肌萎缩侧索硬化症和额颞叶萎缩症最常见的遗传原因 痴呆症提出了一个有趣的问题，即不明重复扩增突变是否有助于其他疾病的发生。 痴呆症包括AD。此外，在AD和AD之间观察到疾病病理学的相似性。 重复扩张障碍患者。这些相似之处包括异常蛋白质的积累， 受影响脑区的神经元损失，以及疾病恶化中的应激参与。虽然重复 元件占人类基因组的很大一部分，检测重复扩增突变， 尤其是富含GC的重复扩增是具有挑战性的。为了克服识别重复的困难， 扩增突变，我已经开发了一种新的基于dCas 9的重复下拉方法（dCas 9 READ）， 允许直接从个体患者的基因组DNA中分离重复扩增突变。的 这项提议的目的是检验新的重复扩增突变有助于晚期 AD及其含有RNA和RAN产物重复序列是有毒的，并导致AD病理学。我是 令人兴奋的是，在最初的筛查中，17.5%的人类AD尸检病例检测为RAN阳性 蛋白质聚集体和RNA聚集体。在这次资助中，我将跟踪这些令人兴奋的初步数据， 新的重复扩增突变在以下特定目的中促成AD的假设：目的1）将 开发一种新的基于dCas 9的技术，用于快速识别重复扩增。目标2）将测试 假设新的重复扩增突变在晚发性AD中的频率更高， 对照样品。目的3）将检验新的重复扩增突变是有毒的并有助于 到AD病理学

PROJECT SUMMARY/ABSTRACT (30 lines of text): Alzheimer’s disease, the most common form of dementia, is characterized by cognitive decline and impairment of behavioral and functional abilities. Approximate 5.8 million people in the United States are affected by Alzheimer’s disease (AD) and this number is anticipated to triple by 2050. While mutations in amyloid precursor protein (APP) and presenillin (PSEN1 and PSEN2) are known to cause familial early onset AD and the APOE4 variant is a well-known disease risk factor, the genetic contributions to the majority of late onset AD cases are not clear. Additionally, while the accumulation of Aβ plaques and hyperphosphorylated tau are considered to be hallmark features of AD cases, Aβ plaques and tau tangles do not fully explain the clinical features and heterogeneity found in AD patients. The identification of the C9orf72 GGGGCC hexanucleotide repeat expansion as the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia raises an intriguing question whether unidentified repeat expansion mutations contribute to other form of dementia including AD. Additionally, similarities in disease pathology are observed between AD and patients with repeat expansion disorders. These similarities include the accumulation of abnormal proteins, neuronal loss in affected brain regions, and the involvement of stress in worsening disease. While repetitive elements account for a large portion of the human genome, the detection repeat-expansion mutations, especially GC-rich repeat expansions, is challenging. To overcome the difficulties in identifying repeat expansion mutations, I have developed a novel dCas9-based repeat pull-down method (dCas9READ) that allows the isolation of repeat expansion mutations directly from the genomic DNA of individual patients. The objective of this proposal is to test the hypothesis that novel repeat expansion mutations contribute to late onset AD and their repeat containing RNA and RAN products are toxic and contribute to AD pathology. I am excited to report that in an initial screen, 17.5% of human AD autopsy cases tested were positive for RAN protein aggregates and RNA foci. In this grant, I will follow-up on these exciting preliminary data and test this hypothesis that novel repeat expansion mutations contribute to AD in the following specific aims: Aim 1) Will develop a novel dCas9-based technique for rapidly identifying repeat expansions. Aim 2) Will test the hypothesis that novel repeat expansions mutations are present at higher frequencies in late onset AD vs. control samples. Aim 3) Will test the hypothesis that novel repeat expansion mutations are toxic and contribute to AD pathology.