Epigenetic Analysis of iPS Cell Models of Aging and Alzheimer's Disease

描述（由申请人提供）：该申请涉及广泛的挑战领域（14）干细胞，以及特定的挑战主题，14- ag -101：用于衰老和神经变性研究的诱导多能干细胞（iPS）。在很大一部分人群中，衰老伴随着认知能力下降，是阿尔茨海默病（AD）的主要危险因素。尽管大脑在疾病的发病和发病中起着核心作用，但在分子水平上对大脑的衰老还没有很好的理解。该应用程序的总体目标是通过探索不同年龄和AD患者皮肤成纤维细胞产生的iPS细胞和iPS细胞衍生神经元的生理学和表观遗传学，获得对人类衰老和神经退行性疾病的新见解。与年龄匹配的对照组相比，AD成纤维细胞的转录谱显示细胞死亡基因、突触基因和编码参与染色质表观遗传修饰蛋白的基因的表达发生了变化。此外，其中一些变化也出现在阿尔茨海默病的前额叶皮层的表达谱中。我们的工作假设是突触和细胞死亡调控基因的表观遗传变化有助于大脑衰老，并在AD的发病机制中发挥作用。这一观点得到了我们发表的研究的支持，这些研究表明，神经元基因表达的抑制，特别是突触基因的抑制，是人类大脑衰老的一个突出特征，在长寿的灵长类动物中已经进化出来（1,2）。我们未发表的研究结果进一步表明，这些与年龄相关的基因表达变化可能反映了染色质的表观遗传变化，并在AD中表现出导致基因表达改变的模式。该项目将汇集来自哈佛医学院、达纳法伯癌症研究所和博德研究所的多学科团队，他们在神经生物学、疾病生物学和基因组学方面具有广泛的专业知识，以表征成年人类（24-90岁）和散发性AD患者的皮肤成纤维细胞衍生的iPS细胞系和神经元。体外诱导多能干细胞向神经元的分化将通过免疫细胞化学、电生理和基因组标准进行表征，并与原代人皮质神经元和神经祖细胞进行比较。特别令人感兴趣的是iPS神经元形成功能性突触和在与衰老和AD相关的应激相关条件下存活的能力，如氧化应激和暴露于淀粉样蛋白(A)，以及这种能力是否会在AD患者的细胞中发生变化。供体来源的iPS细胞和iPS神经元的转录和表观基因组分析将使用微阵列和应用深度测序染色质免疫沉淀（ChIP- seq）的最新创新进行。这种多学科的方法将评估iPS细胞作为衰老和神经变性的模型，并探索基因调控和表观遗传学的作用。由于我们已经从正常老年人和AD供体中建立了类似ips的细胞系，我们预计这些目标可以在两年的挑战申请时间框架内完成。

DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (14) Stem Cells, and specific Challenge Topic, 14-AG-101: Induced Pluripotent Stem (iPS) Cells for Aging and Neurodegeneration Research. Aging is accompanied by cognitive decline in a major segment of the population and is the primary risk factor for Alzheimer's disease (AD). Despite this central role in disease pathogenesis and morbidity, the aging of the brain is not well understood at a molecular level. The overall goal of this application is to gain new insights into human aging and neurodegenerative disease by exploring the physiology and epigenetics of iPS cells and iPS cell-derived neurons generated from skin fibroblasts of individuals at different ages and with AD. Transcriptional profiling of AD fibroblasts compared with age-matched controls shows changes in the expression of cell death genes, synaptic genes and genes encoding proteins involved in epigenetic modification of chromatin. Moreover, some of these changes also appear in the expression profile of the prefrontal cortex in AD. Our working hypothesis is that epigenetic changes in synaptic and cell death regulatory genes contribute to the aging of the brain and play a role in the pathogenesis of AD. This idea is supported by our published studies which show that repression of neuronal gene expression, particularly synaptic genes, is a prominent feature of human brain aging that has evolved in long-lived primates (1, 2). Our unpublished results further suggest that these age-related gene expression changes may reflect epigenetic changes in chromatin, and exhibit an altered pattern in AD leading to altered gene expression. This project will bring together a multidisciplinary team with broad expertise in neurobiology, disease biology and genomics from Harvard Medical School, the Dana Farber Cancer Institute and the Broad Institute to characterize iPS cell lines and neurons derived from dermal fibroblasts of individuals across the adult human lifespan (age 24-90 years) and patients with sporadic AD. Differentiation of iPS cells to neurons in vitro will be characterized by immunocytochemical, electrophysiologic and genomic criteria and compared with primary human cortical neurons and neural progenitors. Of particular interest will be the ability of iPS neurons to form functional synapses and survive under stress-related conditions associated with aging and AD, such as oxidative stress and exposure to amyloid ¿-protein (A¿), and whether this changes in cells derived from AD patients. Transcriptional and epigenomic profiling of donor-derived iPS cells and iPS neurons will be performed using microarrays and by applying recent innovations in deep sequencing chromatin immunoprecipitation (ChIP- seq). This multidisciplinary approach will evaluate iPS cells as models of aging and neurodegeneration, and explore the roles of gene regulation and epigenetics. Since we have already established iPS-like cell lines from normal aged and AD donors, we anticipate that these goals can be accomplished in the two year time frame of a challenge application. PUBLIC HEALTH RELEVANCE: Presently about 4 million Americans suffer from Alzheimer's disease (AD) constituting an enormous financial, emotional and productivity burden on society. Our studies suggest that epigenetic modifications of the genome may play a major role in the aging of the human brain, and may contribute to the vulnerability of the aging brain to AD. This study will determine if neurons derived from induced progenitor stem cells can serve as a model to study the role of epigenetics in aging and AD, providing a new level of analysis of the human brain in health and disease.