Aging and the unstable epigenome

描述(由申请人提供)：已经提出了各种假说来解释细胞和组织水平的衰老过程。其中最常见的是核和线粒体DNA损伤和突变的积累，氧化应激和其他内在化学反应引起的大分子损伤，端粒侵蚀和功能障碍，癌基因的激活，以及增殖组织中干细胞更新的恶化。最有可能的是，所有这些现象的重叠将导致细胞和组织的衰老。然而，在这里，我们提出了一个新的范式：表观基因组的改变对衰老过程有很大的贡献。在这一应用中，我们提出表观遗传变化是衰老的一个标志。我们将分析几个表观遗传标记，包括DNA、CpG甲基化和染色质修饰，在体外和体内经历衰老的细胞。此外，我们还将分析Cockayne综合征细胞中的这些标记，这是一种早衰综合征。这个表观基因组作图项目将利用甲基化CpG岛恢复分析(MIRA)技术进行DNA甲基化分析，并利用染色质免疫沉淀分析组蛋白修饰。全基因组分析将通过微阵列和高通量DNA序列分析完成。这项拨款建议在组蛋白修饰、DNA甲基化和基因表达的水平上对表观基因组在衰老过程和早衰综合征中的表达进行深入分析。来自相同身体部位的同质细胞类型，以及从相同个体连续获得的细胞类型，将使我们能够进行有意义的比较。这些数据将使我们能够估计在衰老过程中发生的表观遗传学变化的程度和特异性，因此我们将能够更好地评估表观遗传学对衰老的确切贡献。

DESCRIPTION (provided by applicant): Various hypotheses have been put forward to explain the aging process at both the cellular and organismal level. Among the most popular ones are accumulation of nuclear and mitochondrial DNA damage and mutations, damage to macromolecules induced by oxidative stress and other intrinsic chemical reactions, telomere erosion and dysfunction, activation of oncogenes, and a deterioration of stem cell renewal in proliferating tissues. Most likely, an overlap of all of these phenomena will contribute to cellular and organismal aging. However, here we propose a new paradigm: that alterations of the epigenome contribute substantially to the aging process. In this application, we propose that epigenetic changes are a hallmark of aging. We will analyze several epigenetic marks including DNA CpG methylation and chromatin modifications in cells that undergo aging in vitro and in vivo. In addition, we will analyze these marks in Cockayne syndrome cells, a premature aging syndrome. This epigenome mapping project will make use of the methylated CpG island recovery assay (MIRA) technique for DNA methylation analysis and chromatin immunoprecipitation for analysis of histone modifications. Genome-wide analysis will be accomplished by microarray and high throughput DNA sequence analysis. This grant proposes an in-depth analysis of the epigenome, at the level of histone modifications, DNA methylation and gene expression during the time course of aging and in premature aging syndromes. A homogenous cell type derived from identical body sites and obtained serially from the same individuals will enable us to make meaningful comparisons. The data will allow an estimation of the extent and specificity of epigenetic changes that occur during the aging process, and hence we will be in a position to better assess the exact contribution of epigenetics to aging.