UNDERSTANDING CELLULAR AND TRANSCRIPTIONAL REGULATORY CHANGES IN HUMAN AGING

衰老的过程被认为涉及转录调控的逐渐失去控制，特别是 涉及被称为“表观遗传”的调节机制。这些变化主要表现为 随着年龄的增长，DNA甲基化的变异性增加，称为表观遗传漂变， 显示了一种有趣的，渐进的DNA甲基化变化，似乎是一个“表观遗传时钟”。 然而，我们注意到，DNA甲基化检测报告的不仅仅是转录调控状态， 研究的细胞。个体之间的DNA甲基化差异现在被理解为指示， 例如，细胞亚型组成或DNA序列差异，而没有任何细胞必须具有 改变了它们的转录调控。因此，DNA甲基化既是转录调控的读数， 以及其他分子和细胞过程，所有这些都会产生DNA甲基化的变化， 大小 为了进行一项研究，让DNA甲基化的变化被解释与信心，我们需要 了解影响这种转录调节因子的变异性来源。因此，一项严格的研究应该 包括测试基因型、细胞亚型比例和转录变异性，所有这些都可以改变DNA 在细胞群体中的甲基化值。此外，了解细胞中的顺式调控景观， 测试是必不可少的，因为这允许集中分析基因座信息的DNA甲基化变化。 在衰老研究中使用的理想细胞类型是CD4+ T淋巴细胞。这不仅是一种细胞类型， 介导许多与年龄相关的表型，并且可从外周血中获得用于全基因组测定 还可以使用T细胞受体测定来测试其库多样性，以及测试其细胞亚型。 使用多个正交技术合成。我们将利用我们机构的内森·肖克的优势 衰老生物学卓越中心为这项研究收集了一个表型良好的队列。 我们的数据将揭示年龄相关的表观遗传变化是否独立于混杂因素发生 影响，但也将使我们能够揭示其他细胞和分子事件发生在CD4+ T细胞 细胞一个创新的目标是鉴定年龄不稳定的功能序列变异体，即改变其功能的基因座。 随着年龄的增长影响基因表达的能力，对DNA序列之间关系的独特见解 多态性和衰老。我们还将检验表观遗传时钟CpG代表基因座介导 年龄相关的糖皮质激素受体抵抗，一个单独的模型，年龄相关的妥协， 功能 该项目的结果将是迄今为止对表观遗传变化的最严格和最明确的研究， 衰老我们预期人类衰老涉及细胞和分子事件的组合。这些发现将 让我们对CD4+ T细胞如何参与介导年龄相关疾病有了新的、全面的了解。

The process of aging is believed to involve progressive loss of control of transcriptional regulation, in particular involving regulatory mechanisms referred to as “epigenetic”. These changes have been mostly characterized as an increase in variability of DNA methylation with age, referred to as epigenetic drift, with a subset of loci showing an intriguing, progressive change of DNA methylation that appears to act as an “epigenetic clock”. We note, however, that a DNA methylation assay reports much more than the transcriptional regulatory state of the cells studied. DNA methylation differences between individuals are now appreciated to indicate, for example, cell subtype compositional or DNA sequence differences, without any cells necessarily having changed their transcriptional regulation. DNA methylation is thus both a readout of transcriptional regulation and of other molecular and cellular processes, all generating changes in DNA methylation of the same modest magnitude. To perform a study that allows DNA methylation changes to be interpreted with confidence, we need to understand the sources of variability affecting this transcriptional regulator. A rigorous study should therefore include test genotypes, cell subtype proportions, and transcriptional variability, all of which can change DNA methylation values in a cell population. Furthermore, understanding the cis-regulatory landscape in the cells tested is essential, as this allows a focused analysis at loci informative for DNA methylation changes. An ideal cell type to use in an aging study is CD4+ T lymphocytes. Not only is this a cell type that appears to mediate a number of age-related phenotypes, and is accessible from peripheral blood for genome-wide assays of cohorts, it can also be tested for repertoire diversity using T cell receptor assays, and for cell subtype composition using multiple orthogonal techniques. We will use the strengths of our institution’s Nathan Shock Center of Excellence in the Biology of Aging to collect a well-phenotyped cohort for this study. Our data will reveal whether age-associated epigenetic changes occur independently of confounding influences, but will also allow us to uncover the other cellular and molecular events taking place in CD4+ T cells. An innovative goal is the identification of age-labile functional sequence variants, loci that change their ability to influence gene expression with age, a unique insight into the relationship between DNA sequence polymorphism and aging. We will also test the hypothesis that epigenetic clock CpGs represent loci mediating age-associated glucocorticoid receptor resistance, a separate model for age-associated compromise in cellular function. The outcome of this project will be the most rigorous and definitive study to date of epigenetic changes in aging. We expect human aging to involve a combination of cellular and molecular events. These findings will allow new, comprehensive insights into how CD4+ T cells are involved in mediating age-related diseases.