UNDERSTANDING CELLULAR AND TRANSCRIPTIONAL REGULATORY CHANGES IN HUMAN AGING

衰老的过程被认为包括逐渐失去对转录调控的控制，特别是 涉及被称为“表观遗传”的调控机制。这些变化的主要特征是 随着年龄的增长，DNA甲基化的可变性增加，称为表观遗传漂移，带有一组基因座 显示了一个耐人寻味的，渐进的DNA甲基化变化，似乎起到了“表观遗传时钟”的作用。 然而，我们注意到，DNA甲基化检测报告的远不止转录调控状态。 所研究的细胞。个体之间的DNA甲基化差异现在被认为表明，对于 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，所有这些都产生了同样适度的DNA甲基化变化 震级。 为了进行一项研究，使DNA甲基化的变化能够得到可靠的解释，我们需要 了解影响这个转录调控因子的变异性的来源。因此，严格的研究应该 包括测试基因类型、细胞亚型比例和转录变异性，所有这些都可以改变DNA 细胞群体中的甲基化值。此外，了解细胞中的顺式调控格局 检测是必不可少的，因为这允许对DNA甲基化变化有信息的基因座进行集中分析。 在衰老研究中使用的理想细胞类型是CD4+T淋巴细胞。这不仅是因为这种类型的单元格似乎 调节一些与年龄相关的表型，并可从外周血中获取以进行全基因组分析 在队列中，也可以使用T细胞受体分析来测试其谱系多样性，以及细胞亚型 使用多个正交化技术的合成。我们将利用我们机构的内森冲击的力量 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。 我们的数据将揭示与年龄相关的表观遗传学变化是否独立于混淆而发生 影响，但也将使我们发现在CD4+T细胞中发生的其他细胞和分子事件 细胞。一个创新的目标是识别年龄不稳定的功能序列变体，这些基因座改变了他们的 能够随年龄影响基因表达，独一无二地洞察DNA序列之间的关系 多态与衰老。我们还将检验表观遗传时钟Cpgs代表基因座的假设 年龄相关的糖皮质激素受体抵抗：细胞内年龄相关妥协的单独模型 功能。 这个项目的结果将是迄今为止关于表观遗传学变化的最严格和最明确的研究 衰老。我们预计人类衰老将涉及细胞和分子事件的组合。这些发现将 允许对CD4+T细胞如何参与调节年龄相关疾病的新的、全面的见解。

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.