Genetic and epigenetic architecture of natural telomere length variation

项目摘要 端粒是进化上保守的蛋白质-DNA复合体，位于 真核生物的线形染色体。在大多数人类体细胞中，端粒随着年龄的增长而缩短，并且 它们的初始长度预先决定了细胞的寿命。端粒维持基因突变 会导致癌症、过早衰老和一些与年龄相关的疾病。而卑鄙的端粒 人类的长度在个体间表现出相当大的差异，似乎在很大程度上 基因控制，确定端粒长度设定点的因素的确切性质仍然存在 难以捉摸。利用模式植物拟南芥，我们先前确定了几个候选 该物种自然端粒长度变异的潜在基因。在这个提案中，我们将利用 遗传、基因组、生化和表观遗传学方法研究它们在端粒中的功能 长度控制和其他主要的细胞过程，并获得关于 功能基因多效性。在目标1中，我们将探索关于直接和间接的几个假设 编码端粒酶催化亚基的拟南芥TERT基因在植物生长发育中的作用 建立不同类型拟南芥的天然端粒长度多态。我们还将 利用强大的拟南芥基因组和转录组分工具来识别和表征TERT 反式调节因子和发现端粒酶自然变异的新因素 多个拟南芥基因间的活性水平。通过一系列的基因 拟南芥端粒长度突变体的互补实验，目标2 将解决端粒生物学之间功能冗余的性质和程度， 核糖体生物发生和染色质组装，并建立解剖蓝图 已识别基因的端粒与非端粒作用。此外，在目标2中，我们将利用 几种创新的基因组和表观遗传学方法来识别和验证其他 参与端粒长度控制的候选基因。总的来说，这项研究的结果是 有望显著提高我们对端粒基因差异的理解 天然拟南芥种群的长度多态。因为端粒调节的方式 都是高度保守的，我们的数据也可能为我们提供对 与端粒长度相关的不同衰老速度和对人类疾病的易感性 异常现象。

Project Summary Telomeres are evolutionarily conserved protein-DNA complexes at the physical ends of linear eukaryotic chromosomes. Telomeres shorten with age in most human somatic cells, and their initial length pre-determines cellular lifespan. Mutations in telomere maintenance genes lead to cancer, premature aging and a number of age-related disorders. While mean telomere length in humans shows considerable inter-individual variation and appears to be under strong genetic control, the exact nature of factors establishing telomere length set point remains elusive. Using the model plant Arabidopsis thaliana, we previously identified several candidate genes underlying natural telomere length variation in this species. In this proposal, we will utilize genetic, genomic, biochemical and epigenetic approaches to explore their functions in telomere length control and other major cellular processes, and to gain an evolutionary perspective on functional gene pleiotropy. In Aim 1, we will explore several hypotheses for direct and indirect roles of Arabidopsis TERT gene, which encodes the catalytic subunit of telomerase, in establishing natural telomere length polymorphism across Arabidopsis genotypes. We will also employ powerful Arabidopsis genomic and transcriptomic tools to identify and characterize TERT trans-regulators and uncover novel factors underlying natural variation in telomerase enzyme activity levels across multiple Arabidopsis genotypes. Through a series of genetic complementation experiments with Arabidopsis telomere length mutants, experiments in Aim 2 will address the nature and extent of functional redundancies between telomere biology, ribosome biogenesis and chromatin assembly, and establish the blueprint for dissecting telomeric versus non-telomeric roles of identified genes. Additionally, in Aim 2 we will utilize several innovative genomic and epigenetic approaches to identify and validate additional candidate genes involved in telomere length control. Overall, the results of this study are expected to significantly increase our understanding of genetic differences underlying telomere length polymorphism in natural Arabidopsis populations. Because modes of telomere regulation are highly conserved, our data may also provide novel insight into the molecular basis for different rates of aging and predisposition to human diseases associated with telomere length abnormalities.