Telomere Structure and Function in Arabidopsis

拟南芥端粒结构和功能

• 批准号: 6464524
• 负责人: Dorothy Shippen
• 金额: $ 28.51万
• 依托单位: TEXAS A&M UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-01 至 2006-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6464524
• 关键词: Arabidopsis; DNA; cell cycle; cell growth regulation; chemical stability; chemical structure function; chromosome disorders; chromosomes; genetic recombination; genetically modified plants; intermolecular interaction; laboratory rabbit; meiosis; molecular cloning; molecular site; nucleic acid structure; nucleoproteins; plant genetics; plant growth /development; plant physiology; plant proteins; polymerase chain reaction; southern blotting; telomerase; telomere; yeast two hybrid system

DESCRIPTION (provided by applicant): Telomeres are higher order nucleoprotein structures that physically cap the chromosome terminus and help to perserve genome integrity. In cells with unlimited proliferative capacity, including 95 percent of human cancers, telomeres are maintained by telomerase. By contrast, telomerase is absent from most cells of the normal soma and telomeres inexorably shorten until chromosome ends become uncapped and indistinguishable from double strand breaks. End-to-end fusions are induced, ultimately leading to cell cycle arrest. Here we propose to exploit Arab idopsis to elucidate the structure and function of the telomere cap to better understand how this device provides stability to the genome, and facilitates continued cell proliferation. Our preliminary results indicate that Arabidopsis has an exceptionally high tolerance for telomere dysfunction. This finding, coupled with the fascile genetics of Arabidopsis, its completely sequenced genome, and arsenal of transgenic tools demonstrate that this system can offer unique opportunities for investigating essential genes in telomere biology. The first two goals of the proposal exploit the telomerase-deficient Arabidopsis model we developed to probe the molecular transition between capped and uncapped chromosomes. In Aim I, we will examine the frequency of telomere recombination in cells with shortened, but functional telomeres. We will also determine the contribution of somatic and meiotic recombination to telomere maintenance in the absence of telomerase. In Aim 2, we will explore the mechanism of telomere fusions by sequencing DNA at chromosome junctions, and by assessing the role of the non-homologous end-joining pathway in this process. A genetic strategy is also proposed to examine the propagation of cells harboring chromosome fusions. The last two aims focus on proteins that form the chromosome cap. In Aim 3, we will examine the function of two putative Pot1 orthologs in Arabidopsis by elucidating their DNA binding properties and molecular partners, and by determining the consequences of over-expression and gene disruption. In Aim 4, biochemical and genetic approaches are described to discover genes that facilitate chromosome capping. Because virtually every mammalian gene involved in telomere homeostasis has an Arabidopsis counterpart, these experiments should uncover mechanisms common to all multicellular organisms.

描述（申请人提供）：端粒是高阶核蛋白 物理限制染色体末端并有助于持久的结构 基因组完整性。在无限增殖能力的细胞中，包括95 人类癌症的百分比是通过端粒酶维持的。相比之下 端粒酶不存在正常躯体和端粒的大多数细胞 无情的缩短，直到染色体末端变得不盖帽和无法区分 从双链断裂。诱发端到端的融合，最终领先 到细胞周期停滞。在这里，我们建议利用阿拉伯偶像来阐明 端粒帽的结构和功能，以更好地了解该设备的方式 为基因组提供了稳定性，并促进了持续的细胞增殖。 我们的初步结果表明拟南芥具有异常高的 端粒功能障碍的耐受性。这个发现，加上Fascile 拟南芥的遗传学，其完全测序的基因组和阿森纳 转基因工具证明该系统可以提供独特的机会 用于研究端粒生物学中的必需基因。前两个目标 该提案利用了我们开发的端粒酶缺陷拟南芥模型 探测盖染色体和未覆盖的染色体之间的分子过渡。目标 i，我们将检查具有 缩短但功能性端粒。我们还将确定 在没有的情况下，体细胞和减数分裂重组以维持端粒 端粒酶。在AIM 2中，我们将通过 在染色体连接处进行DNA测序，并通过评估 在此过程中，非同源的最终连接途径。遗传策略也是 提议检查携带染色体融合的细胞的传播。这 最后两个目的集中在形成染色体帽的蛋白质上。在AIM 3中，我们将 检查拟南芥中两个假定的POT1直系同源物的功能 阐明其DNA结合特性和分子伙伴，并通过 确定过表达和基因破坏的后果。在AIM 4中， 描述了生化方法和遗传学方法以发现基因 促进染色体上限。因为实际上每个哺乳动物基因涉及 在端粒体内平衡中有一个拟南芥，这些实验 应发现所有多细胞生物共有的机制。