Telomere structure and function in Arabidopsis

拟南芥端粒结构和功能

• 批准号: 8041418
• 负责人: Dorothy Shippen
• 金额: $ 32.82万
• 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 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8041418
• 关键词: Animal Model; Arabidopsis; Binding; Binding Sites; Biochemical; Biochemical Genetics; Biological Assay; Biological Models; Biology; CCR8 gene; Cell Proliferation; Chromosomes; Collaborations; Complex; DNA; DNA Replication Factor; DNA biosynthesis; DNA damage checkpoint; DNA-Directed DNA Polymerase; Data; Defect; Enzymes; Eukaryota; Evolution; Failure; Functional disorder; Funding; Genetic; Genetic Screening; Genome; Genome Stability; Genomic Instability; Human; In Vitro; Lead; Length; Maps; Mediating; Modeling; Molecular Chaperones; Mutation; Nucleoproteins; Organism; Orthologous Gene; Phenotype; Plants; Play; Process; Property; Proteins; Recruitment Activity; Regulation; Role; Saccharomycetales; Structure; System; Telomerase; Telomere Capping; Telomere Maintenance; Testing; Two-Dimensional Gel Electrophoresis; Vertebrates; Work; Yeasts; carcinogenesis; chromosome replication; helicase; human disease; in vivo; innovation; insight; novel; scaffold; telomere

DESCRIPTION (provided by applicant): The integrity of eukaryote genomes is derived in part from telomeres, the specialized nucleoprotein complexes that physically cap the chromosome terminus to distinguish it from a double-strand break to facilitate its complete replication. Loss of essential capping proteins or the telomere maintenance enzyme, telomerase, results in activation of DNA damage checkpoints and end-to-end chromosome fusions that culminate in massive genome instability. Defects in telomerase and/or telomere maintenance lead to proliferation-related human diseases, while correct telomerase regulation is essential to impede carcinogenesis. Elucidating how constituents of the telomere complex safeguard the genome is essential for understanding mechanisms that underlie human disease. Here we propose to exploit the many advantages of the Arabidopsis model system to investigate essential components of the telomere cap in a genetically tractable higher eukaryote. The prevailing view has been that telomeres are capped by two distinct complexes, shelterin in vertebrates and CST (Cdc13, Stn1, Ten1) in yeast. In the previous funding period, we discovered a new telomere complex in Arabidopsis comprised of STN1 and TEN1 orthologs and a novel telomere protein, CTC1. This new CST complex is required for telomere integrity in both plants and humans. The plant and human CTC1 orthologs share the same overall domain structure and non-specific ssDNA binding, distinct from yeast Cdc13. However, Arabidopsis CST plays a more pivotal role in chromosome end protection, akin to yeast CST. Thus, studies of Arabidopsis CST may provide a critical evolutionary bridge to elucidate mechanisms of telomere replication and chromosome end protection in higher eukaryotes. The central hypothesis of this renewal application that CTC1 is a multifunctional scaffold that protects chromosome ends and promotes telomeric DNA replication. Aim 1 will investigate interactions within the CST complex and explore the functional relevance of the TEN1- STN1 association for chromosome end protection. Aim 2 will assess the role of CST in telomere protection versus telomeric DNA replication. Aim 3 will test the hypothesis that POT1a recruits telomerase to the chromosome terminus via interactions with CTC1 and TER1. Finally, Aim 4 will employ forward genetic approaches and an innovative genetic screen possible only in Arabidopsis to isolate shelterin and CST- interacting factors and new telomere proteins. The studies will help to reconcile how CST and shelterin work together to promote telomere integrity. Altogether, the results generated from these four Aims will synergize to yield a much broader understanding of how telomeres stabilize higher eukaryotic genomes. PUBLIC HEALTH RELEVANCE: Telomeres are essential for genome integrity and as a consequence, understanding how the telomere complex safeguards genome stability will be crucial for elucidating the fundamental mechanisms that regulate cell proliferation and impede carcinogenesis. Studies in model organisms have established the paradigms for human telomere biology, and continue to uncover novel telomere components and regulatory mechanisms. In this tradition, we will exploit the genetic tractability of Arabidopsis and its extraordinary tolerance to telomere dysfunction to investigate a new telomere capping complex in multicellular organisms.

描述（由申请人提供）：真核生物基因组的完整性部分源自端粒，端粒是特殊的核蛋白复合物，它们可以物理限制染色体末端，以区分双链断裂，以促进其完整的复制。必需封盖蛋白或端粒维持酶的损失导致DNA损伤检查点的激活和端到端的染色体融合，这些融合在大规模基因组不稳定性中达到最终形式。端粒酶和/或端粒维持的缺陷导致与增殖有关的人类疾病，而正确的端粒酶调节对于阻碍癌变至关重要。阐明端粒复合物的成分如何保护基因组对于理解人类疾病构成的机制至关重要。在这里，我们建议利用拟南芥模型系统的许多优势，以研究端粒帽的基本组成部分，这是在遗传上可触及的较高的真核生物中。普遍的观点是，端粒被两个不同的复合物封顶，脊椎动物中的庇护素和酵母中的CST（cdc13，stn1，ten1）封闭。在上一个资金期间，我们在拟南天科中发现了一个新的端粒复合体，该拟南天科由STN1和TEN1直系同源物以及一种新型的端粒蛋白CTC1组成。这种新的CST综合体是植物和人类端粒完整性所必需的。植物和人CTC1直系同源物具有相同的整体结构结构和非特异性ssDNA结合，与酵母CDC13不同。然而，拟南芥CST在类似于酵母CST的染色体终端保护中起着更为关键的作用。因此，拟南芥CST的研究可能为阐明高等真核生物中端粒复制和染色体终端保护的机制提供关键的进化桥。这种更新应用的中心假设是，CTC1是一个多功能支架，可保护染色体末端并促进端粒DNA复制。 AIM 1将研究CST复合体内的相互作用，并探讨TEN1-STN1染色体终端保护协会的功能相关性。 AIM 2将评估CST在端粒保护与端粒DNA复制中的作用。 AIM 3将检验以下假设：POT1A通过与CTC1和Ter1的相互作用将端粒酶募集到染色体末端。最后，AIM 4将采用前瞻性遗传方法和拟南芥中可能的创新遗传筛选，以分离庇护素和CST相互作用因子以及新的端粒蛋白。这些研究将有助于协调CST和Shelterin如何共同努力以促进端粒完整性。总的来说，这四个目标产生的结果将协同作用，以对端粒如何稳定较高的真核基因组有更广泛的了解。 公共卫生相关性：端粒对于基因组完整性至关重要，因此，了解端粒复合物的基因组稳定性如何对于阐明调节细胞增殖并妨碍癌变的基本机制至关重要。模型生物的研究建立了人类端粒生物学的范例，并继续发现新颖的端粒成分和调节机制。在这一传统中，我们将利用拟南芥功能障碍的拟南芥功能障碍的遗传障碍，以研究多细胞生物中新的端粒封盖复合物。