Negative Regulation of Telomerase in Arabidopsis

拟南芥端粒酶的负调控

• 批准号: 1052018
• 负责人: Dorothy Shippen
• 金额: $ 73万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1052018&HistoricalAwards=false
• 关键词: Negative; Regulation; Telomerase; Arabidopsis

Intellectual Merit. Telomeres are the physical ends of chromosomes and they are synthesized and maintained by a specialized ribonucleoprotein (RNP) enzyme called telomerase. Telomerase activity is required to fully replicate the chromosome terminus and to distinguish it from damaged DNA. The prolonged absence of telomerase leads to end-to-end chromosome fusions. Thus, telomerase is essential to sustain genome integrity. On the other hand, inappropriate action of telomerase at internal double-strand breaks in the DNA can be catastrophic if telomeres form inappropriately to cause gene loss. Consequently, telomerase activity must be highly regulated and confined to the tips of natural chromosome ends. Much research has focused on understanding how telomerase is recruited and activated at telomeres, but little is known about mechanisms of negative regulation. The overall goal of this research is to examine mechanisms that suppress telomerase function in the model plant Arabidopsis. Preliminary studies from the Shippen lab reveal a complex and novel regulatory pathway for Arabidopsis telomerase that involves multiple telomerase enzymes composed of different protein subunits and different telomerase RNA (TER) subunits. The TER1 RNP is a positive regulator of telomerase, and like its counterparts in yeast and vertebrates, it is required to maintain telomeres in vivo. In contrast, the TER2 RNP is a novel negative regulator of telomerase activity and telomere maintenance. TER2 is spliced to form TER2s, whose function is unknown. Objective 1 will examine the biogenesis and function of TER2s. Objective 2 will study the dynamics of the TER2 RNP during the cell cycle to understand why this RNP cannot productively engage the chromosome terminus. Objective 3 will exploit a highly efficient new telomere formation assay to study how telomerase action is restricted at internal chromosome breaks. The results of this research will deepen understanding of how telomerase interaction with chromosomes is regulated to promote genome stability.Broader Impacts. In addition to shedding new light on fundamental mechanisms that promote chromosome integrity, the broader impact of this work is that it will provide research opportunities for a postdoctoral fellow and two graduate students in plant molecular biology and biochemistry, allowing them to work at the forefront of genome research. The current NSF study will also provide research opportunities for undergraduate students from Texas A&M and the University of Houston-Downtown, a URM campus. Throughout her career, Dr. Shippen has given numerous lectures for high school students and teachers, and undergraduate and graduate student organizations, including the Texas A&M University Women in Science and Engineering Ethel Ashworth-Tsutsui Memorial Lecture. Dr. Shippen has a long-standing interest in laboratory management. In 2002 she was an Instructor for the Burroughs Wellcome Fund/Howard Hughes Medical Institute Laboratory Management Course. In 2008-2009, Dr. Shippen was on sabbatical leave at Harvard University, where she worked on an NSF-funded project to define best practices in laboratory management. This study is ongoing and has already led to the development of a new graduate course on building scientific relationships and a mentoring program for postdocs and young PIs that provides practical solutions to common problems faced in guiding a research team. All the members of the Shippen lab benefit from this lab management research to develop leadership skills and shared responsibility for the scientific development of their colleagues.

智力优点。 端粒是染色体的物理末端，它们由称为端粒酶的专门核糖核蛋白（RNP）酶合成和维持。需要端粒酶活性以完全复制染色体末端并将其与受损的DNA区分开。端粒酶长时间不存在导致端到端染色体融合。因此，端粒酶对于维持基因组完整性至关重要。另一方面，如果端粒形成不适当会导致基因丧失，则端粒酶在DNA内部双链中断裂的不当作用可能会造成灾难性。因此，端粒酶活性必须受到高度调节，并局限于天然染色体末端的尖端。许多研究集中在理解端粒酶如何在端粒中募集和激活，但对负调节的机制知之甚少。这项研究的总体目的是检查抑制型号植物拟南芥中端粒酶功能的机制。来自Shippen Lab的初步研究揭示了拟南芥端粒酶的复杂而新颖的调节途径，该途径涉及由不同蛋白质亚基和不同端粒酶RNA（TER）亚基组成的多种端粒酶酶。 TER1 RNP是端粒酶的正调节剂，就像其在酵母和脊椎动物中的对应物一样，它必须在体内维持端粒。相反，TER2 RNP是端粒酶活性和端粒维持的新型负调节剂。 ter2被剪接以形成TER2，其功能未知。目标1将检查TER2S的生物发生和功能。目标2将研究细胞周期中TER2 RNP的动力学，以了解为什么该RNP不能有效地参与染色体末端。目标3将利用高效的新端粒形成测定法，以研究如何在内部染色体断裂中限制端粒酶作用。这项研究的结果将加深对端粒酶与染色体的相互作用如何调节以促进基因组稳定性的影响。 除了对促进染色体完整性的基本机制开发新的启示外，这项工作的更广泛影响还将为博士后研究员和两名植物分子生物学和生物化学领域的研究生提供研究机会，从而使它们能够在基因组研究的最前沿工作。当前的NSF研究还将为来自德克萨斯州A＆M的本科生和URM校园休斯敦 - 北镇大学提供研究机会。在她的整个职业生涯中，Shippen博士为高中生和老师，本科生和研究生组织（包括德克萨斯A＆M大学女性科学与工程女性Ethel Ashworth-Tsutsui纪念演讲）提供了许多讲座。 Shippen博士对实验室管理具有长期的兴趣。 2002年，她担任Burroughs Wellcome Fund/Howard Hughes医学研究所实验室管理课程的讲师。 2008 - 2009年，希彭博士在哈佛大学休假，在那里她从事了一个由NSF资助的项目，以定义实验室管理方面的最佳实践。这项研究正在进行中，并且已经导致了建立科学关系的新研究生课程以及针对博士后和年轻PI的指导计划，该课程为指导研究团队而言面临的常见问题提供了实用的解决方案。 Shippen Lab的所有成员都受益于这项实验室管理研究，以发展领导能力，并对同事的科学发展负责。