Mechanisms of Telomere Cohesion

端粒凝聚机制

• 批准号: 10622894
• 负责人: SUSAN SMITH
• 金额: $ 17.67万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-11 至 2028-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10622894
• 关键词: Aging; Binding; Cell Aging; Cell Cycle Arrest; Cells; Centromere; Cessation of life; Chromosomal Stability; Chromosomes; DNA Damage; Deposition; Ensure; Genetic Recombination; Genomic Instability; Goals; Growth; Human; Maintenance; Malignant Neoplasms; Mediating; Mitosis; Monitor; Normal Cell; Pathologic; Prevention; Process; Proteins; Proteome; RNA; Repetitive Sequence; Research; Resolution; Role; S phase; Sister; Sister Chromatid; Structure; TERF1 gene; Tankyrase; Telomerase; Telomere Shortening; Time; Work; arm; cancer cell; cell age; cell type; cohesin; cohesion; daughter cell; genome integrity; insight; premature; prevent; protein complex; recruit; repaired; response; senescence; telomere

Project Summary/Abstract Telomeres, the specialized structures at chromosome ends, are comprised of TTAGGG repeats, telomere repeat containing RNA (TERRA), and the shelterin protein complex. Sister chromatids are held together from the time of their replication in S phase until their separation in mitosis by cohesin rings. Ring-mediated cohesion is essential to ensure accurate distribution of chromosomes to daughter cells in mitosis. Cohesion between sisters is also important for recombination and repair, particularly at repetitive sequences like telomeres, where it keeps them aligned. For this, more intimate contacts (in addition to the cohesin ring) are needed and as such, there are telomere-specific requirements for cohesion. Establishment of cohesion at telomeres requires shelterin subunits and associated proteins. Resolution of cohesion between telomeres requires the PARP, tankyrase. Tankyrase localizes to telomeres by binding to the TTAGGG-repeat binding shelterin subunit TRF1, in late S/G2 to resolve cohesion. In tankyrase-depleted cells sister telomeres remain cohered in mitosis despite normal resolution of arms and centromeres. This persistent telomere cohesion is not just an aberrant state induced by depletion of tankyrase, it occurs naturally in certain human cell types that lack telomerase and have critically short telomeres: normal aged cells and cancer ALT cells. Unexpectedly, (and shown by our lab in the last few years) this persistent cohesion is beneficial to cells; it serves a protective role to prevent premature senescence in aged cells and growth arrest in ALT cancer cells. The goal of our research for the next five years is to elucidate the proteins and mechanisms required for establishment and resolution of cohesion. We will build on our previous work where we identified shelterin subunits and associated factors that are required for cohesion and we will focus on our most recent discovery indicating a role for RNA (TERRA and TERRA R-Loops) in telomere cohesion. We will determine how the telomeric components contribute to the establishment, maintenance, and resolution of telomere cohesion in normal human cells, aging, and cancer. For cohesion establishment, we will determine how and when the required proteins are deposited on telomeres and how far into the chromosome they extend. For cohesion resolution, we will determine how recruitment of tankyrase serves to resolve cohesion. We will characterize the proteins that tankyrase itself recruits to telomeres and investigate how tankyrase uses functional compartmentalization to orchestrate the resolution process. We will determine how TERRA RNA and TERRA R-loops contribute to telomere cohesion in normal cells and to persistent telomere cohesion in pathological conditions of aging and ALT cancer. And finally, we will elucidate the full proteome of the cohered telomeric state. Ultimately, a complete understanding of telomere cohesion will elucidate fundamental mechanisms of chromosome stability and genome integrity in normal human cells and provide insights into prevention of premature senescence in aging cells and into promotion of premature death in ALT cancer cells.

项目概要/摘要 端粒是染色体末端的特殊结构，由 TTAGGG 重复序列、端粒重复序列组成 含有 RNA (TERRA) 和庇护蛋白复合物。姐妹染色单体从那时起就结合在一起 它们在 S 期复制，直到有丝分裂中被粘连蛋白环分离。环介导的内聚力是 对于确保有丝分裂中染色体准确分配到子细胞至关重要。姐妹间的凝聚力 对于重组和修复也很重要，特别是在像端粒这样的重复序列上，它保留 他们对齐。为此，需要更多的亲密接触（除了粘连环），因此，有 是端粒对内聚力的特定要求。端粒内聚力的建立需要庇护 亚基和相关蛋白质。端粒之间的内聚力的解析需要 PARP（坦科聚合酶）。 在 S/G2 晚期，端锚聚合酶通过与 TTAGGG 重复结合庇护蛋白亚基 TRF1 结合来定位于端粒 来解决凝聚力问题。在坦科聚合酶耗尽的细胞中，尽管正常，姐妹端粒在有丝分裂中仍然保持一致 臂和着丝粒的分辨率。这种持久的端粒凝聚力不仅仅是由以下因素引起的异常状态： 坦科聚合酶的耗竭，它自然发生在某些缺乏端粒酶且严重缺乏端粒酶的人类细胞类型中。 短端粒：正常衰老细胞和癌症 ALT 细胞。出乎意料的是，（我们的实验室在过去的几年中表明 年）这种持久的凝聚力对细胞有益；它具有防止过早衰老的保护作用 衰老细胞和 ALT 癌细胞生长停滞。我们未来五年的研究目标是阐明 建立和解决内聚力所需的蛋白质和机制。我们将在之前的基础上 我们确定了内聚子单元和内聚所需的相关因素的工作，我们将 重点关注我们最近的发现，表明 RNA（TERRA 和 TERRA R-Loops）在端粒中的作用 凝聚。我们将确定端粒成分如何有助于建立、维持和 正常人类细胞、衰老和癌症中端粒凝聚力的解决。为了建立凝聚力，我们将 确定所需蛋白质如何以及何时沉积在端粒上以及进入染色体多远 他们延伸。对于内聚力解析，我们将确定端锚聚合酶的募集如何用于解决内聚力。 我们将表征端聚合酶本身招募到端粒的蛋白质，并研究端聚合酶如何使用 功能划分以协调解决过程。我们将确定 TERRA RNA 和 TERRA R 环有助于正常细胞中的端粒凝聚力以及持久的端粒凝聚力 衰老和 ALT 癌症的病理状况。最后，我们将阐明凝聚的完整蛋白质组 端粒状态。最终，对端粒凝聚力的完整理解将阐明基本原理 正常人类细胞中染色体稳定性和基因组完整性的机制，并提供见解 预防衰老细胞过早衰老并促进 ALT 癌细胞过早死亡。