Mechanisms of Acentric Chromosome Transmission

无着丝粒染色体传递的机制

基本信息

批准号：
9311363
负责人：
William T. SULLIVAN
金额：
$ 38.84万
依托单位：
UNIVERSITY OF CALIFORNIA SANTA CRUZ
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-05-01 至 2021-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9311363
关键词：
Ablation Address Alpha Cell Anaphase Area Automobile Driving Back Behavior Cell Cycle Checkpoint Cell Cycle Progression Cell Nucleus Cells Centromere Chromatin Chromosome Segregation Chromosomes Chromosomes, Human, Pair 15 Chromosomes, Human, Pair 19 DNA DNA Damage DNA Double Strand Break DNA damage checkpoint DNA lesion Daughter Drosophila genus Eukaryota Eukaryotic Cell Event Exhibits Genetic Genome Genomic Instability Goals Image Interphase Investigation Kinetochores Lasers Length Malignant - descriptor Malignant Neoplasms Mediating Meiosis Metaphase Microscopy Microtubule Bundle Microtubules Mitosis Mitotic Mitotic Chromosome Molecular Movement Normal Cell Nuclear Envelope Ploidies Positioning Attribute Process Proteins Resolution Resort Role Series Signal Transduction Sister Sister Chromatid System Testing Time X Chromosome base cancer cell chromosome movement combat daughter cell design driving force endonuclease genome integrity genome-wide analysis insight interest neuroblast new therapeutic target novel prevent repaired response segregation telomere telophase transmission process

项目摘要

PROJECT SUMMARY In spite of sophisticated checkpoints, repair mechanisms and other safeguards, cells occasionally enter and exit metaphase with damaged DNA. While much is known about the response of the cell to DNA damage during interphase, the response of a cell entering and exiting metaphase with damaged DNA is largely unexplored. Of particular interest is the consequence of entering and exiting metaphase with unrepaired double-strand breaks (DSB). DSB's are especially troublesome, because they produce chromosome fragments lacking telomeres, as well as fragments lacking centromeres (acentrics). Although acentrics chromosome fragments were described over a century ago and are a common feature of cancer cells, surprisingly little is known about their behavior and fate during mitosis, largely because it has been difficult to generate acentrics that can be analyzed in living cells. To directly address this issue, my lab has developed a system in Drosophila neuroblasts to efficiently generate DSBs at a single defined region at the base of the X chromosome (through induction of I-CreI endonuclease) and follow the behavior of the resulting acentric fragment through high resolution live microscopy. These studies reveal that in spite of lacking a kinetochore, acentrics exhibit highly delayed, but ultimately successful congression, sister chromosome separation, anaphase poleward segregation and incorporation into daughter telophase nuclei. We also discovered that the late segregating acentrics are accompanied by a series of cellular adaptations that facilitate its segregation and inclusion in daughter nuclei. These include an increase in cell and spindle length, expansion of the cytokinetic contractile apparatus, and delayed in initiation and completion of nuclear envelope reformation at telophase. We view congression and segregation of acentric chromosomes into telophase daughter nuclei as a mechanism of last resort for maintaining genomic integrity when the eukaryotic cell enters anaphase with unrepaired DSBs. Our goal is to identify structural and regulatory mechanisms driving acentric segregation and the accompanying cellular adaptations. To achieve this, we propose three specific aims to define the mechanisms that mediate: 1) acentric sister chromatid congression, 2) poleward segregation of the acentrics, 3) the cellular adaptations to the presence of an acentric during anaphase/telophase. It is anticipated that these studies will reveal unsuspected novel mechanisms operating during anaphase and telophase that maintain the integrity of the eukaryotic genome.

项目概要尽管有复杂的检查点、修复机制和其他保障措施，细胞偶尔会带着受损的 DNA 进入和退出中期。虽然人们对各方的反应知之甚少细胞在间期期间对 DNA 损伤的反应，细胞进入和退出中期的反应受损的 DNA 很大程度上尚未被探索。特别令人感兴趣的是进入和退出的结果具有未修复的双链断裂（DSB）的中期。 DSB 特别麻烦，因为它们产生缺乏端粒的染色体片段以及缺乏着丝粒的片段（无心者）。尽管无着丝粒染色体片段在一个多世纪前就已被描述并且是癌细胞的共同特征，令人惊讶的是人们对它们在有丝分裂过程中的行为和命运知之甚少，主要是因为很难产生可在活细胞中分析的无着丝粒。直接到为了解决这个问题，我的实验室开发了一种果蝇神经母细胞系统，可以有效地生成 DSB 位于 X 染色体基部的单个定义区域（通过 I-CreI 的诱导）核酸内切酶）并通过高分辨率实时跟踪所得无心片段的行为显微镜。这些研究表明，尽管缺乏着丝粒，无着丝粒细胞表现出高度延迟，但最终大会成功，姐妹染色体分离，后期极向分离并并入子代末期核。我们还发现，晚期分离无着丝粒细胞伴随着一系列细胞适应，促进其分离和包容在子核中。这些包括细胞和纺锤体长度的增加、细胞因子的扩展收缩装置，并延迟核膜重组的启动和完成末期。我们观察无着丝粒染色体向末期子染色体的聚集和分离细胞核作为真核细胞进入时维持基因组完整性的最后手段具有未修复 DSB 的后期。我们的目标是确定驱动的结构和监管机制无着丝粒分离和伴随的细胞适应。为实现这一目标，我们提出三点建议具体目标是定义介导的机制：1）无心姐妹染色单体大会，2）无着丝粒的极向分离，3）细胞对无着丝粒的存在的适应后期/末期。预计这些研究将揭示意想不到的新机制在后期和末期运行，维持真核基因组的完整性。