Dynamics of heterochromatin DNA repair: novel role of nuclear architecture

异染色质 DNA 修复动力学：核结构的新作用

• 批准号: 8446180
• 负责人: Irene E Chiolo
• 金额: $ 24.6万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-03-20 至 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8446180
• 关键词: Accounting; Address; Architecture; Binding Sites; Biochemical; Biological Models; Cells; Chromatin; Chromosomes; Complex; Congenital Abnormality; Country; DNA; DNA Repair; DNA Sequence; DNA Sequence Rearrangement; DNA biosynthesis; DNA lesion; Data; Detection; Diagnosis; Double Strand Break Repair; Drosophila genus; Employee Strikes; Ensure; Environmental Risk Factor; Euchromatin; Eukaryota; Exposure to; Foundations; Future; Genetic; Genetic Recombination; Genome; Genome Stability; Genomic Instability; Goals; Heterochromatin; Homologous Gene; Human Genome; Image; Imaging technology; Individual; Ionizing radiation; Knowledge; Malignant Neoplasms; Mammalian Cell; Mammals; Metabolism; Methods; Molecular; Motion; Mutation; Normal Cell; Nuclear; Organism; Outcomes Research; Pathway interactions; Predisposition; Prevention; Process; Proteins; Radiation; Regulation; Repetitive Sequence; Research; Resolution; Risk; Role; Saccharomyces cerevisiae; Sister Chromatid; Site; Speed; Testing; Yeasts; base; driving force; environmental mutagens; homologous recombination; human disease; novel; novel strategies; prevent; public health relevance; recombinase; recombinational repair; repaired; response; tool development

DESCRIPTION (provided by applicant): Double-strand breaks (DSBs) in DNA occur as a result of environmental challenges, such as exposure to ionizing radiation (IR) or during normal cell metabolism, such as DNA replication. In heterochromatin, DSBs are a major threat to genome stability, since the abundance of repetitive sequences maximizes the potential for aberrant recombination and genome instability during repair. However, the regulation of repair processes operating in this large chromatin domain is mostly unknown. The Drosophila model system is ideal for studying heterochromatin DSB response. It features genetic tractability comparable to yeast, complex heterochromatin similar to mammals, and is advantageous for cytological approaches because all pericentromeric regions of different chromosomes are concentrated in one distinct nuclear domain. Our previous studies with this model system revealed that heterochromatin responds dynamically to DSBs: the entire domain expands and the damaged sites move to outside the domain to complete homologous recombination (HR) repair. Similar responses in mammalian cells suggest that this pathway is highly conserved. While early HR processing of DSBs occurs within the heterochromatin domain, later HR steps are postponed until relocalization is complete. Loss of heterochromatin components results in defective relocalization of repair centers, aberrant recombination and chromosome rearrangements. These results reveal the importance of heterochromatin proteins in coordinating the spatial and temporal dynamics of HR repair in heterochromatin and in protecting repeated DNA sequences from genome instability. To significantly advance our understanding of this important and novel mechanism, we will combine multi-disciplinary approaches to identify pro-/anti-recombinases and nuclear architecture components required for successful HR repair of heterochromatic DSBs. These studies will uncover the mechanisms that normal cells use to protect repeats from environmental mutagens. In addition, this research will contribute to our understanding of the mechanisms that generate chromosome rearrangements when mutations or environmental challenges inactivate the safeguarding mechanisms. This knowledge is expected to contribute to the future development of tools for prevention, diagnosis, and treatment of human diseases associated with repeated DNA instability, such as cancer and birth defects.

描述（由申请人提供）：DNA中的双链断裂（DSB）是环境挑战的结果，如暴露于电离辐射（IR）或在正常细胞代谢过程中，如DNA复制。在异染色质中，DSB是对基因组稳定性的主要威胁，因为重复序列的丰度最大化了修复期间异常重组和基因组不稳定性的可能性。然而，在这个大的染色质结构域中操作的修复过程的调节大多是未知的。果蝇模型系统是研究异染色质DSB反应的理想系统。它的特点是遗传易处理性与酵母，复杂的异染色质类似于哺乳动物，是有利的细胞学方法，因为所有的不同染色体的着丝粒周围区域集中在一个不同的核域。我们以前的研究与这个模型系统显示，异染色质动态响应DSB：整个域扩展和受损的网站移动到域外完成同源重组（HR）修复。在哺乳动物细胞中的类似反应表明该途径是高度保守的。虽然DSB的早期HR处理发生在异染色质结构域内，但后期HR步骤被推迟，直到重新定位完成。异染色质组分的丢失导致修复中心的缺陷性重新定位、异常重组和染色体重排。这些结果揭示了异染色质蛋白在协调异染色质中HR修复的空间和时间动态以及保护重复DNA序列免受基因组不稳定性影响方面的重要性。为了显著推进我们对这一重要和新颖机制的理解，我们将结合联合收割机多学科方法来鉴定成功HR修复异染色质DSB所需的前/反重组酶和核结构组件。这些研究将揭示正常细胞用于保护重复序列免受环境诱变剂影响的机制。此外，这项研究将有助于我们了解当突变或环境挑战破坏保护机制时产生染色体重排的机制。这些知识有望有助于未来开发预防、诊断和治疗与重复DNA不稳定性相关的人类疾病的工具，如癌症和出生缺陷。