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）是由于环境挑战而发生的，例如暴露于电离辐射（IR）或正常细胞代谢期间，例如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过程中异常重组和基因组不稳定性的潜力。但是，在此大染色质结构域中运行的修复过程的调节大多未知。果蝇模型系统是研究异染色质DSB响应的理想选择。它具有与酵母，复杂的异染色质相当的遗传性障碍性，与哺乳动物相似，对于细胞学方法是有利的，因为不同染色体的所有果粒区域都集中在一个不同的核域中。我们对该模型系统的先前研究表明，异染色质对DSB进行动态反应：整个域扩展，受损的位点移至域外部以完成同源重组（HR）修复。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域内，但后来将HR步骤推迟直到重新定位完成。异染色质成分的丧失导致修复中心的重新定位，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力学方面的重要性，并保护重复的DNA序列免受基因组不稳定性的影响。为了显着提高我们对这种重要和新颖机制的理解，我们将结合多学科的方法，以识别成功的HR修复异质变色DSB所需的亲/抗重组酶和核结构成分。这些研究将发现正常细胞用来保护重复剂免受环境诱变剂的机制。此外，这项研究将有助于我们理解在突变或环境挑战使保护机制失活时产生染色体重排的机制。这些知识有望为预防，诊断和治疗与重复DNA不稳定性（例如癌症和先天缺陷）相关的人类疾病的未来开发。