Nucleosome Dynamics and the Repair of DNA Damage

核小体动力学和 DNA 损伤修复

• 批准号: 8689984
• 负责人: Brendan D Price
• 金额: $ 34.29万
• 依托单位: DANA-FARBER CANCER INST
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8689984
• 关键词: Acetylation; Architecture; Automobile Driving; Binding Proteins; Cells; Chromatin; Chromatin Remodeling Factor; Chromatin Structure; Clinical; Complex; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; Data; Detection; Double Strand Break Repair; Etiology; Event; Excision; G22P1 gene; Genes; Genome; Genome Stability; Genomic Instability; Genomics; Histone Acetylation; Histone H2A; Histones; Human Genome; Intercistronic Region; Lead; Libraries; Malignant Neoplasms; Mammalian Cell; Maps; Molecular; Mutation; Nonhomologous DNA End Joining; Nucleosomes; Pathway interactions; Pattern; Play; Positioning Attribute; Process; Proteins; Radiation; Radiation Tolerance; Radiation therapy; Radiation-Sensitizing Agents; Resected; Resolution; Role; Side; Site; Structure; Techniques; Ubiquitination; Variant; Work; Zinc Fingers; carcinogenesis; chemotherapy; chromatin modification; chromatin remodeling; density; flexibility; histone modification; homologous recombination; inhibitor/antagonist; innovation; insight; neoplastic cell; nuclease; prevent; public health relevance; rapid detection; repaired; stem; tumor; tumor progression; zinc finger nuclease

DESCRIPTION (provided by applicant): The repair of DNA damage is critical to protect the integrity of the genome and prevent genotoxic events which can lead to cancer. However, mammalian cells contain a diverse array of functional and structural chromatin domains, which differ in the pattern of histone modifications, chromatin binding proteins and in the density of nucleosome packing. Consequently, remodeling of the chromatin structure at sites of damage is critical for the detection and repair of DNA damage. However, the underlying mechanism driving changes in nucleosome structure at DSBs remains poorly defined. Our preliminary data demonstrates that a histone variant, histone H2A.Z, is rapidly exchanged onto nucleosomes at DNA double-strand breaks (DSBs). The exchange of H2A.Z at DSBs alters nucleosomes dynamics, driving the formation of open, flexible chromatin domains at the break. Further, this H2A.Z exchange promotes specific patterns of histone modification and is critical for controlling resection and processing of the DNA at the break site. The central hypothesis is that H2A.Z exchange drives remodeling of the chromatin at DSBs and controls both histone modification and end processing of the DNA. A library of Zinc Finger Nucleases (ZFNs) will be used to create sequence-specific DSBs in actively transcribed genes and compact, intergenic regions. We will determine how H2A.Z exchange remodels chromatin structure in genes and intergenic regions and identify key differences in the mechanism of repair between these distinct chromatin domains. We will determine how H2A.Z exchange impacts the positioning of nucleosomes at DSBs and determine how nucleosome positioning at DSBs impacts the subsequent modification of histones and the extent of end resection. Further, we will identify key domains on H2A.Z which alter nucleosome dynamics and promote the formation of open chromatin structures at DSBs. In addition, we will determine how the presence of H2A.Z-nucleosomes at DSBs impacts the mechanism and fidelity of DSB repair. By using Zinc Finger Nucleases to create DSBs in genes and intergenic regions, we can determine how DSB repair proceeds in distinct functional domains and unravel the importance of H2A.Z in altering the local chromatin architecture at DSBs. Further, because many tumor cells have both altered chromatin organization and increased levels of histone H2A.Z, this work will provide new insights into how chromatin structure and H2A.Z impacts processes related to carcinogenesis, tumor progression and the sensitivity of tumors to both radiation therapy and chemotherapy.

描述（由申请人提供）：DNA损伤的修复对于保护基因组完整性并防止遗传毒性事件至关重要，这可能导致癌症。然而，哺乳动物细胞包含各种功能和结构染色质结构域，它们在组蛋白修饰的模式，染色质结合蛋白和核小体堆积的密度上有所不同。 因此，对损伤部位的染色质结构进行重塑对于检测和修复DNA损伤至关重要。但是，DSBS核小体结构中驱动核小体结构的基本机制仍然很差。我们的初步数据表明，在DNA双链断裂（DSB）处，组蛋白变体H2A.Z迅速交换到核小体上。 DSBS上H2A.Z的交换改变了核小体动力学，在断裂时驱动了开放的柔性染色质结构域的形成。此外，此H2A.Z交换促进了组蛋白修饰的特定模式，对于控制断裂位点的DNA的切除和处理至关重要。中心假设是H2A.Z交换驱动DSB上染色质的重塑，并控制了组蛋白的修饰和DNA的终端加工。锌指核酸酶（ZFN）的库将用于在主动转录基因和紧凑的基因间区域中创建序列特异性DSB。我们将确定H2A.Z交换如何重塑基因和基因间区域的染色质结构，并确定这些不同染色质结构域之间修复机理的关键差异。我们将确定H2A.Z交换如何影响DSBS核小体的定位，并确定DSBS的核小体定位如何影响组蛋白的随后修饰和终端切除程度。此外，我们将确定H2A.Z上的关键结构域改变了核小体动力学并促进DSBS上开放染色质结构的形成。此外，我们将确定在DSB上的H2A.Z-核体的存在如何影响DSB修复的机制和保真度。通过使用锌指核酸酶在基因和基因间区域中创建DSB，我们可以确定DSB修复如何在不同的功能域中进行，并揭示H2A.Z在改变DSBS局部染色质体系结构中的重要性。此外，由于许多肿瘤细胞既改变了染色质组织，又改变了组蛋白H2A.Z的水平，因此这项工作将为染色质结构和H2A.Z如何影响与致癌，肿瘤进展以及肿瘤对放射治疗和化学疗法的敏感性有关的过程提供新的见解。