Role of Heterochromatin protein 1 Beta in Genome Maintenance and Oncogenesis

异染色质蛋白 1 Beta 在基因组维护和肿瘤发生中的作用

基本信息

批准号：
8657357
负责人：
Tej K Pandita
金额：
$ 30.31万
依托单位：
METHODIST HOSPITAL RESEARCH INSTITUTE
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-07-16 至 2018-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8657357
关键词：
Acetylation Appearance Applications Grants Binding Biochemical C-terminal Cancer Patient Cell Communication Cell Survival Cell physiology Cells Cessation of life ChIP-on-chip Chromatin Chromatin Structure Chromosomes, Human, Pair 1 Clinical Co-Immunoprecipitations Complement Complex DNA DNA Damage DNA Double Strand Break DNA Repair DNA-PKcs Data Development Double Strand Break Repair Embryo Euchromatin Eukaryota Fibroblasts Frequencies Genes Genome Genomic Instability Genomics Goals Heterochromatin Histone H3 Histone H4 Histones Human Image Individual Investigation Ionizing radiation Kinetics Knockout Mice Lasers Lesion Link Lysine Maintenance Mammalian Cell Mammals Mammary Gland Parenchyma Maps Mediating Modification Mus N-terminal NBS1 gene Neoplastic Cell Transformation Normal Cell Normal tissue morphology Oncogenic Pathway interactions Phenotype Play Post-Translational Protein Processing Predisposition Protein Isoforms Proteins Radiation Induced DNA Damage Radiation Tolerance Radiation therapy Reporting Research Research Personnel Role Site Tail Testing Time Tissues Tumor Tissue Zinc Fingers ataxia telangiectasia mutated protein base cell injury cell killing chromatin protein expression vector heterochromatin-specific nonhistone chromosomal protein HP-1 histone modification improved in vivo insight novel novel strategies nuclease overexpression prevent public health relevance repaired response tumor tumorigenesis

项目摘要

The DNA damage response (DDR) mediates DNA double strand break (DSB) repair and protects cells from damage induced transformation or death. Cellular DNA is organized into protein DNA complexes (chromatin) in order to control DNA access by proteins and regulated DNA dependent functions. In eukaryotes, there are two major types of chromatin: heterochromatin (gene poor) and euchromatin (gene rich) that are distinguished by specific histone tail modifications and differences in nonhistone chromatin protein constituents. Among nonhistone chromatin proteins, heterochromatin protein 1 (HP1) is the best- studied example. In mammals, there are three HP1 isoforms (HP1a, HP1b and HP1g) all structurally characterized by two conserved domains separated by a hinge region: an N-terminal chromodomain (CD) and a C-terminal chromoshadow domain (CSD). We previously demonstrated that overexpression of HP1a or HP1b in human cells increases genomic instability and sensitivity to ionizing radiation (IR)-induced cell killing. Moreover, depletion of Cbx1 (mouse HP1b) in mouse cells increased genomic instability, spontaneous ATM (ataxia-telangiectasia mutated) autophosphorylation, reduced the frequency of IR-induced g-H2AX foci formation, increased IR-induced cell killing and oncogenic transformation. Recent studies by other investigators support our results indicating HP1b has both negative as well as positive effects on DNA DSB repair and suggest that the precise level of functional HP1b is a critical determinant to IR sensitivity. Since most mechanistic details as to how HP1 b interacts with repair associated proteins to modulate DNA DSB repair are unexplored, we will determine how different domains interact with chromatin/repair protein components to regulate DNA DSB repair. We hypothesize that the negative effect of HP1b is mediated through CD domain binding to H3K9me, since deletion of this domain can improve cell survival and the positive effect could be due to HP1b CSD interactions with acetylated histone H4K16 (H4K16ac) a unique histone modification that prevents higher order chromatin packing, which can impede protein access to DNA and with proteins involved in the DDR. Defective DNA damage repair is linked with oncogenic transformation and tumorigenesis, therefore, we will determine the impact of decreased Cbx1 on tumor development in (i) Cbx1+/- mice in the presence and absence of Atm and (ii) Cbx1 conditional knockout mice. These studies will define the mechanism by which HP1b regulates the cellular IR response and tumorigenesis. Our hypothesis-that the non-histone modifying factor HP1b regulates chromatin structure and, through interactions with DDR components, contributes to oncogenesis-is a novel idea requiring in depth studies. Further understanding about the mechanistic basis for biochemical differences between normal and tumor tissue chromatin structure will facilitate the development of new strategies for modifying IR response and improving clinical radiation therapy.

DNA 损伤反应 (DDR) 介导 DNA 双链断裂 (DSB) 修复并保护细胞因损伤引起的转化或死亡。细胞 DNA 被组织成蛋白质 DNA 复合物（染色质）以控制蛋白质进入 DNA 并调节 DNA 依赖性功能。在真核生物中，染色质有两种主要类型：异染色质（基因贫乏）和常染色质（基因贫乏）丰富），通过特定的组蛋白尾部修饰和非组蛋白染色质的差异来区分蛋白质成分。在非组蛋白染色质蛋白中，异染色质蛋白 1 (HP1) 是最好的 - 研究过的例子。在哺乳动物中，存在三种 HP1 亚型（HP1a、HP1b 和 HP1g），其结构均相同其特征是由铰链区分隔的两个保守结构域：N 端染色结构域 (CD) 和 C 端染色体阴影结构域 (CSD)。我们之前证明 HP1a 的过度表达人类细胞中的 HP1b 或 HP1b 会增加基因组的不稳定性以及对电离辐射 (IR) 诱导的细胞的敏感性杀戮。此外，小鼠细胞中 Cbx1（小鼠 HP1b）的缺失增加了基因组的不稳定性，自发性 ATM（共济失调毛细血管扩张突变）自磷酸化，降低 IR 诱导的频率 g-H2AX 病灶形成，增加 IR 诱导的细胞杀伤和致癌转化。最近的研究其他研究人员支持我们的结果，表明 HP1b 对 DNA 既有负面影响，也有正面影响 DSB 修复并表明功能性 HP1b 的精确水平是红外灵敏度的关键决定因素。由于大多数关于 HP1 b 如何与修复相关蛋白相互作用以调节 DNA 的机制细节 DSB 修复尚未探索，我们将确定不同结构域如何与染色质/修复蛋白相互作用调节 DNA DSB 修复的成分。我们假设 HP1b 的负面影响是介导的通过 CD 结构域与 H3K9me 结合，因为删除该结构域可以提高细胞存活率，并且积极作用可能是由于 HP1b CSD 与乙酰化组蛋白 H4K16 (H4K16ac) 的独特相互作用组蛋白修饰可防止高阶染色质堆积，从而阻碍蛋白质接触 DNA 以及参与 DDR 的蛋白质。有缺陷的 DNA 损伤修复与致癌转化和肿瘤发生有关，因此，我们将确定 Cbx1 减少对 (i) Cbx1+/- 小鼠中肿瘤发展的影响不存在 Atm 和 (ii) Cbx1 条件敲除小鼠。这些研究将确定其机制 HP1b 调节细胞 IR 反应和肿瘤发生。我们的假设——非组蛋白修饰 HP1b 因子调节染色质结构，并通过与 DDR 成分相互作用，有助于肿瘤发生是一个需要深入研究的新想法。进一步了解其机制基础正常组织和肿瘤组织染色质结构之间的生化差异将有助于开发改变 IR 反应和改善临床放射治疗的新策略。