Formation, Structure and Function in Heterochromatin

异染色质的形成、结构和功能

• 批准号: 7894293
• 负责人: Sarah C.R. ELGIN
• 金额: $ 20.15万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-10 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7894293
• 关键词: Address; Binding; Biochemical; Biological Models; Cell physiology; Cells; Characteristics; Chromatin; Chromatin Structure; Chromosomal Instability; Chromosome Structures; Chromosomes; Collaborations; Complex; DNA; DNA Packaging; DNA Transposons; Developmental Disabilities; Distal; Documentation; Drosophila genome; Drosophila genus; Elements; Environment; Enzymes; Epigenetic Process; Exhibits; Funding; Gene Expression; Gene Expression Regulation; Gene Silencing; Genes; Genetic; Genetic Screening; Genetic Transcription; Genome; Goals; Grant; Health; Heterochromatin; Histone H3; Histones; Human; Indium; Investigation; Lead; Light; Link; Lysine; Malignant Neoplasms; Maps; Measures; Methods; Methylation; Methyltransferase; Missense Mutation; Mitotic; Mitotic Chromosome; Modeling; Molecular Biology; Molecular Chaperones; Mutation; NURF; Pattern; Phenotype; Phosphorus; Play; Positioning Attribute; Principal Investigator; Progress Reports; Protein Binding Domain; Protein Isoforms; Proteins; Protocols documentation; RNA Interference; Repetitive Sequence; Reporter; Research Design; Research Personnel; Resolution; Role; SU(VAR)3-9; Screening procedure; Shadowing (Histology); Signaling Protein; Structural Protein; Structure; Surface; System; Systems Analysis; Tertiary Protein Structure; Test Result; Testing; The Sun; Transferase; Update; Upper arm; Work; Yeasts; base; biological systems; comparative; density; developmental disease; dimer; dosage; gene function; heterochromatin-specific nonhistone chromosomal protein HP-1; histone methyltransferase; histone modification; human disease; insight; programs; promoter; protein complex; telomere; tumor; vpr Genes; web site; yeast two hybrid system

DESCRIPTION (provided by applicant): The alternative packaging of DNA into euchromatic and heterochromatic forms can be stably maintained in differentiated cells, and represents an important form of epigenetic inheritance. Malfunction in the heterochromatin system can lead to misregulation of gene expression, as well as chromosome instability, and is a contributing factor in many health problems, including cancer and genetically-based developmental disabilities. Heterochromatin packaging can be perpetuated and spread by virtue of an interacting set of structural proteins, with Heterochromatin Protein 1 (HP1a) playing a key role in both recognizing a critical histone modification mark (methylation of H3K9) and interacting with the histone methyl transferase (HMT). Our long term goal is to understand why and how certain regions of the genome are selected for heterochromatin assembly, and to identify the required chromosomal proteins and their interactions. All work will be carried out in Drosophila, a model system that allows genetic, cytological, and biochemical approaches; position effect variegation (PEV) is used as an indicator of heterochromatin packaging. Our studies of chromosome four (entirely heterochromatic by several measures) indicate that remnants of the 1360 DNA transposon serve as targets for heterochromatin formation, but that stable heterochromatin requires a high repeat density. In the first specific aim, the role of genome organization and identity of specific targets will be tested using reporter P elements with different types and copy number of repetitious elements. In our second aim, binding studies and structural analysis will explore how HP1a discriminates among its several partners to assemble a silencing structure. The HMT specific for chromosome four will be identified, its pattern of interactions explored, and the impact on spreading considered. Additional heterochromatin components will be identified by screening for proteins interacting with HP2 in a yeast two hybrid system exploiting recently recovered HP2 mutations as controls. In a third long-term aim, we will ask whether some fourth chromosome genes function optimally in a heterochromatic environment, and explore that adaptation. Taken together these studies will illuminate how heterochromatin formation is initiated and sustained, and will provide new insights into gene regulation at the domain level.

描述（由申请人提供）：DNA包装成常染色质和异染色质形式的替代性包装可在分化细胞中稳定维持，代表了表观遗传的一种重要形式。异染色质系统中的功能障碍可导致基因表达的失调以及染色体不稳定性，并且是许多健康问题的促成因素，包括癌症和基于遗传的发育障碍。异染色质包装可以通过一组相互作用的结构蛋白而永久存在和传播，其中异染色质蛋白1（HP 1a）在识别关键组蛋白修饰标记（H3 K9的甲基化）和与组蛋白甲基转移酶（HMT）相互作用方面发挥关键作用。我们的长期目标是了解为什么以及如何选择基因组的某些区域进行异染色质组装，并确定所需的染色体蛋白质及其相互作用。所有工作将在果蝇中进行，果蝇是一个允许遗传学，细胞学和生物化学方法的模型系统;位置效应杂色（PEV）被用作异染色质包装的指标。我们对4号染色体（通过几种方法完全异染色质）的研究表明，1360 DNA转座子的残余物是异染色质形成的靶点，但稳定的异染色质需要高重复密度。在第一个具体目标中，将使用具有不同类型和拷贝数的重复元件的报告P元件来测试基因组组织的作用和特定靶标的身份。在我们的第二个目标中，结合研究和结构分析将探索HP 1a如何区分其几个合作伙伴组装沉默结构。将确定特定于4号染色体的HMT，探索其相互作用模式，并考虑其对传播的影响。其他异染色质成分将通过筛选与HP 2在酵母双杂交系统中相互作用的蛋白质来鉴定，该系统利用最近恢复的HP 2突变作为对照。在第三个长期目标中，我们将询问某些第四染色体基因是否在异染色质环境中发挥最佳功能，并探索这种适应。总之，这些研究将阐明异染色质的形成是如何启动和持续的，并将提供新的见解，在域水平的基因调控。