Chromosome Architecture and Domains of Repression

染色体结构和抑制域

• 批准号: 6684612
• 负责人: Marc R. Gartenberg
• 金额: $ 47.88万
• 依托单位: UNIV OF MED/DENT NJ-R W JOHNSON MED SCH
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-09-12 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6684612
• 关键词: DNA replication; Saccharomyces cerevisiae; cell cycle; chromatin; chromosomes; electron microscopy; fluorescence microscopy; fungal genetics; gene induction /repression; genetic recombination; heterochromatin; nucleic acid sequence; nucleoproteins

DESCRIPTION (provided by applicant): The long term goals of this project are to elucidate the mechanism of transcriptional control by heterochromatin, a structure that spans and inactivates large regions of eukaryotic genomes. Heterochromatic domains are constitutively condensed, inaccessible structures that contain hypoacetylated histones and specialized non-histone components. Many genes involved in early stages of development are permanently shut off by formation of heterochromatin or related structures. Inappropriate expression of these genes leads to abnormal development, leukemias, and other disease states. Recently, heterochromatin components have been linked to breast cancer and the control of medically relevant euchromatic genes. Inactivation of genes at the silent mating-type loci and telomeres of yeast Saccharomyces cerevisiae involves a chromatin structure, termed silent chromatin or yeast heterochromatin, that bears functional and structural similarities to the heterochromatin of higher eukaryotes. At the silent mating loci, repression requires cis-acting regulatory sequences, termed silencers, and a set of non-histone chromatin components known as the Sir proteins. A critical event during S-G2/M progression establishes a silent state that is maintained during the remainder of the cell cycle and inherited by progeny cells. To further understand the fundamental properties of heterochromatin-mediated repression, we will explore the molecular events leading to establishment of the silent state in yeast. Special focus will be placed on characterizing the changes in chromatin during establishment, and identifying the cell cycle-dependent requirement. Silent chromatin fragments will be purified and the stochiometry of silencing factors will be determined. Electron microscopy will be used to visualize higher order structural features of silent chromatin rings in vitro and real-time fluorescence microscopy will be used to identify parameters that localize silent chromatin in vivo. Genetic methods will be used to investigate how one nuclear periphery protein, Esc 1, contributes to silencing.

描述（由申请人提供）：该项目的长期目标是通过异染色质阐明转录控制的机理，这种结构跨越并灭活真核基因组的大区域。杂色结构域是含有低乙酰化组蛋白和专门的非历史成分的组成型凝结的，难以访问的结构。通过形成异染色质或相关结构，许多参与发育早期阶段的基因被永久关闭。这些基因的不当表达会导致异常发育，白血病和其他疾病状态。最近，异染色质成分已与乳腺癌和医学相关的正念基因的控制有关。在静态的交配型基因座和酵母糖含量酿酒酵母的端粒处的基因失活涉及一种染色质结构，称为静音染色质或酵母异染色质，具有与较高真核生物的异染色质的功能和结构相似性。在沉默的交配基因座上，抑制需要顺式作用调节序列，称为消音器，以及一组称为SIR蛋白质的非内酮染色质成分。 S-G2/M进展过程中的关键事件建立了在细胞周期其余部分中保持的沉默状态，并由后代细胞遗传。为了进一步了解异染色质介导的抑制的基本特性，我们将探索导致在酵母中建立沉默状态的分子事件。特殊的重点将放在表征建立过程中染色质的变化以及确定细胞周期依赖性需求上。将纯化无声的染色质片段，并确定沉默因子的静态测定法。电子显微镜将用于在体外可视化无声染色质环的高阶结构特征，实时荧光显微镜将用于识别在体内定位静音染色质的参数。遗传方法将用于研究一种核外围蛋白ESC 1如何有助于沉默。