Regulation of Gene Activity and Chromatin Structure in Drosophila Heterochromatin

描述（由申请人提供）： 目的：异染色质作为转录抑制结构的传统观点受到最近的研究结果的挑战，这些研究结果显示异染色质内存在许多必需的蛋白质编码基因，并且HPia和其他异染色质因子在介导转录激活中的作用。本研究的长期目标是确定果蝇异染色质的高分辨率高阶染色质组织，并阐明在这种环境中调节转录和抑制的机制。具体目标：（i）生成详细描述染色质组成和异染色质转录活性的高分辨率图谱。(2)异染色质域的空间排列分析。(3)异染色质基因激活所需因子的鉴定与表征。研究设计：ChIP芯片技术和高密度平铺阵列将用于比较最近注释的异染色质结构域上的已知异染色质和常染色质因子的分布。这将用于分析异染色质蛋白质如HPia对染色质组织和异染色质内基因活性的作用。此外，异染色质蛋白质在介导异染色质结构域的长程相互作用中的假定作用将被测试。还将通过表征HPia向异染色质基因的募集和鉴定支配异染色质基因表达的因素来探索对基因表达的更直接的作用。这将通过纯化天然HPia复合物和全基因组范围内基于RNAi筛选有助于异染色质基因表达的因子来进行。相关性：这项研究将对我们理解基因组调控产生广泛的影响，通过提供一个更全面和准确的果蝇异染色质结构和基因功能的模型，它与哺乳动物基因组有许多相似之处。此外，异染色质因子在基因组稳定性、发育调节和常染色质基因表达（包括肿瘤抑制途径）中的核心作用对人类生物学和健康具有重要意义。

DESCRIPTION (provided by applicant): Objectives: Traditional views of heterochromatin as transcriptionally repressive structures are being challenged by recent findings showing the existence of numerous essential protein-coding genes within heterochromatin and the implication of HPia and other heterochromatic factors in mediating transcriptional activation. The long-term objectives of this study are to determine the high-resolution higher-order chromatin organization of Drosophila heterochromatin and to elucidate the mechanisms regulating transcription and repression within this environment. Specific Aims: (i) Generation of high-resolution maps detailing chromatin composition and transcriptional activity of heterochromatin. (2) Analysis of the spatial arrangement of heterochromatic domains. (3) Identification and characterization of factors required for heterochromatin gene activation. Study Design: ChlP-chip technology and high-density tiling arrays will be used to compare the distributions of known heterochromatic and euchromatic factors on recently annotated heterochromatin domains. This will be used to analyze the role of heterochromatin proteins such as HPia on chromatin organization and gene activity within heterochromatin. In addition, a putative role for heterochromatin proteins in mediating long-range interactions of heterochromatic domains will be tested. A more direct role on gene expression will also be explored through characterization of HPia recruitment to heterochromatin genes and identification of factors that govern heterochromatin gene expression. This will be conducted through purification of native HPia complexes and genome-wide, RNAi-based screening of factors that contribute to heterochromatin gene expression. Relevance: This study will have a broad impact on our understanding of genome regulation by providing a more comprehensive and accurate model of Drosophila heterochromatin structure and gene function, which shares many similarities with mammalian genomes. Moreover, the central role of heterochromatin factors in genome stability, developmental regulation, and euchromatic gene expression, which include tumor suppressor pathways, has important implications to human biology and health.