Drosophila Linker Histone H1 Functions in Chromosome Architecture and Activity

描述（申请人提供）：本提案的长期目标是了解H1接头组蛋白在染色体结构和活性中的功能。我们建议使用果蝇，果蝇，作为一个模型系统，因为它提供了许多优势的染色体结构和遗传活性的研究，因为果蝇H1非常类似于哺乳动物H1接头组蛋白。在后生动物中，H1几乎和核小体核心颗粒一样丰富，这表明它在建立和维持染色质纤维的结构中起着重要作用。H1可以在多个水平上影响染色质功能，包括在单个核小体颗粒和阵列的水平上局部地影响染色质功能，以及在长范围内影响染色质功能以确定染色质折叠成更高级结构。H1可能影响基因表达和核DNA代谢的许多其他反应，如复制、重组和修复。我们对连接体组蛋白作用的认识大多来自体外研究。然而，H1功能的体内分析一直滞后。 最近，我们使用RNA干扰（RNAi）几乎完全耗尽H1在果蝇体内。这种方法使我们能够证明H1是果蝇发育所必需的，并且是正常染色体结构所必需的。我们确定异染色质结构和活性作为H1调控的主要目标。我们还发现，H1对基因表达既有积极的影响，也有消极的影响。为了更深入地了解H1控制染色体结构和基因活性的机制，确定与H1协同工作以调节基因组表观遗传状态的因素，并发现依赖H1正常功能的其他细胞过程，我们建议追求以下具体目标。(1)我们将阐明H1调节异染色质的结构和活性的机制。(2)我们将表征与H1在体内功能性相互作用的蛋白质网络。(3)我们将对H1进行详细的体内结构-功能分析。拟议研究的成功完成有望为染色质的这一主要成分影响真核生物染色体结构和活性的方式提供重要见解。

DESCRIPTION (provided by applicant): The long-term goal of this proposal is to understand the functions of H1 linker histone in chromosome structure and activity. We propose to use the fruit fly, Drosphila melanogaster, as a model system because it provides many advantages for studies of chromosome structure and genetic activity and because Drosophila H1 strongly resembles mammalian H1 linker histones. In metazoans, H1 is nearly as abundant as nucleosome core particles, suggesting that it plays important roles in establishing and maintaining the architecture of the chromatin fiber. H1 can influence chromatin functions at several levels, including locally at the level of individual nucleosome particles and arrays as well as over long range to determine the folding of chromatin into higher order structures. H1 is expected to affect gene expression and many other reactions of nuclear DNA metabolism, such as replication, recombination and repair. Much of our knowledge about the roles of linker histones comes from in vitro studies. However, in vivo analyses of H1 functions have been lagging. Recently, we used RNA interference (RNAi) to nearly completely deplete H1 in Drosophila melanogaster in vivo. This approach allowed us to demonstrate that H1 is essential for Drosophila development and that it is required for normal chromosome architecture. We identified heterochromatin structure and activity as primary targets of H1 regulation. We also found that H1 has both positive and negative effects on gene expression. To gain a deeper understanding of the mechanisms by which H1 controls chromosome structure and gene activity, to identify the factors that work in concert with H1 to regulate the epigenetic states of the genome, and to discover other cellular processes that depend upon H1 for proper function, we propose to pursue the following specific aims. (1) We will elucidate mechanisms by which H1 regulates the structure and activity of heterochromatin. (2) We will characterize the network of proteins that functionally interact with H1 in vivo. (3) We will perform a detailed in vivo structure-function analysis of H1. The successful completion of the proposed studies is expected to provide crucial insights into the ways in which this major component of chromatin affects the structure and activity of eukaryotic chromosomes.