Role of Linker Histone H1 in Epigenetic Gene Regulation

描述（由申请人提供）：接头组蛋白H1在表观遗传基因调控中的作用项目概述表观遗传机制对于哺乳动物发育和细胞分化期间的染色质结构重编程和基因表达至关重要。H1连接组蛋白是染色质的主要结构蛋白，与核小体核心颗粒结合，在调节染色质高级结构折叠中起关键作用。然而，H1在表观遗传基因调控中的作用尚未被探索。以前，我们表明，通过同时灭活3个H1接头组蛋白基因，H1的总量是哺乳动物发育所必需的。我们推导出三重H1空胚胎干细胞系，并表明H1在控制这些细胞中的几个印迹基因表达中特别重要。我们还发现，这两个受影响的基因座的印迹控制区的DNA甲基化水平随着H1的减少而降低，从而表明H1和DNA甲基化之间存在新的联系。我们现在建议解决这个新的表观遗传联系的潜在机制，并调查额外的H1调节胚胎干细胞和小鼠模型中的表观遗传事件。具体而言，我们将：1）测试H1组蛋白是否通过募集DNA甲基转移酶来调节特定DNA甲基化模式的建立或维持; 2）鉴定额外的关键H1调节的表观遗传事件，并表征适当控制基因表达所需的此类事件的序列和功能依赖性; 3）研究H1在胚胎发生和配子发生期间表观遗传基因调节中的体内调节作用。这些研究的结果将促进我们对表观遗传基因调控机制的认识。相关性：表观遗传基因调控异常导致了许多人类疾病，如癌症和印记基因疾病。了解表观遗传基因调控机制将为如何通过实验对表观遗传信息进行重新编程以达到治疗目的提供重要线索。

DESCRIPTION (provided by applicant): Role of Linker Histone H1 in Epigenetic Gene Regulation Project Summary Epigenetic mechanisms are crucial for chromatin structure reprogramming and gene expression during mammalian development and cell differentiation. H1 linker histones are major chromatin structural proteins that associate with nucleosome core particles and play a key role in mediating higher order chromatin structure folding. However, the role of H1 in epigenetic gene regulation has not been explored. Previously we showed, by inactivating 3 H1 linker histone genes simultaneously, that the total amount of H1 is essential for mammalian development. We derived triple H1 null embryonic stem cell lines and showed that H1 is particularly important in controlling several imprinted gene expression in these cells. We also found that DNA methylation level at the imprinting control regions of these two affected loci is decreased with H1 reduction, thus suggesting a new link between H1 and DNA methylation. We now propose to address the underlying mechanisms of this novel epigenetic link and to investigate additional H1 regulated epigenetic events in embryonic stem cells and in mouse models. Specifically, we will: 1) Test whether H1 histones regulate establishment or maintenance of specific DNA methylation patterns through recruitment of DNA methyltransferases; 2) Identify additional critical H1 regulated epigenetic events and characterize the sequence and functional dependence of such events that are required for proper control of gene expression; 3) Study the in vivo regulatory role of H1 in epigenetic gene regulation during embryogenesis and gametogenesis. Findings from these studies will advance our knowledge of epigenetic gene regulation mechanisms. Relevance: Aberrant epigenetic gene regulation has been responsible for many human diseases, such as cancer and imprinted gene diseases. Understanding the epigenetic gene regulation mechanisms will provide critical clues as to how the epigenetic information can be experimentally reprogrammed for therapeutic purposes.