Epigenetic inheritance of heterochromatin

项目摘要 这项工作的长期目标是了解组蛋白H3赖氨酸9甲基化(H3K9me)和 异色基因沉默是表观遗传的。异染色质是一种保守的特征 真核细胞的染色体，在基因表达调控和基因维持中起重要作用 从酵母到人类的各种生物中的染色体稳定性。利用裂变型酵母 作为一种模式生物，我们最近证明了异位诱导 在缺乏序列特异性的情况下，H3K9me的结构域和沉默可以表观遗传 当通过缺失Epe1抗沉默因子而降低H3K9me去甲基化的速率时，重新启动。在……里面 此外，我们还发现，在野生型epe1+细胞中，小的非编码RNA(SiRNAs)或转录 因子结合位点在H3K9me的表观遗传维持中起着关键作用。最近，我们已经 已发现的RNAi非依赖性RNA衰变途径的作用，保守组蛋白的自动调节 H3K9甲基转移酶和核心复制分叉相关蛋白在表观遗传维持中的作用 异染色质。在这个提案中，我们将使用体内方法和生化分析相结合的方法来 研究(1)新发现的被称为rixosome的RNA衰变复合体在表观遗传学中的功能 遗传，(2)复制分叉相关的染色质组装复合体在组蛋白保留中的作用 和DNA复制过程中的表观遗传，以及(3)保守的泛素连接酶在调节中的作用 H3K9甲基化和准确的异染色质形成。这些研究的最终目标是 对表观遗传维持沉默染色质结构域机制的分子理解。

Project Summary The long-term goal of this work is to understand how histone H3 lysine 9 methylation (H3K9me) and heterochromatic gene silencing are epigenetically inherited. Heterochromatin is a conserved feature of eukaryotic chromosmes and plays important roles in regulation of gene expression and maintenance of chromosome stability in organisms ranging from yeast to human. Using the fission yeast Schiozosaccharomyces pombe as a model organism, we recently demonstrated that ectopically induced domains of H3K9me and silencing can be epigenetically inherited in the absence of sequence-specific recruitment when the rate of H3K9me demethylation is reduced by deletion of the Epe1 anti-silencing factor. In addition, we have discovered that, in wildtype epe1+ cells, small noncoding RNAs (siRNAs) or transcription factor binding sites play critical roles in epigenetic maintenance of H3K9me. More recently, we have uncovered roles for an RNAi-independent RNA decay pathaway, autoregulation of the conserved histone H3K9 methyltransferase, and core replication fork-associated proteins in epigenetic maintenance of heterochromatin. In this proposal we will use a combination of in vivo approaches and biochemical assays to investigate (1) the functions of a newly discovered RNA decay complex, called the rixosome, in epigenetic inheritance, (2) the role of a replication fork-associated chromatin assembly complex in retention of histones and epigenetic inheritance during DNA replication, and (3) the role of a conserved ubiquitin ligase in regulation of H3K9 methylation and accurate heterochromatin formation. The ultimate goal of these studies is a molecular understanding of the mechanisms that epigenetically maintain silent chromatin domains.