Mechanism of Heterochromatin Assembly and epigenetic inheritance

项目摘要 组蛋白的共价修饰，如乙酰化、甲基化、磷酸化和泛素化，是 对调节染色质结构和功能是必不可少的，组蛋白缺陷修饰具有因果作用 在许多发育障碍和疾病中。我们的长期目标是使用分裂酵母异染色质 组装为实验模型，研究不同的组蛋白修饰活动是如何协调的 启动不同的基因表达状态，以及这些状态是如何表观遗传的。异染色质 优先在重复的DNA元件上组装，对于调节基因表达和 保持基因组的完整性。异染色质的形成严重依赖于H3的甲基化 赖氨酸9(H3K9me)。有趣的是，H3K9甲基转移酶的活性受到泛素化的刺激 H3赖氨酸14(H3K14ub)，尽管其机制尚不清楚。我们将研究H3K14ub如何 刺激H3K9甲基转移酶以及H3K14ub如何在体内调节以帮助异染色质组装。 异染色质也是研究基于染色质的表观遗传机制的一个很好的模型。一个 一个重要的悬而未决的问题是，携带修饰的亲本组蛋白是如何沉积到新的 在细胞周期的S阶段合成DNA以指导这些修饰的复制 女儿染色单体。我们开发了eSPAN(序列蛋白相关新生DNA的浓缩)。 裂解酵母，它使我们能够测量亲代组蛋白在子代DNA链上的分离。我们 将结合这一新的基因组工具和传统的遗传方法来研究调控机制 亲本组蛋白的分离及其对表观遗传的贡献。总而言之，这些研究 将解决有关组蛋白修饰如何调节和遗传以及它们的 失调是导致人类疾病的原因之一。

Project Summary Covalent modifications of histones, such as acetylation, methylation, phosphorylation, and ubiquitylation, are essential for regulating chromatin structure and function and defective histone modifications have causal roles in numerous developmental disorders and diseases. Our long-term goal is to use fission yeast heterochromatin assembly as an experimental model to study how diverse histone modification activities are coordinated to initiate different gene expression states and how these states are epigenetically inherited. Heterochromatin preferentially assembles at repetitive DNA elements, and it is essential for regulating gene expression and maintaining genome integrity. The formation of heterochromatin is critically dependent on the methylation of H3 lysine 9 (H3K9me). Interestingly, the activities of H3K9 methyltransferases are stimulated by the ubiquitylation of H3 lysine 14 (H3K14ub), although the mechanism is poorly understood. We will examine how H3K14ub stimulates H3K9 methyltransferases and how H3K14ub is regulated in vivo to aid heterochromatin assembly. Heterochromatin is also a great model to study chromatin-based mechanisms of epigenetic inheritance. An important unresolved question is how parental histones carrying modifications are deposited onto newly synthesized DNA during the S phase of the cell cycle to direct the duplication of these modifications on daughter chromatids. We developed eSPAN (enrichment of Sequencing Protein-Associated Nascent DNA) in fission yeast, which allows us to measure the segregation of parental histones on daughter DNA strands. We will integrate this new genomic tool and traditional genetic approaches to examine mechanisms that regulate the segregation of parental histones and how they contribute to epigenetic inheritance. Together, these studies will address fundamental questions about how histone modifications are regulated and inherited, and how their dysregulation contributes to human diseases.