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， 对于调节染色质结构和功能至关重要，而有缺陷的组蛋白修饰具有因果作用 在许多发育障碍和疾病。我们的长期目标是利用裂殖酵母异染色质 组装作为实验模型，研究如何协调不同的组蛋白修饰活动， 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 优先在重复DNA元件处组装，并且对于调节基因表达和 维持基因组的完整性异染色质的形成主要依赖于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），尽管其机制知之甚少。我们将研究如何H3K14ub 刺激H3 K9甲基转移酶以及如何在体内调节H3 K14 ub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重要模型。一个 一个重要的未解决的问题是携带修饰的亲本组蛋白如何沉积到新的 在细胞周期的S期合成DNA，以指导这些修饰的复制， 子染色单体我们开发了eSPAN（富集测序蛋白相关新生DNA）， 裂变酵母，这使我们能够测量子代DNA链上亲本组蛋白的分离。我们 将整合这种新的基因组工具和传统的遗传方法，以检查调节 亲本组蛋白的分离以及它们如何促进表观遗传。这些研究一起 将解决有关组蛋白修饰如何调节和遗传的基本问题，以及它们如何在基因组中表达。 失调会导致人类疾病。

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.