Factors that regulate chromatin organization and gene transcription

描述（由申请人提供）： 摘要染色质结构域如常染色质和异染色质是如何建立和维持的，目前还知之甚少。染色质组织的核心是组蛋白，组蛋白通过伴侣蛋白沉积和去除。一种这样的分子伴侣是Spt 6，其在进化上是保守的并且通过其与RNA聚合酶II（RNAPII）C-末端结构域（CTD）的相互作用促进转录延伸。在转录过程中，Spt 6在转录RNAPII之后介导核小体重组，并促进H3 K36甲基化，其募集组蛋白脱乙酰酶和染色质重塑活性，以维持基因编码区的染色质完整性。我们的研究现在已经确定Spt 6作为维持CTD磷酸化的新型调节回路的中心组成部分;该回路本身通过Spt 6蛋白稳定性进行控制。我们还发现Spt 6在S期上调，在此关键阶段，它可能有助于组蛋白基因的转录和/或沉积。此外，我们已经发现了一个意想不到的作用，Spt 6在保持着丝粒的身份，通过潜在的靶向Psh 1 E3连接酶，去除异位沉积的组蛋白H3变体Cse 4。尽管有这些发现，我们对Spt 6如何执行其染色质依赖性活动知之甚少。因此，该提案旨在阐明Spt 6有助于维持基因组编码和调控区染色质结构的基本机制-从而有助于Spt 6的生物学以及建立和维持染色质结构域的机制。为了实现这一目标，我们将解决以下关键问题：1）Spt 6是如何通过与RNAPII的相互作用和发生在该蛋白上的翻译后修饰来调节的？2)为什么Spt 6细胞周期受到调节，它在S期起什么作用？3)Spt 6在转录调控中的作用是否超出了其经典作用，从而调节染色质生物学的其他方面，特别是着丝粒的特性？鉴于Spt 6在进化过程中的保守性，我们的研究将显著影响我们对转录延伸和维持控制基因组完整性的染色质完整性的机制的理解。这些研究也将有助于我们理解Spt 6在人类发育和疾病中的作用。

DESCRIPTION (provided by applicant): ABSTRACT How chromatin domains such as euchromatin and heterochromatin are established and maintained are poorly understood. At the heart of chromatin organization are the histone proteins, which are deposited and removed by chaperone proteins. One such chaperone is Spt6, which is evolutionarily conserved and promotes transcription elongation through its interaction with the RNA polymerase II (RNAPII) C-terminal domain (CTD). During transcription, Spt6 mediates nucleosome reassembly in the wake of transcribing RNAPII and promotes H3K36 methylation, which recruits histone deacetylase and chromatin remodeling activities that maintain chromatin integrity in the coding region of genes. Our studies have now identified Spt6 as a central component of a novel regulatory circuit that maintains CTD phosphorylation; this circuit is itself controlled through Spt6 protein stability. We have also found that Spt6 is up-regulated during S phase, where it likely contributes to histone gene transcription and/or deposition at this critical stage. Further, we have uncovered an unexpected role for Spt6 in maintaining centromere identity through the potential targeting of the Psh1 E3 ligase that removes ectopically deposited histone H3 variant Cse4. Despite these findings, we know little about how Spt6 performs its chromatin-dependent activities. Thus, this proposal aims to elucidate the fundamental mechanisms by which Spt6 contributes to the maintenance of chromatin structure in the coding and regulatory regions of the genome - thereby contributing to the biology of Spt6 and to the mechanisms by which chromatin domains are established and maintained. To accomplish this goal, we will address the following key questions: 1) How is Spt6 regulated through its interactions with RNAPII and by post-translational modifications that occur on this protein? 2) Why is Spt6 cell cycle regulated, and what role does it play in S phase? 3) Does Spt6 function outside of its canonical role in transcriptional regulation to regulate other aspects of chromatin biology, in particular centromere identity? Given the conservation of Spt6 across evolution, our studies will significantly impact our understanding of the mechanisms that underlie transcriptional elongation and the maintenance of chromatin integrity that govern genome integrity. These studies will also be relevant to our understanding of Spt6 in human development and disease.