Roles for chromatin remodeler RSC and histone acetyltransferases in regulating chromatin structure and transcription

项目摘要 染色质结构的动态变化对于调节细胞中的基因表达是必不可少的。这些变化 由染色质相关因子如组蛋白修饰剂、分子伴侣和染色质介导 重塑者这些因子的突变与许多人类疾病密切相关。例如突变 在保守的SWI/SNF家族中，ATP依赖性染色质重塑蛋白与约20%的人类 癌的其中一些突变也与发育和智力残疾综合征有关， Coffin-Siris综合征（CSS）然而，我们并不完全了解SWI/SNF重塑的哪些方面， 活性受到生理条件下致病突变的影响。改造 染色质结构（RSC）复合物是SWI/SNF家族的一员，是SWI/SNF家族中唯一必需的蛋白质结构。 芽殖酵母中的重塑剂。RSC调节许多生物学过程，包括所有三个转录 RNA聚合酶。它主要参与维持基因启动子附近的典型染色质结构。 在RSC ATP酶亚基Sth 1中已鉴定出许多调节其重塑活性的结构域。 另外的结构域涉及与DNA和核小体的相互作用。然而， 对这些在活细胞中决定RSC功能的结构域了解甚少。此外，机制 调控RSC与染色质结合的机制也不清楚。RSC可以结合到特定的区域， 在一些实施方案中，使用其溴结构域的染色质已经显示出在体外结合乙酰化组蛋白。RSC如何 利用组蛋白乙酰化进行其募集或在生理条件下执行其功能仍然存在 以被理解。使用酿酒酵母作为模式生物，在特定的AIM 1）中，我们将 研究各种调节和核小体结合结构域中突变的影响，以及一些 与染色质结构发育异常相关的突变，包括可及性和 基因表达。我们将研究这些重要领域的突变如何影响细胞的能力， 应对压力在特定的AIM 2）中，我们将鉴定促进RSC缔合的组蛋白尾部残基 与染色质和那些帮助RSC脱离染色质。乙酰化残基 影响RSC使DNA可接近的能力也将在全基因组范围内确定。此外，我们将 研究RSC在延伸步骤中调节转录的作用。这些研究将是有价值的， 了解组蛋白修饰剂和染色质重塑剂如何合作调节基因表达。

PROJECT SUMMARY Dynamic changes to chromatin structure are essential for regulating gene expression in cells. These changes are mediated by chromatin-associated factors such as histone modifiers, chaperones, and chromatin remodelers. Mutations in these factors are strongly linked to many human diseases. For example, mutations in the conserved SWI/SNF family of ATP-dependent chromatin remodelers are linked to ~20% of human cancers. Some of these mutations are also linked to developmental and intellectual disability syndrome, such as Coffin-Siris syndrome (CSS). However, we do not fully understand what aspects of SWI/SNF remodeling activities are affected by the disease-causing mutations under physiological conditions. The Remodels the Structure of Chromatin (RSC) complex is a member of the SWI/SNF family, and is the only essential remodeler in budding yeast. RSC regulates many biological processes, including transcription by all three RNA polymerases. It is critically involved in maintaining canonical chromatin structure near gene-promoters. Many domains have been identified within the RSC ATPase subunit Sth1 that modulate its remodeling activity. Additional domains are implicated in interacting with DNA and nucleosomes. However, the contributions of these domains in dictating RSC function in living cells are poorly understood. Furthermore, the mechanisms that regulate the association of RSC with chromatin are also not clear. RSC could bind to specific regions of chromatin using its bromodomains that have been shown to bind acetylated histones in vitro. How RSC exploits histone acetylation for its recruitment or to execute its function under physiological conditions remains to be understood. Using Saccharomyces cerevisiae as a model organism, in the specific AIM 1), we will investigate the impact of mutations in various regulatory and nucleosome-binding domains, and some of the mutations that are linked to developmental abnormalities on chromatin structure, including accessibility and gene expression. We will examine how mutations in these important domains affect the ability of cells to respond to stress. In the specific AIM 2), we will identify the histone tail residues that promote RSC association with chromatin and those that help RSC disengage from chromatin. The extent to which acetylated residues affect RSC ability to make DNA accessible will also be determined, genome-wide. Furthermore, we will examine the role of RSC in regulating transcription during elongation steps. These studies will be valuable in understanding how histone modifiers and chromatin remodelers cooperate to regulate gene expression.