Mechanisms of chromatin remodeling at yeast promoters

描述（由申请人提供）：基因表达的时间和程度最终控制人类和其他生物的正常细胞增殖和细胞分化。将真核生物DNA与组蛋白一起包装成染色质实际上抑制了转录的所有步骤。因此，染色质不仅可以作为调节转录的平台，还可以作为防止异常转录的过滤器。染色质结构的重塑在转录的所有阶段都是不可或缺的。人类染色质重塑的生物学重要性体现在染色质重塑重要基因的突变与许多癌症相关这一事实。该项目的目标是通过阐明重塑染色质结构的分子步骤来了解基因表达如何在染色质的背景下发生。组蛋白变体H2A。Z是染色质重塑的关键角色。H2A。Z标记基因启动子，并被提出通过形成易解体的核小体来帮助平衡基因的转录。然而，H2A。Z核小体是如何被分解的仍不清楚。在此之前，我使用了酵母遗传学、基因组学和生物化学的组合方法来剖析H2A的机制。Z沉积。在这个项目中，我将扩展这种方法来研究H2A的拆卸途径。Z核小体。目的之一是通过筛选H2A中有缺陷的突变体来识别相关基因。Z驱逐。这些突变体将被用来研究H2A的作用。转录激活中的Z驱逐。在第二个目标中，由这些基因编码的蛋白质将在核小体排除试验中进行生化表征。最后，将采用动力学方法来了解H2A的组装和拆卸的相反途径。Z核小体维持在动态平衡状态，为转录准备基因。在人类中，是H2A。Z控制发育和细胞周期调节因子的表达，以及编码H2A基因的过表达。Z与癌症进展有关。鉴于染色质结构及其重塑途径的保守性，为酵母系统开发的原理可能适用于人类。这项研究可能会导致鉴定

DESCRIPTION (provided by applicant): The timing and the extent of gene expression ultimately control normal cell proliferation and cellular differentiation in humans and other organisms. The packaging of eukaryotic DNA with histone proteins into chromatin inhibits virtually all steps in transcription. As such, chromatin functions not only as a platform to regulae transcription, but also as a filter to prevent aberrant transcription. The remodeling of chromatin structure is integral to all stages of transcription. The biological importance of chromatin remodeling in humans is manifested by the fact that mutations in genes important for chromatin remodeling are associated with numerous cancers. The goal of this project is to understand how gene expression occurs in the context of chromatin by elucidating the molecular steps that remodel chromatin structure. The histone variant H2A.Z is a key player in chromatin remodeling. H2A.Z marks gene promoters and has been proposed to help poise genes for transcription by forming nucleosomes that are predisposed for disassembly. However, the mechanism by which H2A.Z nucleosomes are disassembled remains obscure. Previously, I used a combinatorial approach that involves yeast genetics, genomics and biochemistry to dissect the mechanism of H2A.Z deposition. In this project, I will extend the approach to study the disassembly pathway of H2A.Z nucleosomes. One aim is to identify the genes involved by screening mutants that are defective in H2A.Z eviction. These mutants will then be used to study the role of H2A.Z eviction in transcriptional activation. In the second aim, the proteins encoded by these genes will be characterized biochemically in nucleosome eviction assays. Finally, a kinetic approach will be applied to understand how opposing pathways of assembly and disassembly of H2A.Z nucleosomes are maintained in a dynamic equilibrium to prepare genes for transcription. In humans, H2A.Z controls the expression of developmental and cell cycle regulators, and the overexpression of the gene encoding H2A.Z is linked to cancer progression. Given the conserved nature of chromatin structure and its remodeling pathways, the principles developed for the yeast system are likely translatable to humans. This study could lead to the identification of new targets for anticancer drug development.