Comprehensive Characterization of Heterochromatin Domains

描述(申请人提供)：异染色质是一种基因组结构，它在所有真核生物中发挥作用，通过沉默基因来确定细胞身份并维持基因组的稳定性。异染色质组装的要求是将具有组蛋白修饰活性的沉默蛋白复合体的染色质结合到导致基因表达抑制的染色质中。这一一般机制在所有真核生物中都是保守的，尽管存在多种异染色域，即使在同一生物体中也是如此。人们对异染色质的影响因素知之甚少，但对特定途径中的许多关键事件却知之甚少。研究异染色质的一个挑战是，在体内对中心成分的操纵往往会影响细胞中多种类型的异染色质或其他相关途径。本项目的目标将通过三个方面来解决这个问题：首先，通过使用体外重组的功能性异染色质系统来更好地了解隔离环境中异染色质沉默的机制。其次，使用预先组装的异染色质结构域来确定细胞内有助于异染色质形成和维持的新因素。第三，通过建立一个系统来解决特定的非编码RNA元件对异染色质的启动和维持的贡献。异染色质酵母模型的初步研究将对染色质生物学领域做出重要贡献，也将作为过渡到独立研究人员后在人体系统中进行的后续研究的模型。该项目的主要目标是全面描述异染色质结构域，以便比较对基因沉默和基因组稳定性至关重要的保守特征。人类异染色域的多样性是显而易见的，然而管理这些结构域组装的一般原理仍然非常类似于萌芽和分裂酵母模型中的那些。这些基本的相似性使得将酵母研究的结果与人类进行比较是可行的，也可以使用在更简单的酵母模型中开发的方法作为研究人类异染色质的指南。这一主题是这项提议的基础，也是我向独立过渡的方向。 与公共卫生相关：异染色质是一种基因组结构，它在所有真核生物中发挥作用，通过沉默基因来确定细胞身份并维持基因组的稳定性。异染色质组装的一般要求是将具有组蛋白修饰活性的沉默蛋白复合体掺入染色质，从而导致基因表达受抑。同一真核生物体内存在多种异染色质结构域。

DESCRIPTION (provided by applicant): Heterochromatin is a genomic structure that functions in all eukaryotes to determine cell identity and maintain genome stability by silencing genes. The requirements for heterochromatin assembly are incorporation into chromatin of silencing protein complexes with histone modification activity that leads to repressed gene expression. This general mechanism is conserved in all eukaryotes, though multiple varieties of heterochromatic domains exist, even within the same organism. Much is known about the factors that contribute to heterochromatin, yet many key events in specific pathways are poorly understood. One challenge in studying heterochromatin is the fact that manipulation of the central components in vivo often affects multiple types of heterochromatin or other related pathways in the cell. The aims of this project will address this problem in three ways: firstly, by using a functional in vitro reconstituted heterochromatin system to better understand the mechanism of heterochromatic silencing in an isolated environment. Secondly, using a pre- assembled heterochromatin domain to identify new factors within the cell that contribute to heterochromatin formation and maintenance. Third, by establishing a system to address the contribution of specific non-coding RNA elements to initiation and maintenance of heterochromatin. Initial studies in yeast models of heterochromatin will make important contributions to the field of chromatin biology and will also serve as a model for subsequent studies in the human system to be carried out after the transition to independent investigator. The primary goal of the project is to comprehensively characterize heterochromatin domains in order to compare conserved features that are central to gene silencing and genome stability. The diversity of human heterochromatic domains is evident, yet the general principles that govern assembly of these domains remain quite similar to those in the budding and fission yeast models. These basic similarities make it feasible to compare results of yeast studies to humans and also to use the approaches that have been developed in the simpler yeast models as a guide to study human heterochromatin. This theme is the foundation of this proposal and the direction I will take as I transition to independence. PUBLIC HEALTH RELEVANCE: Heterochromatin is a genomic structure that functions in all eukaryotes to determine cell identity and maintain genome stability by silencing genes. The general requirements for heterochromatin assembly are the incorporation into chromatin of silencing protein complexes with histone modification activity that leads to repressed gene expression. Multiple varieties of heterochromatic domains exist within the same eukaryotic organism.