Regulation of Chromatin-associated Proteins by Ubiquitin Modification of Histones H2A and H2B

在真核生物中，遗传物质DNA与蛋白质复合并包装成染色质。组织DNA的蛋白质称为组蛋白。DNA中的遗传信息和与这些组蛋白关联的类型所赋予的额外（或表观遗传）信息之间的相互作用决定了细胞的命运。该项目的长期目标是了解表观遗传信息是如何被细胞机制解释的，这些细胞机制引发基因表达的变化以调节生长和分化。表观遗传信息的一种形式是通过附着一种叫做泛素的小蛋白质来修饰组蛋白。在从苍蝇到人类的生物体中，组蛋白H2 A和H2 B都可以被泛素修饰，但具有不同的生物学后果。H2 A泛素化与基因沉默和DNA修复过程相关，而H2 B泛素化在活性基因表达中起关键作用。泛素如何连接到H2 A和H2 B组蛋白被解释为不同的信号，导致这些不同的下游效应是未知的。为了解决这一知识缺口，将开发方法来获得化学上均质的泛素-H2 A（或H2 B），以鉴定与染色质的关联受泛素调节的蛋白质。生物物理和生物化学技术的组合将被用来表征泛素和组蛋白之间的潜在相互作用，并研究H2 B泛素化在基因表达中的功能意义。总体而言，本项目将建立一种新的方法来研究表观遗传学，并将提供一种表观遗传信息如何调节基因表达和最终细胞命运的机制细节。更广泛的影响：除了在表观遗传学和基因表达领域的科学意义外，本项目还为本科生和研究生提供了出色的培训机会。这些研究的许多方面涉及生化实验，非常适合时间有限和实验室经验有限的本科生。各种生物化学，生物物理和尖端蛋白质组学技术的就业为研究生和博士后提供了广泛的培训。此外，作为更广泛的影响努力的一部分，将为研究生和博士后提供关于创新科学教学方法和导师培训的讲习班。总的来说，这个项目将对未来的科学教育工作者产生直接的积极影响。

In eukaryotes, the genetic material DNA is complexed with proteins and packaged into chromatin. The proteins that organize the DNA are called histones. The interplay between the genetic information in DNA and the additional (or epigenetic) information conferred by the type of association with these histones determines cell fate. The long-term goal of this project is to understand how epigenetic information is interpreted by cellular machineries that instigate changes in gene expression to regulate growth and differentiation. One form of epigenetic information is the modification of histones by attachment of a small protein called ubiquitin. In organisms ranging from flies to human, histones H2A and H2B each can be modified with ubiquitin, but with different biological consequences. Whereas H2A ubiquitination is associated with gene silencing and DNA repair processes, H2B ubiquitination plays critical roles in active gene expression. How ubiquitin attached to H2A and H2B histones are interpreted as distinct signals that result in these different downstream effects is unknown. To address this knowledge gap, methods will be developed to obtain chemically homogeneous ubiquitin-H2A (or H2B) to identify proteins whose associations with chromatin are regulated by ubiquitin. A combination of biophysical and biochemical techniques will be used to characterize potential interactions between ubiquitin and histones and to investigate the functional significance of H2B ubiquitination in gene expression. Overall, this project will establish a new approach to study epigenetics and will provide mechanistic details as to how one type of epigenetic information regulates gene expression and ultimately cell fate.Broader impacts: In addition to its scientific significance in the areas of epigenetics and gene expression, this project provides outstanding training opportunities for undergraduate and graduate students. Many aspects of these studies involve biochemical experiments that are well-suited for undergraduates who may have limited time as well as limited laboratory experience. The employment of a variety of biochemical, biophysical and cutting-edge proteomics technologies provide broad training for graduate students and postdocs. In addition, as part of the broader impact efforts, workshops will be provided to graduate students and postdocs on innovative scientific teaching methods and mentor training. Overall, this project will have a direct positive impact on tomorrow's science educators.