PCGF5介导的组蛋白H2A泛素化修饰对小鼠ES细胞多能性维持和神经分化的调控及其机理研究

PCGF5属于PRC1复合物中PCGF家族的一个成员。我们和其他科学家发现PCGF5和PCGF家族的其它成员竞争结合PRC1核心催化亚基Ring1B。然而，PCGF5是否参与调控组蛋白H2A泛素化修饰以及其在细胞类型转换过程中的功能仍不清楚。本项目在近期研究工作的基础上,运用蛋白互作分析发现PCGF5的Ring结构域与Ring1B的Ring结构域及其C末端存在相互作用。本研究将运用体外生化实验、体内过表达和功能缺失等手段来研究PCGF5是否以及如何参与调控组蛋白H2A泛素化修饰及其机理；解析PcG蛋白Ring1B和RYBP对PCGF5的DNA结合位点分布的影响；同时，阐明缺失PCGF5对小鼠ES细胞多能性维持及其向神经前体细胞分化的影响，并对其调控的内在分子机理进行深入探索。该研究有助于丰富和补充组蛋白H2A泛素化的调控机制，对填补PCGF5在细胞类型转换中的作用等方面的空缺具有重要意义。

PCGF5 is one member of PCGF family in PRC1 complexes. We and other scientists found that PCGF5 and other members of PCGF family competitively bind Ring1B protein, the core catalytic subunit of PRC1. However, regulation of PCGF5 in PRC1-mediated histone H2A ubiquitination and roles of PCGF5 during cell type conversion still remains unclear. Based on our recent research work, we found that Ring domain of PCGF5 interacts with Ring plus C-terminal domains of Ring1B through protein-protein interaction. In this study, by doing in vitro biochemical assay, in vivo gain of function and loss of function, we will study whether and how PCGF5 regulates histone H2A ubiquitination and the involved mechanisms,and investigate the effects of PcG protein Ring1B and RYBP on DNA binding of PCGF5 in the genome. At the same time, we will clarify the effects of PCGF5 knockout on pluripotency and differentiation of mouse embryonic stem cells into neural precursor cells and deeply explore the intrinsic molecular mechanisms of regulation. This study will help us to enrich and supplement the regulatory mechanisms of histone H2A ubiquitination,to fill the vacancies of PCGF5 biological functions during cell type conversion.