Structural Basis of Gene Regulation by Polycomb Repressive Complex 2

项目摘要： 多梳抑制复合物2（PRC2）介导组蛋白H3赖氨酸27（H3K27me3）的三甲基化， 基因沉默和兼性异染色质形成的标志。PRC2由四个核心亚单位组成， 包括催化亚基Ezh2、Eed、Suz12和Rbbp4，它们一起响应无数的 发展线索已知PRC2在染色质底物上的催化作用受到几个因素的影响。 调控层，包括PRC2的酶活性的染色质上下文依赖性控制，辅助 核蛋白因子介导的PRC2向染色质的募集，以及Ezh2磷酸化依赖性 在典型基因抑制和非典型基因激活过程中Ezh2活性的调节。 PRC 2的失调，特别是Ezh2的突变与人类疾病广泛相关，包括 癌症和发育障碍。事实上，PRC2的许多调节机制有待于在 我们提出的实验与疾病表型有关。在这方面，我们的研究可以确定， 新的机制为基础的目标和未来的治疗途径。 我们的长期目标是阐明PRC2调控基因的结构机制， 通过控制染色质结构和转录状态在发育过程中表达。具体来说，在这 研究，我们将解决以下三个关键问题，关于PRC2的催化和调节。（一） PRC2的催化机制是什么，包括辅因子结合，底物识别和变构 监管？(2)PRC2如何被辅助核蛋白因子（包括Aebp2）募集到染色质中， phf 19和jarid 2？(3)Ezh2的基因抑制和激活功能在机制上是如何实现的 连接和调节，特别是通过Ezh2磷酸化？使用组合结构生物学， 生物化学和化学生物学方法，特别是受益于我们的专业知识， 在结构生物学的优势，我们将集中在几个PRC2为中心的多亚基大分子 来解决这些关键问题。

Project Summary: Polycomb repressive complex 2 (PRC2) mediates trimethylation of histone H3 lysine 27 (H3K27me3), a hallmark for gene silencing and facultative heterochromatin formation. PRC2 consists of four core subunits, including the catalytic subunit Ezh2, Eed, Suz12, and Rbbp4, which together respond to a myriad of developmental cues. PRC2 catalysis on chromatin substrate has been known to be subjected to several layers of regulation, including chromatin context-dependent control of the enzyme activity of PRC2, auxiliary nuclear protein factor-mediated recruitment of PRC2 to chromatin, and Ezh2 phosphorylation-dependent regulation of Ezh2 activity in the canonical gene repression and the non-canonical gene activation processes. Dysregulation of PRC2 and in particular mutation of Ezh2 are broadly linked to human disease including cancer and developmental disorder. Indeed, many regulatory mechanisms of PRC2 to be studied in depth in our proposed experiments are associated with disease phenotypes. In this regard, our research may identify novel mechanism-based targets and avenues for future therapeutics. Our long-term objective is to elucidate the structural mechanisms whereby PRC2 regulates gene expression during development by controlling chromatin structure and transcriptional state. Specifically, in this research, we will address the following three key questions concerning PRC2 catalysis and regulation. (1) What are the catalytic mechanism of PRC2, including cofactor binding, substrate recognition, and allosteric regulation? (2) How is PRC2 recruited to chromatin by auxiliary nuclear protein factors, including Aebp2, Phf19, and Jarid2? (3) How are the gene repression and activation function of Ezh2 mechanistically connected and regulated, in particular by Ezh2 phosphorylation? Using a combined structural biology, biochemistry, and chemical biology approach and in particular benefiting from our established expertise and strength in structural biology, we will be focused on several PRC2-centered multi-subunit macromolecular complexes to address each of these key questions.