Molecular Basis of Gene Regulation by Polycomb Repressive Complex 2

项目总结： 多梳抑制复合体2(PRC2)维持对细胞身份和控制的表观遗传记忆 许多基本的细胞过程，如干细胞多能性维持，干细胞分化，X- 染色体失活、印迹等。PRC2功能失调与广泛的 癌症和发育障碍的谱系。在分子水平上，PrC2介导组蛋白H3赖氨酸 27三甲基化(H3K27me3)，基因沉默的标志。细胞类型和发育状态特异的PRC2 功能在很大程度上取决于复合体的动态相互作用。PRC2展示了巨大的 成分的复杂性，这与PrC2在细胞发育中的多效性作用有关。核心PRC2 复合体由EZH1/2、EED、SuZ12和RBBP4/7组成。哺乳动物的对虾EZH1和EZH2是 PrC2的催化亚基。PRC2的酶活性和染色质靶向性受到多种因素的影响 辅助亚单位的阵列，包括AEBP2、JARID2、PHF1、MTF2、PHF19和ePOP，它们形成两个 互斥的PRC2全息复形类。除了这些主要专用的辅助亚单位外， PRC2还与过多的其他细胞因子动态关联，以调节重要的串扰 细胞信号通路，例如DNA损伤反应和修复中的BRCA1，DNA甲基化中的Dnmts 和基因组印迹，以及基因组结构和组织中的CTCF。 虽然在生物学和临床上具有重要意义的PRC2功能已经被广泛认识到，但潜在的 分子机制在很大程度上是缺乏的。由于它们的规模和复杂性，生化重组和 对PrC2分子组装的结构分析是一个艰巨的挑战；直到最近，我们才 另一些学者则开始揭示PrC2催化、染色质结合和疾病突变的结构基础。 MIRA奖的主要主题是PRC2的结构和职能，目的是 了解它们是如何被调控以控制细胞增殖和分化的。拟议的研究将 通过回答以下三个具体问题，弥合实地的理解差距。(1)如何 PRC2的酶活性在不同的细胞环境中被调节？(2)PRC2是如何被特异性地招募到 CpG岛染色质？(3)PrC2的结构机制是如何与基因调控有关的 一些中心生物学过程，如干细胞分化和表观遗传记忆维持 在细胞分裂过程中？

Project Summary: Polycomb Repressive Complex 2 (PRC2) maintains an epigenetic memory of cell identity and controls many fundamental cellular processes, such as stem cell pluripotency maintenance, stem cell differentiation, X- chromosome inactivation, imprinting, and so on. Dysregulation of PRC2 function is associated with a wide spectrum of cancers and developmental disorders. On the molecular level, PRC2 mediates histone H3 lysine 27 trimethylation (H3K27me3), hallmark of gene silencing. Cell type and developmental state-specific PRC2 function largely depends on the dynamic interactome of the complex. PRC2 displays tremendous compositional complexity, which correlates with pleiotropic roles of PRC2 in cell development. The core PRC2 complex consists of EZH1/2, EED, SUZ12 and RBBP4/7. The mammalian paralogs EZH1 and EZH2 are the catalytic subunit of PRC2. The enzymatic activity and chromatin targeting of PRC2 are impacted by a diverse array of accessory subunits, including AEBP2, JARID2, PHF1, MTF2, PHF19 and EPOP, which form two classes of mutually exclusive PRC2 holo complexes. Besides these mostly dedicated accessory subunits, PRC2 also dynamically associates with a plethora of other cellular factors to mediate crosstalk with important cell signaling pathways, for example BRCA1 in DNA damage response and repair, DNMTs in DNA methylation and genomic imprinting, and CTCF in genome structure and organization. While biologically and clinically important PRC2 function has been widely appreciated, the underlying molecular mechanisms are largely lacking. Due to their size and complexity, biochemical reconstitution and structural analysis of the molecular assemblies of PRC2 present a formidable challenge; only recently have we and others started to reveal the structural basis of catalysis, chromatin binding and disease mutation of PRC2. The overarching theme of this MIRA award is focused on the structure and function of PRC2 and aims to understand how they are regulated to control cell proliferation and differentiation. The proposed study will close gaps of understanding in the field by addressing the following three specific questions. (1) How the enzymatic activity of PRC2 is regulated in various cellular contexts? (2) How is PRC2 specifically recruited to CpG island chromatin? (3) How are the structural mechanisms of PRC2 connected to gene regulation during some central biological processes, such as stem cell differentiation and epigenetic memory maintenance during cell division?