Defining the Roles of Polycomb Repressive Complex 2 (PRC2) Subcomplexes in H3 K27M Gliomas

项目摘要/总结 细胞类型特异性基因表达是复杂的多细胞生命的基础，它是通过包装一个 普通的，不变的基因组转化为具有无数调节水平的高阶染色质结构。共价后- 在特定组蛋白残基的翻译修饰（PTM）是动态调节的主要点， 在整个发育过程中进行修改，以确保适当的组织谱系规范，细胞命运转换， 保持细胞的同一性。组蛋白修饰物的突变，以及组蛋白底物本身， 是包括癌症在内的多种人类疾病的基础。残基27处的重复性赖氨酸至甲硫氨酸突变 组蛋白H3（H3 K27 M）在>80%的弥漫性桥脑胶质瘤（DIPG）中发现， 预后很差的脑癌H3 K27 M癌组蛋白部分通过其抑制作用驱动胶质瘤的发生 多梳抑制复合物2（PRC 2），负责甲基化H3 K27的甲基转移酶复合物， 导致抑制性标记H3 K27 me 3的全基因组缺失。 该提案致力于解决H3 K27 M驱动的PRC 2的长期观察到的但表征不佳的方面 失调：在H3 K27 me 3的焦点位点处的残留PRC 2活性。利用生物化学基因组和细胞- 基于方法，本研究中描述的实验试图定义PRC 2亚基， 靶向DIPG细胞中PRC 2募集位点并在该位点具有催化活性。这些结果表明， 加深我们对H3 K27 M-失调染色质的理解，并可能揭示H3 K27 M弥漫性胶质瘤。 本建议书中概述的培训计划将在威斯康星大学麦迪逊分校进行， 优秀的机构研究环境，拥有尖端的资源，设施和动态 合作的机会。在专家导师的指导下执行本培训计划， 癌症生物学、染色质生物化学、蛋白质组学和基因组学领域的合作者将提供一个 这是一个宝贵的基础，意味着作为一名医生科学家癌症研究人员开始一个成功的职业生涯。

PROJECT ABSTRACT/SUMMARY Cell type-specific gene expression, the basis for complex multicellular life, is achieved through packaging a common, invariant genome into higher-order chromatin structures with myriad levels of regulation. Covalent post- translational modifications (PTMs) at specific histone residues are major points of regulation that are dynamically modified throughout development to ensure proper tissue lineage specification, cell fate transitions, and maintenance of cell identity. Mutations in histone modifiers, as well as the histone substrates themselves, underlie a variety of human diseases including cancer. Recurrent lysine-to-methionine mutations at residue 27 of histone H3 (H3 K27M) are found in >80% of diffuse intrinsic pontine gliomas (DIPG), a high-grade pediatric brain cancer with dismal prognosis. The H3 K27M oncohistone drives gliomagenesis in part through its inhibition of polycomb repressive complex 2 (PRC2), the methyltransferase complex responsible for methylating H3K27, resulting in genome-wide depletion of the repressive mark H3K27me3. This proposal endeavors to address a long-observed yet poorly characterized aspect of H3K27M-driven PRC2 dysregulation: residual PRC2 activity at focal sites of H3K27me3. Leveraging biochemical, genomic, and cell- based approaches, the experiments described in this study seek to define the PRC2 subunits necessary for targeting to, and catalytic activity at, sites of PRC2 recruitment in DIPG cells. These results stand to significantly deepen our understanding of H3K27M-dysregulated chromatin and may reveal exploitable vulnerabilities for H3 K27M diffuse gliomas. The training plan outlined in this proposal will be performed at the University of Wisconsin-Madison within an excellent institutional research environment boasting cutting-edge resources, facilities, and dynamic opportunities for collaboration. Execution of this training plan, under the guidance of expert mentors and collaborators in fields of cancer biology, chromatin biochemistry, proteomics, and genomics, will provide an invaluable foundation meant to launch a successful career as a physician-scientist cancer researcher.