Role of Histone and Histone-like Mutations in the Oncogenesis of Human Cancers

项目总结(总体) 染色质景观影响基本的细胞过程，包括基因表达、DNA损伤 修复、细胞命运和分化，所有这些在癌症中都存在广泛的失调。集体数字 染色质调节器中致癌基因突变的研究导致了对潜在驱动因素突变的新观点 癌症表观基因组。顺应主题，在过去的几年里，我们目前的合作项目 成员们在发现和表征癌基因突变方面起到了关键作用。 组蛋白H3.3的N末端尾巴。这些突变通过抑制染色质的活性来改变染色质 修饰酶。虽然在理解这些影响方面取得了很大进展，但重要的问题 仍然包括这些突变引起的染色质修饰酶失调的性质以及如何 这些突变会导致癌症。此外，计划成员最近确定了更多的 与癌症相关的体细胞组蛋白突变，出现在多达4%的人类癌症中，并同时涉及两者 所有四个核心组蛋白的球状和尾状结构域。这些发现产生了其他重要的问题，如 似乎新观察到的组蛋白突变对染色质有功能影响，以及通过什么机制 他们依靠的是。鉴于一些最常见的突变位于组蛋白的球状结构域中，我们 假设这些突变影响核小体结构和/或完整性。最后，我们和其他人也 发现了EZHIP蛋白的一种新功能，该蛋白在A后颅窝室管膜瘤中过表达，以及 作为癌组蛋白模拟物，直接抑制多梳抑制复合体2(PRC2)的功能。单曲 我们计划的目标是阐明经典的和新的“癌组蛋白”背后的分子机制 突变和癌组蛋白模拟物促进诊断和探索治疗途径 癌症。具体地说，我们将：i)开发和采用基于患者样本、细胞培养和动物模型的新技术 重述与癌组蛋白相关的癌症并研究其潜在致病机制的系统； Ii)评估一组新的与癌症相关的组蛋白突变的活性 多学科方法，包括遗传学(条形码癌组蛋白文库、小鼠模型、条形码细胞 品系)、表观遗传学(ChIP-SEQ、ATAC-SEQ、DNA甲基化图谱)、转录学(RNA-SEQ)和化学 生物学(“设计染色质”，小分子抑制物)；iii)定义肿瘤组蛋白的机制，以及 癌组蛋白模拟，失调多梳抑制复合体(PRC1和PRC2)的活性以促进 神经胶质瘤和骨肿瘤；以及iv)确定哪些新的组蛋白突变扰乱了染色质状态(并通过 什么机制)随后使用新开发的高通量 生化和酵母菌遗传筛选工具。这些研究将为今后的开发工作提供信息 旨在改善组蛋白突变和癌组蛋白致病效应的治疗策略 在癌症中具有模仿性。

Project Summary (Overall) The chromatin landscape impacts fundamental cellular processes including gene expression, DNA damage repair, and cell fate and differentiation, all of which are extensively dysregulated in cancer. The collective number of oncogenic mutations in chromatin regulators has led to the emerging view of driver mutations underlying cancer epigenomes. In keeping with theme, over the past several years our current collaborative program members have been critical to the discovery and characterization of ‘classical’ oncohistone mutations in the histone H3.3 N-terminal tail. These mutations globally alter chromatin by inhibiting the activity of chromatin modifying enzymes. While much progress has been made to understand these effects, important questions remain including the nature of the dysregulation of chromatin modifying enzymes by these mutations and how these mutations lead to cancer. In addition, Program members have recently identified an expanded number of cancer-associated somatic histone mutations that occur in as many as 4 % of human cancers and involve both globular and tail domains of all four core histones. These findings generate additional important questions such as if the newly observed histone mutations have functional effects on chromatin and through what mechanisms they rely on. Given that some of the most prevalent mutations are in the globular domains of histones, we hypothesize that these mutations affect nucleosome structure and/or integrity. Lastly, we and others have also identified a novel function of the EZHIP protein, which is overexpressed in posterior fossa A ependymomas, and acts as an oncohistone mimic to directly inhibit the Polycomb Repressive Complex 2 (PRC2) function. The single goal of our Program is to illuminate the molecular mechanisms underlying classical and novel “oncohistone” mutations and oncohistone mimics to advance the diagnosis and exploration of therapeutic avenues for the cancers. Specifically, we will: i) develop and employ novel patient sample-, cell culture- and animal model-based systems to recapitulate oncohistone-associated cancers and investigate the underlying pathogenic mechanisms; ii) evaluate the activity of a comprehensive set of novel cancer-associated histone mutations using a multidisciplinary approach that includes genetics (barcoded oncohistone libraries, mouse models, barcoded-cell lines), epigenetics (ChIP-seq, ATAC-seq, DNA-methylation profiling), transcriptomics (RNA-seq), and chemical biology (“designer chromatin”, small molecule inhibitors); iii) define the mechanisms by which oncohistones, and oncohistone-mimics, dysregulate the Polycomb Repressive Complexes (PRC1 and PRC2) activity to promote gliomas and bone tumors; and iv) identify which of novel histone mutations perturb chromatin states (and by what mechanisms) to subsequently cause cellular phenotype using newly developed high-throughput biochemical and yeast genetic screening tools. These studies will inform future work towards the development of therapeutic strategies designed to ameliorate the pathogenic effects of histone mutations and oncohistone mimics in cancer.