Epigenetic Mechanisms of Oncohistone Detoxification

肿瘤组蛋白解毒的表观遗传机制

基本信息

批准号：
9247701
负责人：
Katharine Diehl
金额：
$ 5.67万
依托单位：
PRINCETON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-04-01 至 2019-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9247701
关键词：
Abate Acetylation Affect Amination Amines Antibodies Biology CRISPR/Cas technology Cancerous Cell Line Cell physiology Cells ChIP-seq Chemicals Childhood Brain Neoplasm Childhood Malignant Brain Tumor Chromatin Complex DNA Detection Diffuse Drug Metabolic Detoxication Enzyme Inhibition Enzymes Epigenetic Process Eukaryotic Cell Fluorescence Resonance Energy Transfer Future Gene Expression Gene Expression Regulation Gene Silencing Genes Genomics Glean Glioblastoma Glioma Goals Histone Acetylation Histone Deacetylase Histone Deacetylase Inhibitor Histones Individual Knock-out Lead Link Lysine Malignant Neoplasms Mammalian Cell Maps Measures Methionine Methods Methylation Methyltransferase Modification Mutate Mutation Names Nucleosomes Optical Methods Output Pathogenicity Pathway interactions Peptides Polycomb Pontine structure Population Post-Translational Protein Processing Proteins Research Role Series Signal Transduction Site Small Interfering RNA Specificity Tail Technology Testing Therapeutic Therapeutic procedure Time Toxic effect Training Transcriptional Regulation Work base cancer cell cellular development chromatin modification combat design experimental study genome wide methylation glycosylation histone modification inhibitor/antagonist insight mouse model mutant programs public health relevance therapeutic development tool

项目摘要

DESCRIPTION (provided by applicant): The proposed research in this training plan will focus on investigating the mechanisms by which the toxicity of oncohistones in cells can be abated by manipulating histone post-translational modifications. In eukaryotic cells, DNA is stored as chromatin, which consists of repeating units called nucleosomes made up of DNA wrapped around histone proteins. Extending out from each histone are peptide tails that are post-translationally modified in a variety of ways, including by acetylation, methylation, glycosylation and ubiquitylation. These modifications (PTMs) modulate access to the DNA, which in turn controls transcription, replication, and other cellular processes. Importantly, misregulation of these epigenetic processes has been linked to cancer, and recently it has also been shown by our group and others that mutations in the core histone proteins are found in cancer cells. In particular, mutations in histone 3 (H3) are associated with a deadly form of pediatric brain tumor. In a majority of diffuse pontine glioblastomas (DIPGs), lysine 27 in H3 is mutated to methionine (H3K27M) in a small percentage of nucleosomes. This mutation acts as a potent inhibitor of the polycomb repressor complex 2 (PRC2), which is a methyltransferase. In general, methylation of H3K27 by PRC2 is associated with gene silencing, so reduced levels of H3K27me3 due to H3K27M lead to disruption of genomic programs and thus perturbation of cellular development. Since PRC2 is able to sense chromatin states and modulate its methyltransferase output based on those signals, we hypothesized that PRC2 inhibition could be impacted by existing PTMs on the same H3 tail (i.e. in cis). Indeed, we found that PTMs, particularly polyacetylation of H3, have been found to diminish the inhibitory effect of H3K27M peptides. Therefore, we postulate that the deliberate manipulation of PTM levels relevant to PRC2 could be used to abate the pathogenicity of H3K27M. The strategy explored in this project is to use histone deacetylase (HDAC) inhibitors to achieve elevated levels of acetylation of H3 in H3K27M mutant cells and to study the mechanisms by which this manipulation impacts the PTM cross-talks. The work described herein employs a chemical biology approach to probe specific mechanisms associated with H3K27M "detoxification" as well as to provide a better understanding of epigenetic misregulation by "oncohistones" in general. The specific aims of this project are: (1) To screen HDAC inhibitors for their effect on methyltransferase activity in cells expressing the mutant H3K27M. (2) To characterize mechanisms by which HDACs impact methyltransferase activity in cells expressing H3K27M. (3) To determine the effect of HDAC inhibitors on the pathogenicity of glioblastoma cells that express the H3K27M mutant. This research applies chemical biology tools to elucidate mechanisms by which this cancerous mutation is affected by manipulating the acetylation/methylation cross-talk in cells via HDAC inhibitors. The long term goal of performing these fundamental studies is to illuminate these interconnected PTM pathways and inform the future development of therapeutic procedures.

描述（由申请人提供）：本培训计划中拟议的研究将重点研究通过操纵组蛋白翻译后修饰来减轻细胞中癌组蛋白毒性的机制。在真核细胞中，DNA 以染色质形式存储。由称为核小体的重复单元组成，该单元由包裹在组蛋白周围的 DNA 组成，从每个组蛋白延伸出来的是经过翻译后修饰的肽尾。这些修饰 (PTM) 可以通过多种方式调节 DNA 的获取，进而控制转录、复制和其他细胞过程。重要的是，这些表观遗传过程的失调与癌症有关。最近，我们的团队和其他人也发现，在癌细胞中发现了核心组蛋白的突变，特别是组蛋白 3 (H3) 的突变与儿童大脑的致命形式有关。在大多数弥漫性脑桥胶质母细胞瘤 (DIPG) 中，一小部分核小体中 H3 中的赖氨酸 27 突变为甲硫氨酸 (H3K27M)，该突变充当多梳阻遏物复合物 2 (PRC2) 的有效抑制剂。一般来说，PRC2 对 H3K27 的甲基化与基因沉默有关，因此减少。 H3K27M 导致的 H3K27me3 水平会导致基因组程序中断，从而扰乱细胞发育，因为 PRC2 能够感知染色质状态并根据这些信号调节其甲基转移酶输出，因此我们发现 PRC2 抑制可能会受到现有 PTM 的影响。事实上，我们发现 PTM，特别是 H3 的多乙酰化，可以减弱抑制作用。因此，我们假设故意操纵与 PRC2 相关的 PTM 水平可用于减轻 H3K27M 的致病性，该项目探索的策略是使用组蛋白脱乙酰酶 (HDAC) 抑制剂来提高乙酰化水平。 H3K27M 突变细胞中的 H3 并研究这种操作影响 PTM 串扰的机制。此处描述的工作采用了化学生物学。该项目的具体目的是：（1）筛选 HDAC 抑制剂对甲基转移酶活性的影响。 (2) 表征 HDAC 影响表达 H3K27M 的细胞中甲基转移酶活性的机制。 HDAC 抑制剂对表达 H3K27M 突变体的胶质母细胞瘤细胞的致病性这项研究应用化学生物学工具来阐明通过 HDAC 抑制剂操纵细胞中的乙酰化/甲基化串扰来影响这种癌性突变的机制。进行这些基础研究的目的是阐明这些相互关联的 PTM 途径并为治疗程序的未来发展提供信息。