Epigenetic regulation by tumor suppressor p53

抑癌基因 p53 的表观遗传调控

• 批准号: 9674890
• 负责人: SHELLEY L BERGER
• 金额: $ 5.45万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9674890
• 关键词: Acetylation; Acetylesterase; Address; Alleles; Apoptosis; Architecture; Binding; Binding Sites; Cancer Cell Growth; Cancerous; Carbon; Cell Cycle Arrest; Cell Line; Cells; Chromatin; Chromatin Loop; Code; Complex; DNA; DNA Binding; DNA Binding Domain; DNA Damage; DNA Repair; Data; Disease; Distal; Enhancers; Enzymes; Epigenetic Process; Fibroblasts; Funding; Gene Activation; Gene Expression; Gene Targeting; Gene-Modified; Genes; Genetic Transcription; Genome; Genomics; Grant; Growth; Histone H3; Histones; Hot Spot; Human; Impairment; Investigation; Location; Lysine; MLL gene; MLL2 gene; Malignant Neoplasms; Mammary Neoplasms; Maps; Mediating; Methylation; Methyltransferase; Mutate; Mutation; Pathway interactions; Pattern; Phenotype; Post-Translational Protein Processing; Process; Protein p53; Publishing; Regulation; Regulator Genes; Research; Resolution; Role; Small Interfering RNA; Stress; TP53 gene; Techniques; Teratocarcinoma; Transcription Coactivator; Transcription Initiation Site; Transcriptional Activation; Tumor Suppressor Proteins; Tumor-Derived; Work; base; cell type; chromosome conformation capture; cohesin; combinatorial; efficacy testing; epigenetic regulation; epigenetic therapy; gain of function; genetic signature; genome-wide; high throughput screening; histone modification; in vivo; member; mouse model; mutant; novel; overexpression; promoter; recruit; response; rho; small hairpin RNA; transcription factor; tumor; tumorigenesis

ABSTRACT p53 is the most commonly mutated gene in human cancer. The p53 protein is a stress- and DNA damage-responsive transcriptional activator that binds to DNA to activate cell protective pathways, including cell cycle arrest, DNA repair, and apoptosis. The majority of p53 mutations in cancer inactivate the tumor suppressor via disruption of p53 DNA binding and hence transcriptional activation activity. The p53 protein is subject to numerous regulatory post-translational modifications, and additionally, the p53 transcription factor binds to target genes to recruit chromatin and histone modifiers as a key mechanism in gene activation. Given p53's normal role in chromatin regulation, p53 mutations and alterations in oncogenesis likely impair epigenetic pathways targeted by p53. Further elucidation of interactions between p53 and chromatin will therefore illuminate cancerous disruptions. Our recent published and preliminary data explore key mechanisms in the function and regulation of p53 as a transcriptional activator and regulating chromatin, and we will clarify these pathways in the proposed studies. First, we find that certain well-known p53 gain-of-function substitution mutations bind to and up- regulate an epigenetic gene signature, which, in turn, modifies histones to activate downstream ras/rho growth pathways. We plan to critically evaluate the mechanism and importance of this epigenetic signature in human tumor-derived cell lines bearing p53 gain-of-function substitutions and with related in vivo mouse models. Second, teratocarcinoma tumors paradoxically express high levels of wild type inactive p53; we show p53 in these cancers is decorated with elevated levels of repressive lysine methylation. In the proposed research, we will determine whether the methylation is crucial to inhibition of wild type p53 in teratocarcinomas. Third, we find that, beyond well-known p53 binding to promoters of target genes, surprisingly, the majority of stress- inducible p53 binding sites are distal to genes, appearing to be at enhancers. In the proposed studies we will address the interplay between p53 and certain histone modifiers in establishing enhancer function and gene activation. Fourth, by way of a high throughput si/shRNA screen for epigenetic regulators of p53-mediated gene activation, we observe an association of p53 with factors that mediate large-scale chromatin architecture. We will investigate direct roles of cohesin and CTCF in regulating the p53 transcriptional response via regulation of specific chromatin looping and architecture. Results from these studies will elucidate epigenetic mechanisms regulating p53 function, will explore involvement of these epigenetic pathways in p53 function in vivo and in cancer, and will launch investigation of tailored epigenetic therapies to ameliorate specific p53-driven cancer phenotypes.

抽象的 p53 是人类癌症中最常见的突变基因。 p53 蛋白是一种应激和 DNA 损伤响应转录激活剂，与 DNA 结合以激活细胞保护途径，包括 细胞周期停滞、DNA 修复和细胞凋亡。癌症中的大多数 p53 突变都会使肿瘤失活 通过破坏 p53 DNA 结合从而破坏转录激活活性来抑制。 p53 蛋白是 受到许多翻译后调节修饰，此外，p53 转录因子 与靶基因结合以招募染色质和组蛋白修饰剂作为基因激活的关键机制。给定 p53 在染色质调节中的正常作用、p53 突变和肿瘤发生的改变可能会损害表观遗传 p53 靶向的途径。因此，进一步阐明 p53 和染色质之间的相互作用将 阐明癌症的破坏。 我们最近发表的初步数据探讨了功能和调节的关键机制 p53 作为转录激活剂并调节染色质，我们将在拟议的研究中阐明这些途径 研究。首先，我们发现某些众所周知的 p53 功能获得性替代突变会结合并上调 调节表观遗传基因特征，进而修改组蛋白以激活下游 ras/rho 生长 途径。我们计划批判性地评估这种表观遗传特征在人类中的机制和重要性 带有 p53 功能获得性取代的肿瘤衍生细胞系以及相关的体内小鼠模型。 其次，畸胎瘤肿瘤相反地表达高水平的野生型失活 p53；我们在中显示 p53 这些癌症具有升高水平的抑制性赖氨酸甲基化。在拟议的研究中，我们 将确定甲基化是否对于抑制畸胎瘤中野生型 p53 至关重要。第三，我们 令人惊讶地发现，除了众所周知的 p53 与靶基因启动子的结合之外，大多数应激- 诱导型 p53 结合位点位于基因远端，似乎位于增强子处。在拟议的研究中，我们将 解决 p53 和某些组蛋白修饰剂在建立增强子功能和基因方面的相互作用 激活。第四，通过高通量si/shRNA筛选p53介导的表观遗传调节因子 基因激活后，我们观察到 p53 与介导大规模染色质结构的因子之间存在关联。 我们将通过以下方式研究粘连蛋白和 CTCF 在调节 p53 转录反应中的直接作用 特定染色质环和结构的调节。 这些研究的结果将阐明调节 p53 功能的表观遗传机制，将探索 这些表观遗传途径参与体内 p53 功能和癌症，并将推出 研究定制表观遗传疗法以改善特定的 p53 驱动的癌症表型。