Role of PADI4 as a key epigenetic regulator of the p53 pathway and tumor suppression

PADI4 作为 p53 通路和肿瘤抑制的关键表观遗传调节因子的作用

基本信息

批准号：
10603437
负责人：
Alexandra Indeglia
金额：
$ 4.77万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-05-01 至 2026-04-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10603437
关键词：
ATAC-seq Address Agar Antigens Arginine Biological Assay Cell Line Cells Chromatin Citrulline Clustered Regularly Interspaced Short Palindromic Repeats Co-Immunoprecipitations Complex Data Defect Epigenetic Process Genes Genetic Transcription Genetic study Goals Histones Human Immune Immunocompetent Immunocompromised Host Impairment Individual Injury Knockout Mice Knowledge Ligation Malignant Neoplasms Mediating Melanoma Cell Methylation Mus Mutate Mutation Oncogenes Oncogenic Pathway interactions Pharmaceutical Preparations Play Population Post-Translational Protein Processing Process Proliferating Property Protein-arginine deiminase Proteins Regulation Reporting Research Role TP53 gene Testing Tetracyclines The Cancer Genome Atlas Time Tissues Transactivation Transcriptional Activation Tumor Cell Line Tumor Suppression Tumor Suppressor Genes Tumor Suppressor Proteins Variant cancer cell cancer risk cancer therapy chromatin immunoprecipitation data integration druggable target experimental study genotoxicity histone modification immune activation immune function insight melanoma neoplastic cell new therapeutic target novel novel therapeutics overexpression recruit response small molecule inhibitor transcription factor transcriptome sequencing tumor tumor growth tumor xenograft unnatural amino acids

项目摘要

PROJECT SUMMARY TP53 is the most frequently mutated gene in human cancer. While it is well understood that the ability of p53 to act as a transcription factor is required for tumor suppression, the key target genes downstream of p53 required for tumor suppression are still incompletely understood. Moreover, attempts at drugging p53 have proven ineffective, generating a need to understand downstream players in the tumor suppressive pathway to develop novel therapies. The Murphy lab has characterized three p53 variants termed “hypomorphs” that are minimally impaired for p53 transcriptional function but have increased cancer-risk. These three p53 hypomorphs are impaired for transactivation of only a few target genes, with the top target gene impaired being peptidyl-arginine deiminase 4 (PADI4). PADI4 is a regulator of histone modification via citrullination, which is the process of deiminating unmodified or mono-methylated arginine to the non-natural amino acid citrulline. Histone citrullination is predicted to regulate gene transcription and is known in some cases to decondense chromatin. PADI4 dependent citrullination is also involved in immune cell activation and recruitment. Previous reports have suggested PADI4 may act as an oncogene or a tumor suppressor, and the reasons underlying this controversy remain unclear. Additionally, mechanistic studies on PADI4 and histone citrullination in cancer are lacking. TCGA analysis reveals that PADI4 is downregulated or mutated in multiple human cancers, including mutations in 8% of melanoma, suggesting that this gene is a tumor suppressor. I have found that PADI4 levels increase in response to genotoxic injury in multiple tissues, but this is abolished in p53Y107H and PADI4 KO mice. PADI4 also suppresses the proliferation of both p53 wild type (WT) and p53-null cancer cells. RNA-seq analysis of cells treated with the p53 stabilizer Nutlin-3a, +/- si-PADI4, reveals PADI4 to be required for transcriptional activation of a subset of p53 target genes. Collectively, these data suggest that PADI4 as a novel epigenetic regulator in cancer and may play a key role in p53-mediated tumor suppression. I hypothesize that PADI4 contributes to tumor suppression through interaction with p53, and through regulating chromatin organization by citrullinating histones and opening chromatin at targeted loci. To test this hypothesis, I propose two aims. In the first aim, I will establish the direct transcriptional targets of PADI4 in p53 WT and p53 null melanoma cells. I will also formally test the hypothesis that PADI4 increases histone citrullination to induce changes in chromatin accessibility. In the second aim, I will assess the tumor suppressive ability of PADI4 and PADI4 target genes in xenograft tumor growth studies. Finally, whereas PADI4 has a clear transcriptional role, PADI4 is also known to enhance antigen recognition, but whether this contributes to tumor suppression is unknown. I will test this hypothesis. In sum, this proposal seeks to uncover new information about an exciting but poorly understood epigenetic modifier and its role in tumor suppression and the p53 pathway.

项目概要 TP53 是人类癌症中最常见的突变基因，而众所周知，p53 的能力。作为肿瘤抑制所需的转录因子，p53 的关键靶下游基因此外，对 p53 进行药物治疗的尝试尚未完全明确。被证明无效，需要了解肿瘤抑制途径的下游参与者 Murphy 实验室已鉴定出三种称为“次形体”的 p53 变体。 p53 转录功能受损程度最低，但这三种 p53 却增加了癌症风险。低效型仅少数靶基因的反式激活受损，其中顶级靶基因受损肽基精氨酸脱亚胺酶 4 (PADI4) 是通过瓜氨酸化进行组蛋白修饰的调节剂，这是将未修饰或单甲基化精氨酸脱亚胺化为非天然氨基酸的过程组蛋白瓜氨酸化预计可调节基因转录，并且在某些情况下已知可以调节基因转录。 PADI4 依赖性瓜氨酸化也参与免疫细胞激活和先前的报告表明 PADI4 可能充当癌基因或肿瘤抑制因子，并且此外，PADI4 和 PADI4 的机制研究尚不清楚。癌症中缺乏组蛋白瓜氨酸化，TCGA 分析表明 PADI4 下调或突变。在多种人类癌症中，包括 8% 的黑色素瘤中存在突变，表明该基因是一种肿瘤我发现 PADI4 水平会随着多种组织中的基因毒性损伤而增加，但是这在 p53Y107H 和 PADI4 KO 小鼠中被消除，PADI4 也抑制 p53 野生的增殖。使用 p53 稳定剂 Nutlin-3a 处理的细胞的 RNA-seq 分析，+/- si-PADI4，表明 PADI4 是 p53 靶基因子集转录激活所必需的。总的来说，这些数据表明 PADI4 作为癌症中的一种新型表观遗传调节因子，可能发挥关键作用在 p53 介导的肿瘤抑制中，我认为 PADI4 通过以下方式有助于肿瘤抑制。与 p53 相互作用，并通过瓜氨酸组蛋白和调节染色质组织为了检验这个假设，我提出了两个目标。我也将正式在 p53 WT 和 p53 null 黑色素瘤细胞中建立 PADI4 的直接转录靶点。检验 PADI4 增加组蛋白瓜氨酸化以诱导染色质可及性变化的假设。在第二个目标中，我将评估PADI4和PADI4靶基因在异种移植中的肿瘤抑制能力最后，虽然 PADI4 具有明显的转录作用，但 PADI4 也被认为是增强抗原识别，但这是否有助于肿瘤抑制尚不清楚，我将对此进行测试。总之，该提案旨在发现有关令人兴奋但知之甚少的新信息。表观遗传修饰剂及其在肿瘤抑制和 p53 通路中的作用。