Epigenetic Regulation of Epstein-Barr Virus Latency Programs

EB 病毒潜伏期程序的表观遗传调控

• 批准号: 7883328
• 负责人: PAUL M LIEBERMAN
• 金额: $ 32.13万
• 依托单位: WISTAR INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7883328
• 关键词: Accounting; Affinity Chromatography; Area; B lymphocyte immortalization; B-Lymphocytes; Binding; Binding Proteins; Biochemical Genetics; Burkitt Lymphoma; Carcinoma; Cell Cycle; Cell Cycle Regulation; Cell Maturation; Cell Survival; Chromatin; Chromosomes; DNA; DNA Methylation; Detection; Down-Regulation; E2F1 gene; Enhancers; Enzymes; Epigenetic Process; Epithelial Cells; Epstein-Barr Virus latency; Epstein-Barr pathogenesis; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Goals; Growth; Higher Order Chromatin Structure; Histone H3; Hodgkin Disease; Human; Human Herpesvirus 4; Immune; Immune system; Infection; Investigation; LMP1; Link; Lymphoid; Lymphoma; Lymphoproliferative Disorders; Lysine; Lytic; Malignant Neoplasms; Mediating; Methods; Methylation; Modification; Molecular; Molecular Conformation; Nasopharynx Carcinoma; Neoadjuvant Therapy; Nose; Nucleic Acid Regulatory Sequences; Oncogenes; Pattern; Play; Process; Publishing; Regulation; Resistance; Role; Signal Transduction; T-Lymphocyte; Testing; Transcript; Tumor Suppressor Proteins; Viral; Viral Genes; Viral Pathogenesis; Viral Proteins; Virus; base; carcinogenesis; cell transformation; cell type; chromatin modification; clinically relevant; histone modification; immunogenic; latent infection; lytic gene expression; neoplastic cell; pathogen; programs; promoter; public health relevance; viral DNA; virus host interaction

DESCRIPTION (provided by applicant): The latent infection of Epstein-Barr Virus (EBV) is associated with human lymphoid and epithelial cell malignancies. Reversible epigenetic silencing of EBV-encoded oncogenes is known to provide the virus with a survival strategy that includes controlling B-cell maturation and evading immune system detection. The cellular signals and mechanisms regulating the epigenetic silencing have not been fully elucidated. We have investigated the chromatin organization and epigenetic modifications in the control regions of the major latency transcripts of EBV in different latency types. Our studies suggest that epigenetic modifications play a key role in regulating the different gene expression programs of EBV latency. We focus on the control of the major latency promoters Cp and Qp, and how they are regulated by the tumor suppressor protein Rb (aim1), the viral- encoded origin binding protein EBNA1 (aim 2), and the chromatin boundary factor CTCF (aim 3). Rb and Rb-associated factors bind to Cp and regulate a cell cycle-dependent change in chromatin modifications. We propose to explore the role of Rb and Rb-associated factors in the epigenetic silencing that occurs at Cp in type I latency, and cell cycle regulation in type III. For aim 2, we focus on the role of EBNA1 in the transcription enhancement of Cp and how this is regulated in different cell types. We propose to identify a B-cell specific mediated of EBNA1 enhancer function and whether enhancer-promoter activation correlates with changes in viral chromosome conformation. In aim 3, we focus on the role of CTCF in regulating the interactions between enhancers and promoters, and in insulating active promoters from silent genes during latency. The long-term goal of this project is to understand the epigenetic mechanisms regulating viral gene expression during latency, and how these mechanisms contribute to viral pathogenesis. PUBLIC HEALTH RELEVANCE: EBV is an important human pathogen that has been linked to multiple malignances and lymphoproliferative disorders. EBV can escape immune detection and clearance by several mechanisms including the ability to reversibly down-regulate immunogenic viral proteins. This down-regulation is known to be regulated by epigenetic changes in the latent viral chromosome. In this application, we propose to investigate key regulatory steps in the formation of epigenetic silencing during EBV latent infection. In aim 1 we focus on the process by which the major latency promoter is transcriptionally silenced by the Rb tumor suppressor protein, and how this leads to histone H3 K9 and DNA methylation. In aim 2, we focus on the mechanism of EBNA1 enhancer activation of Cp and the requirement for a B-cell specific coactivator. This B-cell coactivator may account for the type II latency observed in epithelial carcinomas where LMP1 is expressed in the absence of EBNA2. In aim 3, we explore whether higher order chromatin structure and chromatin organizing factors, like CTCF, are responsible for transcriptional silencing observed in type I latent infections. These studies will help to elucidate mechanisms of viral gene regulation in different latency types. This is clinically relevant because eradication of the immune-resistant latent forms of EBV (type I and type II) will be necessary to eliminate many viral-associated cancers. The recent advent of lytic-induction therapies will also require a better understanding of the mechanisms that control transcription silencing specific for the latent viral chromosome. The proposed studies should further our understanding of EBV latent cycle gene regulation and host-virus interactions.

描述（由申请人提供）：爱泼斯坦 - 巴尔病毒（EBV）的潜在感染与人淋巴和上皮细胞恶性肿瘤有关。已知EBV编码的癌基因的可逆表观遗传沉默可为病毒提供一种生存策略，其中包括控制B细胞的成熟和逃避免疫系统检测。调节表观遗传沉默的细胞信号和机制尚未完全阐明。我们已经研究了EBV主要潜伏期类型的主要潜伏期转录本的控制区域的染色质组织和表观遗传修饰。我们的研究表明，表观遗传修饰在调节EBV潜伏期的不同基因表达程序中起关键作用。我们专注于控制主要延迟启动子CP和QP，以及它们如何受到肿瘤抑制蛋白RB的调节（AIM1），病毒编码的起源结合蛋白EBNA1（AIM 2）和染色质边界因子CTCF（AIM 3）。 RB和RB相关因子与CP结合，并调节染色质修饰的细胞周期依赖性变化。我们建议探索RB和与RB相关因子在I型潜伏期中发生在CP的表观遗传沉默中的作用，以及III型中的细胞周期调节。对于AIM 2，我们关注EBNA1在CP转录增强中的作用以及如何在不同细胞类型中调节它。我们建议确定B细胞特异性EBNA1增强子函数的介导的特异性介导，以及增强子促进剂激活是否与病毒染色体构象的变化相关。在AIM 3中，我们着重于CTCF在调节增强子与启动子之间的相互作用以及在潜伏期期间与静音基因绝缘的启动子中的作用。该项目的长期目标是了解导致潜伏期病毒基因表达的表观遗传机制，以及这些机制如何促进病毒发病机理。公共卫生相关性：EBV是一种重要的人类病原体，与多种恶性肿瘤和淋巴增生性疾病有关。 EBV可以通过多种机制避免免疫检测和清除，包括可逆地调节免疫原性病毒蛋白的能力。已知这种下调受到潜在病毒染色体的表观遗传变化的调节。在此应用中，我们建议研究在EBV潜在感染过程中形成表观遗传沉默的关键调节步骤。在AIM 1中，我们关注的是由RB肿瘤抑制蛋白在转录沉默的主要潜伏期启动子以及这如何导致组蛋白H3 K9和DNA甲基化的过程中。在AIM 2中，我们关注CP的EBNA1增强子激活的机理以及对B细胞特异性共激活因子的需求。该B细胞共激活因子可以解释在上皮癌中观察到的II型潜伏期，其中LMP1在没有EBNA2的情况下表达。在AIM 3中，我们探讨了高阶染色质结构和染色质组织因子（例如CTCF）是否负责在I型潜伏感染中观察到的转录沉默。这些研究将有助于阐明不同潜伏类型的病毒基因调节机制。这在临床上是相关的，因为消除免疫抗性潜在EBV（I型和II型）对于消除许多病毒相关的癌症是必要的。裂解诱导疗法的最近出现还需要更好地理解控制对潜在病毒染色体特有的转录沉默的机制。拟议的研究应进一步了解我们对EBV潜在周期基因调控和宿主病毒相互作用的理解。