EBV reactivation causes widespread host de novo promoter transcription and transcriptional interference

EBV 重新激活导致广泛的宿主从头启动子转录和转录干扰

基本信息

批准号：
10548370
负责人：
ERIK K FLEMINGTON
金额：
$ 42.13万
依托单位：
TULANE UNIVERSITY OF LOUISIANA
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-07-01 至 2027-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10548370
关键词：
AIDS population AIDS related cancer AIDS/HIV problem Architecture Automobile Driving Binding Binding Sites Biological Models Cell Nucleus Cells Chromatin Complex Cues DNA Polymerase II DNA Tumor Viruses Data Direct Lytic Factors Down-Regulation Environment Fostering Frequencies Gene Expression Genes Genetic Genetic Transcription Genome Genomics HIV Handedness Herpesviridae Human Herpesvirus 4 Human Herpesvirus 8 Incidence Individual Link Lymphoma Lymphomagenesis Lytic Mediating Messenger RNA Metabolism Modeling Mus Nature Pathway interactions Play Population Positioning Attribute Predisposition Process Production Proteins RNA RNA-Binding Proteins Resources Role Site Stimulus Structural Protein Trans-Activators Transcript Transcription Initiation Translations Viral Viral Packaging Viral Proteins Viral Structural Proteins Virion Virus Virus Diseases Virus Latency Virus Replication Virus-Cell Membrane Interaction co-infection gammaherpesvirus humanized mouse insight lytic replication mRNA Expression mRNA Transcript Degradation mouse model particle programs promoter response therapeutic target transcription factor transcriptome virus host interaction virus related cancer

项目摘要

Summary The Epstein Barr virus (EBV) is a DNA tumor virus that causes an elevated incidence of lymphoma in the HIV/AIDS population. While more than 90% of the world's population carries EBV, the virus typically exists in a “latent” state with little impact on the host. In response to certain stimuli or local microenvironmental cues, however, EBV enters the lytic viral replication program, leading to viral spread both between and within hosts. In addition to the known role of viral latency proteins in EBV associated cancers, there are well-established links between lytic replication and EBV associated cancers; and elevated EBV lytic replication in HIV co- infection (+ or – ART) likely contributes to the increased susceptibility of HIV infected individuals to EBV associated lymphomas. With minimal genetic content, viruses are inexorably dependent on host cell resources for their replication and they evolve mechanisms to modulate host cell metabolic processes to facilitate efficient virus production. One of the most conserved virus-host interactions in herpesvirus replication is “host shut off” where virus encoded factors degrade host cell mRNAs, freeing up translation resources for dedicated production of viral structural proteins. Recently, the Glaunsinger lab showed that the murine γ-herpesvirus, MHV68 also inhibits Pol II loading on cell genes. This illustrates the utilization of layered host shut off mechanisms that together overcome the rate-limiting step of viral structural protein production. Using EBV reactivation models that facilitate assessment of transcriptome changes in pure reactivating cell populations, we gained new and unexpected insights into EBV's interactions with the host cell transcriptome. Among a number of observed transcriptome alterations is our finding that EBV causes transcription initiation at more than 25,000 cell genomic sites that have no previous evidence of promoter activity. These “de novo” promoters are unusually simple, being composed of only one or two short viral transcription factor binding motif(s) that due to their short nature, occur randomly at a high frequency across the cell genome. Our preliminary data suggests that one of these motifs is recognized by the viral preinitiation complex, vPIC, which binds a “TATA”-like motif (TATT(TA)AA) and has been shown in some cases to activate viral late genes without apparent support from other transcription factors. We hypothesize that EBV utilizes the ability of vPIC to single-handedly activate transcription through these simple motifs to spawn thousands of host de novo promoters and substantially alter the cell transcriptome and chromatin architecture. Our preliminary studies also show that the most highly active de novo promoters have enriched localization within 1.5 kb of canonical cell promoters, with transcriptional orientations toward the respective canonical promoters. We hypothesize that while EBV utilizes the primal nature of late viral promoter motifs to target thousands of sites throughout the cell genome, it leverages chromatin context near canonical promoters to drive high-level de novo promoter transcription, leading to targeted transcriptional interference (TI) of host promoters. This represents a new mechanistic concept for virus-host interactions that contributes to disrupted cell gene expression and dedicated production of viral structural proteins. In this proposal, we will 1) investigate the underlying mechanisms of de novo promoter specification and local chromatin context driving high level transcription near existing canonical promoters, and 2) investigate the impact of de novo transcription and transcriptional interference in downregulating cell mRNA expression.

概括 Epstein Barr 病毒 (EBV) 是一种 DNA 肿瘤病毒，可导致淋巴瘤发病率升高 HIV/艾滋病人群虽然世界上 90% 以上的人口携带 EBV，但该病毒通常存在于人体中。对宿主影响很小的“潜伏”状态，以响应某些刺激或局部微环境线索。然而，EBV 进入裂解性病毒复制程序，导致病毒在宿主之间和宿主内传播。除了已知的病毒潜伏蛋白在 EBV 相关癌症中的作用外，还有一些已被证实的裂解性复制与 EBV 相关癌症之间的联系；以及 HIV 感染中 EBV 裂解性复制的升高感染（+ 或 – ART）可能会导致 HIV 感染者对 EBV 的易感性增加相关淋巴瘤。由于遗传含量极低，病毒的复制和复制不可避免地依赖于宿主细胞资源。它们进化出调节宿主细胞代谢过程的机制，以促进有效的病毒生产。疱疹病毒复制中最保守的病毒与宿主相互作用是病毒编码的“宿主关闭” 因子降解宿主细胞 mRNA，释放翻译资源用于专门生产病毒结构最近，Glaunsinger 实验室表明，鼠 γ-疱疹病毒 MHV68 也能抑制 Pol II。这说明了分层宿主关闭机制的利用。克服病毒结构蛋白产生的限速步骤。使用 EBV 再激活模型促进纯再激活细胞中转录组变化的评估通过对人群的研究，我们对 EBV 与宿主细胞转录组的相互作用获得了新的、意想不到的见解。在许多观察到的转录组改变中，我们发现 EBV 导致转录起始于超过 25,000 个细胞基因组位点之前没有启动子活性的证据。启动子非常简单，仅由一两个短病毒转录因子结合组成由于其短的性质，在我们的细胞基因组中以高频率随机出现的基序。初步数据表明，这些基序之一被病毒前起始复合物 vPIC 识别，该复合物结合“TATA”样基序 (TATT(TA)AA)，在某些情况下已被证明可以激活病毒晚期基因没有其他转录因子的明显支持，我们发现 EBV 利用了 vPIC 的能力。通过这些简单的基序单手激活转录，从头产生数千个宿主启动子并显着改变细胞转录组和染色质结构。我们的初步研究还表明，最活跃的从头启动子丰富了本地化距离规范细胞启动子 1.5 kb 以内，转录方向朝向相应的规范细胞启动子我们认为，EBV 利用晚期病毒启动子基序的原始性质来定位目标。整个细胞基因组的数千个位点，它利用规范启动子附近的染色质背景来驱动高水平从头启动子转录，导致宿主的靶向转录干扰（TI）这代表了病毒与宿主相互作用的新机制概念，有助于破坏。细胞基因表达和病毒结构蛋白的专用生产。在这个提案中，我们将1）研究从头启动子规范和本地启动子规范的潜在机制。染色质环境驱动现有规范启动子附近的高水平转录，2) 研究从头转录和转录干扰对下调细胞 mRNA 表达的影响。