Investigation of histone exchange mechanisms and their roles in viral gene expression

组蛋白交换机制及其在病毒基因表达中的作用的研究

• 批准号: RGPIN-2019-05452
• 负责人: Conn, Kristen
• 金额: $ 2.19万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715554
• 关键词: Investigation; histone; exchange; mechanisms; their

The regulated expression of genes is fundamental to growth and development. Although much progress has been made towards a comprehensive understanding of the mechanisms that regulate gene expression, many areas remain unknown. Transcription and other processes that require access to the DNA are physically impeded by the assembly of DNA into chromatin with histones. DNA assembled in accessible chromatin is competent for transcription whereas that assembled in inaccessible chromatin is not. The mechanisms that regulate chromatin accessibility are not fully understood. It is also not clear how chromatin accessibility is modulated to enable transcription activation of DNA that is assembled into inaccessible chromatin. This proposed research program will use herpes simplex virus 1 (HSV) as a model system to investigate the processes that regulate chromatin accessibility and how they relate to transcription activation. Infecting HSV genomes are assembled into chromatin with cellular histones shortly after nuclear entry. Some HSV genomes are assembled into highly accessible, transcriptionally competent, chromatin, whereas the rest are assembled into highly inaccessible, transcriptionally incompetent, chromatin. The two populations of HSV chromatin within the same nucleus support a model whereby cellular antiviral defences attempt to silence HSV genomes through their assembly into inaccessible chromatin. HSV must counteract and disrupt silencing for viral genes to be expressed. Consistent with this model, the only essential HSV transcription activator, ICP4, enhances histone dynamics. Enhancing the dynamics of histones within the HSV chromatin would increase its accessibility and allow transcription. The enhancement of histone dynamics appears to be a novel mechanism of gene activation acquired by HSV to counteract cellular silencing attempts, although the mechanisms whereby ICP4 enhances histone dynamics are not known. Our hypothesis is that histone dynamics regulate HSV chromatin accessibility. Graduate (4 MSc, 2 PhD) and Undergraduate students (5) will be recruited and trained in virology, cell culture, DNA- and protein-centered techniques, and advanced cell imaging to: (1) Identify the minimal ICP4 domains necessary and sufficient to enhance histone dynamics, (2) Identify ICP4-interacting proteins functionally relevant to the enhancement of histone dynamics, and (3) Test the conservation of ICP4 enhancement of histone dynamics and chromatin accessibility among alphaherpesviruses. This research will support my long-term objective to characterize the mechanisms that regulate chromatin accessibility in order to increase our fundamental understanding of the processes that activate transcription of DNA assembled into inaccessible chromatin. Knowledge gained from this research program will be of importance to researchers in the fields of virology, epigenetics and chromatin biology, developmental biology, and oncology, among others.

基因的调控表达对生长和发育至关重要。尽管在全面了解调节基因表达的机制方面取得了很大进展，但许多领域仍然未知。 转录和其他需要接触DNA的过程会受到DNA与组蛋白组装成染色质的物理阻碍。组装在可接近的染色质中的DNA能够转录，而组装在不可接近的染色质中的DNA则不能。调节染色质可及性的机制尚未完全了解。也不清楚如何调节染色质可接近性以使组装成不可接近的染色质的DNA的转录激活成为可能。 这项拟议的研究计划将使用单纯疱疹病毒1型（HSV）作为模型系统来研究调节染色质可及性的过程以及它们如何与转录激活相关。感染的HSV基因组在进入细胞核后不久与细胞组蛋白组装成染色质。一些HSV基因组被组装成高度可接近的、有转录能力的染色质，而其余的被组装成高度不可接近的、无转录能力的染色质。同一核内的两个HSV染色质群体支持细胞抗病毒防御试图通过将HSV基因组组装成不可接近的染色质来沉默HSV基因组的模型。HSV必须抵消和破坏病毒基因表达的沉默。与该模型一致，唯一必需的HSV转录激活因子ICP4增强组蛋白动力学。增强HSV染色质内组蛋白的动力学将增加其可及性并允许转录。组蛋白动力学的增强似乎是HSV获得的基因激活的新机制，以抵消细胞沉默尝试，尽管ICP 4增强组蛋白动力学的机制尚不清楚。 我们的假设是组蛋白动力学调节HSV染色质可及性。研究生（4个硕士，2个博士）和本科生（5）将被招募和培训病毒学，细胞培养，DNA和蛋白质为中心的技术，和先进的细胞成像：（1）鉴定增强组蛋白动力学所必需和足够的最小ICP 4结构域，（2）鉴定与增强组蛋白动力学功能相关的ICP 4相互作用蛋白，和（3）测试在α疱疹病毒中ICP4增强组蛋白动力学和染色质可及性的保守性。这项研究将支持我的长期目标，以表征调节染色质可及性的机制，以增加我们对激活组装成不可及染色质的DNA转录过程的基本理解。从这项研究计划中获得的知识将对病毒学，表观遗传学和染色质生物学，发育生物学和肿瘤学等领域的研究人员具有重要意义。