Function of histone chaperones in HSV-1 chromatin sturcture during latency, establishing maintenance and reactivation

潜伏期 HSV-1 染色质结构中组蛋白伴侣的功能、建立维持和重新激活

• 批准号: 8930277
• 负责人: David C. Bloom
• 金额: $ 22.5万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-16 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8930277
• 关键词: Address; Antiviral Agents; Binding; Biology; Blindness; CCCTC-binding factor; Cell Nucleus; Cell physiology; Cells; Chromatin; Clinical; Complex; DAXX gene; DNA; DNA Binding; Data; Deposition; Disease; Elements; Epigenetic Process; Episome; Equilibrium; Ganglia; Gene Expression; Gene Silencing; Genes; Genetic Transcription; Genital system; Genome; Herpes Labialis; Herpesvirus 1; Heterochromatin; Histone H1; Histone H1(s); Histone H3; Histone H3.3; Histones; Human; Human Herpesvirus 2; In Vitro; Indium; Infection; Infectious Skin Diseases; Lead; Lesion; Life; Life Cycle Stages; Lip structure; Lytic; Lytic Phase; Maintenance; Mediating; Modeling; Modification; Molecular; Molecular Chaperones; Nervous system structure; Neurons; Nuclear; Nuclear Protein; Nucleosomes; Oral cavity; Organism; Pain; Pathway interactions; Pilot Projects; Play; Positioning Attribute; Post-Translational Protein Processing; Process; Recruitment Activity; Recurrence; Regulatory Element; Repression; Research Personnel; Role; Severities; Simplexvirus; Staging; Symptoms; Testing; Therapeutic Intervention; Transcriptional Regulation; Variant; Viral; Viral Genes; Viral Genome; Virus; Virus Diseases; Virus Latency; afferent nerve; ds-DNA; experience; genital herpes; improved; in vivo; innovation; insight; latency associated transcript; latent infection; new therapeutic target; prevent; public health relevance; reactivation from latency; viral DNA; virus pathogenesis

 DESCRIPTION (provided by applicant): Herpes simplex virus (HSV) causes significant pain and suffering in humans. It is acquired by skin infection (typically mouth/lips for HSV-1 and genitals for HSV-2) where it replicates lytically and then spreads to the nervous system. It establishes a life-long latent infection within sensory nerve ganglia and persists as a double-stranded DNA (episome) within the nuclei of latently infected neurons. Periodically HSV reactivates from this latent state and causes cold sores (HSV-1) or genital lesions (HSV-2). The mechanism of how HSV establishes a latent infection or reactivates from latency is not understood. Over 50 million people in the US experience clinical recurrent HSV disease. HSV-1 is also the leading cause of infectious blindness in the US with over 30,000 new cases a year. While antiviral drugs can reduce the severity of symptoms, they do not block reactivation and they are not curative. Understanding how HSV interacts with the cell to regulate its lytic and latent life cycle could provide new targets for therapeutic intervention. Recent advantages in the field have demonstrated that transcriptional control of viral genes at the chromatin level plays a key role in the delicate balance between latency and reactivation, suggesting that chromatin is the key element in HSV latency. While the details of these regulatory processes are largely unknown, several recent findings have provided clues such as: evidence that HSV lytic genes are silenced by post-translational modifications of histones (epigenetic repression); insulator protein CTCF establishes epigenetic borders on viral DNA during latency, separating repressed lytic genes and active LAT region; nuclear protein DAXX and its interaction partner ATRX play a pivotal role by chaperoning the histone variants that can facilitate formation of mobile, transcriptionally active chromatin; DAXX and ATRX participate in intrinsic antiviral defenses repressing lytic infection. During latency establishing, DAXX complex participates in chromatin formation on HSV-1 DNA. In turn, this may create specific chromatin signature to establish proper loading and maintenance of CTCF at specific CTCF-binding elements of HSV genome thus creating epigenetic boundaries on this genome to regulate latency. These observations allowed us to formulate the main hypothesis of this proposal: the DAXX/ATRX-mediated loading of histone variants regulates dynamic deposition of CTCF on HSV-1 genome thus controlling appropriate chromatin formation that is critical for latency. We expect that the balanced deposition of histone variants represents a key necessary step in latency and predict that DAXX/ATRX complex plays an essential role in this process. In order to test this hypothesis we are combining the expertise of two co-investigators. Dr. Alexander Ishov is an expert in the DAXX/ATRX biology and in the analysis of intra-nuclear aspects of viral infection. Dr. David Bloom is an expert in epigenetic control of HSV gene expression and models to study HSV pathogenesis and latency. The key studies proposed in this project will investigate the involvement of DAXX/ATRX in recruiting histones variants to the regulatory elements of HSV genome and whether this alters the ability of the genome to establish and maintain latency via CTCF deposition in both in vitro and in vivo settings. These studies will determine whether DAXX/ATRX chaperone complex is involved in the regulatory balance between HSV lytic and latent infection and will provide essential data for the mechanistic understanding of this process. In addition to providing insight into the mechanism of HSV latency and reactivation, this highly innovative and focused pilot study has the potential to identify new therapeutic targets for treating HSV infections. If DAXX/ATRX were shown to have a role in regulating the switch between lytic and latent infection, this complex would be highlighted as target for anti-viral therapy.

 描述（由申请人提供）：单纯疱疹病毒（HSV）给人类带来严重的疼痛和折磨。它是通过皮肤感染（HSV-1 通常为口腔/嘴唇，HSV-2 为生殖器）获得的，在皮肤感染中进行裂解性复制，然后扩散到神经系统。它在感觉神经节内建立终生潜伏感染，并以双链 DNA（附加体）形式持续存在于潜伏感染神经元的细胞核内。 HSV 会定期从这种潜伏状态重新激活，并导致唇疱疹 (HSV-1) 或生殖器病变 (HSV-2)。 HSV 如何建立潜伏感染或从潜伏状态重新激活的机制尚不清楚。美国有超过 5000 万人患有临床复发性 HSV 疾病。 HSV-1 也是美国感染性失明的主要原因，每年新增病例超过 30,000 例。虽然抗病毒药物可以减轻症状的严重程度，但它们不能阻止病毒的重新激活，也没有治愈作用。了解 HSV 如何与细胞相互作用以调节其裂解和潜伏生命周期可以为治疗干预提供新的目标。该领域的最新优势表明，病毒基因在染色质水平上的转录控制在潜伏期和重新激活之间的微妙平衡中发挥着关键作用，这表明染色质是HSV潜伏期的关键因素。虽然这些调控过程的细节在很大程度上尚不清楚，但最近的一些发现提供了一些线索，例如： HSV 裂解基因通过组蛋白翻译后修饰（表观遗传抑制）而沉默的证据；绝缘体蛋白 CTCF 在潜伏期在病毒 DNA 上建立表观遗传边界，将受抑制的裂解基因和活跃的 LAT 区域分开；核蛋白 DAXX 及其相互作用伙伴 ATRX 通过陪伴组蛋白变体发挥着关键作用，这些变体可以促进可移动的、转录活性染色质的形成； DAXX 和 ATRX 参与抑制裂解性感染的内在抗病毒防御。在潜伏期建立期间，DAXX 复合物参与 HSV-1 DNA 上染色质的形成。反过来，这可能会产生特定的染色质特征，以在 HSV 基因组的特定 CTCF 结合元件处建立 CTCF 的正确加载和维持，从而在该基因组上创建表观遗传边界以调节潜伏期。这些观察结果使我们能够制定该提案的主要假设：DAXX/ATRX 介导的组蛋白变体负载调节 CTCF 在 HSV-1 基因组上的动态沉积，从而控制对潜伏期至关重要的适当染色质形成。我们预计组蛋白变体的平衡沉积代表了潜伏期的关键必要步骤，并预测 DAXX/ATRX 复合物在此过程中发挥重要作用。为了检验这一假设，我们结合了两位联合研究人员的专业知识。 Alexander Ishov 博士是 DAXX/ATRX 生物学和病毒感染核内分析方面的专家。 David Bloom 博士是 HSV 基因表达表观遗传控制和研究 HSV 发病机制和潜伏期模型方面的专家。该项目提出的关键研究将调查 DAXX/ATRX 在将组蛋白变体招募到 HSV 基因组调控元件中的作用，以及这是否会改变基因组在体外和体内环境中通过 CTCF 沉积建立和维持潜伏期的能力。这些研究将确定 DAXX/ATRX 伴侣复合物是否参与 HSV 裂解和潜伏感染之间的调节平衡，并将为理解这一过程的机制提供必要的数据。 除了深入了解 HSV 潜伏和重新激活的机制外，这项高度创新且重点突出的试点研究还有可能确定治疗 HSV 感染的新治疗靶点。如果 DAXX/ATRX 被证明在调节溶解感染和潜伏感染之间的转换方面发挥作用，那么该复合物将被强调作为抗病毒治疗的靶点。