Mechanisms of Human Cytomegalovirus Latency in Primary Human Hematopoietic Cells

人原代造血细胞中人巨细胞病毒潜伏期的机制

• 批准号: 9916085
• 负责人: Felicia D Goodrum
• 金额: $ 37.76万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-19 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9916085
• 关键词: Address; Antiviral Agents; Biology; Cell physiology; Cells; Cercopithecine Herpesvirus 1; Code; Complex; Cytomegalovirus; Disease; Epidermal Growth Factor Receptor; Funding; Genes; Genome; Hematopoietic; Herpesviridae; Herpesviridae Infections; Human; Immune; Individual; Infection; Latent virus infection phase; Length; Life; Maintenance; Membrane; Modeling; Mutation; N-terminal; Organ Transplantation; Pathway interactions; Phenotype; Protein Isoforms; Proteins; Recurrence; Research; Role; Signal Transduction; Solid; Stem cells; System; Therapeutic; Time; Transplant Recipients; Ubiquitin; Viral Genes; Virus; Virus Diseases; Virus Latency; Virus Replication; Work; base; cellular targeting; chronic infection; latent infection; molecular mass; novel; prevent; programs; reactivation from latency; recombinant virus; trafficking; ubiquitin-protein ligase

PROJECT SUMMARY Human cytomegalovirus (HCMV) is a β-herpesvirus that establishes a lifelong latent infection in its host. Reactivation from latency can result in life-threatening disease in immune deficient individuals, particularly stem cell and solid organ transplant recipients. Our research program has a long-standing focus on defining HCMV determinants and host interactions at the mechanistic core of latency and reactivation. In previous funding periods, we defined a polycistronic locus within the ULb' region of the HCMV genome that spans the genes UL133-UL138. Within this region, we have identified virus-coded repressors and activators of virus replication. UL138 represses replication for latency, whereas UL135 activates replication for reactivation, in part, by overcoming the repressive action of UL138. UL135 and UL138 regulate EGFR with opposing effects and together comprise a switch to control viral latency and reactivation by regulating host signaling. Recently, UL136 has emerged as a key modulator of this switch. UL136 encodes 5 alternant protein forms or isoforms (p33, p26, p25, p23, and p19, based on their molecular mass) that differ only in their N-terminal sequences. UL136 isoforms accumulate at later times relative to UL135 and UL138 in productive infection, requiring the onset of HCMV genome synthesis for maximum expression. Some UL136 isoforms are required for reactivation (p33 and p26 isoforms), while others function in latency (p23 and 19 isoforms). However, nothing is known about the mechanism by which UL136 isoforms function or their interplay with other UL133-UL138 proteins to regulate latency and reactivation. Intriguingly, the full-length, membrane-bound isoform of UL136 (p33) is unstable and targeted for rapid turnover (t1/2≤1h), whereas other UL136 isoforms are stable (t1/2>6h). Stabilization of p33 by specific mutation results in a virus that cannot maintain latency and replicates, indicating that its rapid turnover is critical for maintenance of latency. From these findings, we hypothesize that the UL136 isoforms modulate the UL135/UL138 switch to reinforce decisions to stably maintain or exit latency. We propose 3 aims to address this hypothesis. Aim 1 will determine how UL136 p33 is targeted for rapid turnover and the significance of its destabilization to the decision to maintain latency or to reactivate. Aim 2 will define epistatic interplay between the UL136 isoforms and with other UL133-UL138 proteins to modulate latency and reactivation. Aim 3 will identify UL136-host interacting partners to define the mechanisms by which UL136 modulates the switch between latency and reactivation. Our work reveals new directions in HCMV latency- specifically, distinct roles for each UL136 isoform in modulating decisions to maintain the latent infection (UL138-dominant) or to reactivate (UL135-dominant). Understanding the mechanisms by which UL136 isoforms modulate the tipping point between latency and reactivation will expand the mechanistic paradigms surrounding herpesvirus latency and reactivation.

项目概要 人类巨细胞病毒 (HCMV) 是一种 β-疱疹病毒，可在宿主体内建立终生潜伏感染。 潜伏期的重新激活可能会导致免疫缺陷个体患上危及生命的疾病，特别是 干细胞和实体器官移植受者。我们的研究计划长期致力于定义 HCMV 决定因素和宿主相互作用是潜伏和重新激活的机制核心。在之前的 在资助期间，我们在 HCMV 基因组的 ULb' 区域内定义了一个多顺反子位点，该位点跨越 基因 UL133-UL138。在该区域内，我们已经确定了病毒编码的病毒抑制子和激活子 复制。 UL138 抑制复制以产生延迟，而 UL135 则激活复制以重新激活， 部分，通过克服 UL138 的压制作用。 UL135 和 UL138 调节 EGFR，具有相反的作用 并共同构成一个开关，通过调节宿主信号传导来控制病毒潜伏期和重新激活。最近， UL136 已成为该开关的关键调制器。 UL136 编码 5 种替代蛋白质形式或亚型 （p33、p26、p25、p23 和 p19，基于其分子量）仅在 N 端序列上有所不同。 相对于 UL135 和 UL138，UL136 同种型在生产性感染中的积累时间较晚，因此需要 HCMV 基因组合成开始以达到最大表达。需要一些 UL136 同工型 重新激活（p33 和 p26 亚型），而其他亚型则在潜伏期发挥作用（p23 和 19 亚型）。然而，什么也没有 已知 UL136 同工型发挥作用的机制或其与其他 UL133-UL138 的相互作用 调节潜伏期和重新激活的蛋白质。有趣的是，UL136 的全长膜结合亚型 (p33) 不稳定，目标是快速周转 (t1/2≤1h)，而其他 UL136 亚型是稳定的 (t1/2>6h)。 通过特定突变使 p33 稳定，导致病毒无法维持潜伏期和复制，这表明 其快速周转对于维持延迟至关重要。根据这些发现，我们假设 UL136 同工型调节 UL135/UL138 开关，以强化稳定维持或退出延迟的决策。我们 提案3旨在解决这一假设。目标 1 将确定如何针对 UL136 p33 进行快速周转 以及其不稳定对于维持潜伏或重新激活的决定的重要性。目标 2 将定义 UL136 异构体与其他 UL133-UL138 蛋白之间的上位相互作用可调节潜伏期和 重新激活。目标 3 将确定 UL136 主机交互伙伴，以定义 UL136 的机制 调节延迟和重新激活之间的切换。我们的工作揭示了 HCMV 潜伏期的新方向 - 具体来说，每种 UL136 同工型在调节维持潜伏感染的决策中发挥着不同的作用 （UL138-主导）或重新激活（UL135-主导）。了解 UL136 的机制 同工型调节潜伏期和重新激活之间的临界点将扩展机械范式 周围疱疹病毒潜伏期和重新激活。