Disruption of Cellular Messenger RNA Processing Events by the Kaposi's Sarcoma-As

卡波西肉瘤对细胞信使 RNA 加工事件的破坏

• 批准号: 7929210
• 负责人: Britt A Glaunsinger
• 金额: $ 29.68万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-12 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7929210
• 关键词: AIDS related neoplasm; Acquired Immunodeficiency Syndrome; B-Lymphocytes; Cancer Etiology; Cell Culture Techniques; Cell Nucleus; Cell physiology; Cells; Common Neoplasm; Cytoplasm; Data; Degradation Pathway; Disease; Event; Gene Expression; Gene Expression Profile; Herpesviridae; Herpesviridae Infections; Human; Human Herpesvirus 8; Human Virus; Individual; Kaposi Sarcoma; Knowledge; Link; Lymphoproliferative Disorders; Lytic; Mediating; Messenger RNA; Modeling; Monitor; Mus; Nuclear; Pathogenesis; Pathway interactions; Patients; Phenotype; Play; Poly(A)-Binding Proteins; Polyadenylation; Proteins; Quality Control; RNA; RNA Decay; RNA Degradation; RNA Processing; RNA Stability; Research; Role; Time; Translating; Translations; Viral; Viral Proteins; Virus; Work; human disease; lytic replication; novel; protein function; public health relevance; tool

DESCRIPTION (provided by applicant): Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of the most common neoplasm in untreated AIDS patients, and is also affiliated with two B cell lymphoproliferative disorders. The lytic viral replication cycle has previously been shown to be an essential component of KSHV-induced pathogenesis. One prominent consequence of lytic KSHV infection is a near total destruction of the cellular transcriptome, termed 'host shutoff'. This phenotype is mediated by the viral SOX protein which promotes enhanced cellular messenger RNA (mRNA) degradation, likely via interception of cellular RNA stability pathways. We have identified 2 novel SOX activities linked to host shutoff: SOX induces nuclear re-localization of cytoplasmic poly(A) binding protein (PABPC), and triggers disruption of the 3' end processing of cellular mRNAs in the nucleus leading to their hyperadenylation. PABPC is a cellular protein that plays a key role in mRNA translation and stability in the cytoplasm yet has no known nuclear functions. Thus, we hypothesize that its aberrant localization in SOX-expressing cells is a significant contributor to cytoplasmic mRNA destruction. Within the nucleus, the nascent hyperadenylated cellular mRNAs are not exported, and we predict they are destroyed by cellular quality control mechanisms. Interestingly, we have preliminary data indicating that nuclear PABPC is an important driver of the hyperadenylation phenotype. Thus, KSHV appears to target PABPC to eliminate both nuclear and cytoplasmic cellular messages via distinct mechanisms. This represents a completely novel mechanism of virus-induced termination of host gene expression and, additionally, reveals for the first time in human cells a mechanism for polyadenylation-stimulated mRNA decay and a role for PABPC in the nucleus. Emerging connections between disruption of normal cellular RNA turnover pathways and human disease have highlighted the importance of understanding mechanisms by which such events become deregulated; it is in this regard that KSHV SOX represents an excellent tool to probe how pathogenic human viruses may interface with these critical cellular pathways. This proposal will explore the connections between SOX-induced PABPC import and mRNA hyperadenylation, as well as explore the contribution of cellular quality control pathways towards the ultimate destruction of these messages. Specifically, we will begin by confirming that nuclear PABPC drives hyperadenylation then proceed to dissect the mechanisms by which this occurs. PABPC is a key antagonist of the nonsense-mediated mRNA decay pathway in the cytoplasm, and we will therefore explore the potential aberrant activation of this and other quality control pathways during KSHV infection. Finally, we will monitor the contribution of host shutoff towards viral replication and pathogenesis both in cell culture and in murine models. PUBLIC HEALTH RELEVANCE: Viruses not only cause disease, but are also superb tools to probe the inner workings of our own cells. We investigate how a cancer causing human herpesvirus destroys cellular messages to enhance its own replication, as this information will provide important clues both into how this virus thrives in infected individuals and also how cellular gene expression is regulated.

描述（由申请人提供）：卡波西肉瘤相关疱疹病毒（KSHV）是未经治疗的艾滋病患者中最常见肿瘤的病原体，并且还与两种B细胞淋巴增殖性疾病有关。先前已证明裂解病毒复制周期是 KSHV 诱导的发病机制的重要组成部分。裂解性 KSHV 感染的一个显着后果是细胞转录组几乎完全被破坏，称为“宿主关闭”。这种表型由病毒 SOX 蛋白介导，该蛋白可能通过拦截细胞 RNA 稳定性途径促进细胞信使 RNA (mRNA) 降解。我们已经确定了 2 种与宿主关闭相关的新型 SOX 活性：SOX 诱导细胞质多聚腺苷酸结合蛋白 (PABPC) 的核重新定位，并触发细胞核中细胞 mRNA 3' 端加工的破坏，导致其高腺苷酸化。 PABPC 是一种细胞蛋白，在 mRNA 翻译和细胞质稳定性中发挥关键作用，但没有已知的核功能。因此，我们推测其在表达 SOX 的细胞中的异常定位是细胞质 mRNA 破坏的重要原因。在细胞核内，新生的高腺苷酸化细胞 mRNA 不会被输出，我们预测它们会被细胞质量控制机制破坏。有趣的是，我们的初步数据表明核 PABPC 是高腺苷酸化表型的重要驱动因素。因此，KSHV 似乎以 PABPC 为目标，通过不同的机制消除细胞核和细胞质的细胞信息。这代表了病毒诱导宿主基因表达终止的全新机制，此外，首次在人类细胞中揭示了多聚腺苷酸化刺激的 mRNA 衰减机制以及 PABPC 在细胞核中的作用。正常细胞 RNA 周转途径的破坏与人类疾病之间的新联系凸显了了解此类事件放松管制机制的重要性；正是在这方面，KSHV SOX 是一个很好的工具，可以用来探究人类致病病毒如何与这些关键的细胞途径相互作用。该提案将探讨 SOX 诱导的 PABPC 输入与 mRNA 腺苷酸过多之间的联系，并探讨细胞质量控制途径对最终破坏这些信息的贡献。具体来说，我们将首先确认核 PABPC 驱动高腺苷酸化，然后继续剖析发生这种情况的机制。 PABPC 是细胞质中无义介导的 mRNA 衰减途径的关键拮抗剂，因此我们将探讨 KSHV 感染期间该途径和其他质量控制途径的潜在异常激活。最后，我们将在细胞培养和小鼠模型中监测宿主关闭对病毒复制和发病机制的贡献。 公共卫生相关性：病毒不仅会引起疾病，而且还是探索我们自身细胞内部运作的极好工具。我们研究导致癌症的人类疱疹病毒如何破坏细胞信息以增强其自身复制，因为这些信息将为了解该病毒如何在感染个体中繁殖以及细胞基因表达如何受到调节提供重要线索。