Disruption of Cellular RNA Processing by Kaposi's Sarcoma-Associated Herpesvirus

摘要 卡波西肉瘤相关疱疹病毒(KSHV)是大多数艾滋病的病原体- 相关癌症。它是非洲许多地区的地方病，在那里，由于异常高的艾滋病毒 负担，卡波西肉瘤已成为非洲大陆最常见的癌症之一。在艾滋病期间- 诱导免疫抑制，KSHV复制不再得到有效控制，与一种 大量潜伏感染的细胞，有助于疾病的进展。在裂解复制期间， KSHV和密切相关的模型小鼠伽马疱疹病毒MHV68戏剧性地重塑宿主 基因表达环境。这种重塑的关键是其病毒编码的信使核糖核酸(Mrna)。 被称为SOX的特定内切酶，它加速了广泛的mRNAs的降解。SOX 在体内伽马疱疹病毒的生命周期和免疫逃避中，活性扮演着不同的角色。然而， SOX的RNA靶标特异性的潜在机制在很大程度上仍不清楚，尽管它们 在感染过程中塑造信使核糖核酸丰度分布方面的突出作用。我们的数据显示，SOX使用了 结合RNA序列和结构以捕获广泛的mRNA靶标，同时保存 选择性。在目标1中，我们将探索Sox和组件之间新的蛋白质-蛋白质相互作用 RNA加工机制的不同会影响mRNAs对核酸内切酶靶向的敏感性 一系列单元格类型。然后我们将定义SOX靶向mRNA的下游后果， 包括mRNA降解的大规模变化如何对基因产生深刻的“涟漪效应” 表情景观。在目标2中，我们将机械地描述我们在 在功能上将信使核糖核酸生命周期的最后阶段(降解)与第一阶段联系起来的哺乳动物细胞 阶段(转录)。SOX和结果激活了这条mRNA衰减-转录“反馈”途径 在大规模减少RNA聚合酶II选择性地在哺乳动物中占据而不是在 病毒基因组。从这项提案中得出的结论应对以下领域产生持续影响 伽马疱疹病毒生物学，并改变目前对压力或病毒诱导的改变如何改变的看法 信使核糖核酸的稳定性似乎影响了基因调控电路的远端组件。

ABSTRACT Kaposi sarcoma-associated herpesvirus (KSHV) is the etiologic agent of the majority of AIDS- associated cancers. It is endemic in many areas of Africa where, due to the extraordinarily high HIV burden, Kaposi sarcoma has emerged as one of the most common cancers on the continent. During AIDS- induced immunosuppression, KSHV replication is no longer effectively controlled, and, together with a large latently infected population of cells, contributes to disease progression. During lytic replication, KSHV and the closely related model murine gammaherpesvirus MHV68 dramatically remodel the host gene expression environment. Key to this remodeling is its virally encoded, messenger RNA (mRNA) specific endonuclease termed SOX, which accelerates degradation of a broad spectrum of mRNAs. SOX activity plays diverse roles in the in vivo gammaherpesvirus lifecycle and immune evasion. However, the mechanisms underlying the RNA target specificity of SOX remain largely unknown, despite their prominent roles in shaping the mRNA abundance profile during infection. Our data show that SOX uses a combination of RNA sequence and structure to capture a broad set of mRNA targets while preserving selectivity. In Aim 1, we will probe how novel protein-protein interactions between SOX and components of the RNA processing machinery influence the susceptibility of mRNAs to endonuclease targeting across a range of cell types. We will then define the downstream consequences of mRNA targeting by SOX, including how large scale changes to mRNA degradation cause profound ‘ripple effects’ to the gene expression landscape. In Aim 2, we will mechanistically characterize a new pathway we discovered in mammalian cells that functionally links the last stage of the mRNA lifecycle (degradation) to the first stage (transcription). This mRNA decay-transcription “feedback” pathway is activated by SOX and results in a large-scale reduction of RNA polymerase II occupancy selectively across the mammalian but not the viral genome. Findings derived from this proposal should have a sustained impact on the field of gammaherpesvirus biology, and change current perceptions on how stress or virus-induced alterations to mRNA stability influence seemingly distal components of the gene regulation circuitry.