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。它在非洲许多地区流行，由于艾滋病毒感染率极高， 由于负担过重，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- 诱导的免疫抑制，KSHV的复制不再有效控制，并且，连同 大量潜伏感染的细胞群，有助于疾病进展。在裂解复制期间， KSHV和密切相关的模型鼠γ疱疹病毒MHV 68显著重塑宿主 基因表达环境这种重塑的关键是它的病毒编码，信使RNA（mRNA） 一种称为SOX的特异性内切核酸酶，其加速广谱mRNA的降解。Sox 活性在体内γ疱疹病毒的生命周期和免疫逃避中起着不同的作用。但 SOX的RNA靶向特异性的潜在机制在很大程度上仍然未知，尽管它们 在感染期间形成mRNA丰度谱中的突出作用。我们的数据显示，SOX使用 RNA序列和结构的组合，以捕获广泛的mRNA靶点，同时保留 选择性在目标1中，我们将探索SOX和组分之间的新型蛋白质-蛋白质相互作用 RNA加工机制的改变影响mRNA对核酸内切酶靶向的敏感性， 一系列细胞类型。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” 表达景观。在目标2中，我们将从机械上描述我们在 哺乳动物细胞，在功能上将mRNA生命周期的最后阶段（降解）与第一阶段联系起来， 转录（Transcription）这种mRNA衰变-转录“反馈”途径被SOX激活， 在大规模减少RNA聚合酶II占用选择性地跨越哺乳动物，但不是 病毒基因组从这项建议得出的结论应在以下领域产生持续的影响： 伽玛疱疹病毒生物学，并改变目前的看法，如何压力或病毒引起的变化， mRNA的稳定性影响基因调控回路中看似远端的成分。

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.