Translational control of gene expression during poxvirus infection

在翻译水平上的基因表达的转录后调节是空间和生物学的核心。 在许多生物学背景下，包括病毒感染，蛋白质生产的时间控制。真核 翻译起始因子（eIF）4F，其将核糖体桥接至mRNA的5'甲基化帽， 提供解旋酶活性以促进核糖体扫描，在调节帽依赖性 翻译起始并被多种病毒靶向。事实上，由于它们对宿主的绝对依赖 翻译系统和相对容易的基因操作，病毒系统有 在发现和解剖基本生物过程中被证明是非常宝贵的，并定义了许多 在感染和未感染细胞中均起作用的翻译控制范例。然而，仍有许多工作要做， 了解参与调节翻译起始的机制，特别是如何选择性和 mRNA的翻译受到控制。牛痘病毒（VacV）是痘病毒大家族的成员， 双链DNA病毒，只在膜内感染细胞的细胞质中复制， 被称为复制区室或病毒工厂的结合结构。在本提案中，我们的目标是利用 VacV的区室化复制，其mRNA与其宿主相似地被加帽和聚腺苷酸化 研究翻译因子激活和再分布的机制，以及它们对病毒感染的影响。 和宿主蛋白质合成。最近，我们已经证明VacV激活PI 3 K-Akt-mTOR信号传导， 抑制翻译阻遏蛋白并增强宿主eIF 4F复合物的形成。这是 伴随着eIF 4F的核心组分重新分布到病毒工厂内的离散区域， 病毒蛋白质的合成被认为发生。我们的初步数据已经确定了一种病毒蛋白，I3， eIF 4F支架蛋白eIF 4G和这两种因子共定位在病毒的相同区域内， 工厂虽然VacV诱导宿主蛋白质合成的全面抑制，我们的初步多核糖体， 分析表明，某些宿主mRNA的翻译不仅持续存在，而且在选择的情况下增加。我们 建议表征I3在调节eIF 4F分布和局部蛋白质合成中的作用， 筛选参与mTOR激活的其他病毒因子。此外，我们建议确定以下方面的作用： eIF 4F在某些宿主mRNA亚群的持续合成中的作用，补充了我们对eIF 4F的研究 再分配和激活的上游信号通路，以提供一个全面的分析的作用， 这种帽结合复合物在痘病毒感染期间选择性宿主和病毒mRNA翻译中起作用。总的来说，这些 aims不仅将为痘病毒的复制提供重要的见解，而且还将有助于我们 更广泛地理解局部和选择性mRNA翻译控制的一般机制。

Post-transcriptional regulation of gene expression at the level of translation is central to the spatial and temporal control of protein production in many biological contexts, including viral infection. The eukaryotic translation initiation factor (eIF) 4F, which bridges the ribosome to the 5' methylated cap of the mRNA and provides helicase activity to facilitate ribosome scanning, plays a pivotal role in regulating cap-dependent translation initiation and is targeted by diverse viruses. Indeed, with their absolute dependence on their host translation system and the relative ease with which they can be genetically manipulated, viral systems have proven invaluable in the discovery and dissection of basic biological processes and have defined many translational control paradigms that operate in both infected and uninfected cells. However, much remains to be learned about the mechanisms involved in regulating translation initiation, in particular how selective and localized mRNA translation is controled. Vaccinia Virus (VacV) is a member of the poxvirus family of large, double stranded DNA viruses that replicate exclusively in the cytoplasm of infected cells within membrane- bound structures termed replication compartments or viral factories. In this proposal we aim to exploit the compartmentalized replication of VacV, whose mRNAs are capped and polyadenylated similar to their host counterparts, to study mechanisms of translation factor activation and redistribution, and their effects on viral and host protein synthesis. Recently, we have shown that VacV activates PI3K-Akt-mTOR signaling to inactivate translational repressor proteins and enhance the formation of host eIF4F complexes. This is accompanied by a redistribution of core components of eIF4F to discrete regions within viral factories where synthesis of viral proteins is thought to occur. Our preliminary data has identified a viral protein, I3 that binds the eIF4F scaffold protein, eIF4G, and both of these factors colocalize within the same regions of viral factories. Although VacV induces global suppression of host protein synthesis, our preliminary polysome profiling shows that translation of certain host mRNAs not only persists but, in select cases, is increased. We propose to characterize the role of I3 in regulating both eIF4F distribution and localized protein synthesis, and screen for additional viral factors involved in mTOR activation. In addition, we propose to determine the role of eIF4F in the continued synthesis of certain subset of host mRNAs, complementing our studies of eIF4F redistribution and activation by upstream signaling pathways to provide a comprehensive analysis of the role of this cap-binding complex in selective host and viral mRNA translation during poxvirus infection. Overall, these aims will not only provide important insights into the replication of poxviruses, but will also contribute to our broader understanding of general mechanisms of localized and selective mRNA translational control.