PDF(Pubmed)
Abstract：
Herpesviral infection reflects thousands of years of coevolution and the constant struggle between virus and host for control of cellular gene expression. During Kaposi\'s sarcoma-associated herpesvirus (KSHV) lytic replication, the virus rapidly seizes control of host gene expression machinery by triggering a massive RNA decay event via a virally encoded endoribonuclease, SOX. This virus takeover strategy decimates close to 80% of cellular transcripts, reallocating host resources toward viral replication. The host cell, however, is not entirely passive in this assault on RNA stability. A small pool of host transcripts that actively evade SOX cleavage has been identified over the years. One such \"escapee,\" C19ORF66 (herein referred to as Shiftless [SHFL]), encodes a potent antiviral protein capable of restricting the replication of multiple DNA and RNA viruses and retroviruses, including KSHV. Here, we show that SHFL restricts KSHV replication by targeting the expression of critical viral early genes, including the master transactivator protein, KSHV ORF50, and thus subsequently the entire lytic gene cascade. Consistent with previous reports, we found that the SHFL interactome throughout KSHV infection is dominated by RNA-binding proteins that influence both translation and protein stability, including the viral protein ORF57, a crucial regulator of viral RNA fate. We next show that SHFL affects cytoplasmic RNA granule formation, triggering the disassembly of processing bodies. Taken together, our findings provide insights into the complex relationship between RNA stability, RNA granule formation, and the antiviral response to KSHV infection. IMPORTANCE In the past 5 years, SHFL has emerged as a novel and integral piece of the innate immune response to viral infection. SHFL has been reported to restrict the replication of multiple viruses, including several flaviviruses and the retrovirus HIV-1. However, to date, the mechanism(s) by which SHFL restricts DNA virus infection remains largely unknown. We have previously shown that following its escape from KSHV-induced RNA decay, SHFL acts as a potent antiviral factor, restricting nearly every stage of KSHV lytic replication. In this study, we set out to determine the mechanism by which SHFL restricts KSHV infection. We demonstrate that SHFL impacts all classes of KSHV genes and found that SHFL restricts the expression of several key early genes, including KSHV ORF50 and ORF57. We then mapped the interactome of SHFL during KSHV infection and found several host and viral RNA-binding proteins that all play crucial roles in regulating RNA stability and translation. Lastly, we found that SHFL expression influences RNA granule formation both outside and within the context of KSHV infection, highlighting its broader impact on global gene expression. Collectively, our findings highlight a novel relationship between a critical piece of the antiviral response to KSHV infection and the regulation of RNA-protein dynamics.
摘要：
疱疹病毒感染反映了数千年的共同进化以及病毒与宿主之间为控制细胞基因表达而不断的斗争。在卡波西肉瘤相关疱疹病毒（KSHV）裂解复制过程中，该病毒通过病毒编码的核糖核酸内切酶触发大量RNA衰变事件，从而迅速控制宿主基因表达机制，SOX.这种病毒接管策略摧毁了近80%的细胞转录本，将宿主资源重新分配给病毒复制。宿主细胞，然而,在这种对RNA稳定性的攻击中并不完全被动。多年来，已经发现了一小部分积极逃避SOX裂解的宿主转录本。一个这样的“逃犯”，\"C19ORF66(在此称为无袖[SHFL])，编码一种有效的抗病毒蛋白，能够限制多种DNA和RNA病毒以及逆转录病毒的复制，包括KSHV。这里,我们表明，SHFL通过靶向关键病毒早期基因的表达来限制KSHV复制，包括主反式激活蛋白，KSHVORF50，因此随后整个裂解基因级联。与以前的报告一致，我们发现，在整个KSHV感染过程中，SHFL相互作用组由RNA结合蛋白主导，这些蛋白会影响翻译和蛋白质稳定性，包括病毒蛋白ORF57，病毒RNA命运的关键调节因子。我们接下来显示SHFL影响细胞质RNA颗粒的形成，触发加工机构的拆卸。一起来看,我们的发现提供了对RNA稳定性之间复杂关系的见解，RNA颗粒形成，以及对KSHV感染的抗病毒反应。重要性在过去的5年里，SHFL已成为对病毒感染的先天免疫反应的新颖且不可或缺的部分。据报道，SHFL可以限制多种病毒的复制，包括几种黄病毒和逆转录病毒HIV-1。然而,到目前为止,SHFL限制DNA病毒感染的机制在很大程度上仍然未知.我们之前已经表明，在它从KSHV诱导的RNA衰变中逃脱后，SHFL作为一个有效的抗病毒因子，限制KSHV裂解复制的几乎每个阶段。在这项研究中,我们着手确定SHFL限制KSHV感染的机制.我们证明了SHFL影响所有类型的KSHV基因，并发现SHFL限制了几个关键的早期基因的表达。包括KSHVORF50和ORF57。然后，我们在KSHV感染期间绘制了SHFL的相互作用组，并发现了几种宿主和病毒RNA结合蛋白，它们都在调节RNA稳定性和翻译中起着至关重要的作用。最后,我们发现SHFL表达在KSHV感染的外部和内部都会影响RNA颗粒的形成，强调其对全球基因表达的更广泛影响。总的来说，我们的研究结果强调了KSHV感染抗病毒反应的一个关键部分与RNA-蛋白质动力学调节之间的新关系.
