The herpes simplex virus host shutoff (vhs) RNase limits accumulation of double stranded RNA in infected cells: Evidence for accelerated decay of duplex RNA
The herpes simplex virus host shutoff (vhs) RNase limits accumulation of double stranded RNA in infected cells: Evidence for accelerated decay of duplex RNA
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DOI：
10.1371/journal.ppat.1008111
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发表时间：
2019-10-01
期刊：
影响因子：
6.7
通讯作者：
Smiley, James R.
中科院分区：
文献类型：
--
作者：
Dauber, Bianca;Saffran, Holly A.;Smiley, James R.
单纯疱疹病毒病毒体宿主关闭（vhs）RNA酶使细胞和病毒mRNA不稳定并钝化宿主先天性抗病毒应答。先前的工作表明，vhs突变体感染的细胞显示宿主双链RNA（dsRNA）激活的蛋白激酶R（PKR）的激活增强，这意味着vhs限制了dsRNA在感染细胞中的积累。证实了这一假设，我们表明，部分互补的转录本的UL 23/UL 24和UL 30/31区域的病毒基因组的丰度增加时，vhs被灭活，从而导致大大增加的水平的细胞内dsRNA形成的退火重叠部分的这些RNA。因此，vhs至少部分地通过降低互补病毒转录物的水平来限制dsRNA的积累。然后，我们询问vhs是否也在其初始形成后使dsRNA不稳定。在此，我们使用了报告系统，该报告系统采用两个带有互补3'UTR的mCherry表达质粒，以在未感染的细胞中产生限定的dsRNA种类。dsRNA是不稳定的，但通过共表达HSV dsRNA结合蛋白US 11而显著稳定。引人注目的是，在存在和不存在US 11的情况下，由超感染HSV病毒体递送的vhs加速了这些预先形成的dsRNA的衰变，US 11是vhs的一种新的和未预料到的活性。Vhs结合宿主RNA解旋酶eIF 4A，我们发现vhs诱导的dsRNA衰变被eIF 4A抑制剂马尿酸减弱，提供了eIF 4A参与该过程的证据。我们的研究结果表明，疱疹病毒宿主关闭RNase不稳定的双链RNA，除了针对部分互补的病毒mRNA，提高的可能性，mRNA不稳定蛋白质的其他病毒病原体抑制宿主响应dsRNA通过类似mechanism.Author摘要基本上所有的病毒产生双链RNA（dsRNA）在感染过程中。因此，宿主生物体部署各种dsRNA受体以触发先天性抗病毒防御。毫不奇怪，病毒反过来产生一系列拮抗剂来阻断这种宿主反应。最佳表征的病毒拮抗剂通过结合并掩蔽dsRNA和/或阻断下游信号传导事件来起作用。其他研究较少的病毒拮抗剂似乎通过降低受感染细胞中dsRNA的水平来发挥作用，但它们究竟是如何发挥作用的仍然未知。在这里，我们表明，这样的病毒拮抗剂，单纯疱疹病毒vhs核糖核酸酶，减少dsRNA水平在两个不同的方式。首先，如前所述，它抑制了部分互补病毒mRNA的积累，降低了产生dsRNA的可能性。其次，它有助于在dsRNA形成后去除dsRNA，这是一种新颖且令人惊讶的蛋白质活性，其最为人所知的是其对单链mRNA的活性。许多其他病毒病原体产生靶向mRNA的蛋白质以快速破坏，并且确定这些蛋白质是否也以类似的方式限制宿主dsRNA反应将是重要的。
The herpes simplex virus virion host shutoff (vhs) RNase destabilizes cellular and viral mRNAs and blunts host innate antiviral responses. Previous work demonstrated that cells infected with vhs mutants display enhanced activation of the host double-stranded RNA (dsRNA)-activated protein kinase R (PKR), implying that vhs limits dsRNA accumulation in infected cells. Confirming this hypothesis, we show that partially complementary transcripts of the UL23/UL24 and UL30/31 regions of the viral genome increase in abundance when vhs is inactivated, giving rise to greatly increased levels of intracellular dsRNA formed by annealing of the overlapping portions of these RNAs. Thus, vhs limits accumulation of dsRNA at least in part by reducing the levels of complementary viral transcripts. We then asked if vhs also destabilizes dsRNA after its initial formation. Here, we used a reporter system employing two mCherry expression plasmids bearing complementary 3' UTRs to produce defined dsRNA species in uninfected cells. The dsRNAs are unstable, but are markedly stabilized by co-expressing the HSV dsRNA-binding protein US11. Strikingly, vhs delivered by super-infecting HSV virions accelerates the decay of these pre-formed dsRNAs in both the presence and absence of US11, a novel and unanticipated activity of vhs. Vhs binds the host RNA helicase eIF4A, and we find that vhs-induced dsRNA decay is attenuated by the eIF4A inhibitor hippuristanol, providing evidence that eIF4A participates in the process. Our results show that a herpesvirus host shutoff RNase destabilizes dsRNA in addition to targeting partially complementary viral mRNAs, raising the possibility that the mRNA destabilizing proteins of other viral pathogens dampen the host response to dsRNA through similar mechanisms.Author summary Essentially all viruses produce double-stranded RNA (dsRNA) during infection. Host organisms therefore deploy a variety of dsRNA receptors to trigger innate antiviral defenses. Not surprisingly, viruses in turn produce an array of antagonists to block this host response. The best characterized of the viral antagonists function by binding to and masking dsRNA and/or blocking downstream signaling events. Other less studied viral antagonists appear to function by reducing the levels of dsRNA in infected cells, but exactly how they do so remains unknown. Here we show that one such viral antagonist, the herpes simplex virus vhs ribonuclease, reduces dsRNA levels in two distinct ways. First, as previously suggested, it dampens the accumulation of partially complementary viral mRNAs, reducing the potential for generating dsRNA. Second, it helps remove dsRNA after its formation, a novel and surprising activity of a protein best known for its activity on single-stranded mRNA. Many other viral pathogens produce proteins that target mRNAs for rapid destruction, and it will be important to determine if these also limit host dsRNA responses in similar ways.