Multiple Posttranscriptional Strategies To Regulate the Herpes Simplex Virus 1 vhs Endoribonuclease.
Multiple Posttranscriptional Strategies To Regulate the Herpes Simplex Virus 1 vhs Endoribonuclease.
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DOI：
10.1128/jvi.00818-18
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发表时间：
2018-09-01
影响因子：
5.4
通讯作者：
Jones J
中科院分区：
文献类型：
--
作者：
Elliott G;Pheasant K;Ebert-Keel K;Stylianou J;Franklyn A;Jones J
通过对病毒进行的研究，已经发现了无数的基因表达策略。这份报告涉及的HSV-1的VHS核糖核酸内切酶，病毒因子，这是重要的抵消主机的抗病毒反应，通过降解他们的mRNA，但必须在感染过程中进行调节，以确保它不采取行动反对和抑制病毒本身的调节。我们表明，调控VHS涉及多方面的转录后细胞和病毒过程，包括异常的mRNA定位和一个新的，自动调节的负反馈环，以针对其自身的和共表达的mRNA的核保留，一个活动，这是缓解了共表达的两个其他病毒蛋白，VP 22和VP 16。这些研究揭示了多种病毒编码因子在需要时协调基因表达的策略的相互作用。这些发现与病毒和细胞基因表达广泛相关。单纯疱疹病毒1型（HSV-1）病毒体宿主关闭（vhs）蛋白是一种核糖核酸内切酶，可与细胞翻译起始机制结合并降解相关mRNA，导致宿主蛋白质合成关闭。因此，其不受限制的活性被认为是致命的，并且已经提出vhs由另外两种病毒蛋白VP 22和VP 16调节。我们已经发现，在感染过程中，vhs的翻译需要VP 22，而不是VP 22-VP 16复合物。此外，在没有VP 22的情况下，vhs对细胞或病毒转录物没有过度活性。在转染的细胞中，vhs的翻译也很差，这与其mRNA的异常定位有关。与直觉相反，在检测到vhs蛋白的细胞中，vhs mRNA主要在细胞核中。同样地，来自共转染质粒的转录物也保留在vhs mRNA所在的相同细胞核中，而多聚腺苷酸结合蛋白（PABP）以vhs依赖性方式重新定位于细胞核，这意味着对mRNA输出的一般阻断。VP 16和VP 22的共表达拯救了vhs mRNA的胞质定位，但未能拯救vhs翻译。我们在vhs的5′端区域发现了一个230个核苷酸的序列，该序列阻断了vhs的翻译，当转移到异源绿色荧光蛋白转录物上时，减少了翻译而不改变mRNA水平或定位。我们认为，vhs的表达受到固有的不可翻译性和其mRNA的自诱导核滞留的组合的严格调控，这导致了一个负反馈回路，vhs mRNA的核滞留而不是翻译是vhs-VP 16-VP 22复合物的救援目标。重要性通过对病毒的研究发现了无数的基因表达策略。这份报告涉及的HSV-1的VHS核糖核酸内切酶，病毒因子，这是重要的抵消主机的抗病毒反应，通过降解他们的mRNA，但必须在感染过程中进行调节，以确保它不采取行动反对和抑制病毒本身的调节。我们表明，调控VHS涉及多方面的转录后细胞和病毒过程，包括异常的mRNA定位和一个新的，自动调节的负反馈环，以针对其自身的和共表达的mRNA的核保留，一个活动，这是缓解了共表达的两个其他病毒蛋白，VP 22和VP 16。这些研究揭示了多种病毒编码因子在需要时协调基因表达的策略的相互作用。这些发现与病毒和细胞基因表达广泛相关。
A myriad of gene expression strategies has been discovered through studies carried out on viruses. This report concerns the regulation of the HSV-1 vhs endoribonuclease, a virus factor that is important for counteracting host antiviral responses by degrading their mRNAs but that must be regulated during infection to ensure that it does not act against and inhibit the virus itself. We show that regulation of vhs involves multifaceted posttranscriptional cellular and viral processes, including aberrant mRNA localization and a novel, autoregulated negative feedback loop to target its own and coexpressed mRNAs for nuclear retention, an activity that is relieved by coexpression of two other virus proteins, VP22 and VP16. These studies reveal the interplay of strategies by which multiple virus-encoded factors coordinate gene expression at the time that they are needed. These findings are broadly relevant to both virus and cellular gene expression. The herpes simplex virus 1 (HSV-1) virion host shutoff (vhs) protein is an endoribonuclease that binds to the cellular translation initiation machinery and degrades associated mRNAs, resulting in the shutoff of host protein synthesis. Hence, its unrestrained activity is considered lethal, and it has been proposed that vhs is regulated by two other virus proteins, VP22 and VP16. We have found that during infection, translation of vhs requires VP22 but not the VP22-VP16 complex. Moreover, in the absence of VP22, vhs is not overactive against cellular or viral transcripts. In transfected cells, vhs was also poorly translated, correlating with the aberrant localization of its mRNA. Counterintuitively, vhs mRNA was predominantly nuclear in cells where vhs protein was detected. Likewise, transcripts from cotransfected plasmids were also retained in the same nuclei where vhs mRNA was located, while poly(A) binding protein (PABP) was relocalized to the nucleus in a vhs-dependent manner, implying a general block to mRNA export. Coexpression of VP16 and VP22 rescued the cytoplasmic localization of vhs mRNA but failed to rescue vhs translation. We identified a 230-nucleotide sequence in the 5′ region of vhs that blocked its translation and, when transferred to a heterologous green fluorescent protein transcript, reduced translation without altering mRNA levels or localization. We propose that expression of vhs is tightly regulated by a combination of inherent untranslatability and autoinduced nuclear retention of its mRNA that results in a negative feedback loop, with nuclear retention but not translation of vhs mRNA being the target of rescue by the vhs-VP16-VP22 complex. IMPORTANCE A myriad of gene expression strategies has been discovered through studies carried out on viruses. This report concerns the regulation of the HSV-1 vhs endoribonuclease, a virus factor that is important for counteracting host antiviral responses by degrading their mRNAs but that must be regulated during infection to ensure that it does not act against and inhibit the virus itself. We show that regulation of vhs involves multifaceted posttranscriptional cellular and viral processes, including aberrant mRNA localization and a novel, autoregulated negative feedback loop to target its own and coexpressed mRNAs for nuclear retention, an activity that is relieved by coexpression of two other virus proteins, VP22 and VP16. These studies reveal the interplay of strategies by which multiple virus-encoded factors coordinate gene expression at the time that they are needed. These findings are broadly relevant to both virus and cellular gene expression.