Alphavirus-induced transcriptional and translational shutoffs play major roles in blocking the formation of stress granules.
Alphavirus-induced transcriptional and translational shutoffs play major roles in blocking the formation of stress granules.
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甲病毒诱导的转录和翻译关闭在阻止应激颗粒的形成中发挥着重要作用。
DOI：
10.1101/2023.07.05.547824
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Frolov,Ilya
中科院分区：
文献类型：
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作者：
Palchevska,Oksana;Dominguez,Francisco;Frolova,ElenaI;Frolov,Ilya
甲病毒感染引起细胞内环境的多种改变，这些改变可以对病毒复制产生积极和消极的影响。旧世界甲病毒，如辛德毕斯病毒（SINV）、基孔肯雅病毒（CHIKV）和塞姆利基森林病毒，阻碍脊椎动物细胞形成应激颗粒（SG）的能力。以前，这种抑制功能归因于nsP3的高变结构域（HVD），其隔离关键SG组分G3BP1和G3BP2，以及nsP3宏结构域。该大结构域具有ADP-核糖基水解酶活性，可在病毒复制过程中减少G3BP1的ADP-核糖基化。然而，我们最近的研究结果并不支持流行的观念。我们证明，SINV或CHIKV特异性nsP3和G3BP之间的相互作用，以及ADP-核糖基水解酶活性不是抑制过程的主要贡献者，至少当nsP3在生物学相关水平表达时。相反，负责抑制SG形成的主要因素是病毒诱导的转录和翻译关闭，其在感染后的最初几个小时内迅速发展。携带突变的nsP3 HVD的复制不良的SINV变体即使在亚砷酸钠（NaAs）存在下也仍然抑制SG发育。相反，缺乏转录和/或翻译抑制功能的SINV突变体失去其抑制SG形成的能力，尽管表达高水平的wt nsP3。此外，我们发现表达GFP-nsP3融合体的稳定细胞系在暴露于NaAs时保留形成SG的能力。然而，我们的研究结果并不排除的可能性，即额外的甲病毒诱导的细胞生物学的变化可能有助于抑制SG的形成。IMPORTANCEOur研究突出了背后的机制，细胞的抗应激颗粒（SG）的形成后，感染旧世界甲病毒。感染后不久，这些病毒的复制会阻碍细胞形成SG的能力，即使暴露于亚砷酸钠等化学诱导剂也是如此。这种抗性主要归因于病毒诱导的转录和翻译关闭，而不是病毒nsP3与SGs的关键组分G3BP 1/2之间的相互作用或nsP3宏结构域的ADP-核糖基水解酶活性。虽然G3BPs和nsP3之间的相互作用对于病毒复制复合物的形成是必不可少的，但它们在调节SG发育中的作用似乎很小（如果有的话）。携带具有较低抑制转录和/或翻译能力的复制病毒或复制子但表达野生型nsP3的细胞保留SG发育的能力。了解SG形成的这些调节机制有助于我们了解病毒复制以及甲病毒与宿主细胞之间的复杂关系。
Alphavirus infections cause multiple alterations in the intracellular environment that can have both positive and negative effects on viral replication. The Old World alphaviruses, such as Sindbis (SINV), chikungunya (CHIKV), and Semliki Forest viruses, hinder the ability of vertebrate cells to form stress granules (SGs). Previously, this inhibitory function was attributed to the hypervariable domain (HVD) of nsP3, which sequesters the key SG components, G3BP1 and G3BP2, and to the nsP3 macro domain. The macro domain possesses ADP-ribosylhydrolase activity, which can diminish the ADP-ribosylation of G3BP1 during viral replication. However, our recent findings do not support the prevailing notions. We demonstrate that the interactions between SINV- or CHIKV-specific nsP3s and G3BPs, and the ADP-ribosylhydrolase activity are not major contributors to the inhibitory process, at least when nsP3 is expressed at biologically relevant levels. Instead, the primary factors responsible for suppressing SG formation are virus-induced transcriptional and translational shutoffs that rapidly develop within the first few hours post infection. Poorly replicating SINV variants carrying mutated nsP3 HVD still inhibit SG development even in the presence of sodium arsenite (NaAs). Conversely, SINV mutants lacking transcription and/or translation inhibitory functions lose their ability to inhibit SG formation, despite expressing high levels of wt nsP3. Moreover, we found that stable cell lines expressing GFP-nsP3 fusions retain the capacity to form SGs when exposed to NaAs. However, our results do not rule out the possibility that additional alphavirus-induced changes in cell biology may contribute to the suppression of SG formation.IMPORTANCEOur study highlights the mechanisms behind the cell’s resistance to stress granule (SG) formation after infection with Old World alphaviruses. Shortly after infection, the replication of these viruses hinders the cell’s ability to form SGs, even when exposed to chemical inducers such as sodium arsenite. This resistance is primarily attributed to virus-induced transcriptional and translational shutoffs, rather than interactions between the viral nsP3 and the key components of SGs, G3BP1/2, or the ADP-ribosylhydrolase activity of nsP3 macro domain. While interactions between G3BPs and nsP3 are essential for the formation of viral replication complexes, their role in regulating SG development appears to be small, if any. Cells harboring replicating viruses or replicons with lower abilities to inhibit transcription and/or translation, but expressing wild-type nsP3, retain the ability for SG development. Understanding these mechanisms of regulation of SG formation contributes to our knowledge of viral replication and the intricate relationships between alphaviruses and host cells.