Retinoic Acid Inducible Gene I and Protein Kinase R, but Not Stress Granules, Mediate the Proinflammatory Response to Yellow Fever Virus
Retinoic Acid Inducible Gene I and Protein Kinase R, but Not Stress Granules, Mediate the Proinflammatory Response to Yellow Fever Virus
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DOI：
10.1128/jvi.00403-20
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发表时间：
2020-11-01
影响因子：
5.4
通讯作者：
Jouvenet, Nolwenn
中科院分区：
文献类型：
--
作者：
Beauclair, Guillaume;Streicher, Felix;Jouvenet, Nolwenn
黄热病病毒（YFV）是一种主要靶向肝脏的RNA病毒。严重的YF病例是出血热的原因，可能是过度的促炎细胞因子反应所致。已知病原体识别受体（PRR），如细胞质视黄酸诱导基因I（RIG-I）样受体（RLR）和病毒RNA传感器蛋白激酶R（PKR），在识别病毒基因组时启动促炎反应。在这里，我们试图揭示的主要决定因素，负责急性细胞因子的表达发生在人肝细胞后YFV感染。使用RIG-I缺陷的人肝癌细胞系，我们发现RIG-I在很大程度上有助于YFV感染后的细胞因子分泌。在感染的RIG-I-精通肝癌细胞，RIG-I被定位在应激颗粒。这些颗粒是已知的聚集RLR和PKR的停滞翻译前起始复合物的大聚集体，并且迄今为止被认为是协调RNA病毒感测的枢纽。PKR在肝癌细胞中的稳定敲低揭示PKR有助于YFV感染后的应激颗粒形成和细胞因子诱导。然而，应力颗粒破坏并不影响细胞因子对YFV感染的反应，如通过小干扰RNA（siRNA）敲低介导的应力颗粒组装的抑制所评估的。最后，没有检测到病毒RNA的压力颗粒，荧光原位杂交方法结合免疫荧光。我们的研究结果表明，RIG-I和PKR介导的促炎细胞因子诱导YFV感染的肝细胞，在一个应力颗粒独立的方式。因此，通过显示解偶联的应激颗粒形成的细胞因子反应，我们的模型挑战目前的观点，其中的应激颗粒是需要安装的急性抗病毒respons.IMPORTANCE黄热病是一种蚊媒急性出血性疾病引起的黄热病病毒（YFV）。其发病机制在很大程度上仍然未知，尽管炎症增加与预后恶化有关。YFV靶向肝脏，主要感染肝细胞。我们发现两种RNA敏感蛋白RIG-I和PKR参与了感染YFV的人肝细胞中促炎介质的诱导。我们发现，YFV感染促进细胞质结构的形成，称为应力颗粒，在PKR-但不是RIG-I-依赖的方式。虽然先前假设应激颗粒是免疫激活的必要平台，但我们发现它们不是YFV感染后促炎介质产生所必需的。总的来说，我们的工作揭示了由YFV复制引发的分子事件，这可能有助于阐明疾病的发病机制，并可能对疾病管理产生影响。
Yellow fever virus (YFV) is an RNA virus primarily targeting the liver. Severe YF cases are responsible for hemorrhagic fever, plausibly precipitated by excessive proinflammatory cytokine response. Pathogen recognition receptors (PRRs), such as the cytoplasmic retinoic acid inducible gene I (RIG-I)-like receptors (RLRs), and the viral RNA sensor protein kinase R (PKR), are known to initiate a proinflammatory response upon recognition of viral genomes. Here, we sought to reveal the main determinants responsible for the acute cytokine expression occurring in human hepatocytes following YFV infection. Using a RIG-I-defective human hepatoma cell line, we found that RIG-I largely contributes to cytokine secretion upon YFV infection. In infected RIG-I-proficient hepatoma cells, RIG-I was localized in stress granules. These granules are large aggregates of stalled translation preinitiation complexes known to concentrate RLRs and PKR and are so far recognized as hubs orchestrating RNA virus sensing. Stable knockdown of PKR in hepatoma cells revealed that PKR contributes to both stress granule formation and cytokine induction upon YFV infection. However, stress granule disruption did not affect the cytokine response to YFV infection, as assessed by small interfering RNA (siRNA)-knockdown-mediated inhibition of stress granule assembly. Finally, no viral RNA was detected in stress granules using a fluorescence in situ hybridization approach coupled with immunofluorescence. Our findings suggest that both RIG-I and PKR mediate proinflammatory cytokine induction in YFV-infected hepatocytes, in a stress granule-independent manner. Therefore, by showing the uncoupling of the cytokine response from the stress granule formation, our model challenges the current view in which stress granules are required for the mounting of the acute antiviral response.IMPORTANCE Yellow fever is a mosquito-borne acute hemorrhagic disease caused by yellow fever virus (YFV). The mechanisms responsible for its pathogenesis remain largely unknown, although increased inflammation has been linked to worsened outcome. YFV targets the liver, where it primarily infects hepatocytes. We found that two RNA-sensing proteins, RIG-I and PKR, participate in the induction of proinflammatory mediators in human hepatocytes infected with YFV. We show that YFV infection promotes the formation of cytoplasmic structures, termed stress granules, in a PKR- but not RIG-I-dependent manner. While stress granules were previously postulated to be essential platforms for immune activation, we found that they are not required for the production of proinflammatory mediators upon YFV infection. Collectively, our work uncovered molecular events triggered by the replication of YFV, which could prove instrumental in clarifying the pathogenesis of the disease, with possible repercussions for disease management.