Laboratory of Molecular Genetics, Institute for Virus Research, Kyoto University, Kyoto, Japan.
PLoS One. 2012;7(8):e43031. doi: 10.1371/journal.pone.0043031. Epub 2012 Aug 13.
Retinoic acid inducible gene I (RIG-I)-like receptors (RLRs) function as cytoplasmic sensors for viral RNA to initiate antiviral responses including type I interferon (IFN) production. It has been unclear how RIG-I encounters and senses viral RNA. To address this issue, we examined intracellular localization of RIG-I in response to viral infection using newly generated anti-RIG-I antibody. Immunohistochemical analysis revealed that RLRs localized in virus-induced granules containing stress granule (SG) markers together with viral RNA and antiviral proteins. Because of similarity in morphology and components, we termed these aggregates antiviral stress granules (avSGs). Influenza A virus (IAV) deficient in non-structural protein 1 (NS1) efficiently generated avSGs as well as IFN, however IAV encoding NS1 produced little. Inhibition of avSGs formation by removal of either the SG component or double-stranded RNA (dsRNA)-dependent protein kinase (PKR) resulted in diminished IFN production and concomitant enhancement of viral replication. Furthermore, we observed that transfection of dsRNA resulted in IFN production in an avSGs-dependent manner. These results strongly suggest that the avSG is the locus for non-self RNA sensing and the orchestration of multiple proteins is critical in the triggering of antiviral responses.
维甲酸诱导基因 I (RIG-I)-样受体 (RLRs) 作为细胞内病毒 RNA 的感应器，启动抗病毒反应，包括Ⅰ型干扰素 (IFN) 的产生。然而，RLR 如何识别和感知病毒 RNA 仍不清楚。为了解决这个问题，我们使用新生成的抗 RIG-I 抗体检测了病毒感染后 RIG-I 的细胞内定位。免疫组织化学分析显示，RLRs 与病毒 RNA 和抗病毒蛋白一起定位于病毒诱导的颗粒中，这些颗粒包含应激颗粒 (SG) 标志物。由于形态和成分相似，我们将这些聚集物称为抗病毒应激颗粒 (avSGs)。缺乏非结构蛋白 1 (NS1) 的甲型流感病毒 (IAV) 能够有效地产生 avSGs 和 IFN，然而编码 NS1 的 IAV 产生的很少。通过去除 SG 成分或双链 RNA (dsRNA)-依赖性蛋白激酶 (PKR) 抑制 avSGs 的形成，导致 IFN 产生减少，同时病毒复制增强。此外，我们观察到 dsRNA 的转染以依赖于 avSGs 的方式导致 IFN 的产生。这些结果强烈表明，avSG 是非自身 RNA 感应的场所，多个蛋白的协调在触发抗病毒反应中至关重要。
