Faculty of Pharmacy, Université de Montréal, Montréal, Canada.
Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital, Toronto, Ontario, Canada.
PLoS Pathog. 2021 Jan 7;17(1):e1009111. doi: 10.1371/journal.ppat.1009111. eCollection 2021 Jan.
Antiviral innate immune response to RNA virus infection is supported by Pattern-Recognition Receptors (PRR) including RIG-I-Like Receptors (RLR), which lead to type I interferons (IFNs) and IFN-stimulated genes (ISG) production. Upon sensing of viral RNA, the E3 ubiquitin ligase TNF Receptor-Associated Factor-3 (TRAF3) is recruited along with its substrate TANK-Binding Kinase (TBK1), to MAVS-containing subcellular compartments, including mitochondria, peroxisomes, and the mitochondria-associated endoplasmic reticulum membrane (MAM). However, the regulation of such events remains largely unresolved. Here, we identify TRK-Fused Gene (TFG), a protein involved in the transport of newly synthesized proteins to the endomembrane system via the Coat Protein complex II (COPII) transport vesicles, as a new TRAF3-interacting protein allowing the efficient recruitment of TRAF3 to MAVS and TBK1 following Sendai virus (SeV) infection. Using siRNA and shRNA approaches, we show that TFG is required for virus-induced TBK1 activation resulting in C-terminal IRF3 phosphorylation and dimerization. We further show that the ability of the TRAF3-TFG complex to engage mTOR following SeV infection allows TBK1 to phosphorylate mTOR on serine 2159, a post-translational modification shown to promote mTORC1 signaling. We demonstrate that the activation of mTORC1 signaling during SeV infection plays a positive role in the expression of Viperin, IRF7 and IFN-induced proteins with tetratricopeptide repeats (IFITs) proteins, and that depleting TFG resulted in a compromised antiviral state. Our study, therefore, identifies TFG as an essential component of the RLR-dependent type I IFN antiviral response.
抗病毒先天免疫反应是由模式识别受体（PRR）支持的，包括 RIG-I 样受体（RLR），这导致了 I 型干扰素（IFN）和 IFN 刺激基因（ISG）的产生。在检测到病毒 RNA 后，E3 泛素连接酶 TNF 受体相关因子 3（TRAF3）与它的底物 TANK 结合激酶（TBK1）一起被招募到包含 MAVS 的亚细胞隔室中，包括线粒体、过氧化物酶体和线粒体相关内质网膜（MAM）。然而，这些事件的调节在很大程度上仍未得到解决。在这里，我们鉴定了 TRK 融合基因（TFG），一种参与通过 Coat Protein complex II（COPII）转运囊泡将新合成的蛋白质运输到内膜系统的蛋白质，作为一种新的 TRAF3 相互作用蛋白，允许 TRAF3 在后发性腮腺炎病毒（SeV）感染后有效地被招募到 MAVS 和 TBK1。通过 siRNA 和 shRNA 方法，我们表明 TFG 是病毒诱导的 TBK1 激活所必需的，导致 C 端 IRF3 磷酸化和二聚化。我们进一步表明，TRAF3-TFG 复合物在 SeV 感染后与 mTOR 结合的能力允许 TBK1 在丝氨酸 2159 上磷酸化 mTOR，这是一种被证明能促进 mTORC1 信号的翻译后修饰。我们证明，在 SeV 感染过程中 mTORC1 信号的激活在 Viperin、IRF7 和 IFN 诱导的具有四肽重复的蛋白质（IFITs）蛋白的表达中起着积极的作用，并且耗尽 TFG 导致抗病毒状态受损。因此，我们的研究将 TFG 鉴定为 RLR 依赖性 I 型 IFN 抗病毒反应的必需组成部分。
