Hepatitis C Virus Infection Is Inhibited by a Noncanonical Antiviral Signaling Pathway Targeted by NS3-NS4A.
Hepatitis C Virus Infection Is Inhibited by a Noncanonical Antiviral Signaling Pathway Targeted by NS3-NS4A.
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NS3-NS4A 靶向的非典型抗病毒信号通路可抑制丙型肝炎病毒感染。
DOI：
10.1128/jvi.00725-19
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发表时间：
2019
影响因子：
5.4
通讯作者：
Horner,StacyM
中科院分区：
文献类型：
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作者：
Vazquez,Christine;Tan,ChinYee;Horner,StacyM
丙型肝炎病毒NS3-NS4A蛋白复合体是病毒复制所必需的，是病毒先天免疫逃避的主要因子。NS3-NS4A通过灭活几种蛋白质来逃避抗病毒的先天免疫，包括MAV，RIG-I和MDA5的信号适配器，以及Riplet，一种激活RIG-I的E3泛素连接酶。在这里，我们发现了NS4A跨膜结构域的Tyr-16-Phe(Y16F)变化，该变化阻止了NS3-NS4A靶向Riplet，而不是MAV。这种Y16F替换减少了Huh7细胞中的丙型肝炎病毒复制，但不能在Huh-7.5细胞中复制，已知的Huh-7.5细胞缺乏RIG-I信号。令人惊讶的是，在Huh7细胞中RIG-I的缺失并没有恢复Y16F病毒的复制。相反，我们发现Huh-7.5细胞缺乏Riplet的表达，并且Riplet的加入降低了丙型肝炎病毒Y16F的复制，而添加缺少环区的Riplet则恢复了丙型肝炎病毒Y16F的复制。此外，在Huh7细胞中抑制Tbk1或IRF3的缺失足以恢复丙型肝炎病毒Y16F的复制，而Y16F蛋白酶缺乏阻止IRF3激活或干扰素诱导的能力。综上所述，这些数据表明，NS4A Y16残基调控非规范Riplet-TBK1-IRF3依赖，但RIG-I-MAVS不依赖的信号通路，限制丙型肝炎病毒感染。重要信息丙型肝炎病毒NS3-NS4A蛋白酶复合体通过切割和灭活抗病毒天然免疫信号蛋白MAVS和Riplet来促进病毒复制，这是RIG-I激活所必需的。因此，NS3-NS4A可阻止丙型肝炎病毒感染期间IRF3的激活和干扰素的诱导。在这里，我们发现了NS4A跨膜结构域中的一个氨基酸残基，它是Riplet失活所必需的，但不影响NS3-NS4A对MAV的切割。我们的研究表明Riplet参与了一条RIG-I和MAVS无关的信号通路，激活了IRF3，并且在丙型肝炎病毒感染过程中，这一通路通常被NS3-NS4A灭活。我们的研究选择性地解偶联了NS3-NS4A中的这些不同的调节机制，并定义了Riplet在抗丙型肝炎病毒反应中的新角色。由于Riplet已知可被其他RNA病毒抑制，例如甲型流感病毒，这种先天免疫信号通路在控制其他RNA病毒感染方面也可能是重要的。
The hepatitis C virus (HCV) NS3-NS4A protease complex is required for viral replication and is the major viral innate immune evasion factor. NS3-NS4A evades antiviral innate immunity by inactivating several proteins, including MAVS, the signaling adaptor for RIG-I and MDA5, and Riplet, an E3 ubiquitin ligase that activates RIG-I. Here, we identified a Tyr-16-Phe (Y16F) change in the NS4A transmembrane domain that prevents NS3-NS4A targeting of Riplet but not MAVS. This Y16F substitution reduces HCV replication in Huh7 cells, but not in Huh-7.5 cells, known to lack RIG-I signaling. Surprisingly, deletion of RIG-I in Huh7 cells did not restore Y16F viral replication. Rather, we found that Huh-7.5 cells lack Riplet expression and that the addition of Riplet to these cells reduced HCV Y16F replication, whereas the addition of Riplet lacking the RING domain restored HCV Y16F replication. In addition, TBK1 inhibition or IRF3 deletion in Huh7 cells was sufficient to restore HCV Y16F replication, and the Y16F protease lacked the ability to prevent IRF3 activation or interferon induction. Taken together, these data reveal that the NS4A Y16 residue regulates a noncanonical Riplet-TBK1-IRF3-dependent, but RIG-I-MAVS-independent, signaling pathway that limits HCV infection.IMPORTANCEThe HCV NS3-NS4A protease complex facilitates viral replication by cleaving and inactivating the antiviral innate immune signaling proteins MAVS and Riplet, which are essential for RIG-I activation. NS3-NS4A therefore prevents IRF3 activation and interferon induction during HCV infection. Here, we uncover an amino acid residue within the NS4A transmembrane domain that is essential for inactivation of Riplet but does not affect MAVS cleavage by NS3-NS4A. Our study reveals that Riplet is involved in a RIG-I- and MAVS-independent signaling pathway that activates IRF3 and that this pathway is normally inactivated by NS3-NS4A during HCV infection. Our study selectively uncouples these distinct regulatory mechanisms within NS3-NS4A and defines a new role for Riplet in the antiviral response to HCV. Since Riplet is known to be inhibited by other RNA viruses, such as such influenza A virus, this innate immune signaling pathway may also be important in controlling other RNA virus infections.