A distinct role of Riplet-mediated K63-Linked polyubiquitination of the RIG-I repressor domain in human antiviral innate immune responses.
A distinct role of Riplet-mediated K63-Linked polyubiquitination of the RIG-I repressor domain in human antiviral innate immune responses.
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DOI：
10.1371/journal.ppat.1003533
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发表时间：
2013
期刊：
影响因子：
6.7
通讯作者：
Seya T
中科院分区：
文献类型：
--
作者：
Oshiumi H;Miyashita M;Matsumoto M;Seya T
先天免疫系统对于控制病毒感染是必不可少的，但有几种病毒已经进化出逃避先天免疫的策略。RIG-I是一种细胞质病毒RNA传感器，它能触发信号，诱导I型干扰素的产生，以应对病毒感染。Rig-I的激活受Riplet和TRIM25泛素连接酶介导的K63连接的多泛素链的调节。TRIM25是RIG-I齐聚和与IPS-1适配器分子相互作用所必需的。一项基因敲除研究表明Riplet对于RIG-I的激活是必不可少的。然而Riplet激活RIG-I的分子机制尚不清楚，Riplet和TRIM25之间的功能差异也尚不清楚。一项遗传学研究和下拉分析表明，Riplet对于RIG-I RNA结合活性是必不可少的，但TRIM25需要激活RIG-I。突变分析表明，Rig-I抑制域中的Lys-788对于Riplet介导的K63连接的多泛素化是关键的，Riplet是释放Rig-I自身抑制其N-末端卡片所必需的，这导致RIG-I与TRIM25泛素连接酶和TBK1蛋白激酶相关联。我们的数据表明Riplet是TRIM25激活RIG-I信号的先决条件。我们研究了这一机制在人类细胞中的生物学意义，发现丙型肝炎病毒(丙型肝炎病毒)废除了这一机制。有趣的是，丙型肝炎病毒NS3-4A蛋白酶靶向Riplet蛋白，取消了内源性RIG-I多泛素化以及与TRIM25和TBK1的关联，强调了这一机制在人类抗病毒先天免疫中的生物学重要性。综上所述，我们的结果证明Riplet介导的K63连接的多泛素化释放了RIG-I RD自身抑制，从而允许阳性因子进入RIG-I蛋白。细胞质病毒RNA传感器RIG-I识别各种类型的致病病毒并激发天然免疫反应，而几种病毒已经进化出逃避宿主天然免疫反应的策略。RIG-I触发信号诱导I型干扰素和炎性细胞因子。RIG-I的激活受泛素连接酶TRIM25和Riplet介导的K63连接的多泛素链的调节，然而，这两种泛素连接酶之间的功能差异尚不清楚，Riplet介导的RIG-I激活的分子机制也不清楚。我们揭示了两种泛素连接酶在RIG-I激活过程中的顺序作用，并发现Riplet介导的RIG-I抑制器域的多泛素化释放了负责触发信号的N-端卡的RIG-I自抑制，从而导致与TRIM25泛素连接酶和TBK1蛋白激酶的关联。有趣的是，我们发现这一机制是丙型肝炎病毒的靶点，丙型肝炎病毒是肝细胞癌的主要原因。这一结果强调了Riplet介导的RIG-I RD自身抑制的释放在抗病毒反应中的重要作用。我们的结果证明Riplet释放RIG-I RD自身抑制，并证明了这一机制在人类先天免疫反应中的生物学意义。
The innate immune system is essential for controlling viral infections, but several viruses have evolved strategies to escape innate immunity. RIG-I is a cytoplasmic viral RNA sensor that triggers the signal to induce type I interferon production in response to viral infection. RIG-I activation is regulated by the K63-linked polyubiquitin chain mediated by Riplet and TRIM25 ubiquitin ligases. TRIM25 is required for RIG-I oligomerization and interaction with the IPS-1 adaptor molecule. A knockout study revealed that Riplet was essential for RIG-I activation. However the molecular mechanism underlying RIG-I activation by Riplet remains unclear, and the functional differences between Riplet and TRIM25 are also unknown. A genetic study and a pull-down assay indicated that Riplet was dispensable for RIG-I RNA binding activity but required for TRIM25 to activate RIG-I. Mutational analysis demonstrated that Lys-788 within the RIG-I repressor domain was critical for Riplet-mediated K63-linked polyubiquitination and that Riplet was required for the release of RIG-I autorepression of its N-terminal CARDs, which leads to the association of RIG-I with TRIM25 ubiquitin ligase and TBK1 protein kinase. Our data indicate that Riplet is a prerequisite for TRIM25 to activate RIG-I signaling. We investigated the biological importance of this mechanism in human cells and found that hepatitis C virus (HCV) abrogated this mechanism. Interestingly, HCV NS3-4A proteases targeted the Riplet protein and abrogated endogenous RIG-I polyubiquitination and association with TRIM25 and TBK1, emphasizing the biological importance of this mechanism in human antiviral innate immunity. In conclusion, our results establish that Riplet-mediated K63-linked polyubiquitination released RIG-I RD autorepression, which allowed the access of positive factors to the RIG-I protein. The cytoplasmic viral RNA sensor RIG-I recognizes various types of pathogenic viruses and evokes innate immune responses, whereas several viruses have evolved strategies to escape the host innate immune responses. RIG-I triggers a signal to induce type I interferon and inflammatory cytokines. RIG-I activation is regulated by K63-linked polyubiquitin chains mediated by the ubiquitin ligases TRIM25 and Riplet; however, the functional difference between the two ubiquitin ligases remains unclear, and the molecular mechanism underlying Riplet-mediated RIG-I activation is unknown. We revealed sequential roles of the two ubiquitin ligases during RIG-I activation and found that Riplet-mediated polyubiquitination of the RIG-I repressor domain released RIG-I autorepression of its N-terminal CARDs responsible for triggering the signal, which resulted in an association with TRIM25 ubiquitin ligase and TBK1 protein kinase. Interestingly, we found that this mechanism was targeted by hepatitis C virus, which is a major cause of hepatocellular carcinoma. This result emphasizes the vital role of Riplet-mediated release of RIG-I RD autorepression in antiviral responses. Our results establish that Riplet releases RIG-I RD autorepression and demonstrated the biological significance of this mechanism in human innate immune responses.
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影响因子：
6.7
作者：
Arnaud N;Dabo S;Akazawa D;Fukasawa M;Shinkai-Ouchi F;Hugon J;Wakita T;Meurs EF
通讯作者：
Meurs EF
影响因子：
3.7
作者：
Gao D;Yang YK;Wang RP;Zhou X;Diao FC;Li MD;Zhai ZH;Jiang ZF;Chen DY
通讯作者：
Chen DY
影响因子：
7.7
作者：
Friedman, Constantin S.;O'Donnell, Marie Anne;Ting, Adrian T.
通讯作者：
Ting, Adrian T.
DOI：
10.1073/pnas.2237236100
发表时间：
2004-01-06
影响因子：
11.1
作者：
McWhirter, SM;Fitzgerald, KA;Maniatis, T
通讯作者：
Maniatis, T
影响因子：
64.8
作者：
Meylan, E;Curran, J;Tschopp, R
通讯作者：
Tschopp, R