Cui Jun, Song Yanxia, Li Yinyin, Zhu Qingyuan, Tan Peng, Qin Yunfei, Wang Helen Y, Wang Rong-Fu
1] Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, College of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China [2] Center for Inflammation and Epigenetics, The Methodist Hospital Research Institute, Houston, TX 77030, USA.
1] Center for Inflammation and Epigenetics, The Methodist Hospital Research Institute, Houston, TX 77030, USA [2] Central Laboratory, The First Affiliated Hospital, Jilin University, Changchun 130012, China.
Cell Res. 2014 Apr;24(4):400-16. doi: 10.1038/cr.2013.170. Epub 2013 Dec 24.
Lysine 63 (K63)-linked ubiquitination of RIG-I plays a critical role in the activation of type I interferon pathway, yet the molecular mechanism responsible for its deubiquitination is still poorly understood. Here we report that the deubiquitination enzyme ubiquitin-specific protease 3 (USP3) negatively regulates the activation of type I interferon signaling by targeting RIG-I. Knockdown of USP3 specifically enhanced K63-linked ubiquitination of RIG-I, upregulated the phosphorylation of IRF3 and augmented the production of type I interferon cytokines and antiviral immunity. We further show that there is no interaction between USP3 and RIG-I-like receptors (RLRs) in unstimulated or uninfected cells, but upon viral infection or ligand stimulation, USP3 binds to the caspase activation recruitment domain of RLRs and then cleaves polyubiquitin chains through cooperation of its zinc-finger Ub-binding domain and USP catalytic domains. Mutation analysis reveals that binding of USP3 to polyubiquitin chains on RIG-I is a prerequisite step for its cleavage of polyubiquitin chains. Our findings identify a previously unrecognized role of USP3 in RIG-I activation and provide insights into the mechanisms by which USP3 inhibits RIG-I signaling and antiviral immunity.
维甲酸诱导基因I（RIG-I）的赖氨酸63（K63）连接的泛素化在I型干扰素途径的激活中起关键作用，但其去泛素化的分子机制仍知之甚少。在此，我们报道去泛素化酶泛素特异性蛋白酶3（USP3）通过靶向RIG-I负向调节I型干扰素信号的激活。敲低USP3可特异性增强RIG-I的K63连接的泛素化，上调干扰素调节因子3（IRF3）的磷酸化，并增加I型干扰素细胞因子的产生和抗病毒免疫。我们进一步表明，在未受刺激或未感染的细胞中，USP3与RIG-I样受体（RLRs）之间没有相互作用，但在病毒感染或配体刺激后，USP3与RLRs的半胱天冬酶激活募集结构域结合，然后通过其锌指泛素结合结构域和USP催化结构域的协同作用切割多聚泛素链。突变分析表明，USP3与RIG-I上的多聚泛素链结合是其切割多聚泛素链的前提步骤。我们的研究结果确定了USP3在RIG-I激活中以前未被认识的作用，并为USP3抑制RIG-I信号和抗病毒免疫的机制提供了见解。
