Liu Dong, Sheng Chunjie, Gao Shijuan, Yao Chen, Li Jiandong, Jiang Wei, Chen Huiming, Wu Jiaoxiang, Pan Changchuan, Chen Shuai, Huang Wenlin
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China.
Medical Oncology, Sichuan Cancer Hospital and Institute, Second People's Hospital of Sichuan Province, Chengdu, People's Republic of China.
Mol Cell Biol. 2015 Jul;35(14):2400-13. doi: 10.1128/MCB.00090-15. Epub 2015 May 4.
TANK-binding kinase 1 (TBK1)-mediated induction of type I interferon (IFN) plays a critical role in host antiviral responses and immune homeostasis. The negative regulation of TBK1 activity is largely unknown. We report that suppressor of cytokine signaling 3 (SOCS3) inhibits the IFN-β signaling pathway by promoting proteasomal degradation of TBK1. Overexpression and knockdown experiments indicated that SOCS3 is a negative regulator of IFN regulatory factor 3 (IRF3) phosphorylation and IFN-β transcription. Moreover, SOCS3 directly associates with TBK1, and they colocalize in the cytoplasm. SOCS3 catalyzes K48-linked polyubiquitination of TBK1 at Lys341 and Lys344 and promotes subsequent TBK1 degradation. On the contrary, SOCS3 knockdown markedly increases the abundance of TBK1. Interestingly, both the BOX domain of SOCS3 and Ser172 phosphorylation of TBK1 are indispensable for the processes of ubiquitination and degradation. Ectopic expression of SOCS3 significantly inhibits vesicular stomatitis virus (VSV) and influenza A virus strain A/WSN/33 (WSN)-induced IRF3 phosphorylation and facilitates the replication of WSN virus by detecting the transcription of its viral RNA (vRNA). Knockdown of SOCS3 represses WSN replication. Collectively, these results demonstrate that SOCS3 acts as a negative regulator of IFN-β signal by ubiquitinating and degrading TBK1, shed light on the understanding of antiviral innate immunity, and provide a potential target for developing antiviral agents.
TANK结合激酶1（TBK1）介导的I型干扰素（IFN）诱导在宿主抗病毒反应和免疫稳态中起关键作用。TBK1活性的负调控在很大程度上尚不清楚。我们报道细胞因子信号转导抑制因子3（SOCS3）通过促进TBK1的蛋白酶体降解来抑制IFN-β信号通路。过表达和敲低实验表明，SOCS3是IFN调节因子3（IRF3）磷酸化和IFN-β转录的负调节因子。此外，SOCS3直接与TBK1结合，并且它们在细胞质中共定位。SOCS3催化TBK1在赖氨酸341和赖氨酸344处发生K48连接的多聚泛素化，并促进随后的TBK1降解。相反，敲低SOCS3会显著增加TBK1的丰度。有趣的是，SOCS3的BOX结构域和TBK1的丝氨酸172磷酸化对于泛素化和降解过程都是必不可少的。异位表达SOCS3显著抑制水疱性口炎病毒（VSV）和甲型流感病毒A/WSN/33株（WSN）诱导的IRF3磷酸化，并通过检测其病毒RNA（vRNA）的转录来促进WSN病毒的复制。敲低SOCS3会抑制WSN的复制。总的来说，这些结果表明，SOCS3通过泛素化和降解TBK1作为IFN-β信号的负调节因子，有助于对抗病毒先天免疫的理解，并为开发抗病毒药物提供了一个潜在靶点。
