Research
| Title： | A novel role of Zebrafish TMEM33 in negative regulation of interferon production by two distinct mechanisms |
|---|---|
| First author： | Lu, Long-Feng; Zhang, Can; Li, Zhuo-Cong; Zhou, Xiao-Yu; Jiang, Jing-Yu; Chen, Dan-Dan; Zhang, Yong-An; Xiong, Feng; Zhou, Fang; Li, Shun |
| Journal： | PLOS PATHOGENS |
| Years： | 2021 |
| DOI： | 10.1371/journal.ppat.1009317 |
| Abstract： | The transmembrane protein 33 (TMEM33) was originally identified as an endoplasmic reticulum (ER) protein that influences the tubular structure of the ER and modulates intracellular calcium homeostasis. However, the role of TMEM33 in antiviral immunity in vertebrates has not been elucidated. In this article, we demonstrate that zebrafish TMEM33 is a negative regulator of virus-triggered interferon (IFN) induction via two mechanisms: mitochondrial antiviral signaling protein (MAVS) ubiquitination and a decrease in the kinase activity of TANK binding kinase 1 (TBK1). Upon stimulation with viral components, tmem33 was remarkably upregulated in the zebrafish liver cell line. The IFN phi 1 promoter (IFN phi 1pro) activity and mRNA level induced by retinoic acid-inducible gene (RIG)-I-like receptors (RLRs) were significantly inhibited by TMEM33. Knockdown of TMEM33 increased host ifn transcription. Subsequently, we found that TMEM33 was colocalized in the ER and interacted with the RLR cascades, whereas MAVS was degraded by TMEM33 during the K48-linked ubiquitination. On the other hand, TMEM33 reduced the phosphorylation of mediator of IFN regulatory factor 3 (IRF3) activation (MITA)/IRF3 by acting as a decoy substrate of TBK1, which was also phosphorylated. A functional domain assay revealed that the N-terminal transmembrane domain 1 (TM1) and TM2 regions of TMEM33 were necessary for IFN suppression. Finally, TMEM33 significantly attenuated the host cellular antiviral capacity by blocking the IFN response. Taken together, our findings provide insight into the different mechanisms employed by TMEM33 in cellular IFN-mediated antiviral process. Author summary The water environment of fish enhances the chance of aquatic viral infection which leads to host IFN production, thus fish IFN as a critical antiviral role need to be modulated precisely to avoid adverse pathogenic effects, however, the IFN expression balance in fish is still unclear. In this study, we identify that zebrafish transmembrane protein 33 (TMEM33) negatively regulates IFN production by two distinct mechanisms: TMEM33 interacted with and degraded MAVS through K48-linked ubiquitination; TMEM33 acted as a decoy substrate for cellular TBK1 and reduced the phosphorylation of MITA/IRF3. Our findings reveal the role for fish TMEM33 in regulating cellular immune responses and expand our knowledge of the IFN negative regulatory mechanisms. |
