Zebrafish Uba1 Degrades IRF3 through K48-Linked Ubiquitination to Inhibit IFN Production

Abstract

Fish IFN regulatory factor 3 (IRF3) is a crucial transcription factor in the IFN activation signaling pathway, which leads to IFN production and a positive cycle. Unrestricted IFN expression results in hyperimmune responses and therefore, IFN must be tightly regulated. In the current study, we found that zebrafish Ub-activating enzyme (Uba1) negatively regulated IRF3 via the K-48 ubiquitin proteasome degradation of IRF3. First, ifn expression stimulated by spring viraemia of carp virus infection was blunted by the overexpression of Uba1 and enhanced by Uba1 knockdown. Afterward, we found that Uba1 was localized in the cytoplasm, where it interacted with and degraded IRF3. Functional domains analysis revealed that the C-terminal ubiquitin-fold domain was necessary for IRF3 degradation by Uba1 and the N-terminal DNA-binding domain of IRF3 was indispensable for the degradation by Uba1.The degradation of IRF3 was subsequently impaired by treatment with MG132, a ubiquitin proteasome inhibitor. Further mechanism analysis revealed that Uba1 induced the K48-linked Ub-proteasomal degradation of IRF3. Finally, the antiviral capacity of IRF3 was significantly attenuated by Uba1. Taken together, our study reveals that zebrafish Uba1 interacts with and activates the ubiquitinated degradation of IRF3, providing evidence of the IFN immune balance mechanism in fish.

Novel causative variants of VEXAS in UBA1 detected through whole genome transcriptome sequencing in a large cohort of hematological malignancies

“…Some of the identified somatic variants were also on functional residues (S478, R551, N606, S621, R747), one of which is a partial loss of function site (R747). The literature and prevalence in public databases on the identified putative somatic variants are summarized in Table 2 [7,20,33,[35][36][37][38][39][40][41][42][43][44].…”

Foot-and-Mouth Disease Virus Capsid Protein VP1 Antagonizes Type I Interferon Signaling via Degradation of Histone Deacetylase 5

“…We found that HDAC5 promoted the transcriptional activity of IFN-β stimulated by these plasmids, respectively ( Figure 4 A–F). IRF3 is essential for IFN-β expression and the antiviral response [ 29 , 30 , 31 ]. Compared with the control groups, the overexpression of HDAC5 remarkably promoted the phosphorylation of IRF3 upon FMDV infection ( Figure 4 G).…”

Proteasome inhibition triggers tissue-specific immune responses against different pathogens in C. elegans

“…A similar phenomenon has been shown to regulate activation of NF-κB in Drosophila , where IMD is proteasomally degraded owing to permanent presence of Ub K48 linkages, which are lost upon bacterial infection thereby stabilizing the protein and activating the pathway [ 26 , 27 ]. Likewise, Uba1-mediated proteasomal degradation of IRF3 in Zebrafish keeps activation of IFN signaling and activation of anti-viral immune response in check [ 44 ]. While our findings are consistent with a potential direct role for the proteasome in stabilizing factors that may be necessary for ORR/IPR induction, we cannot rule out that the bounce-back response pathway may also act in parallel.…”