Fig. 4.

Ythdc2 inhibits host antiviral innate immunity. A Relative protein and mRNA levels of Ythdc2 in MIC cells after transfected with NC or si-circYthdc2. B Relative protein levels of STING in MIC cells after transfected with NC or si-Ythdc2 and in MKC cells with pcDNA3.1 or Ythdc2. C and D qPCR assays were performed to determine the expression levels of IFN1, TNF-α, Mx1, ISG15, and Viperin in MIC cells transfected with NC or si-Ythdc2 (C) and transfected in MKC cells with pcDNA3.1 and Ythdc2 after SCRV infection (D). E Ythdc2 counteracts the negative effect of STING. Relative luciferase activities were detected in MKC after cotransfection with STING expression plasmid, pRL-TK Renilla luciferase plasmid, luciferase reporters, pcDNA3.1, Ythdc2. F Ythdc2 promotes SCRV replication. MIC cells transfected with NC or si-Ythdc2 and MKC cells were transfected with pcDNA3.1 or Ythdc2 for 24 h, respectively, then infected with SCRV at 24 h. The qPCR analysis was conducted for intracellular and supernatant SCRV RNA expression. (G) MIC cells seeded in 48-well plates overnight were treated with cultural supernatants at the dose indicated for 48 h. Then, cell monolayers were fixed with 4% paraformaldehyde and stained with 1% crystal violet. MIC cells were transfected with NC or si-Ythdc2. H Effect of Ythdc2 on cell viability after SCRV infection. MIC cells was transfected with NC or si-Ythdc2 for 24 h and then treated with SCRV for 24 h. Cell viability assay were measured. All data represented the mean ± SE from three independent triplicated experiments. *, p < 0.05; **, p < 0.01