RNF20 affects macrophage polarization after RNA virus infection
This study was designed to investigate the role of ring finger protein 20(RNF20)in host innate immunity against RNA viruses.Dual luciferase reporter assay was employed to examine the effects of RNF20 overexpression on Sendai virus(SeV)infection-induced activation of interferon a4(Ifna4)gene promoter in 293T human embryonic kidney epithelial cells.Rnf20 myeloid conditional knockout mouse model was constructed(Rnf2OF/F;Lyz2-Cre),and the frequency of myeloid subsets in the bone marrow,spleen,blood of Rnf20F/F;Lyz2-Cre mice and littermate Rnf20F/F mice were detected by flow cytometry.After bone marrow-derived macrophages(BMDMs)were cultured and subjected to the infection of SeV and vesicular stomatitis virus(VSV),Western blot was used to detect the phosphorylation of transcription factor interferon regulatory factor 3(IRF3)and nuclear factor-κB(NF-κB).ELISA was used to detect the production of IFN-β,TNF-α and IL-6,and Bulk RNA-sequencing was employed to explore transcriptional changes.Furthermore,M1 and M2 macrophage polarization was induced by LPS and IL-4,respectively,to confirm the changes revealed by transcriptome analysis.Data showed that RNF20 overexpression showed no significant effect on SeV infection-induced activation of Ifna4 gene promoter in 293T cells.There is almost no difference in the development of myeloid subsets between Rnf20F/F;Lyz2-Cre and Rnf2OF/F mice.After RNA viral infection of BMDMs from Rnf20F/F;Lyz2-Creand Rnf201 mice,the phosphorylation of IRF3 and NF-κB p65 and the expression of IFN-[3,TNF-α and IL-6 were comparable between the two groups,while the expression levels of several genes related to macrophage polarization were significantly different.The loss of RNF20 showed the tendency of hindering M1 macrophage polarization while promoting M2 macrophage polarization.In conclusion,RNF20 does not affect RNA viral infection-induced activation of IRF3 or NF-κB pathways,but it might get involved in the resolution of inflammation afterwards.