RNF135 is a positive regulator of IFN expression and involved in RIG-I signaling pathway by targeting RIG-I

Abstract RIG-I-like receptors (RLRs) play a key role in antiviral and inflammatory responses. Increasing evidence indicates that ubiquitination is crucial for regulation of RIG-I signaling pathway. Several ubiquitin ligases were reported to be involved in RIG-I-mediated signal transduction. In the present study, we demonstrated zebrafish RING finger protein 135 (zbRNF135) was a critical player in the regulation of RIG-I signaling pathway. zbRNF1 35 mRNA was widely expressed in different tissues of zebrafish. The expression of zbRNF135 was up-regulated post poly(I:C) treatment in vivo and in vitro . Furthermore, the expression profiles of RIG-I signaling pathway related genes ( LGP2 , MDA5 , RIG-I , MAVS , TRAF3 , IRF3 and IRF7 ), together with its downstream molecules ( IFN1 , ISG15 , Mx and PKR ), were up-regulated by overexpression of zbRNF135 in ZF4 cells. Luciferase and ubiquitination assays revealed that overexpression of zbRNF135 facilitated zebrafish RIG-I (zbRIG-I)-mediated IFN1 promoter activation by mediating K63-linked ubiquitination of zbRIG-I. The co-immunoprecipitation assay showed that zbRNF135 specifically interacted with zbRIG-I. Our study indicated that zbRNF135 participated in innate immune response through modulating RIG-I signaling pathway.