Figure 1.

TRIM38 positively regulates RIG-I– and MDA5-mediated signaling. (A) Coimmunoprecipitation of TRIM38 with MDA5 and RIG-I in mammalian overexpression system. HEK293 cells were transfected with the indicated plasmids for 24 h, followed by coimmunoprecipitation experiments and immunoblotting analysis. (B) Endogenous association of TRIM38 with RIG-I and MDA5. THP-1 cells were left uninfected or infected with SeV (top) or EMCV (bottom) for the indicated times followed by coimmunoprecipitation and immunoblotting analysis with the indicated antibodies. (C and D) Domain mapping of TRIM38 with RIG-I and MDA5. Experiments were performed as in B, except for the different transfected plasmids. (E) Effects of TRIM38 or TRIM38(C31S) on RIG-I– and MDA5-mediated activation of the IFN-β promoter. HEK293 cells were transfected with the indicated plasmids for 24 h before luciferase assays. (F) Effects of TRIM38 or TRIM38(C31S) on RIG-I– and MDA5-mediated cellular antiviral response. HEK293 cells were transfected with the indicated plasmids for 24 h, followed by VSV (MOI = 0.1) infection for 24 h, and then the supernatants were collected for plaque assays to determine the viral titers. (G) Effects of knockdown of TRIM38 on SeV- or poly(I:C)-induced activation of the IFN-β promoter. (left) HEK293 cells were transfected with the indicated plasmids for 24 h before immunoblot analysis. (right) HEK293 cells were transfected with the indicated plasmids for 36 h, and then transfected with infected with SeV or poly(I:C) for 18 h for 10 h before luciferase assays. (H) Effects of TRIM38 knockdown on SeV- or poly(I:C)-induced transcription of downstream antiviral genes. HEK293 cells were transfected and treated as in (I) before qPCR analysis. Data are from one representative experiment with four (E and G) or three (H) technical replicates. The error bars are mean ± SD in E, G, and H. All experiments were repeated twice.