Fig 6.

Activation of the RLR pathway does not lead to SG formation. (A) Immunofluorescence images of mock- and recombinant IFN-treated HeLa and MEF cells. Cells were fixed 24 h posttreatment and stained for G3BP. Nuclei were stained with Hoechst-33258. (B) Plasmids encoding the Flag-CARD of RIG-I or GFP-MAVS were transfected in HeLa cells. Cells were fixed 24 h posttransfection and stained for Flag (green) and G3BP (red). Nuclei were stained with Hoechst-33258. (C) In the same experiment, total RNA was isolated from plasmid-transfected cells and used for RT-qPCR analysis of IFN-β mRNA levels. Data are presented as the means ± SD of the results of triplicate experiments. (D) Immunofluorescence images of MEFs from mice deficient in RIG-I (RIG-I^KO), MDA5 (MDA5^KO), or MAVS (MAVS^KO) expression and wild-type control cells (wt) were mock transfected, transfected with pppRNA ligand, or infected with mengo-Zn (MOI = 10). Cells were fixed 6 h postinfection or -transfection and stained for G3BP. Nuclei were stained with Hoechst-33258. In the same experiment, total RNA was isolated from infected and transfected MEFs and used for RT-qPCR analysis of IFN-β mRNA levels (right panels). Data are presented as the means ± SD of the results of triplicate experiments. Note that cells that lacked IFN-β mRNA induction still formed SG via activation of PKR.