Repression of IFN-I responses by NFAT5 requires its DBD. (A) Nfat5 ^−/− MEF express a spliced mRNA that lacks a region comprising the DNA-binding residues in the first exon of its DBD (ΔDBD NFAT5) but preserves the dimerization and C-terminal domains. Results show the mean ± SEM of the four independent experiments shown in C. (B) Western blot with an antibody that recognizes a C-terminal peptide of NFAT5 shows that Nfat5^−/− MEF produce a shorter NFAT5 protein (ΔDBD NFAT5) due to the lack of a portion of the DBD, but maintains an in-frame C-terminal domain. Results are from two independent pairs (#1 and #2) of WT and Nfat5^−/− (ΔDBD NFAT5) MEF. Tubulin expression was used as a loading control. (C) RT-qPCR analysis of Ifnb1 and Ifit2 mRNA expression 6 h after VSV infection of wild-type and Nfat5^−/− (ΔDBD NFAT5) MEF. mRNA values for each gene were normalized to L32 RNA and are represented as relative to MOI 1-infected wild-type MEF. Results show the mean ± SEM of four independently performed experiments. Statistical significance was determined with a one-sample t test for comparisons with the reference sample (MOI 1-infected wild-type MEF) or with an unpaired t test for comparisons between the other samples. *, P < 0.05; **, P < 0.01.