FIG 9.

TTP regulates IFN-β production in response to LPS. (A and B) BMDMs were isolated from wild-type, DUSP1 knockout, TTP knock-in, or DUSP1/TTP double-mutant mice. The cells were stimulated with 100 ng/ml LPS for either 1 h (A) or 4 h (B), and then 50 μM 5,6-dichloro-1β-1-ribofuranosylbenzimidazole (DRB), and 5 μg/ml actinomycin D was added. IFN-β mRNA levels were then determined at the indicated times after DRB/actinomycin D addition. The levels were calculated relative to the LPS-stimulated cells prior to DRB/actinomycin D addition. The results represent the means and standard deviations of independent cultures from 3 mice per genotype. (C and D) BMDMs were isolated from wild-type, DUSP1 knockout, TTP knock-in, or DUSP1/TTP double-mutant mice. The cells were stimulated with 100 ng/ml LPS, and the levels of IFN-β mRNA were determined at 0, 1, and 4 h. Due to the different fold inductions, the results are shown on separate graphs for 1 h (C) and 4 h (D). The results represent individual cultures from 3 wild-type mice or 4 mice for other genotypes. The error bars represent standard deviations. (E) As for panel D, but the levels of IFN-β protein secreted into the medium were determined by a Luminex-based assay. The results represent the means and standard deviations of independent cultures from 4 mice per genotype. (C to E) For comparisons of TTP knock-in to wild type or DUSP1/TTP double mutants to DUSP1 knockout, *, P < 0.05 (two-tailed Student t test).