Kinase activity of ROP18 suppresses NF-κB activation.
A, 293T cells were transfected with a luciferase reporter construct containing three copies of the NF-κB binding site (3×κB-Luc) together with ROP18Δ27-WT-GFP, ROP18Δ27-MUT-GFP, or empty expression vectors for 24 h and treated with or without TNF-α (10 ng/ml) for 6 h before the luciferase assays were performed. RLU, relative light units. B, RAW264.7 cells were transfected with a luciferase reporter construct containing three copies of the NF-κB binding site (3×κB-Luc) together with ROP18Δ27-WT-GFP, ROP18Δ27-MUT-GFP, or empty expression vectors for 24 h and stimulated with or without LPS (100 ng/ml) for 6 h before the luciferase assays were performed. C, dose-dependent effect of ROP18 on TNF-α-induced NF-κB reporter gene activity. The cells were transiently co-transfected with NF-κB-Luc reporter plasmid and different amounts of the indicated plasmids or empty expression vectors. At 24 h after transfection, the cells were treated with TNF-α (10 ng/ml) for 8 h. D, 293T cells were infected with or without the indicated different RH strains at an m.o.i. of 1 for >12 h before the luciferase assays were performed. Data are the means ± S.D. of at least three independent experiments. *, p < 0.05; **, p < 0.01; ***, p < 0.001, compared with the control vectors.