Fig. 4.
Effect of diesel emission samples on AhR and Nrf2 activity. A) Activation of DRE and Nrf2 luciferase activity by diesel emission samples. U937 macrophages were transiently transfected with DRE- and Nrf2-luciferase reporter plasmids for 24 h and treated with S100 (10 μg/ml) and CARB ULSD (10 μg/ml) or TCDD (1nM), and tert-butylhydroquinone (tert-BHQ 10 μM) as positive controls. Values are given as mean ± SD of three independent experiments. An asterisk indicates significantly different from control cells (p < 0.05). B) Increased DNA binding of AhR by diesel emission samples. Nuclear protein extracts of non-stimulated (Ctrl), CARB ULSD (10 μg/ml), S100 (10 μg/ml), and 1 nM TCDD-stimulated U937 macrophages were incubated with a DRE consensus probe. Competition (Comp.) with a 100-fold excess of unlabeled DRE consensus (lane 5) oligonucleotide. One representative experiment of three independently performed experiments is shown.