Figure 4.

1,2-NQ and 1,4-NQ directly stimulate mouse and human AhR transformation and DNA binding in vitro. In vitro synthesized hAhR, mAhR-hAhRLBD, or mAhR and hARNT or mARNT were incubated in the presence of DMSO (1%, v/v), TCDD (20 nM), 1,2-NQ (0.5 nM–1 μM), or 1,4-NQ (0.5 nM–1 μM) for 2 h and protein-DNA complexes were detected by gel retardation analysis. Inducible AhR:ARNT:[³²P]dioxin response element (DRE) complexes (indicated by the arrows) were quantified using Fujifilm MultiGauge software and values corrected for the amount of protein: DNA complex in the presence of DMSO (control), and then normalized to the amount of complex induced by TCDD. Values represent the mean ± standard deviation of three exposure replicates and three experiments and representative gels are shown.