Figure 2.

Differential effect of TRα/T₃ signaling on the promoter activity of steroidogenic enzyme genes. A and B, Effects of TRα and/or T₃ on steroidogenic enzyme gene promoters were tested using promoter-luciferase reporter constructs. MA-10 cells were transfected with 100 ng of TRα expression plasmids and 150 ng of the indicated luciferase reporter gene. Cells were treated with 8Br-cAMP (0.5 mM) and T₃ (100 nM) and assayed for luciferase activity after 24 hours' incubation. In all panels, values are the means ± SEM of 3 independent experiments performed in duplicate. *, P < .05; **, P < .01.