Figure 10.

The effects of the expression of Nur77, SF-1, and DAX-1, independently or in combination on StAR promoter activity; the effects of DAX-1, (Bu)₂cAMP, and PMA on Nur77, SF-1; and P450scc expression in MA-10 cells. A, Using the −151/−1-bp StAR reporter segment, cells were transfected with empty vector (pcDNA3), Nur77, SF-1, DAX-1, or a combination thereof as indicated in the presence of 15–20 ng of pRL-SV40. After 36 h of transfection, cells were incubated for an additional 6 h in the absence (basal) or presence of (Bu)₂cAMP (0.5 mm) and PMA (10 nm), and luciferase activity in the cell lysates was determined [relative light units (RLU), luciferase/renilla] and expressed in terms of fold activity. Data represent the mean ± se of three to five independent experiments. Cells were also transfected with either empty vector (pcDNA3) or DAX-1 expression plasmids and subjected to immunoblotting for Nur77, SF-1, and P450scc expression using 20–25 μg of total cellular protein (B). Cells were treated with (Bu)₂cAMP (0.5 mm) and PMA (10 nm) for 6 h, and the expression of Nur77, SF-1, and P450scc proteins was determined by immunoblotting. Actin expression demonstrates equal loading. Representative immunoblots illustrate the expression of Nur77, SF-1, and P450scc proteins in different treatment groups. Integrated OD (IOD) values of each band were quantified and compiled data from three independent experiments are presented (lower panel). Letters above the bars indicate that these groups differ significantly from each other, at least at P < 0.05. *, P < 0.05; **, P < 0.01; ***, P < 0.001 represent significant differences in comparison with respective controls.