Fig. 8.

Co-expression of FOXL2 and Ubc9 is required for repression of the StAR gene promoter. A. Native CHO cells and CHO cells stably expressing FOXL2 were transfected with 5nM non-silencing siRNA or 5nM Ubc9 siRNA. After 24 h, the cells were transfected with −95-bp StAR promoter-luciferase, incubated for 24 h and then lysed for determination of luciferase activity. Luciferase activity values were normalized against activity levels in cells transfected with StAR promoter plasmid and pcDNA3 backbone vector (Control, value = 1). StAR promoter activity is repressed in cells stably expressing FOXL2, compared to that in native CHO cells which lack FOXL2 expression. This repression is unaffected by non-silencing siRNA, but is reduced following transfection with Ubc9 siRNA. B. and C. CHO cells stably expressing FOXL2 were transfected with 5nM non-silencing siRNA or 5nM Ubc9 siRNA. Forty-eight hours after siRNA transfection, cells were lysed and Ubc9 (B) and FOXL2 protein expression (C) in cell lysates were detected by immunoblotting. Transfection with Ubc9 siRNA reduces the amounts of Ubc9 in these cells (B) and also reduces the amount of SUMO-modified FOXL2 (SUMO-FOXL2, indicated by the bracket) (C). The results were similar for at least three separate experiments. The standard error (±SE) and statistically significant differences are shown (*, p<0.001).