Figure 3.

Sp1 overexpression increases the activity of the Ucn promoter. A, PC12 cells were cotransfected with pGL2-hUS2 or deleted mutants of the hUcn promoter, or the empty reporter vector (pGL2-Basic) (0.75 μg), and the Sp1 expression vector (Sp1) or the respective empty vector (pCGN) (0.8 μg). Luciferase activity of pGL2-Basic plus pCGN was 0.081 ± 0.006 and of pGL2-Basic plus Sp1 was 0.406 ± 0.059. B, PC12 cells were cotransfected with pGL2-hUS2 (0.5 μg) and Sp1 and pcDNA-ERα (0.35 μg) expression vectors. PC12 cells were cotransfected with PGL2-hUS2 and pcDNA-ERα and increasing amounts of Sp1 expression vector (0.15, 0.35, and 0.75 μg). Transfected cells were treated for 24 h with 10 nm E₂ or vehicle (V; ethanol). Luciferase activity corresponds to light units of firefly luciferase normalized to total protein. Statistical analysis by ANOVA followed by Newman–Keuls post hoc test gave the following significances: (in A) ★, p < 0.001, ✚, p < 0.01, and ▪, p < 0.05 compared with the empty vector; (in B) ★, p < 0.001 and ▪, p < 0.05 compared with respective vehicle control; ×, p < 0.001, compared with 0.15 and 0.35 μg Sp1/pcDNA-ERα treated to vehicle; ♦, p < 0.01, compared with 0.35 Sp1/pcDNA-ERα.