FIGURE 6

Agonistic effects of 1,25(OH)₂D₃ and its analogs in HaCaT cells. Luciferase reporter gene assays were performed with extracts from HaCaT cells that were transiently transfected with a reporter gene construct-driven by three copies of the GAL4 binding site and an expression vector for a GAL4_DBDVDR_LBD fusion protein (A) or with a luciferase reporter gene construct driven by four copies of the rat ANF DR3-type VDRE together with the expression vectors for VDR and RXR (B) as schematically depicted above the respective figures. The cells were treated for 16 h with graded concentrations of 1,25(OH)₂D₃ or its analogs. Stimulation of luciferase activity was calculated in comparison with solvent-induced controls. Data points represent the mean of triplicates and the bars indicate SD. The EC₅₀ values for stimulation of VDR-driven gene activity were determined from the respective dose–response curves.