Figure 4.
The proximal CYP24A1 promoter contains the elements necessary for enhancement of 1,25(OH)2D3 transactivation by PMA. Differentiated Caco-2 cells were transfected with one of two different hCYP24A1 promoter-luciferase plasmids (−298 to +74 bp or −5500 to −22 bp). 15 h after transfection, cells were pre-treated with 100 nM PMA for 10 min followed by 10 nM 1,25(OH)2D3 for 4 h in the absence of PMA. Data are expressed as mean±sem (n=6) relative to the 1,25(OH)2D3-induced expression of the −298 to +74 bp hCYP24A1 promoter (calculated as 1,25(OH)2D3/vehicle = 100). Bars with different letter superscripts are significantly different from one another (P< 0.05, Fisher’s protected LSD).
