Ellison, T.I., Eckert, R.L. and MacDonald, P.N.
Notes: While the absence of the Vitamin D receptor (VDR) has profound effects in skin cells, mutation of 25-hydroxyvitamin D 1α-hydroxylase (24OHase), the enzyme required for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) hormone biosynthesis, has little effect on the skin. To determine how VDR may transactivate independent of the 1,25(OH)2D3 ligand, the human 24-hydroxylase promoter was amplified from MCF-7 genomic DNA, digested with XhoI and HindIII and inserted into the pGL3-Basic Vector. Mutations in the proximal and distal vitamin D response elements in the human 24-hydroxylase promoter were introduced using the GeneEditor™ Site-Directed Mutagenesis System. HaCaT cells, primary human fibroblasts or primary human keratinocytes were seeded at a density of 3.2 × 104 cells/well in 12-well plates and transiently transfected with reporter constructs. After 18 hours, the cells were exposed to 1,25(OH)2D3, 9-cis-retinoic acid, ethanol vehicle, or no additive and harvested 24 hours later. The luciferase activity of the cell lysates was measured using the Dual-Luciferase® Reporter Assay System. Five micrograms of RNA purified from mouse keratinocyte and fibroblast cultures was reverse transcribed and amplified for the 24OHase transcripts using the PCR Master Mix. The products were analyzed on ethidium bromide-stained 2% agarose gels. (3695)