Abstract: AIM: To study whether there is significant difference in the inductive effects on CYP3A4 between human vitamin D Receptor (hVDR) wild type and start codon Fok I mutant. METHODS: Total RNA was extracted from liver samples.cDNA of hVDR wild type was acquired by RT-PCR, and cDNA with hVDR Fok I mutant was acquired using site-directed mutagenesis.Eukaryotic expression vectors of both wild type and mutant of hVDR were constructed according to cDNA.Meanwhile, luciferase reporter gene vector was constructed with proximal ER6 element of CYP3A4. COS-7 cells with hVDR eukaryotic expression vectors, CYP3A4 luciferase reporter gene vector and the internal control vector were transiently transfected for 24 h and then were incubated with 1 nmol/L, 10 nmol/L and 100 nmol/L 1, 25(OH)₂D₃ for 48 h.Finally the cells were lysed and the luciferase activity was detected with cell lysis. RESULTS: hVDR eukaryotic expression vectors of wild type and Fok I mutant, and CYP3A4 luciferase reporter gene vector were successfully constructed.The results of luciferase activity showed that CYP3A4 transcription could be activated by hVDR eukaryotic expression vectors of wild type and Fok I mutant when incubated with 1 nmol/L, 10 nmol/L and 100 nmol/L 1, 25 (OH)₂D₃, respectively.However, there was no significant difference between the luciferease activities of hVDR wild type and mutant. CONCLUSION: Both hVDR wild type and Fok I mutant have inductive effect on CYP3A4 when incubated with vitamin D₃ (VD₃).But Fok I mutant could not significantly change the regulational capacity of wild type VDR on CYP3A4.

Key words: vitamin D receptor, CYP3A4A, Fok I mutation, transcriptional control