New insights into the regulation of cytochrome P450 2C9 gene expression: the role of the transcription factor GATA-4
Abstract
CYP2C9 is an important drug-metabolizing enzyme. However, its endogenous regulation is largely unknown.
We examined the role of GATA transcription factors in the gene expression of CYP2C9. We investigated four putative GATA binding sites within the first 200bp of CYP2C9 promoter at the positions I: -173/-170, II: -167/-164, III: -118/-115, and IV: -106/-103.
Luciferase activity driven by a wild-type CYP2C9 promoter construct was strongly up-regulated in Huh-7 cells co-transfected with GATA-2 and GATA-4, whereas mutations introduced into GATA binding site III or I and II reduced this induction significantly. Electrophoretic mobility shift assays revealed specific binding of GATA-4 and GATA-6 to the oligonucleotides containing GATA binding sites I and II.
Furthermore, the association of GATA-4 with CYP2C9 promoter was confirmed by chromatin immunoprecipitation in HepG2 cells. These data strongly suggest an involvement of GATA-4 in the transcriptional regulation of CYP2C9. 10.1124/dmd.109.029405