MOLECULAR GENETIC AND ENZYMATIC BASIS OF INTERINDIVIDUAL AND INTERETHNIC DIFFERENCES IN DRUG METABOLISM

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New insights into the regulation of CYP2C9 gene expression: The role of the transcription factor GATA-4

Publication . Mwinyi, Jessica; Nekvindova, Jana; Cavaco, Isa; Hofmann, Yvonne; Pedersen, Rasmus Steen; Landman, Ellie; Mkrtchian, Souren; Ingelman-Sundberg, Magnus

CYP2C9 is an important drug-metabolizing enzyme that metabolizes, e. g., warfarin, antidiabetics, and antiphlogistics. However, the endogenous regulation of this enzyme is largely unknown. In this study, we examined the role of GATA transcription factors in the gene expression of CYP2C9. We investigated four putative GATA binding sites within the first 200 base pairs of CYP2C9 promoter at the positions I: -173/-170, II: -167/-164, III: -118/ -115, and IV: -106/-103. Luciferase activity driven by a wildtype CYP2C9 promoter construct was strongly up-regulated in Huh-7 cells upon cotransfection with expression plasmids for GATA-2 and GATA-4, whereas mutations introduced into GATA binding site III or I and II reduced this induction to a significant extent. 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 assays in HepG2 cells. Taken together, these data strongly suggest an involvement of liver-specific transcription factor GATA-4 in the transcriptional regulation of CYP2C9.

2010-03Journal article

Open Access

Cytochrome 1A1 and 1B1 gene diversity in the Zanzibar islands

Publication . Cavaco, I.; Piedade, R.; Msellem, M. I.; Bjorkman, A.; Gil, José Pedro

Amodiaquine (AQ) is a 4-aminoquinoline widely used in the treatment of malaria as part of the artemisinin combination therapy (ACT). AQ is metabolised towards its main metabolite desethylamodiaquine mainly by cytochrome P450 2C8 (CYP2C8). CYP1A1 and CYP1B1 play a minor role in the metabolism but they seem to be significantly involved in the formation of the short-lived quinine-imine. To complete the genetic variation picture of the main genes involved in AQ metabolism in the Zanzibar population, previously characterised for CYP2C8, we analysed in this study CYP1A1 and CYP1B1 main genetic polymorphisms. The results obtained show a low frequency of the CYP1A1*2B/C allele (2.4%) and a high frequency of CYP1B1*6 (approximately 42%) followed by CYP1B1*2 (approximately 27%) in Zanzibar islands. Genotype data for CYP1A1 and CYP1B1 show a low incidence of fast metabolisers, revealing a relatively safe genetic background in Zanzibars population regarding the appearance of adverse effects.

2012-07Journal article

Open Access