We reported the human
flavin-containing monooxygenase 3 (FMO3) haplotypes (
Pharmacogenet. Genomics:
17, 827, 2007). The objective was to gain the insight into transcriptional regulation in a Japanese population. The wild-type FMO3 reporter plasmids carrying 5′-flanking sequence from the transcriptional initiation site of the
FMO3 haplotype 1 (prepared from three individuals) showed higher luciferase activities in HepG2 cells than those from the
FMO3 haplotypes 2 and 3, with the wild-type coding region. Several deletion mutants of the
FMO3 haplotype 1 (extending from −5,167 to −1,764, numbered relative to the A of the ATG translational initiation codon) revealed that the region of −2,064 to −1,804 contained an important
cis-acting element(s) for activation of the
FMO3 gene expression. Putative hepatocyte nuclear factor-4 (HNF-4) binding site and CCAAT box, but not Yin Yang 1 element, could be responsible
cis-acting elements of the
FMO3 gene, by site-directed mutagenesis analysis. The unknown suppressive
cis-element(s) at the 5′-upstream region from −2,064 might show genetic polymorphism, because the
FMO3 haplotypes 2 and 3 had three and ten mutations, respectively. These results suggest that the putative HNF-4 binding site and CCAAT box could be responsible
cis-acting elements of the
FMO3 gene in Japanese.
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