%0 Journal Article %A Anuradha Ramamoorthy %A Lang Li %A Andrea Gaedigk %A L. DiAnne Bradford %A Eric A. Benson %A David A. Flockhart %A Todd C. Skaar %T In Silico and In Vitro Identification of MicroRNAs that Regulate HNF4A Expression %D 2012 %R 10.1124/dmd.111.040329 %J Drug Metabolism and Disposition %P dmd.111.040329 %X Hepatic nuclear factor 4 α (HNF4A) is a nuclear transcription factor that regulates the expression of many genes involved in drug disposition. To identify additional molecular mechanisms that regulate HNF4A, we identified microRNAs (miRNAs) that target HNF4A expression. In silico analyses suggested that HNF4A is targeted by many miRNAs. We conducted in vitro studies to validate several of these predictions. Using an HNF4A 3′UTR luciferase reporter assay, five out of six miRNAs tested significantly down-regulated (~20–40%) the luciferase activity. In HepG2 cells, miR-34a and miR-449a also down-regulated the expression of both the HNF4A protein and an HNF4A target gene, PXR (~30-40%). This regulation appeared without reduction in HNF4A mRNA expression, suggesting that they must be blocking HNF4A translation. Using additional bioinformatic algorithms, we identified polymorphisms that are predicted to alter the miRNA targeting of HNF4A. Luciferase assays indicated that miR-34a and miR-449a were less effective in regulating a variant (rs11574744) than the wildtype HNF4A 3′UTR. In vivo, although not statistically significant (p=0.16), subjects with the variant HNF4A had lower CYP2D6 enzyme activity. In conclusion, our findings demonstrate strong evidence for a role of miRNAs in the regulation of HNF4A. %U https://dmd.aspetjournals.org/content/dmd/early/2012/01/09/dmd.111.040329.full.pdf