title: Transforming growth factor β1 represses proximal tubular cell microRNA-192 expression through decreased hepatocyte nuclear factor DNA binding.
abstract: miR (microRNA)-192 plays key roles in renal pathological and physiological responses, by repressing targets including Zeb1, Zeb2 and Wnk1. In the present study, we have assessed the regulation of miR-192 expression. We found that TGF-β1 (transforming growth factor β1) down-regulates miR-192 and miR-194, co-transcribed in the shared precursor pri-miR (primary miR transcript)-192/194. Luciferase reporter analysis showed constitutive promoter activity within nucleotides +21 to -223. We identified HNF (hepatocyte nuclear factor) and p53 binding sites within this region that were required for constitutive promoter activity, which was decreased by TGF-β1 through an Alk5-dependent mechanism. TGF-β1 treatment decreased HNF binding to the miR-194-2/192 promoter, whereas knockdown of HNF-1 inhibited mature miR-192 and miR-194 expression. miR-192, miR-194 and HNF expression were restricted to a defined subset of human tissues including kidney, small intestine, colon and liver. Our results from the present study identify co-ordinated regulation of miR-192 and miR-194, with binding of HNF and p53 transcription factors necessary for activation of transcription, and TGF-β1-mediated repression through decreased HNF binding to its cognate promoter element.
authors.affiliation: Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff, UK.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Jenkins
authors.forename: John
authors.initials: J
authors.lastname: Martin
authors.forename: Aled O
authors.initials: AO
authors.lastname: Phillips
authors.forename: Timothy
authors.initials: T
authors.lastname: Bowen
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Fraser
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D051536:Hepatocyte Nuclear Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D051536:Hepatocyte Nuclear Factors; C546783:MIRN192 microRNA, human; D035683:MicroRNAs; D034741:RNA, Small Interfering; C508960:TGFB1 protein, human; C495901:TP53 protein, human; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53; D004247:DNA