title: Farnesoid X receptor, hepatocyte nuclear factors 1alpha and 3beta are essential for transcriptional activation of the liver-specific organic anion transporter-2 gene.
abstract: BACKGROUND
  We isolated the human liver-specific organic anion transporter gene, LST-2 (OATP8/SLCO1B3), which is exclusively expressed in the basolateral membrane of the hepatocytes. In this study, we analyzed the transcriptional regulation of the LST-2 gene in hepatocyte-derived cells and the effect of bile acid.
  
  
  METHODS
  Transcriptional activity of the LST-2 gene was measured using a human LST-2 promoter-luciferase reporter plasmid under various concentrations of bile acids. Electrophoresis mobility shift assays of farnesoid X receptor (FXR), hepatocyte nuclear factor (HNF) 1alpha, and HNF3beta were performed.
  
  
  RESULTS
  Luciferase analysis showed that the 5'-flanking region from -180 to -20 bp is responsible for LST-2 transcriptional activity. By site-directed mutation analysis, it was revealed that the consensus binding sites for FXR, HNF1alpha, and HNF3beta play important roles in the transcriptional activity of the LST-2 gene. By electrophoresis mobility shift assay, we observed specific protein-DNA complexes of FXR, HNF1alpha, and HNF-3beta. Luciferase activity was increased fivefold when chenodeoxycholate or deoxycholate were added. Northern blot analyses revealed that the expression of LST-2 was increased by addition of chenodeoxycholate or deoxycholate in a dose-dependent manner.
  
  
  CONCLUSIONS
  This study demonstrated that the transcription of the LST-2 gene is regulated by three transcription factors, FXR, HNF1alpha, and HNF3beta. HNF1alpha and HNF3beta might contribute to its liver-specific expression, and FXR might play a role in its transcriptional activation by bile acids.
authors.affiliation: Division of Gastroenterological Surgery, Department of Surgery, Tohoku University Graduate School of Medical Science, Sendai 980-8574, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Ohtsuka
authors.forename: Takaaki
authors.initials: T
authors.lastname: Abe
authors.forename: Tohru
authors.initials: T
authors.lastname: Onogawa
authors.forename: Noriko
authors.initials: N
authors.lastname: Kondo
authors.forename: Takeaki
authors.initials: T
authors.lastname: Sato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Oshio
authors.forename: Hiroya
authors.initials: H
authors.lastname: Mizutamari
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Mikkaichi
authors.forename: Masaya
authors.initials: M
authors.lastname: Oikawa
authors.forename: Toshiki
authors.initials: T
authors.lastname: Rikiyama
authors.forename: Yu
authors.initials: Y
authors.lastname: Katayose
authors.forename: Michiaki
authors.initials: M
authors.lastname: Unno
mesh_terms: D001647:Bile Acids and Salts / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000378:metabolism*; D051542:Hepatocyte Nuclear Factor 3-beta / Q000378:metabolism*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D016296:Mutagenesis; D029362:Organic Anion Transporters, Sodium-Independent / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D000074542:Solute Carrier Organic Anion Transporter Family Member 1B3; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D000099150:Receptor, Farnesoid X-Activated
chemical_list: D001647:Bile Acids and Salts; D004247:DNA; D004268:DNA-Binding Proteins; D051538:Hepatocyte Nuclear Factor 1-alpha; D051542:Hepatocyte Nuclear Factor 3-beta; D029362:Organic Anion Transporters, Sodium-Independent; D018160:Receptors, Cytoplasmic and Nuclear; D000074542:Solute Carrier Organic Anion Transporter Family Member 1B3; D014157:Transcription Factors; D000099150:Receptor, Farnesoid X-Activated; C421209:SLCO1B3 protein, human