title: Involvement of multiple elements in FXR-mediated transcriptional activation of FGF19.
abstract: The intestinal endocrine hormone human fibroblast growth factor 19 (FGF19) is involved in the regulation of not only hepatic bile acid metabolism but also carbohydrate and lipid metabolism. In the present study, bile acid/farnesoid X receptor (FXR) responsiveness in the FGF19 promoter region was investigated by a reporter assay using the human colon carcinoma cell line LS174T. The assay revealed the presence of bile acid/FXR-responsive elements in the 5'-flanking region up to 8.8 kb of FGF19. Deletion analysis indicated that regions from -1866 to -1833, from -1427 to -1353, and from -75 to +262 were involved in FXR responsiveness. Four, four, and two consecutive half-sites of nuclear receptors were observed in the three regions, respectively. An electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay revealed FXR/retinoid X receptor α (RXRα) heterodimer binding in these three regions. EMSA and reporter assays using mutated constructs indicated that the nuclear receptor IR1, ER2, and DR8 motifs in the 5'-flanking region were involved in FXR responsiveness of FGF19. Lithocholic acid (LCA) (10 μM), chenodeoxycholic acid (CDCA) (10 μM), or GW4064 (0.1 μM) treatment increased reporter activity in a construct including the three motifs under FXR-expressing conditions whereas LCA and not CDCA or GW4064 treatment increased the reporter activity under pregnane X receptor (PXR)-expressing conditions. These results suggest that FGF19 is transcriptionally activated through multiple FXR-responsive elements in the promoter region.
authors.affiliation: Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan. miyata@m.tohoku.ac.jp
authors.forename: Masaaki
authors.initials: M
authors.lastname: Miyata
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hata
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamakawa
authors.forename: Tatehiro
authors.initials: T
authors.lastname: Kagawa
authors.forename: Kouichi
authors.initials: K
authors.lastname: Yoshinari
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Yamazoe
mesh_terms: D045744:Cell Line, Tumor; D002635:Chenodeoxycholic Acid / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D000077297:Pregnane X Receptor; D011401:Promoter Regions, Genetic / Q000235:genetics*; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000378:metabolism; D011987:Receptors, Steroid / Q000235:genetics; D047490:Retinoid X Receptor alpha / Q000378:metabolism; D015533:Transcriptional Activation; D000099150:Receptor, Farnesoid X-Activated
chemical_list: D002635:Chenodeoxycholic Acid; D005346:Fibroblast Growth Factors; D000077297:Pregnane X Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D047490:Retinoid X Receptor alpha; D000099150:Receptor, Farnesoid X-Activated; C117476:FGF19 protein, human