title: SREBP-2 negatively regulates FXR-dependent transcription of FGF19 in human intestinal cells.
abstract: Sterol regulatory element-binding protein-2 (SREBP-2) is a basic helix-loop-helix-leucine zipper transcription factor that positively regulates transcription of target genes involved in cholesterol metabolism. In the present study, we have investigated a possible involvement of SREBP-2 in human intestinal expression of fibroblast growth factor (FGF)19, which is an endocrine hormone involved in the regulation of lipid and glucose metabolism. Overexpression of constitutively active SREBP-2 decreased FGF19 mRNA levels in human colon-derived LS174T cells. In reporter assays, active SREBP-2 overexpression suppressed GW4064/FXR-mediated increase in reporter activities in regions containing the IR-1 motif (+848 to +5200) in the FGF19 gene. The suppressive effect disappeared in reporter activities in the region containing the IR-1 motif when the mutation was introduced into the IR-1 motif. In electrophoretic mobility shift assays, binding of the FXR/retinoid X receptor α heterodimer to the IR-1 motif was attenuated by adding active SREBP-2, but SREBP-2 binding to the IR-1 motif was not observed. In chromatin immunoprecipitation assays, specific binding of FXR to the IR-1-containing region of the FGF19 gene (+3214 to +3404) was increased in LS174T cells by treatment with cholesterol and 25-hydroxycholesterol. Specific binding of SREBP-2 to FXR was observed in glutathione-S-transferase (GST) pull-down assays. These results suggest that SREBP-2 negatively regulates the FXR-mediated transcriptional activation of the FGF19 gene in human intestinal cells.
authors: Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan; Department of Food Science and Technology, National Fisheries University, 2-7-1, Nagatahonmatch, Shimonoseki 759-6595, Japan. Electronic address: mmiyata@fish-u.ac.jp.
authors: Masaaki
authors: M
authors: Miyata
authors: Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors: Tatsuya
authors: T
authors: Hata
authors: Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors: Yasushi
authors: Y
authors: Yamazoe
authors: Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
authors: Kouichi
authors: K
authors: Yoshinari
mesh_terms: D002460:Cell Line; D015536:Down-Regulation; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D051782:Sterol Regulatory Element Binding Protein 2 / Q000378:metabolism*; D015533:Transcriptional Activation; D000099150:Receptor, Farnesoid X-Activated
chemical_list: D005346:Fibroblast Growth Factors; D018160:Receptors, Cytoplasmic and Nuclear; D051782:Sterol Regulatory Element Binding Protein 2; D000099150:Receptor, Farnesoid X-Activated; C117476:FGF19 protein, human; C497390:SREBF2 protein, human
keywords: ChIP; DR-1; EMSA; ER-8; FGF19; FXR; GST; IR-1; LDLR; LS174T; PXR; RXRα; SREBP-2; Transcription; chromatin immunoprecipitation; direct repeat separated by 1 nucleotide; electrophoretic mobility shift assay; everted repeat separated by 8 nucleotides; farnesoid X receptor; fibroblast growth factor 19; glutathione-S-transferase; inverted repeat separated by 1 nucleotide; low-density lipoprotein receptor; pregnane X receptor; retinoid X receptor α; sterol regulatory element-binding protein-2