SREBP-2 negatively regulates FXR-dependent transcription of FGF19 in human intestinal cells

• Published in: Biochemical and biophysical research communications Vol. 443; no. 2; pp. 477 - 482
• Main Authors: Miyata, Masaaki, Hata, Tatsuya, Yamazoe, Yasushi, Yoshinari, Kouichi
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10.01.2014
• Subjects: Cell Line; Down-Regulation; FGF19; Fibroblast Growth Factors - metabolism; FXR; Gene Expression Regulation - physiology; Humans; Intestines - metabolism; IR-1; LS174T; Receptors, Cytoplasmic and Nuclear - metabolism; SREBP-2; Sterol Regulatory Element Binding Protein 2 - metabolism; Transcription; Transcriptional Activation; FXR; RXRα; Transcription; SREBP-2; GST; PXR; ChIP; IR-1; DR-1; LS174T; EMSA; FGF19; ER-8; LDLR; glutathione-S-transferase; low-density lipoprotein receptor; sterol regulatory element-binding protein-2; pregnane X receptor; retinoid X receptor α; chromatin immunoprecipitation; direct repeat separated by 1 nucleotide; electrophoretic mobility shift assay; inverted repeat separated by 1 nucleotide; fibroblast growth factor 19; farnesoid X receptor; everted repeat separated by 8 nucleotides
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2013.11.126

•Activated SREBP-2 suppresses FGF19 expression in LS174T cells.•The suppressive effects are dependent on FXR-responsive elements in FGF19 gene.•SREBP-2 suppresses FXR binding to the FXR-responsive element.•SREBP-2 directly binds to FXR. 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.