FIGURE 6.

UDCA decreases LXRα target gene expression via induction of SMILE. A and B, mouse primary hepatocytes and HepG2 cells were infected with adenovirus US (Ad-US) or adenovirus sh-SMILE (Ad-shSMILE), and the cells treated with vehicle (dimethyl sulfoxide), T7 (10 μm), and UDCA (200 μm). After 12 h, the cells were harvested for Western blot analysis using the indicated antibodies. Protein levels were normalized to those of α-tubulin. Data represent mean ± S.D. of three individual experiments. C, HepG2 cells were co-transfected with pSUPER-empty or pSUPER-siSMILE together with the LXRα expression vector and the Srebp-1c-luc promoter vectors. After 24 h, the cells were treated with vehicle (dimethyl sulfoxide), 10 μm T7, and 200 μm UDCA for 12 h, and luciferase activity was quantified. D, HepG2 cells were co-transfected with pSUPER-empty and pSUPER-siSMILE. After 24 h, the cells treated with vehicle (dimethyl sulfoxide), 10 μm T7, and 200 μm UDCA for 6 h. Chromatin immunoprecipitation analysis was performed using LXRα antibody. PCR amplification of immunoprecipitated chromatin fragments was conducted using primer pairs specific for the proximal, regulatory, and a distal, nonregulatory region of the Srebp-1c gene promoter.