nubiscan.unibas.ch). The SHP1-Luc-pGL3-basic vector was prepared as described11 containing the −571 to +1 bp fragment of the 5′-UTR of SHP1 (NR0B2)

gene inserted in the luciferase reporter containing vector pGL3-basic (Promega, Madison, WI). The BSEP promoter construct containing a 140-bp fragment of the 5′-UTR BSEP (ABCB11) has been described.12 Detailed outline of primers and subcloning strategies for the promoter fragments of the 5′-UTR of the SLCO1B1 from genomic DNA is summarized in Supporting Table 1. HepG2 cells were plated in 24-well plates. After 24 hours, the cells were transfected with 250 ng of the reporter vector (pGL3 basic variants), 25 ng of pRL-CMV (Promega) to normalize transfection efficiency, and 250 ng of the human nuclear receptors expression plasmid (LXRα- or FXR-pEF6) or vector control in 200 μL Opti-MEM Epacadostat datasheet (Invitrogen) using Lipofectin (Invitrogen). Cells were incubated for 16 hours with the transfection mixture, then treated

for 24 beta-catenin activation hours with 1 μM of a tested compound. Luminescence was quantified using a plate reader (Fluoroskan Ascent FL, Thermo-Fisher, Waltham, MA). Luciferase activities in the presence of the nuclear receptor were expressed as the percentage of cells transfected with blank vector. Huh-7 cells or primary hepatocytes were grown in 12-well plates and pretreated with agonists of LXRα or FXR or vehicle control, respectively, for

12 hours. Afterward, the cells were briefly washed with OptiMEM and then incubated with tritium-labeled taurocholate (0.4 μM) or rosuvastatin (1 μM). After 10 minutes of incubation at 37°C, the cells were washed twice with ice-cold PBS and lysed in the presence of 1% sodium dodecyl sulfate. Cellular uptake Glycogen branching enzyme was determined using a liquid scintillation counter (Tri-Carb 2900TR, PerkinElmer Life Sciences). After treatment of human hepatocytes, the cells were harvested and lysed by way of repeated thawing and freezing in 5 mM Tris HCl in the presence of Protease Inhibitors. Protein content was determined using bicinchoninic acid. Cell lysates were separated by way of sodium dodecyl sulfate–polyacrylamide gel electrophoresis and electrotransferred to a nitrocellulose membrane in a tank-blotting system (Bio-Rad, Munich, Germany). For detection of OATP1B1, a specific antiserum was used as described.4 For DNA cross-linking and chromatin immunoprecipitation, the EZ ChIP Assay (Millipore, Billerica, MA) was used according tot the manufacturer’s instructions. Briefly, Huh-7 cells were cultured in 10-cm dishes and treated for 24 hours with dimethyl sulfoxide, chenodeoxycholic acid (CDCA) (1 μM), fexaramine (1 μM), GW4065 (1 μM), TO-901317 (1 μM), or GW3965 (1 μM). DNA was cross-linked, sheared by sonication (Virsonic 100, Virtis, Gardiner, NY), then incubated with 5 μg antibody overnight at 4°C.