DMEM and fetal bovine serum (FBS) was obtained from Gibco Life Technologies, Inc. (Hercules, CA, USA). The chromatin immunoprecipitation (ChIP) assay kit was purchased from Millipore (Billerica, MA, USA). The M-PER mammalian protein extraction reagent, BCA, and Bradford protein assay kits were from Pierce Biotechnology Inc. (Rockford, IL, USA). ECL or enhanced kinase inhibitor Ixazomib ECL chemiluminescence reagents were obtained from either Pierce Biotechnology or Pharmacia (Erlangen, Germany). Antibodies anti-SR-BI (H-180), anti-ISX (C-16), and anti-RAR (M-454) were from Santa Cruz Biotechnologies (Santa Cruz, CA, USA), and anti-RAN was from Abcam (Cambridge, MA, USA). The anti-mouse-HRP and anti-rabbit-HRP conjugated secondary antibodies were purchased from Promega (Madison, WI, USA).

Oligonucleotides were purchased from Integrated DNA Technologies (Coralville, IA, USA). Animals, diets, and experimental procedures Mice were maintained in accordance with the Swiss and American animal protection laws throughout these experimental studies. B6;129S6-Bcmo1tm1dnp-knockout (Cmo1?/?) and control (B6;129S6) mice were housed individually under environmentally controlled conditions (24��C, 12-h light-dark cycle) with ad libitum access to feed and water. Powdered ��vitamin A-free�� diet Ssniff?EF 1/51, containing a residual amount of 0.15 IU vitamin A/g (Ssniff GmbH, Soest, Germany) was used as the basal diet. This was supplemented with control beadlets (DSM Ltd, Sisseln, Switzerland) in group 1 or with ��,��-carotene-containing beadlets (10% CWS; DSM Ltd) in groups 2 and 3 to provide 150 ��g/g ��,��-carotene.

Mice of group 3 also received 300 IU vitamin A in the form of retinyl palmitate (Dr. Ehrenstorfer GmbH, Augsburg, Germany) by weekly oral gavage in Miglyol 812 (Sasol, Witten, Germany). Lrat?/? mice used in this study have been described previously (23). For determination of the effects of vitamin A deficiency (VAD) and vitamin A sufficiency (VAS) on ISX expression in the duodenum and jejunum of these mice, they were fed AIN-93 formulation diets supplemented with 10 IU vitamin A (VAS diet) and without vitamin A supplementation (VAD diet). Diets were purchased from ResearchDiets (New Brunswick, NJ, USA). For determination of the effect of RA on intestinal ISX mRNA expression, 8 wk old Lrat?/? mice were subjected to a vitamin A-deficient diet for 10 d (AIN-93G Growing Rodent Diet Without Added Vitamin A; Research Diets, New Brunswick, NJ, USA). Animals (n=3 each) were gavaged twice, 24 h apart, with 0.5 mg RA (Sigma) dissolved in 100 ��l of corn oil or with vehicle alone. After 24 h, animals were sacrificed, and the small intestine and liver were removed and snap-frozen in liquid Entinostat nitrogen until further analyses.