Fig. 3.

The RAR mediates increases in the expression levels of lipogenesis-related genes in response to retinol. a Luciferase activity of the pGL3-RARE construct in transfected HepG2 cells. The cells were treated with or without the indicated concentrations of retinol, the RAR antagonist AGN193109 (AGN), the RXR antagonist PA452 (PA), and the LXR blocker GSK2033 (GSK) in DMSO as its vehicle for 24 h. FLU: Firefly Luciferase Unit; RLU: Renilla Luciferase Unit. Reproducible result from three independent experiments was shown. b The luciferase activity of the pGL3-RARE construct in Hepa1C1C7 cells. The cells were treated as described for A. Reproducible result from three independent experiments was shown. C. The expression levels of the mRNAs encoding human STRA6, FASN, and SREBP1 in HepG2 cells treated with or without 1 μM retinol and/or 100 nM AGN in DMSO for 1 day. The experiments were performed in triplicate. Unpaired Student’s t-tests were performed in Prism8. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. D. The expression levels of the mRNAs encoding mouse STRA6, FASN, and SREBP1 in Hepa1C1C7 cells treated with or without 1 μM retinol and/or 100 nM AGN for 1 day. The experiments were performed in triplicate. Unpaired Student’s t-tests were performed in Prism8. **P < 0.01, ***P < 0.001, ****P < 0.0001. e Oil red-O staining showing the accumulation of triglyceride in HepG2 cells treated with or without 1 μM retinol and/or 100 nM AGN for 3 days. Oil-red-O-positive area % per 0.04 mm² were quantified using Image J program. Reproducible result from two independent experiments was shown. ****P < 0.0001. The nuclei were stained with hematoxylin. Scale bar: 2 μm