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. 2021 Feb 23;62:100051. doi: 10.1016/j.jlr.2021.100051

Fig. 3.

Fig. 3

4β-HC induces lipogenic programs through the LXRs. A: 4β-HC interacts with LXR and RXR agonists and antagonists like an LXR ligand. Huh7 cells were treated with 20 μM 4β-HC, RXR agonist, 9-cis-retinoic acid (9-RA), LXR antagonist (GSK-2033), and LXR agonist (GW3965). For convenience, agonists are marked in green and antagonists are marked in red (N = 3). B: LXRα and LXRβ are required for SREBP1c induction by 4β-HC in Huh7 cells. Knockdown of LXRα or LXRβ by siRNA for 72 h followed by treatment with 5 μM 4β-HC for 24 h followed by RT-PCR of SREBP1c. (N = 3). C: Knockdown efficiency was evaluated by measurement of LXRα and LXRβ protein levels (N = 3). D: 4β-HC induction of lipogenic genes. Huh7 cells were treated for 24 h with 4β-HC, 24-HC, or LXR agonist (GW3965) followed by mRNA measurement of fatty acid synthase (FASN), stearoyl-CoA desaturase 1 (SCD1), and lipin1 (LPIN1) (N = 3). E: 4β-HC increases de novo lipogenesis. Huh7 cells were treated for 24 h with 5 μM 4β-HC, 24-HC, or LXR agonist (GW3965) with media containing C13 glucose followed by lipid extraction. C13 incorporation into TAGs was measured via LC/MS (N = 5). The asterisk denotes an unspecific band in the LXRα blot. Bars are the mean + SD. Statistical significance was calculated by one-way ANOVA. ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001, ∗∗∗∗P < 0.0001. 4β-HC, 4β-hydroxycholesterol; 24-HC, 24-hydroxycholesterol.