Fig. 2.

4β-HC induces expression and activation of SREBP1 but not SREBP2. A: 4β-HC increases SREBP1 protein expression. Huh7 cells were treated with 20 μM 4β-HC and a translation inhibitor, cycloheximide (CHX), for 4 h followed by measurement of SREBP1 and SREBP2 mRNA (N = 3) and (B) protein level (N = 1). C: 4β-HC increases SREBP1 cytosolic and nuclear levels while not affecting SREBP2. Huh7 cells were treated with 4β-HC or 25-HC for 24 h followed cytosolic-nuclear fractionation to measure protein level of SREBP1 and SREBP2 cytoplasmic and nuclear levels (N = 1). Asterisk denotes unspecific band in SREBP2 nuclear blot. Bars are the mean + SD. Statistical significance calculated by one-way ANOVA. ∗∗∗∗P < 0.0001. Cyto, cytosolic; Nuc, nuclear; 4β-HC, 4β-hydroxycholesterol.