Figure 9.

Activation of peroxisome proliferator-activated receptor-γ (PPARγ) differentially regulated gene expression of sterol regulatory element-binding proteins (SREBPs) and low-density lipoprotein receptor (LDLR) in cultured hepatic stellate cells (HSCs). (A). Semi-confluent HSC in six-well plates were co-transfected with the cDNA expression plasmid pPPARγ plus the luciferase reporter plasmid pSREBP-1-Luc, or pSREBP-2-Luc, containing a fragment of the 5′-flanking promoter region of srebp-1 or srebp-2 respectively. After recovery, cells were cultured for 24 h. Luciferase activities were expressed as relative units after β-galactosidase normalization [means ± standard deviation (SD); n≥ 6]; (B). Real-time PCR analyses of the steady-state mRNA levels of SREBPs and LDLR in HSC treated with the PPARγ agonist 15d-PGJ₂ (0–15 µmol·L⁻¹) for 24 h. GAPDH was used as an invariant control for calculating mRNA fold changes. Values were expressed as means ± SD (n≥ 3). *P < 0.05 versus the untreated control (the first columns on the left); (C). Western blotting analyses of the abundance of SREBPs and LDLR in HSC treated with 15d-PGJ₂ (0–15 µmol·L⁻¹) for 24 h. β-actin was used as an invariant control for equal loading. Representative results from one of three independent experiments. Italic numbers beneath the blots were fold changes in the densities of the bands compared with the control without treatment in the blot (mean; n= 3), after normalization with the internal invariable control β-actin. Because of the limited space, standard deviations are not presented.