Figure 4

Extra-genomic functionality of the PPRE-containing promoter regions of PPAR target genes. Reporter gene assays were performed with extracts from (a-c) HEK293 and (d-f) HepG2 cells that were transiently transfected with luciferase reporter constructs containing genomic regions of eight human PPAR target genes (please note that the APOC3 gene forms a cluster with the genes APOC1 and APOC4). These were co-transfected with empty expression vector (endogenous PPAR) or the indicated expression vectors for PPARα, PPARγ and PPARβ/δ. Cells were then treated for 16 h with solvent or PPAR subtype-specific ligands. Relative luciferase activity was determined and normalized to the activity of empty cloning vector control co-transfected with empty expression vector (dashed horizontal red line). The genomic regions were subdivided according to their location into close to TSS (a, d), upstream of TSS (b, e) and downstream of TSS (c, f); for further details see Figure 3 and Table 2. Columns represent the means of at least three experiments and bars indicate standard deviations. Two-tailed Student's t-tests were performed to determine the significance of the ligand induction in reference to solvent controls (*p < 0.05, **p < 0.01, ***p < 0.001).