Figure 4.

Functional assays indicate enhancer activity for a representative primate-conserved element, human LDLR PS4. Luciferase assay analysis of (a) transient transfections into human HepG2 cells and (b) plasmid DNA transfer into mouse liver. The luciferase reporter constructs tested are either the LDLR promoter alone (promoter), or the promoter in combination with the human LDLR PS4 (+ PS4). Fold increase over the empty vector is shown. Error bars in (a) indicate standard deviation. Each triangle in (b) represents luciferase activity in an individual mouse. Red bars denote the median activity of each construct. Luciferase activity is reported in arbitrary units. (c) DNase I hypersensitive site mapping around the LDLR PS4 region in human liver cell line HepG2. Vertical arrows indicates the lane with internal size marker that was generated by enzyme digestion of the LDLR PS4 sequence. The hypersensitive site is indicated by a horizontal arrow. Co-migration of the internal size marker with the hypersensitive site localizes the hypersensitive site to the LDLR PS4 sequence.