FIG. 4.

Effects of overexpression of different PKC isoforms on the induction of human LDL receptor promoter transcription. (A) HepG2 cells were grown as described and cotransfected with LDL receptor-luciferase reporter (14, 33) and a vector control plasmid or each of the PKC isoform wild-type or CA cDNA expression vectors. After 24 h, cells were incubated in medium containing 10% LPDS, as described in the legend to Fig. 2. After 12 h, cells were harvested, and luciferase activity was determined and normalized to the protein content of each extract. Luciferase activity expressed by cells transfected with empty vector was given an arbitrary value of 1. The amounts of DNA used were as follows: LDL receptor-luciferase reporter, 0.6 μg per well; and expression vector, 0.3 μg per well. The results are presented as means ± standard error and represent at least four individual experiments. (B) HepG2 cells were cotransfected with LDL receptor-luciferase reporter plasmid (0.6 μg per well) and the indicated amounts of expression vector encoding CA PKCɛ. Transfected cells were incubated in 10% LPDS, as mentioned above, and luciferase activity and protein contents were measured after 12 h. Each column represents the mean ± standard error of three independent experiments performed in duplicate.