FIGURE 2.

HCV NS4B protein increases the transcriptional activity of SREBP-2. A, Huh7 cells were cotransfected with SRE-Luc reporter plasmid together with the indicated expression plasmids. At 36 h after transfection, cells were harvested, and luciferase activities were determined. The amount of DNA in each transfection was kept constant by adding an appropriate amount of pEF6-Myc empty vector. Data represent the mean of two independent experiments. B, HCV NS4B increases the transcriptional activity of SREBP-2 in a dose-dependent manner. Huh7 cells were cotransfected with SRE-Luc reporter plasmid together with increasing amounts of Myc-tagged NS4B expression plasmid. At 36 h after transfection, cells were harvested, and then luciferase activities were determined (upper panel). Equal amounts of cell lysates were subjected to immunoblotting with anti-Myc monoclonal antibody (lower panel). C, both vector and NS4B-Myc stable cells were transfected with SRE-Luc reporter plasmid. At 36 h after transfection, cells were harvested and then luciferase activities were determined. D, Huh7 cells were transfected with either vector control or NS4B-Myc expression plasmid. At 36 h after transfection, total cell lysates were immunoblotted with the indicated antibodies. E, total cell lysates harvested from both vector stable and NS4B-Myc stable cells were immunoblotted with the indicated antibodies. Protein expression of β-actin was used as a loading control for the same amount of cell lysates.