FIG. 2.

EBNA-3C potentiates EBNA-2 activation of the LMP1 promoter in BJAB, a non-EBV-infected BL cell line. (A) BJAB cells were transfected with reporter plasmid p(−512/+72)LMP1p-Luc, which has two tandem copies of the −512/+72 LMP1 promoter upstream of the luciferase gene, in addition to the indicated amounts of the pSG5-EBNA-2 (E2) and pSG5-EBNA-3C (E3C) expression vectors. Fold increase in luciferase activity is shown on the left. The panels below the graph show corresponding immunoblots using a monoclonal antibody against EBNA-2 (PE2). The results are representative of at least two independent experiments. WB, Western blot. (B) Response of p(−512/+72)LMP1p-Luc activity to 1 μg of pSG5-EBNA-2 and various increasing amounts (0.1 to 20 μg) of pSG5-EBNA-3C. The values shown are representative ratios of observed luciferase activity relative to that of EBNA-2 alone from at least two experiments. (C) Representative reporter assay using BJAB cells transfected with a reporter construct (pLuc-Cp) containing eight copies of the RBP-Jκ-binding site from the Cp promoter, 1 μg of pSG5-EBNA-2, and various amounts of pSG5-EBNA-3C. The relative luciferase values, indicated on the left in all experiments, were normalized to the β-galactosidase activity of a cotransfected plasmid, pGK-βgal.