FIGURE 1.

Activation of BLV LTR activity by DNA methylation inhibitors. A, Raji cells were transiently transfected using the DEAE-dextran procedure with 500 ng of pLTRmSssIme, where the BLV LTR had previously been methylated in vitro by the SssI methyltransferase. At 22 h after transfection, cells were mock-treated or treated with increasing concentrations of procaine (0, 2.5, 5, 7.5, and 10 mm), procainamide (0, 2.5, 5, 7.5, and 10 mm), 5-AZAdc (0, 50, 100, 150, and 200 nm), or zebularine (0, 0.05, 0.1, 0.25, and 0.5 mm). Luciferase activities were measured in cell lysates 96 h after transfection and normalized to protein concentrations. Results are presented as histograms indicating the procaine, procainamide, 5-AZAdc, and zebularine inductions of pLTRmSssIme with respect to its basal activity, which was assigned a value of 1. Means ± S.E. are shown. Results from a representative experiment of three independent transfections are shown. B, Raji cells were transiently transfected using the DEAE-dextran procedure with 500 ng of the episomal vector pLTR*mSssIme, where the BLV LRT had previously been methylated in vitro by the SssI methyltransferase. At 22 h posttransfection, cells were mock-treated or treated with increasing concentrations of procaine (0, 0.1, 0.5, 1, and 10 mm), procainamide (0, 0.1, 0.5, 1, and 10 mm), 5-AZAdc (0, 250, 500, 1000, and 2500 nm), or zebularine (0, 0.05, 0.075, 0.1, and 1 mm). Luciferase activities were measured in cell lysates 96 h after transfection and normalized to protein concentrations. Results are presented as histograms indicating the procaine, procainamide, 5-AZAdc and zebularine inductions of pLTR*mSssIme with respect to its basal activity, which was assigned a value of 1. Means ± S.E. are shown. The results from a representative experiment of three independent transfections are shown.