FIG. 3.

The AP-1 binding site is necessary for synergistic activation of the TNFα promoter. (A) Comparison of −120 and −95 TNFα promoter reporter constructs on C/EBPβ-plus-c-Jun activation in PMA-induced Jurkat T cells. Jurkat T lymphocytes were transfected with plasmid vectors expressing C/EBPβ (1 μg) and c-Jun (0.25 μg), separately or together, plus the −120 TNFα or the −95 TNFα promoter reporter (3 μg/transfection). The experiments were performed and analyzed as described for Fig. 2A. The results presented are the means ± 1 SE of three experiments. (B) Effects of cotransfection of c-Jun and c-Jun mutants on activation of the −95 TNFα promoter reporter construct. Jurkat T cells were transfected with the −95 TNFα-luciferase promoter reporter (3 μg), the CMV-C/EBPβ expression vector (2 μg), and various concentrations of wild-type or mutant c-Jun expression vectors (each at 0.25, 1, 3, and 5 μg/transfection). The experiments were performed, and cells were harvested and analyzed, as described for Fig. 2A. The results presented are the means ± 1 SE of two experiments.