Figure 3.
NF-κB involvement in LMP1-mediated suppression of the SAP gene. (A) Nuclear translocation of NF-κB/p65 was increased on LMP1-H9 cells. H9 cells were transfected with pSG5 and pSG5-LMP1 with or without TRAF2/5 dominant-negative (DN) mutants. Both nuclear (N) and cytoplasmic (C) p65RelA protein in H9 cells were detected by Western blotting. α-actin and histone H1 were used as controls for cytoplasmic and nuclear fractions, respectively. The nuclear-cytoplasm ratio of NF-κB/p65 protein was significantly increased on LMP1-H9 cells. Cotransfection with TRAF2/5 dominantnegative mutants could reduce this effect. (B) NF-κB activation was enhanced by expressing LMP1 in H9 cells. H9 cells and its sublines were transfected with NF-κB–driven luciferase constructs. Constitutive activation of NF-κB was clearly demonstrated in LMP1-expressing H9 T cells, but decreased in those cells coexpressed with dominant-negative TRAF2 or TRAF5 constructs. (C) Inhibition of LMP1-mediated suppression of SAP by NF-κB inhibitor. LMP1-H9 cells were first treated with 0.005, 0.01, or 0.02 μg/μL Bay11-7082 for 2 hours, washed by PBS, and then incubated with normal medium for an additional 6 hours. Dosage-dependent induction of SAP protein by Bay11-7082 in LMP1-H9 cells was shown. Error bars representing the standard deviation of 3 experiments are shown.