FIG. 9.

The recruitment of IRF-1 and NF-κB regulates different stages of TAP1 and LMP2 gene expression in response to CD40 stimulation. (A and B) Effects of IRF-1 knockdown on CD40-mediated TAP1 and LMP2 upregulation. EJ cells were transfected with either IRF-1 siRNA (IRF-1) or control scramble siRNA (scr), stimulated with CD40L, and lysed. The levels of IRF-1 expression were assessed by immunoblotting (A). Alternatively, RNA was isolated and subjected to RT-PCR using primers specific for the IRF-1, TAP1, or LMP2 gene or the GAPDH housekeeping gene, which served as an amplification control (B). The data shown are representative of results from three independent experiments. +, present; −, absent. (C) Effects of NF-κB inhibition on CD40-mediated TAP1 and LMP2 upregulation. EJ cells were pretreated with an IKKβ inhibitor (lanes 4 and 5) or a vehicle control (dimethyl sulfoxide; lanes 1 to 3) and then stimulated with CD40L for 1 or 5 h, as indicated. RNA was isolated and subjected to RT-PCR using primers specific for the IRF-1, TAP1, or LMP2 gene or the GAPDH housekeeping gene. The data are representative of results from four independent experiments.