PCAF interacts with XBP-1S and mediates XBP-1S-dependent transcription

Lew, Qiao Jing; Chu, Kai Ling; Lee, Jialing; Koh, Poh Ling; Rajasegaran, Vikneswari; Teo, Jin Yuan; Chao, Sheng-Hao

Cells were co-transfected with the luciferase reporter (i.e. HTLV-Luc or BiP-Luc), a XBP-1S plasmid, and an indicated siRNA ( Figure 4B and C) . Compared to the transfection excluding the XBP-1S expression vector, 6and 18-fold enhancement in the activation of HTLV and BiP promoters was observed ( Figure 4B and C, the first two transfections). The GL3 siRNA, which specifically targeted the GL3 luciferase used in the HTLV-Luc and BiP-Luc reporters, was used as a positive control and caused 90% decreases in luciferase expression under the control of HTLV and BiP promoters ( Figure 4B and C, the second and third transfections). The two PCAF siRNAs inhibited 40% luciferase expression driven by HTLV promoter, while no significant effects were caused by either p300 siRNA ( Figure 4B ). Similar observations were found in the BiP-Luc reporter assays ( Figure 4C ). Results obtained from the PCAF overexpression and knockdown reporter assays (Figures 3 and 4) demonstrate the functional involvement of PCAF in the genes regulated by XBP-1S.