Fig 4. HSPs positively regulate IE2 transaction activity.

(A) vAcIE2 and vAcL co-transduced Vero E6 cells were treated with KNK437 at various concentrations, followed by luciferase assays at 48 hpt. The results show that IE2 trans-activation activity on the CMV promoter was down-regulated in a dose-dependent manner. KNK437 did not have a negative effect on the control group represented by vAcE transduction. (B) siRNA against hsp70 (B1) and hsp90 (B2) genes were transfected into Vero E6 cells, followed by vAcIE2 and vAcL co-transduction. A luciferase assay at 48 hpt detected negative effects on the IE2 trans-activation of the CMV promoter. (C) siRNA against hsp70 (C1), hsp90 (C2) and negative control siRNA against a scrambled sequence (Santa Cruz) were transfected into Vero E6 cells, followed by vAcIE2 or vAcE transduction. Cell extracts were harvested at 48 hpt and analyzed by Western blotting. (D) PGA₁, which stimulates the heat shock response, further enhanced the IE2 trans-activation effect on the CMV promoter in a dose-dependent manner.