FIG 8.

NS1 expression activated caspase-9 and -3. (A and B) Caspase activity in NS1-transfected cells. HEK293T cells were transfected with plasmids as indicated. At the indicated time points posttransfection, the caspase-9 and -3 activities of the transfected cells were measured using Caspase-Glo 9 (A) and Caspase-Glo 3/7 (B) luminescent assay kits, respectively. The bar chart presents the means ± SEMs from three independent experiments. *, P < 0.05, and **, P < 0.01, versus the control group. (C) Caspase-9 and -3 are activated by NS1 expression. HEK293T cells were transfected with pEGFP-NS1 or pEGFP vector. Cells expressing pEGFP-NS1 demonstrated active caspase-9 and -3 with fluorescence in red, while the active caspases were not observed in cells expressing enhanced green fluorescent protein (EGFP) only. (D) Western blotting of pro- and cleaved caspases and PARP. NS1- transfected cells were collected at various time points posttransfection and analyzed by Western blotting for expression of caspase-9 and -3, PARP, and their cleaved proteins. β-Actin was probed as a loading control.