FIGURE 3.

Nuclearly targeted PrxII protects cancer cell death against DNA damage in a peroxidase-independent manner. A and B, ectopic expression of PrxII in cytosol and nucleus of HeLa cells. HeLa cells were transfected with either control or PrxII siRNA for 24 h. Then PrxII siRNA-transfected cells were infected with the retroviruses encoding PrxII wild type (WT) targeted to cytosol (Cyto) and nucleus (NLS), respectively. The expression was assessed by immunoblotting (IB) (A) and immunostaining (B). Immunostaining of the expressed PrxII proteins were detected with anti-Myc antibody (green). Nuclei are labeled with DAPI (blue). C, reduction of etoposide (ETO)-induced cell death by add-back expression of PrxII WT in cytosol and nuclei. D, reduction of etoposide-induced cell death by add-back expression of PrxII WT and activity-dead mutant (DM) in nuclei. A and D, the extent of endogenous (endo) and exogenous (exo) Myc-tagged PrxII expression shows percent of the band intensities versus one in control cells (mean values from three experiments). Data in the graph are means ± S.D. of results from three independent death assays as done in Fig. 2 (n = 3; *, p < 0.005). N/T, not treated.