Figure 4.

Participation of mitochondrial survivin in cell death. (A) Defective mitochondrial import of survivin in INS-1 cells. INS-1 (upper panel) or MCF-7 (lower panel) cells were left untreated (None) or transduced with pAd-Survivin, and isolated mitochondrial or cytosolic fractions were analyzed by immunoblotting. (B) Cytoprotection. INS-1 or MCF-7 cells were transduced with pAd-GFP or pAd-Survivin, treated with staurosporine, and analyzed for hypodiploid DNA content. Data are the mean ± SEM of 3 independent experiments. Inset: Immunoblotting of survivin in transduced INS-1 or MCF-7 cells at the indicated time intervals. (C) Differential sensitivity to apoptosis. INS-1 or MCF-7 cells were treated with suboptimal concentrations of staurosporine (STS) or UVB and analyzed for nuclear morphology of apoptosis by DAPI staining. Data are the mean ± SD of 2 independent experiments. (D) RNAi knock-down. INS-1 or MCF-7 cells were transfected with dsRNA oligonucleotides to survivin (S4) or control (VIII), and analyzed by immunoblotting. (E) Cell cycle analysis. INS-1 or MCF-7 cells transfected with control or survivin dsRNA oligonucleotides were analyzed for cell cycle distribution by flow cytometry. The percentage of cells with hypodiploid (Sub-G1) DNA content is indicated.