Figure 6
ADAR1 confers cell death protection under apoptosis signaling. (a – d) Role of ADAR1 in the cellular apoptotic response. For loss-of-function experiments, 293 or WI38 cells were transfected with siRNAs targeting ADAR1 (siADAR1) or GFP (siCtrl), and subsequently treated with 500 nM staurosporine (STA) for 4 h (a) and 12 h (b–d). Cells were harvested for either immunoblot analysis of the indicated proteins (293 cells; a) or flow cytometry-based apoptosis detection, with differential labeling of PI and Annexin V as the readout (see Materials and Methods) (WI38 in b, 293 in c). For the anti-MDM2 blots shown in (a), the control and treatment groups are of two different exposures. In (b) and (c), numbers shown in the upper right quadrant indicate the percentage of apoptotic cells. (d) Quantitative representation of extent of apoptosis for experiments shown in (b) and (c). Values were normalized to the control group and represented as means±S.D. (e) Cells harboring control (siCtrl) siRNAs or siRNAs targeting ADAR1 (siADAR1), or both ADAR1 and XIAP (siADAR1, siXIAP) were treated without or with STA and subjected to apoptosis detection by flow cytometry, which was performed as described above. (f) Quantitative representation of the results shown in (e), with columns and error bars representing means±S.D. of at least three independent experiments. Relative levels of apoptosis are shown as normalized to the Ctrl group (for statistical analyses shown in this figure: NS, not significant or P>0.05; *P<0.05; **P<0.01; ***P<0.001)
