Figure 4

BAX translocates to lysosome, releases cathepsin B and activates the BID cleavage. (a) A549 cells were treated with 3NP (500 μM) for 48 h. The cytoplasmic (Cyto) and lysosomal (Lyso) fractions were fractionated and then subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). (b) Lysosomes from cells transfected with or without DRAM1 small interfering RNA (siRNA) were fractionated and then incubated with BAX protein at 37 °C for 2 h. The lysosomal fractions were subjected to SDS-PAGE. (c) A549 cells were treated with 3NP (500 μM) for 48 h. The Cyto and Lyso were fractionated and then subjected to SDS-PAGE. (d) A549 cells were transfected with BAX siRNA or a non-silencing siRNA for 24 h and then treated with 3NP (500 μM) for another 24 h; the cytoplasm was fractionated for western blot analysis. (e) A549 cells were transfected with BAX siRNA or a non-silencing siRNA for 24 h and then treated with or without 3NP (500 μM) for another 24 h. Bars represent mean±S.E.; n=4; **P<0.01 versus NC; ^##P<0.01 versus 3NP+NC. (f) A549 cells were treated with 3NP (500 μM) and the cathepsin B inhibitor for 24 h. Bars represent mean±S.E.; n=4; **P<0.01 v ersus control; ^##P<0.01 versus 3NP. NC, negative control