Modulation of caspase activation and p27(Kip1) degradation in the p53-induced apoptosis in IW32 erythroleukemia cells.
To examine the p53-mediated biological activities and signalling pathways, we generated stable transfectants of the p53-null IW32 murine erythroleukemia cells expressing the temperature-sensitive p53 mutant DNA, tsp53(val135). Two clones with different levels of p53 protein expression were selected for further characterization. At permissive temperature, clone 1-5 cells differentiated along the erythroid pathway, and clone 3-2 cells that produced greater levels (3.5-fold) of p53 underwent apoptosis. Apoptosis of 3-2 cells was accompanied by mitochondrial cytochrome c release and caspase activation as well as by cleavage of caspase substrates. Bax protein was induced to a similar extent in these clones by wild-type p53; expression of p21(Cip1/Waf1) and p27(Kip1) proteins was also increased. However, significantly lesser extent of induction for both CDK inhibitors was detected in the apoptotic 3-2 clone. The general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD.fmk) blocked the p53-induced apoptosis in 3-2 cells, with a concomitant elevation of p27(Kip1), suggesting that p27(Kip1) protein underwent caspase-dependent proteolysis in the apoptotic 3-2 cells. Together these results linked a pathway involving cytochrome c release, caspase activation and p27(Kip1) degradation to the p53-induced apoptosis in IW32 erythroleukemia cells.
Tang
Pi-Pei
PP
Institute of Biochemistry, National Yang-Ming University, Shih-Pai, Taipei, Taiwan.
Hsieh
Shu-Chen
SC
Wang
Fung-Fang
FF
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002999:Clone Cells / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005057:Eukaryotic Cells / Q000187:drug effects / Q000201:enzymology*; D004915:Leukemia, Erythroblastic, Acute; D051379:Mice; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency* / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein
D000590:Amino Acid Chloromethyl Ketones; C494827:Bax protein, mouse; C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D050760:Cyclin-Dependent Kinase Inhibitor p27; D020169:Caspases