Apoptosis induced by the nuclear death domain protein p84N5 is associated with caspase-6 and NF-kappa B activation.
Although the mechanisms involved in responses to extracellular or mitochondrial apoptotic signals have received considerable attention, the mechanisms utilized within the nucleus to transduce apoptotic signals are not well understood. We have characterized apoptosis induced by the nuclear death domain-containing protein p84N5. Adenovirus-mediated N5 gene transfer or transfection of p84N5 expression vectors induces apoptosis in tumor cell lines with nearly 100% efficiency as indicated by cellular morphology, DNA fragmentation, and annexin V staining. Using peptide substrates and Western blotting, we have determined that N5-induced apoptosis is initially accompanied by activation of caspase-6. Activation of caspases-3 and -9 does not peak until 3 days after the peak of caspase-6 activity. Expression of p84N5 also leads to activation of NF-kappaB as indicated by nuclear translocation of p65RelA and transcriptional activation of a NF-kappaB-dependent reporter promoter. Changes in the relative expression level of Bcl-2 family proteins, including Bak and Bcl-Xs, are also observed during p84N5-induced apoptosis. Finally, we demonstrate that p84N5-induced apoptosis does not require p53 and is not inhibited by p53 coexpression. We propose that p84N5 is involved in an apoptotic pathway distinct from those triggered by death domain-containing receptors or by p53.
Doostzadeh-Cizeron
J
J
Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA.
Yin
S
S
Goodrich
D W
DW
D000256:Adenoviridae / Q000235:genetics; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis; D015153:Blotting, Western; D053148:Caspase 3; D053178:Caspase 6; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D053938:DNA Fragmentation; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D006801:Humans; D020287:In Situ Nick-End Labeling; D008565:Membrane Proteins / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016601:RNA-Binding Proteins; D013997:Time Factors; D051996:Transcription Factor RelA; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein
D017304:Annexin A5; C494772:BAK1 protein, human; C494811:BCL2L1 protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D016328:NF-kappa B; D009687:Nuclear Proteins; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D016601:RNA-Binding Proteins; C400546:THOC1 protein, human; D051996:Transcription Factor RelA; D016159:Tumor Suppressor Protein p53; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein; C505407:CASP3 protein, human; C505514:CASP6 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053178:Caspase 6; D053453:Caspase 9; D020169:Caspases