Caspase-activated DNase (CAD)-independent oligonucleosomal DNA fragmentation in chronic myeloid leukaemia cells; a requirement for serine protease and Mn2+-dependent acidic endonuclease activity.
We have previously reported that the pro-apoptotic pyrrolobenzoxazepine, PBOX-6, induces apoptosis in chronic myelogenous leukaemia (CML) cells which is accompanied by oligonucleosomal DNA fragmentation. In this study we show that PBOX-6-induced oligonucleosomal DNA fragmentation occurs in the absence of caspase and CAD activation in CML cells. Dissection of the signalling pathway has revealed that induction of apoptosis requires the upstream activation of a trypsin-like serine protease that promotes the phosphorylation and inactivation of anti-apoptotic Bcl-2. In addition, in this system chymotrypsin-like serine proteases are dispensable for high molecular weight DNA fragmentation, however are required for the activation of a relatively small manganese-dependent acidic endonuclease that is responsible for oligonucleosomal fragmentation of DNA. Furthermore, we demonstrate mitochondrial involvement during PBOX-6-induced apoptosis and suggest the existence of unidentified mitochondrial effectors of apoptosis.
McGrath
L B
LB
UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, margaret.mcgee@ucd.ie.
Onnis
V
V
Campiani
G
G
Williams
D C
DC
Zisterer
D M
DM
Mc Gee
M M
MM
D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002457:Cell Extracts / Q000032:analysis; D003593:Cytoplasm / Q000378:metabolism; D053938:DNA Fragmentation; D003851:Deoxyribonucleases / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D010077:Oxazepines / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism*
D002457:Cell Extracts; D010077:Oxazepines; D019253:Proto-Oncogene Proteins c-bcl-2; D011758:Pyrroles; C011545:semen liquefaction factor; C114880:trypsin-like serine protease; D008345:Manganese; D003851:Deoxyribonucleases; D004720:Endonucleases; C109663:caspase-activated deoxyribonuclease; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases; D053148:Caspase 3; C418868:PBOX-6