Acceleration of apoptotic cell death after the cleavage of Bcl-XL protein by caspase-3-like proteases.
Interleukin-2 (IL-2)-dependent T cell clone CTLL-2 underwent apoptosis by deprivation of IL-2 from culture medium. The decrease in the anti-apoptotic Bcl-XL protein level was observed during apoptosis after IL-2 withdrawal. We found that Bcl-XL protein was cleaved to produce two 18 kDa fragments during CTLL-2 cell apoptosis. When the activation of caspases was suppressed by overexpressing human Bcl-2 protein or by the addition of caspase inhibitors, cleavage of Bcl-XL protein was suppressed in vivo. Bcl-XL protein cleavage by incubation with apoptosed CTLL-2 cell lysate was suppressed by the caspase-3/CPP32-specific tetrapeptide inhibitor in vitro. Therefore, caspase-3/CPP32-like proteases were activated and involved in the cleavage of Bcl-XL protein during CTLL-2 cell apoptosis. We found that Bcl-XL protein was cleaved by caspase-3/CPP32 at two sites in the loop domain (i.e., HLAD61/S and SSLD76/A). The transfection of the carboxy-terminal 18 kDa Bcl-XL fragment increased the sensitivity to apoptosis. These results indicate that caspase-3/CPP32-like proteases cleaved anti-apoptotic Bcl-XL protein and resulted in accelerated apoptotic cell death.
Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
N
N
Fujita
A
A
Nagahashi
K
K
Nagashima
S
S
Rokudai
T
T
Tsuruo
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001665:Binding Sites; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D003374:Coumarins / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation; D005047:Etoposide / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D014162:Transfection; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D003374:Coumarins; D015853:Cysteine Proteinase Inhibitors; D007376:Interleukin-2; D009842:Oligopeptides; D010446:Peptide Fragments; D011480:Protease Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; C102580:acetyl-aspartyl-glutamyl-valyl-aspartyl-amino-4-methylcoumarin; D051020:bcl-X Protein; C093260:benzyloxycarbonyl-Asp-CH2OC(O)-2,6-dichlorobenzene; D001224:Aspartic Acid; D005047:Etoposide; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases