Cleavage of CPP32 by granzyme B represents a critical role for granzyme B in the induction of target cell DNA fragmentation.
Cytotoxic T lymphocytes (CTLs) are able to recognize and destroy target cells bearing foreign antigen using one of two distinct mechanisms: granule- or Fas-mediated cytotoxicity. The exact mechanisms involved in the induction of apoptotic cell death remain elusive; however, it seems likely that a family of cysteine proteases related to interleukin-1beta converting enzyme are involved. One family member, CPP32, has been identified as an intracellular substrate for granzyme B, a CTL-specific serine protease responsible for the early induction of target cell DNA fragmentation. Here we use cytolytic cells from granzyme B-deficient mice to confirm that cleavage and activation of CPP32 represents a nonredundant role for granzyme B and that this activation plays a role in the induction of DNA fragmentation in target cells, a signature event for apoptotic cell death. A peptide inhibitor of CPP32-like proteases confirmed the function of these enzymes in fragmentation. 51Cr release was not suppressed under these conditions, suggesting that granzyme B cleavage of CPP32 is primarily involved in the induction of DNA fragmentation and not membrane damage during CTL-induced apoptosis.
Darmon
A J
AJ
Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
Ley
T J
TJ
Nicholson
D W
DW
Bleackley
R C
RC
D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity; D017209:Apoptosis; D029742:Caenorhabditis elegans Proteins; D020170:Caspase 1; D053148:Caspase 3; D020169:Caspases; D002460:Cell Line; D002857:Chromium / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D053804:Granzymes; D015801:Helminth Proteins / Q000378:metabolism; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism*; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D015853:Cysteine Proteinase Inhibitors; D015801:Helminth Proteins; D009842:Oligopeptides; C099158:acetyl-aspartyl-glutamyl-valyl-aspartal; D002857:Chromium; C096429:L 709049; D004247:DNA; D053804:Granzymes; C509214:Gzmb protein, mouse; D012697:Serine Endopeptidases; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; C089223:ced-3 protein, C elegans; D020170:Caspase 1; D013936:Thymidine; D004121:Dimethyl Sulfoxide