Acceleration of apoptotic cell death after the cleavage of Bcl-XL protein by caspase-3-like proteases

Oncogene. 1998 Sep 10;17(10):1295-304. doi: 10.1038/sj.onc.1202065.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Aspartic Acid / analogs & derivatives
  • Aspartic Acid / pharmacology
  • Binding Sites
  • Caspase 3
  • Caspases / metabolism*
  • Coumarins / pharmacology
  • Cysteine Endopeptidases / metabolism*
  • Cysteine Proteinase Inhibitors / pharmacology
  • Enzyme Activation
  • Etoposide / pharmacology
  • Gene Expression Regulation
  • Humans
  • Interleukin-2 / pharmacology
  • Mice
  • Oligopeptides / pharmacology
  • Peptide Fragments / metabolism
  • Protease Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / metabolism
  • Transfection
  • bcl-X Protein


  • BCL2L1 protein, human
  • Bcl2l1 protein, mouse
  • Coumarins
  • Cysteine Proteinase Inhibitors
  • Interleukin-2
  • Oligopeptides
  • Peptide Fragments
  • Protease Inhibitors
  • Proto-Oncogene Proteins c-bcl-2
  • acetyl-aspartyl-glutamyl-valyl-aspartyl-amino-4-methylcoumarin
  • bcl-X Protein
  • benzyloxycarbonyl-Asp-CH2OC(O)-2,6-dichlorobenzene
  • Aspartic Acid
  • Etoposide
  • CASP3 protein, human
  • Casp3 protein, mouse
  • Caspase 3
  • Caspases
  • Cysteine Endopeptidases