Reduction in mitochondrial membrane potential is an early event in Fas-independent CTL-mediated apoptosis.
Cytotoxic T lymphocytes (CTL) can destroy target cells via the Fas-mediated pathway or the granule-mediated pathway. We used Fas-negative target cells to examine for target-cell reduction in mitochondrial membrane potential (DeltaPsi(m)) induced by intact CTL via the granule-mediated pathway. We find that reduction in DeltaPsi(m) is an early step in Fas-independent CTL killing of target cells that precedes phosphatidyl serine translocation, cytosolic protein release, or loss of plasma membrane integrity. Target-cell reduction in DeltaPsi(m) and cytoplasmic protein release in Fas-independent CTL killing were inhibited by N-carbobenzoxy-Ala-Pro-Phe chloromethyl ketone, but not by caspase inhibitors N-carbobenzoxy-Val-Ala-Asp fluoromethyl ketone (z-VAD-fmk) or N-carbobenzoxy-Asp-Glu-Val-Asp fluoromethyl ketone (z-DEVD-fmk). This contrasts with Fas-mediated apoptosis, in which the reduction in DeltaPsi(m) can be inhibited by z-VAD-fmk or z-DEVD-fmk. Assessing the changes in target-cell DeltaPsi(m) can provide for a sensitive and rapid means with which to monitor CTL activity.
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Department of Medicine, University of California at San Diego School of Medicine, La Jolla, California, 92093-0663, USA.
Kipps
T J
TJ
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D001692:Biological Transport; D002463:Cell Membrane Permeability; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials; D051379:Mice; D008808:Mice, Inbred CBA; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D010718:Phosphatidylserines / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D019014:fas Receptor / Q000502:physiology*
D000590:Amino Acid Chloromethyl Ketones; D015853:Cysteine Proteinase Inhibitors; D009842:Oligopeptides; D010455:Peptides; D010718:Phosphatidylserines; D011480:Protease Inhibitors; D011506:Proteins; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor