Apoptosis of CTLL-2 cells induced by an immunosuppressant, ISP-I, is caspase-3-like protease-independent.
In our previous study, the sphingosine-like immunosuppressant ISP-1 was shown to induce apoptosis in the mouse cytotoxic T cell line CTLL-2. In this study, we characterized the ISP-1-induced apoptotic pathway. Although caspase-3-like protease activity increases concomitantly with ISP-1-induced apoptosis in CTLL-2 cells, the apoptosis is not inhibited by caspase-3-like protease inhibitors, i.e. DEVD-cho and z-DEVD-fmk. In contrast, sphingosine-induced apoptosis in CTLL-2 cells is caspase-3-like protease-dependent. A caspase inhibitor with broad specificity, z-VAD-fmk, protects cells from apoptosis induced by ISP-1, indicating that ISP-1-induced apoptosis is dependent on caspase(s) other than caspase-3. Overexpression of Bcl-2 or Bcl-xL suppresses the apoptosis induced by ISP-1, although sphingosine-induced apoptosis is not efficiently inhibited by Bcl-2. Finally, ISP-1-induced mitochondrial depolarization, which is thought to be a checkpoint dividing the apoptotic pathway into upstream and downstream stages, is not inhibited by DEVD-cho, but is inhibited by z-VAD-fmk. These data suggest that a pathway dependent on caspase(s) other than caspase-3 is involved upstream of mitochondrial depolarization in ISP-1-induced apoptosis.
Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, and Laboratory of Membrane Biochemistry and Biophysics, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
T
T
Yamaji
S
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Nakamura
H
H
Takematsu
T
T
Kawasaki
Y
Y
Kozutsumi
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology*; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D013107:Sphingolipids / Q000494:pharmacology; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D051020:bcl-X Protein
C494812:Bcl2l1 protein, mouse; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D005229:Fatty Acids, Monounsaturated; D007166:Immunosuppressive Agents; D009842:Oligopeptides; D019253:Proto-Oncogene Proteins c-bcl-2; D013107:Sphingolipids; C108637:aspartyl-glutamyl-valyl-aspartal; D051020:bcl-X Protein; C118632:tyrosyl-valyl-alanyl-aspartal; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; C001996:thermozymocidin