Regulation of tumor necrosis factor cytotoxicity by calcineurin.
Cyclosporin (CsA) inhibits mitochondrial death signaling and opposes tumor necrosis factor (TNF)-induced apoptosis in vitro. However, CsA is also a potent inhibitor of calcineurin, a phosphatase that may participate in cell death. Therefore, we tested the hypothesis that calcineurin regulates TNF cytotoxicity in rat hepatoma cells (FTO2B). TNF-treated FTO2B cells appeared apoptotic by DNA fragmentation, nuclear condensation, annexin V binding, and caspase activation. We studied two calcineurin inhibitors, CsA and FK506, and found that each potently inhibited TNF cytotoxicity. Western blot demonstrated calcineurin in FTO2B homogenates. In a model of mitochondrial permeability transition (MPT), we found that CsA prevented MPT and cytochrome c release, while FK506 inhibited neither. In summary, we present evidence that calcineurin participates in an apoptotic death pathway activated by TNF. CsA may oppose programmed cell death by inhibiting calcineurin activity and/or inhibiting mitochondrial signaling.
Kantrow
S P
SP
Department of Medicine, Louisiana State University Health Sciences Center, New Orleans, 70012, USA. skantr@lsumc.edu
Gierman
J L
JL
Jaligam
V R
VR
Zhang
P
P
Piantadosi
C A
CA
Summer
W R
WR
Lancaster
J R
JR
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D019703:Calcineurin / Q000494:pharmacology*; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D016572:Cyclosporine / Q000494:pharmacology; D003574:Cytochrome c Group / Q000187:drug effects / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004273:DNA, Neoplasm / Q000187:drug effects / Q000235:genetics; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology; D007770:L-Lactate Dehydrogenase / Q000187:drug effects / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D008933:Mitochondrial Swelling / Q000187:drug effects; D010539:Permeability / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D016559:Tacrolimus / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D003574:Cytochrome c Group; D004273:DNA, Neoplasm; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin; D016572:Cyclosporine; D007770:L-Lactate Dehydrogenase; D019703:Calcineurin; D020169:Caspases; D016559:Tacrolimus