Cytochrome c-Dependent Activation of Caspase-3 by Tumor Necrosis Factor Requires Induction of the Mitochondrial Permeability Transition

• Published in: The American journal of pathology Vol. 156; no. 6; pp. 2111 - 2121
• Main Authors: Tafani, Marco, Schneider, Timothy G., Pastorino, John G., Farber, John L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2000; ASIP; American Society for Investigative Pathology
• Subjects: Animals; BH3 Interacting Domain Death Agonist Protein; Biological Transport - physiology; Carrier Proteins - metabolism; Caspase 3; Caspase 8; Caspase 9; Caspases - metabolism; Cell Line; Cell Survival - drug effects; Cyclosporine - pharmacology; Cysteine Proteinase Inhibitors - pharmacology; Cytochrome c Group - physiology; DNA Fragmentation - drug effects; Enzyme Activation - physiology; Fibroblasts - drug effects; Fibroblasts - enzymology; Fibroblasts - metabolism; Fibroblasts - physiology; Malate Dehydrogenase - metabolism; Mice; Mitochondria - drug effects; Mitochondria - metabolism; Oligopeptides - pharmacology; Permeability - drug effects; Poly(ADP-ribose) Polymerase Inhibitors; Regular; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0002-9440; 1525-2191
• DOI: 10.1016/S0002-9440(10)65082-1

The killing of L929 mouse fibroblasts by tumor necrosis factor-α (TNF-α) in the presence of 0.5 μg/ml actinomycin D (Act D) is prevented by inhibition of the mitochondrial permeability transition (MPT) with cyclosporin A (CyA) in combination with the phospholipase A 2 inhibitor aristolochic acid (ArA). The MPT is accompanied by the release of cytochrome c from the mitochondria, caspase-8 and caspase-3 activation in the cytosol, cleavage of the nuclear enzyme poly(ADP-ribose)polymerase (PARP), and DNA fragmentation, all of which were inhibited by CyA plus ArA. The caspase-3 inhibitor z-Asp-Glu-Val-aspartic acid fluoromethyl-ketone (Z-DEVD-FMK) did not prevent the loss of viability or the redistribution of cytochrome c, but it did prevent caspase-3 activation, PARP cleavage, and DNA fragmentation. Inhibition of the MPT reduced the activation of caspase-8 to the level occurring with TNF-α alone (no ActD). The caspase-8 inhibitor z-Ile-Glu(OMe)-Thr-Asp(OMe) fluoromethylketone (Z-IETD-FMK) did not prevent the cell killing and decreased only slightly the translocation of Bid to the mitochondria. These data indicate that induction of the MTP by TNF-α causes a release of cytochrome c, caspase-3 activation with PARP cleavage and DNA fragmentation. The loss of viability is dependent on the MPT but independent of the activation of caspase-3. The activation of caspase-8 is not dependent on the MPT. There is no evidence linking this enzyme to the loss of viability. Thus, the killing of L929 fibroblasts by TNF-α can occur in the absence of either caspase-3 or caspase-8 activity. Alternatively, cell death can be prevented despite an activation of caspase-8.