Implication of mitochondrial hydrogen peroxide generation in ceramide-induced apoptosis.

Abstract

The key events implicated in ceramide-triggered apoptosis remain unknown. In this study we show that 25 microM C6-ceramide induced significant H2O2 production within 60 min, which increased up to 180 min in human myeloid leukemia U937 cells. Inactive analogue dihydro-C6-ceramide had no effect. Furthermore, no H2O2 production was observed in C6-ceramide-treated U937 rho degrees cells, which are mitochondrial respiration-deficient. We also present evidence that ceramide-induced activation of the transcription factors NF-kappaB and AP-1 is mediated by mitochondrial derived reactive oxygen species. Both H2O2 production, transcription factor activation as well as apoptosis could be inhibited by rotenone and thenoyltrifluoroacetone (specific mitochondrial complexes I and II inhibitors) and antioxidants, N-acetylcysteine and pyrrolidine dithiocarbamate. These effects could be potentiated by antimycin A (specific complex III mitochondrial inhibitor). H2O2 production was also inhibitable by ruthenium red, suggesting a role of mitochondrial calcium homeostasis alterations in ceramide-induced oxidative stress. Finally, C6-ceramide had no influence on mitochondrial membrane potential within the first 6 h. Altogether, our study points to reactive oxygen species, generated at the ubiquinone site of the mitochondrial respiratory chain, as an early major mediator in ceramide-induced apoptosis.

• Authors: A Quillet-Mary, J P Jaffrézou, V Mansat, C Bordier, J Naval, G Laurent
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 272 Issue 34 Pg. 21388-95 (Aug 22 1997) ISSN: 0021-9258 [Print] United States
• PMID: 9261153 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antioxidants
• Ceramides
• NF-kappa B
• Reactive Oxygen Species
• Transcription Factor AP-1
• Hydrogen Peroxide
• Calcium

Topics

• Antioxidants (pharmacology)
• Apoptosis (drug effects)
• Calcium (metabolism)
• Ceramides (pharmacology)
• DNA Fragmentation (drug effects)
• Humans
• Hydrogen Peroxide (metabolism)
• Membrane Potentials
• Mitochondria (metabolism, physiology)
• NF-kappa B (metabolism)
• Reactive Oxygen Species (metabolism)
• Transcription Factor AP-1 (metabolism)
• Tumor Cells, Cultured