Caspase 3 inhibition attenuates hydrogen peroxide‐induced DNA fragmentation but not cell death in neuronal PC12 cells

• Published in: Journal of neurochemistry 2001-03, Vol.76 (6), p.1745-1755
• Main Authors: Jiang, Dongmei, Jha, Nandita, Boonplueang, Rapee, Andersen, Julie K.
• Format: Article
• Language: English
• Subjects: Ageing, cell death; Animals; apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Biological and medical sciences; Caspase 3; Caspase Inhibitors; Caspases - metabolism; catalase; Catalase - metabolism; Cell Death - drug effects; Cell Death - physiology; Cell physiology; Cell Survival - drug effects; Cysteine Proteinase Inhibitors - pharmacology; DNA fragmentation; DNA Fragmentation - drug effects; DNA Fragmentation - physiology; Enzyme Activation; Fundamental and applied biological sciences. Psychology; Glutathione - metabolism; H2O2; Hydrogen Peroxide - toxicity; Molecular and cellular biology; Neurons - cytology; Neurons - drug effects; Neurons - physiology; PC12; PC12 Cells; Rats; Recombinant Fusion Proteins - metabolism; Signal Transduction; Trans-Activators - metabolism; Transfection
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.2001.00151.x

Exposure of neurons to H2O2 results in both necrosis and apoptosis. Caspases play a pivotal role in apoptosis, but exactly how they are involved in H2O2‐mediated cell death is unknown. We examined H2O2‐induced toxicity in neuronal PC12 cells and the effects of inducible overexpression of the H2O2‐scavenging enzyme catalase on this process. H2O2 caused cell death in a time‐ and concentration‐dependent manner. Cell death induced by H2O2 was found to be mediated in part through an apoptotic pathway as H2O2‐treated cells exhibited cell shrinkage, nuclear condensation and marked DNA fragmentation. H2O2 also triggered activation of caspase 3. Genetic up‐regulation of catalase not only significantly reduced cell death but also suppressed caspase 3 activity and DNA fragmentation. While the caspase 3 inhibitor DEVD inhibited both caspase 3 activity and DNA fragmentation induced by H2O2 it did not prevent cell death. Treatment with the general caspase inhibitor ZVAD, however, resulted in complete attenuation of H2O2‐mediated cellular toxicity. These results suggest that DNA fragmentation induced by H2O2 is attributable to caspase 3 activation and that H2O2 may be critical for signaling leading to apoptosis. However, unlike inducibly increased catalase expression and general caspase inhibition both of which protect cells from cytotoxicity, caspase 3 inhibition alone did not improve cell survival suggesting that prevention of DNA fragmentation is insufficient to prevent H2O2‐mediated cell death.