EGF mediates protection against Fas-induced apoptosis by depleting and oxidizing intracellular GSH stocks

Several pieces of evidence have demonstrated the importance of reduction/oxidation (redox) signaling in biological processes, including sensitivity toward apoptosis. In parallel, it was recently reported that growth factors induce the generation of reactive oxygen species (ROS). Therefore, we tested...

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Bibliographic Details
Published in:Journal of cellular physiology 2004-01, Vol.198 (1), p.62-72
Main Authors: Musallam, Lina, Éthier, Chantal, Haddad, Pierre Selim, Bilodeau, Marc
Format: Article
Language:English
Subjects:
Animals
Apoptosis - physiology
Caspase 3
Caspases - metabolism
Cells, Cultured
Enzyme Inhibitors - metabolism
Epidermal Growth Factor - metabolism
ErbB Receptors - metabolism
fas Receptor - metabolism
Glutathione - metabolism
Glutathione Reductase
Hepatocytes - cytology
Hepatocytes - metabolism
Male
Mice
Mice, Inbred BALB C
NADH, NADPH Oxidoreductases - metabolism
Oxidation-Reduction
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Summary:Several pieces of evidence have demonstrated the importance of reduction/oxidation (redox) signaling in biological processes, including sensitivity toward apoptosis. In parallel, it was recently reported that growth factors induce the generation of reactive oxygen species (ROS). Therefore, we tested the hypothesis that the anti‐apoptotic effect of epidermal growth factor (EGF) was mediated by changes in the redox state of hepatocytes through changes in GSH stocks. Isolated mouse hepatocytes were cultured and exposed to anti‐Fas stimulation in order to induce apoptosis. Cell death by apoptosis was assessed by Hoechst 33258 staining and by measuring caspase‐3 proteolysis activity. Cell treatment with EGF significantly decreased total (GSx) and reduced (GSH) glutathione levels in the presence and the absence of anti‐Fas. Furthermore, glutathione reductase activity was lower in EGF‐treated cultures (by 28%) as compared to untreated cultures which lead to a significant decline in GSH/GSx ratio. These effects were found to be EGF‐receptor tyrosine kinase activity dependent. Co‐stimulation of cells with anti‐Fas and EGF attenuated caspase‐3 activation and cell death by apoptosis by 70%. GSH monoethylester (GSHmee) significantly attenuated the effect of EGF on GSH and GSH/GSx ratio. It caused an increase in caspase‐3 activation and in the percentage of apoptotic cells in anti‐Fas + EGF‐treated cells, thus resulting in a 53% decline in the protective effect of EGF. In conclusion, EGF induces a significant and specific depletion and oxidization of intracellular GSH, paralleled by a protection against Fas‐induced apoptosis. GSH replenishment partly counteracted these effects suggesting that GSH depletion contributed to the protective effect of EGF against caspase‐3 activation and cell death by apoptosis. J. Cell. Physiol. 198: 62–72, 2004. © 2003 Wiley‐Liss, Inc.
ISSN:0021-9541
1097-4652
DOI:10.1002/jcp.10389