Ceramide-mediated apoptosis in lung epithelial cells is regulated by glutathione.
Reactive oxygen species (ROS) are mediators of lung injury, and glutathione (GSH) is the major nonprotein antioxidant that protects the cell from oxidative stress. We have recently shown that H(2)O(2) induces ceramide-mediated apoptosis in human lung epithelial cells. We hypothesized that ROS-mediated depletion of GSH plays a regulatory role in ceramide generation, and thus in the induction of apoptosis. Our present studies demonstrate that GSH at physiologic concentrations (1 to 10 mM) inhibits ceramide production in a time- and dose-dependent manner in A549 human alveolar epithelial cells. On the other hand, buthionine-sulfoximine-mediated depletion of intracellular GSH induces elevation of ceramide levels and apoptosis. In addition, GSH blocks H(2)O(2)-mediated induction of intracellular ceramide generation and apoptosis. These effects were not mimicked by oxidized GSH (GSSG) or other thiol antioxidants, such as dithiothreitol and 2-mercaptoethanol. Moreover, increase of intracellular H(2)O(2), mediated by inhibition of catalase by aminotriazole, also induces ceramide generation and apoptosis. These effects were blocked by N-acetylcysteine. Our results suggest that GSH depletion may be the link between oxidative stress and ceramide-mediated apoptosis in the lung.
Lavrentiadou
S N
SN
Center for Comparative Respiratory Biology and Medicine, Department of Internal Medicine, University of California, Davis, California 95616, USA.
Chan
C
C
Kawcak
T
T
Ravid
T
T
Tsaba
A
A
van der Vliet
A
A
Rasooly
R
R
Goldkorn
T
T
D000111:Acetylcysteine / Q000494:pharmacology; D000640:Amitrole / Q000494:pharmacology; D017304:Annexin A5 / Q000032:analysis; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001980:Bronchi / Q000166:cytology / Q000187:drug effects; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002374:Catalase / Q000037:antagonists & inhibitors / Q000502:physiology; D002478:Cells, Cultured / Q000378:metabolism; D002518:Ceramides / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D053938:DNA Fragmentation; D019852:Diacylglycerol Kinase / Q000032:analysis; D004229:Dithiothreitol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D005978:Glutathione / Q000032:analysis / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D008623:Mercaptoethanol / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014132:Trachea / Q000166:cytology / Q000187:drug effects
D017304:Annexin A5; D000975:Antioxidants; D002518:Ceramides; D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; C101954:N-caproylsphingosine; D019328:Buthionine Sulfoximine; D008623:Mercaptoethanol; D006861:Hydrogen Peroxide; D002374:Catalase; D019852:Diacylglycerol Kinase; D005978:Glutathione; D004229:Dithiothreitol; D000111:Acetylcysteine; D000640:Amitrole