Published ahead of print on September 8, 2005, doi:10.1165/rcmb.2004-0361OC
© 2005 American Thoracic Society DOI: 10.1165/rcmb.2004-0361OC Poly(ADP-ribose)polymerase Activation Mediates Lung Epithelial Cell Death In Vitro but Is Not Essential in Hyperoxia-Induced Lung InjuryDepartments of Pediatrics and Pathology-Immunology, University of Geneva, Medical School, Geneva, Switzerland Correspondence and requests for reprints should be addressed to Dr. Constance Barazzone Argiroffo, Departments of Pediatrics and Pathology, Centre Médical Universitaire, 1, rue Michel Servet, 1211, Geneva, 4, Switzerland. E-mail: constance.barazzone{at}hcuge.ch Hyperoxia induces extensive DNA damage and lung cell death by apoptotic and nonapoptotic pathways. We analyzed the regulation of Poly(ADP-ribose)polymerase-1 (PARP-1), a nuclear enzyme activated by DNA damage, and its relation to cell death during hyperoxia in vitro and in vivo. In lung epithelial-derived A549 cells, which are known to die by necrosis when exposed to oxygen, a minimal amount of PARP-1 was cleaved, correlating with the absence of active caspase-3. Conversely, in primary lung fibroblasts, which die mainly by apoptosis, the complete cleavage of PARP-1 was concomitant to the induction of active caspase-3, as assessed by Western blot and caspase activity. Blockade of caspase activity by Z-VAD reduced the amount of cleaved PARP-1 in fibroblasts. Hyperoxia induced PARP activity in both cell types, as revealed by poly-ADP-ribose accumulation. In A549 cells, the final outcome of necrosis was dependent on PARP activity because it was prevented by the PARP inhibitor 3-aminobenzamide. In contrast, apoptosis of lung fibroblasts was not sensitive to 3-aminobenzamide and was not affected by PARP-1 deletion. In vivo, despite evidence of PARP activation in hyperoxia-exposed mouse lungs, absence of PARP-1 did not change the extent of lung damage, arguing for redundant oxidative stress–induced cell death pathways.
Key Words: apoptosis • caspase-3 • hyperoxia • necrosis • PARP-1 This article has been cited by other articles:
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