Activation of phospholipase D involved in both injury and survival in A549 alveolar epithelial cells exposed to H2O2.
To determine the role of the phospholipase D (PLD) pathway in injury and survival of alveolar epithelial cells, A549 cells were exposed to H(2)O(2) (500 microM) which resulted in time-dependent injury and bi-phasic increase of PLD activity at 5 min and at 3 h, respectively. n-Butanol (0.5%) inhibited PLD activation, attenuated cell injury at 5 min of H(2)O(2) exposure, but enhanced injury at 3h of exposure. This activation was inhibited by treatment with catalase (500 units/ml). Exogenous phosphatidic acid mimicked the effects of PLD activation, and diphenyliodonium (NADPH oxidase inhibitor) reversed the decline in cell viability induced by H(2)O(2) exposure. Propranolol (phosphatidic acid phospholydrolase inhibitor) and quinacrine (phospholipase A2 inhibitor) had weak effects on H(2)O(2)-induced PLD activation but reversed H(2)O(2)-induced injury. We speculate that PLD activation at the initiation of H(2)O(2) exposure predominantly results in NAPDH oxidase activation, which mediates A549 cell injury, but turns to mediating cell survival as the H(2)O(2) attack continues, which might be mainly due to the accumulation of intracellular phosphatidic acid.
Wu
Ming
M
Department of Cardiothoracic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, China.
Wang
Qi
Q
Luo
Jiang-Yun
JY
Jiang
Bo
B
Li
Xu-Yun
XY
Chen
Ru-Kun
RK
Lu
Yun-Bi
YB
D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D010712:Phosphatidic Acids / Q000494:pharmacology; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects*; D011796:Quinacrine / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism
D010712:Phosphatidic Acids; D017382:Reactive Oxygen Species; D011433:Propranolol; D006861:Hydrogen Peroxide; D010739:Phospholipase D; D011796:Quinacrine