Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell injury and cell death of pulmonary epithelium plays an important role in the pathogenesis of acute lung injury in animals exposed to prolonged hyperoxia. The aim of this study was to decipher the molecular mechanisms modulating cell death induced by hyperoxia in lung epithelium. Cell death is thought to be either apoptotic, with shrinking phenotypes and activated caspases, or oncotic, with swelling organelles. Exposure to 95% O2 (hyperoxia) induced cell death of MLE-12 cells with cellular as well as nuclear swelling, cytosolic vacuolation, and loss of mitochondrial structure and enzyme function. Neither elevated caspase-3 activity nor phosphatidylserine translocation were detected, suggesting that in hyperoxia, MLE-12 cells die via oncosis rather than apoptosis. In addition, hyperoxia triggered a sustained activation of the transcription factor AP-1, as well as mitogen-activated protein kinase (MAPK) family members p38 and JNK. Importantly, survival of MLE-12 cells in hyperoxia was significantly enhanced when either AP-1, p38, or JNK activation was inhibited by either specific inhibitors or dominant negative DNA constructs, indicating that in lung epithelial cells hyperoxia induces a program-driven oncosis, involving AP-1, JNK, and p38 MAPK. Interestingly, hydrogen peroxide-induced oxidative apoptosis of MLE-12 cells, with a shrinking nuclear morphology and activated caspase-3 activity, is also mediated by AP-1, JNK, and p38. Therefore, our data indicate that although they have divergent downstream events, oxidative oncosis and apoptosis share upstream JNK/p38 and AP-1 pathways, which could be used as potential targets for reducing hyperoxic inflammatory lung injury.
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PMID:MAPK pathways mediate hyperoxia-induced oncotic cell death in lung epithelial cells. 1455 62

Exposure of lung epithelial cells to hyperoxia results in the generation of excess reactive oxygen species (ROS), cell damage, and production of proinflammatory cytokines (interleukin-8; IL-8). Although activation of the NF-kappaB and c-Jun N-terminal kinase (JNK)/activator protein (AP)-1 transcription pathways occurs in hyperoxia, it is unclear whether activation of the AP-1 pathway has a direct impact on IL-8 production and whether overexpression of superoxide dismutase (SOD) can mitigate these proinflammatory processes. A549 cells were exposed to 95% O(2), and ROS production, AP-1 activation, and IL-8 levels were determined. Experimental groups included cells transduced with a recombinant adenovirus encoding CuZnSOD or MnSOD (two- to threefold increased activity) or transfected with a JNK1 small interfering RNA (RNAi). Hyperoxia resulted in significant increases in ROS generation, AP-1 activation, and IL-8 production, which were significantly attenuated by overexpression of either MnSOD or CuZnSOD. JNK1 RNAi also moderated IL-8 induction. The data indicate that activation of JNK1/AP-1 and subsequent IL-8 induction in hyperoxia are mediated by intracellular ROS, with SOD having significant protective effects.
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PMID:Superoxide dismutase attenuates hyperoxia-induced interleukin-8 induction via AP-1. 1869 29

For nearly 100 y, pediatricians have regularly used oxygen to treat neonatal and childhood diseases. During this time, it has become clear that oxygen is toxic and that overzealous use can lead to significant morbidity. As we have learned more about the appropriate clinical indications for oxygen therapy, studies at the bench have begun to elucidate the molecular mechanisms by which cells respond to hyperoxia. In this review, we discuss transcription factors whose activity is regulated by oxygen, including nuclear factor, erythroid 2-related factor 2 (Nrf2), activator protein 1 (AP-1), p53, nuclear factor kappaB (NF-kappaB), signal transducers and activators of transcription protein (STAT), and ccat/enhancer binding protein (CEBP). Special attention is paid to the mechanisms by which hyperoxia affects these transcription factors in the lung. Finally, we identify downstream targets of these transcription factors, with a focus on heme oxygenase-1. A better understanding of how oxygen affects various signaling pathways could lead to interventions aimed at preventing hyperoxic injury.
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PMID:Manipulation of gene expression by oxygen: a primer from bedside to bench. 1928 38

With the recognition that chronic exposure to oxidative stress occurs in many disease states and can be deleterious to the human health, great interest has emerged in understanding the mechanisms by which mammalian cells develop resistance to chronic oxidative stress. In order to study the mechanisms of development of resistance to chronic oxidative stress, a model system where Chinese hamster fibroblasts (HA1) are chronically exposed to progressively increasing concentrations of H(2)O(2) (50-800 muM) or hyperoxia (80-95% O(2)) has been developed. Following >200 d of exposure to H(2)O(2) (or 18 months of exposure to hyperoxia), the cells developed stable H(2)O(2)-resistant (or O(2)-resistant) phenotypes that are characterized by increases in total glutathione, antioxidant enzyme activity, heme oxygenase activity, stress protein gene expression, DNA repair pathways, and resistance to a wide variety of other toxic stress known to cause oxidant injury. In addition, these oxidant-resistant cells exhibited amplification of the gene for catalase and constitutively elevated AP-1 DNA binding activity. Further, beyond 240 d genomic instability as evidenced by chromosomal rearrangements and alterations in ploidy was stably maintained upon removal from the chronic oxidative stress conditions. These results demonstrate the capability of mammalian cells to develop stable oxidative stress-resistant phenotypes in response to both exogenous (H(2)O(2)) as well as endogenous (95% O(2)) oxidative stress. The understanding of mechanisms of resistance to oxidative stress and its possible relevance in various disease states are discussed.
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PMID:The generation of stable oxidative stress-resistant phenotypes in Chinese hamster fibroblasts chronically exposed to hydrogen peroxide or hyperoxia. 2001 79


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