Abstract
Leukocyte elastase induces apoptosis of lung epithelial cells via alterations in mitochondrial permeability, but the signaling pathways regulating this response remain uncertain. Here we investigated the involvement of proteinase-activated receptor-1 (PAR-1), the transcription factor NF-kappaB, and the protooncogene p53 in this pathway. Elastase-induced apoptosis of lung epithelial cells correlated temporally with activation of NF-kappaB, phosphorylation, and nuclear translocation of p53, increased p53 up-regulated modulator of apoptosis (PUMA) expression, and mitochondrial translocation of Bax resulting in enhanced permeability. Elastase-induced apoptosis was also prevented by pharmacologic inhibitors of NF-kappaB and p53 and by short interfering RNA knockdown of PAR-1, p53, or PUMA. These inhibitors prevented elastase-induced PUMA expression, mitochondrial translocation of Bax, increased mitochondrial permeability, and attenuated apoptosis. NF-kappaB inhibitors also reduced p53 phosphorylation. We conclude that elastase-induced apoptosis of lung epithelial cells is mediated by a PAR-1-triggered pathway involving activation of NF-kappaB and p53, and a PUMA- and Bax-dependent increase in mitochondrial permeability leading to activation of distal caspases. Further, p53 contributes to elastase-induced apoptosis by both transcriptional and post-transcriptional mechanisms.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Active Transport, Cell Nucleus
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Apoptosis / drug effects
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Apoptosis / physiology*
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Apoptosis Regulatory Proteins / antagonists & inhibitors
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Apoptosis Regulatory Proteins / genetics
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Apoptosis Regulatory Proteins / metabolism
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Caspase 3 / metabolism
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Cell Line
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Cells, Cultured
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Epithelial Cells / cytology
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Epithelial Cells / drug effects
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Epithelial Cells / metabolism
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Humans
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Leukocyte Elastase / metabolism*
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Leukocyte Elastase / pharmacology
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Lung / cytology*
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Lung / drug effects
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Lung / metabolism*
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Mitochondria / metabolism
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Models, Biological
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NF-kappa B / antagonists & inhibitors
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NF-kappa B / metabolism*
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Permeability
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Phosphorylation
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Proto-Oncogene Proteins / antagonists & inhibitors
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism
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RNA, Small Interfering / genetics
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Receptor, PAR-1 / antagonists & inhibitors
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Receptor, PAR-1 / genetics
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Receptor, PAR-1 / metabolism*
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Signal Transduction
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Tumor Suppressor Protein p53 / antagonists & inhibitors
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Tumor Suppressor Protein p53 / genetics
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Tumor Suppressor Protein p53 / metabolism*
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bcl-2-Associated X Protein / metabolism
Substances
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Apoptosis Regulatory Proteins
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BAX protein, human
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BBC3 protein, human
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NF-kappa B
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Proto-Oncogene Proteins
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RNA, Small Interfering
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Receptor, PAR-1
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TP53 protein, human
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Tumor Suppressor Protein p53
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bcl-2-Associated X Protein
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Leukocyte Elastase
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CASP3 protein, human
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Caspase 3