Neutrophil elastase induces IL-8 gene transcription and protein release through p38/NF-{kappa}B activation via EGFR transactivation in a lung epithelial cell line.
In this study, we investigated the regulation and mechanism of IL-8 expression by A549 human lung carcinoma cells treated with neutrophil elastase (NE). NE-treated cells exhibited significantly higher IL-8 protein levels in culture media compared with cells treated with vehicle alone. Blocking of gene transcription with actinomycin D suggested that NE stimulated IL-8 synthesis via increased mRNA expression, which was verified by real-time RT-PCR. NE activated the IL-8 promoter but did not alter the stability of its mRNA, confirming that the protease induced IL-8 synthesis through increased gene transcription. The results from the use of chemical inhibitors and mutant gene constructs against various signal transduction components seem to suggest the linear signaling pathway involving the activation of PKC-delta --> dual oxidase 1 --> reactive oxygen species --> TNF-alpha-converting enzyme --> EGF receptor --> p38 --> NF-kappaB for NE-activated IL-8 gene expression. A NF-kappaB potential binding site, located between nucleotides -82 and -69 of the IL-8 promoter, was identified as necessary for NE-induced IL-8 transcription. We conclude that NE increases IL-8 transcription through p38/NF-kappaB activation via EGFR transactivation.
Kuwahara
Ippei
I
Respiratory Immunology and Asthma Program, Lovelace Respiratory Research Institute, Albuquerque, NM 87108, USA.
Lillehoj
Erik P
EP
Lu
Wenju
W
Singh
Ishwar S
IS
Isohama
Yoichiro
Y
Miyata
Takeshi
T
Kim
K Chul
KC
D001665:Binding Sites; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D019272:Leukocyte Elastase / Q000494:pharmacology*; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D051745:Protein Kinase C-delta / Q000378:metabolism; D020871:RNA Stability; D015398:Signal Transduction; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D016209:Interleukin-8; D016328:NF-kappa B; D066246:ErbB Receptors; D051745:Protein Kinase C-delta; D048051:p38 Mitogen-Activated Protein Kinases; D019272:Leukocyte Elastase