Toll-like receptor 2-mediated sequential activation of MyD88 and MAPKs contributes to lipopolysaccharide-induced sp-a gene expression in human alveolar epithelial cells

Chi Yuan Chuang, Tyng-Guey Chen, Yu-Ting Tai, Ta-Liang Chen, Yu Hua Lin, Cheng Hsiu Tsai, Ruei-Ming Chen

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Abstract

Surfactant proteins (SPs) produced by pulmonary epithelial cells participate in the regulation of sepsis-induced acute lung injury. Our previous study has shown that lipopolysaccharide (LPS), a Gram-negative bacterial outer membrane component, can regulate sp-a gene expression in human lung carcinoma type II epithelial A549 cells. This study was further designed to evaluate the signal-transducing mechanisms of LPS-induced sp-a gene expression. Exposure of A549 cells to LPS induced SP-A mRNA and protein production in time-dependent manners. Application of toll-like receptor 2 (TLR2) siRNA into A549 cells decreased the levels of this receptor and simultaneously inhibited LPS-induced SP-A mRNA expression. Sequentially, LPS enhanced phosphorylation of mitogen-activated protein kinase (MEK) 4 and c-Jun NH2 terminal kinase 1 (JNK1) in time-dependent manners. Application of TLR2 siRNA decreased LPS-enhanced phosphorylation of MEK4 and JNK1. After knocking-down the translation of MyD88 by RNA interference, the LPS-triggered MEK4 phosphorylation was attenuated. Consequently, LPS augmented the translocation of c-Jun from the cytoplasm to nuclei without affecting c-Fos. Pretreatment of A549 cells with SP600125, an inhibitor of JNK1, significantly lowered LPS-induced SP-A mRNA production. Analyses of an electrophoretic mobility shift assay and a reporter gene further showed that LPS increased the transactivation activity of AP-1 in A549 cells. Therefore, the present study demonstrates that LPS can induce sp-a gene expression in human type II epithelial A549 cells through TLR2-mediated sequential activation of MyD88-MEK4-JNK1-AP-1.

Original languageEnglish
Pages (from-to)707-714
Number of pages8
JournalImmunobiology
Volume216
Issue number6
DOIs
Publication statusPublished - Jun 2011

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Alveolar Epithelial Cells
Toll-Like Receptor 2
Lipopolysaccharides
Gene Expression
JNK Mitogen-Activated Protein Kinases
Pulmonary Surfactant-Associated Protein A
Epithelial Cells
Transcription Factor AP-1
Phosphorylation
Messenger RNA
Small Interfering RNA
Lung
Acute Lung Injury
Electrophoretic Mobility Shift Assay
RNA Interference
Reporter Genes
Surface-Active Agents
Transcriptional Activation
A549 Cells
Sepsis

Keywords

  • Acute lung injury
  • Alveolar epithelial cells
  • Lipopolysaccharide
  • MyD88-MEK4-JNK1-AP-1
  • Surfactant protein-A
  • Toll-like receptor 2

ASJC Scopus subject areas

  • Immunology
  • Immunology and Allergy
  • Hematology

Cite this

@article{10896264d8ea4abfa11c0a08e7fd5bd0,
title = "Toll-like receptor 2-mediated sequential activation of MyD88 and MAPKs contributes to lipopolysaccharide-induced sp-a gene expression in human alveolar epithelial cells",
abstract = "Surfactant proteins (SPs) produced by pulmonary epithelial cells participate in the regulation of sepsis-induced acute lung injury. Our previous study has shown that lipopolysaccharide (LPS), a Gram-negative bacterial outer membrane component, can regulate sp-a gene expression in human lung carcinoma type II epithelial A549 cells. This study was further designed to evaluate the signal-transducing mechanisms of LPS-induced sp-a gene expression. Exposure of A549 cells to LPS induced SP-A mRNA and protein production in time-dependent manners. Application of toll-like receptor 2 (TLR2) siRNA into A549 cells decreased the levels of this receptor and simultaneously inhibited LPS-induced SP-A mRNA expression. Sequentially, LPS enhanced phosphorylation of mitogen-activated protein kinase (MEK) 4 and c-Jun NH2 terminal kinase 1 (JNK1) in time-dependent manners. Application of TLR2 siRNA decreased LPS-enhanced phosphorylation of MEK4 and JNK1. After knocking-down the translation of MyD88 by RNA interference, the LPS-triggered MEK4 phosphorylation was attenuated. Consequently, LPS augmented the translocation of c-Jun from the cytoplasm to nuclei without affecting c-Fos. Pretreatment of A549 cells with SP600125, an inhibitor of JNK1, significantly lowered LPS-induced SP-A mRNA production. Analyses of an electrophoretic mobility shift assay and a reporter gene further showed that LPS increased the transactivation activity of AP-1 in A549 cells. Therefore, the present study demonstrates that LPS can induce sp-a gene expression in human type II epithelial A549 cells through TLR2-mediated sequential activation of MyD88-MEK4-JNK1-AP-1.",
keywords = "Acute lung injury, Alveolar epithelial cells, Lipopolysaccharide, MyD88-MEK4-JNK1-AP-1, Surfactant protein-A, Toll-like receptor 2",
author = "Chuang, {Chi Yuan} and Tyng-Guey Chen and Yu-Ting Tai and Ta-Liang Chen and Lin, {Yu Hua} and Tsai, {Cheng Hsiu} and Ruei-Ming Chen",
year = "2011",
month = "6",
doi = "10.1016/j.imbio.2010.10.009",
language = "English",
volume = "216",
pages = "707--714",
journal = "Immunobiology",
issn = "0171-2985",
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T1 - Toll-like receptor 2-mediated sequential activation of MyD88 and MAPKs contributes to lipopolysaccharide-induced sp-a gene expression in human alveolar epithelial cells

AU - Chuang, Chi Yuan

AU - Chen, Tyng-Guey

AU - Tai, Yu-Ting

AU - Chen, Ta-Liang

AU - Lin, Yu Hua

AU - Tsai, Cheng Hsiu

AU - Chen, Ruei-Ming

PY - 2011/6

Y1 - 2011/6

N2 - Surfactant proteins (SPs) produced by pulmonary epithelial cells participate in the regulation of sepsis-induced acute lung injury. Our previous study has shown that lipopolysaccharide (LPS), a Gram-negative bacterial outer membrane component, can regulate sp-a gene expression in human lung carcinoma type II epithelial A549 cells. This study was further designed to evaluate the signal-transducing mechanisms of LPS-induced sp-a gene expression. Exposure of A549 cells to LPS induced SP-A mRNA and protein production in time-dependent manners. Application of toll-like receptor 2 (TLR2) siRNA into A549 cells decreased the levels of this receptor and simultaneously inhibited LPS-induced SP-A mRNA expression. Sequentially, LPS enhanced phosphorylation of mitogen-activated protein kinase (MEK) 4 and c-Jun NH2 terminal kinase 1 (JNK1) in time-dependent manners. Application of TLR2 siRNA decreased LPS-enhanced phosphorylation of MEK4 and JNK1. After knocking-down the translation of MyD88 by RNA interference, the LPS-triggered MEK4 phosphorylation was attenuated. Consequently, LPS augmented the translocation of c-Jun from the cytoplasm to nuclei without affecting c-Fos. Pretreatment of A549 cells with SP600125, an inhibitor of JNK1, significantly lowered LPS-induced SP-A mRNA production. Analyses of an electrophoretic mobility shift assay and a reporter gene further showed that LPS increased the transactivation activity of AP-1 in A549 cells. Therefore, the present study demonstrates that LPS can induce sp-a gene expression in human type II epithelial A549 cells through TLR2-mediated sequential activation of MyD88-MEK4-JNK1-AP-1.

AB - Surfactant proteins (SPs) produced by pulmonary epithelial cells participate in the regulation of sepsis-induced acute lung injury. Our previous study has shown that lipopolysaccharide (LPS), a Gram-negative bacterial outer membrane component, can regulate sp-a gene expression in human lung carcinoma type II epithelial A549 cells. This study was further designed to evaluate the signal-transducing mechanisms of LPS-induced sp-a gene expression. Exposure of A549 cells to LPS induced SP-A mRNA and protein production in time-dependent manners. Application of toll-like receptor 2 (TLR2) siRNA into A549 cells decreased the levels of this receptor and simultaneously inhibited LPS-induced SP-A mRNA expression. Sequentially, LPS enhanced phosphorylation of mitogen-activated protein kinase (MEK) 4 and c-Jun NH2 terminal kinase 1 (JNK1) in time-dependent manners. Application of TLR2 siRNA decreased LPS-enhanced phosphorylation of MEK4 and JNK1. After knocking-down the translation of MyD88 by RNA interference, the LPS-triggered MEK4 phosphorylation was attenuated. Consequently, LPS augmented the translocation of c-Jun from the cytoplasm to nuclei without affecting c-Fos. Pretreatment of A549 cells with SP600125, an inhibitor of JNK1, significantly lowered LPS-induced SP-A mRNA production. Analyses of an electrophoretic mobility shift assay and a reporter gene further showed that LPS increased the transactivation activity of AP-1 in A549 cells. Therefore, the present study demonstrates that LPS can induce sp-a gene expression in human type II epithelial A549 cells through TLR2-mediated sequential activation of MyD88-MEK4-JNK1-AP-1.

KW - Acute lung injury

KW - Alveolar epithelial cells

KW - Lipopolysaccharide

KW - MyD88-MEK4-JNK1-AP-1

KW - Surfactant protein-A

KW - Toll-like receptor 2

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