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Regulation of macrophage inflammatory protein‐2 gene expression by oxidative stress in rat alveolar macrophages

Regulation of macrophage inflammatory protein‐2 gene expression by oxidative stress in rat... Chemokines are important mediators in the development of inflammation. Our previous work demonstrated that an oxidative stress can up‐regulate mRNA expression of a CC chemokine macrophage inflammatory protein (MIP)‐1α in rat alveolar macrophages. In the present study, we further investigate whether an oxidative stress can regulate the gene expression of a related CXC chemokine MIP‐2, involved in both neutrophil chemotaxis and activation. A rat alveolar macrophage cell line (NR8383) was exposed to 10 μg/ml bacterial lipopolysaccharide (LPS) and MIP‐2 mRNA levels dramatically increased after 4 hr of stimulation. This increase by LPS was attenuated by co‐treatment with the antioxidants N‐acetylcysteine and dimethylsulphoxide, suggesting that the induction of MIP‐2 mRNA is mediated via the generation of reactive oxygen species. To assess directly the role of oxidative stress on regulation of MIP‐2 mRNA expression, macrophages were exposed to H2O2. MIP‐2 mRNA levels had significantly increased after 1 hr exposure to 0·5 mm H2O2, were maximally increased after 4 hr and decreased after 6 hr. Co‐treatment of macrophages with the transcriptional inhibitor actinomycin D eliminated the H2O2‐induction of MIP‐2 mRNA, implicating a role for transcriptional activation in increased expression of MIP‐2. Genomic cloning of the rat MIP‐2 gene 5′‐flanking region has identified a consensus nuclear factor‐κB (NF‐κB) binding site. Gel‐mobility shift assays revealed NF‐κB binding to the MIP‐2 promoter/enhancer sequence was induced by H2O2. LPS treatment for 4 hr also significantly activated NF‐κB binding, which could also be attenuated by pretreatment with N‐acetylcysteine at the doses that reduced MIP‐2 mRNA expression. The half‐life of MIP‐2 mRNA transcripts was also increased by H2O2 treatment. These observations indicate that MIP‐2 gene expression is subject to both transcriptional and post‐transcriptional control in response to an H2O2 oxidative stress. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Immunology Wiley

Regulation of macrophage inflammatory protein‐2 gene expression by oxidative stress in rat alveolar macrophages

Shi,; Chong,; Godleski,; Paulauskis,
Immunology , Volume 97 (2) – Jun 1, 1999
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References (57)

Publisher
Wiley
Copyright
Copyright © 1999 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0019-2805
eISSN
1365-2567
DOI
10.1046/j.1365-2567.1999.00798.x
Publisher site
See Article on Publisher Site

Abstract

Chemokines are important mediators in the development of inflammation. Our previous work demonstrated that an oxidative stress can up‐regulate mRNA expression of a CC chemokine macrophage inflammatory protein (MIP)‐1α in rat alveolar macrophages. In the present study, we further investigate whether an oxidative stress can regulate the gene expression of a related CXC chemokine MIP‐2, involved in both neutrophil chemotaxis and activation. A rat alveolar macrophage cell line (NR8383) was exposed to 10 μg/ml bacterial lipopolysaccharide (LPS) and MIP‐2 mRNA levels dramatically increased after 4 hr of stimulation. This increase by LPS was attenuated by co‐treatment with the antioxidants N‐acetylcysteine and dimethylsulphoxide, suggesting that the induction of MIP‐2 mRNA is mediated via the generation of reactive oxygen species. To assess directly the role of oxidative stress on regulation of MIP‐2 mRNA expression, macrophages were exposed to H2O2. MIP‐2 mRNA levels had significantly increased after 1 hr exposure to 0·5 mm H2O2, were maximally increased after 4 hr and decreased after 6 hr. Co‐treatment of macrophages with the transcriptional inhibitor actinomycin D eliminated the H2O2‐induction of MIP‐2 mRNA, implicating a role for transcriptional activation in increased expression of MIP‐2. Genomic cloning of the rat MIP‐2 gene 5′‐flanking region has identified a consensus nuclear factor‐κB (NF‐κB) binding site. Gel‐mobility shift assays revealed NF‐κB binding to the MIP‐2 promoter/enhancer sequence was induced by H2O2. LPS treatment for 4 hr also significantly activated NF‐κB binding, which could also be attenuated by pretreatment with N‐acetylcysteine at the doses that reduced MIP‐2 mRNA expression. The half‐life of MIP‐2 mRNA transcripts was also increased by H2O2 treatment. These observations indicate that MIP‐2 gene expression is subject to both transcriptional and post‐transcriptional control in response to an H2O2 oxidative stress.

Journal

Immunology – Wiley

Published: Jun 1, 1999

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