Tuberc Respir Dis.  1995 Aug;42(4):522-534.

Superoxide Dismutase Gene Expression Induced by Lipopolysaccharide in Alveolar Macrophage of Rat

• Park KY
• Yoo CG
• Kim YW
• Han SK
• Shim YS
• Hyun IG

Abstract

BACKGROUND
In the pathogenesis of acute lung injury induced by lipopolysaccharide(LPS), oxygen radiclls are known to be involved in one part. Superoxide dismutase(SOD) protects oxygen radical-induced tissue damage by dismutating superoxide to hydrogen peroxide. In eukaryotic cells, two forms of SOD exist intracellularly as a cytosolic, dimeric copper/zinc-containing SOD (CuZnSOD) and a mitochondrial, tetrameric manganese-containing SOD(MnSOD). But there has been little information about SOD gene expression and its regulation in pulmonary alveolar macrophages(PAMs). The objective of this study is to evaluate the SOD gene expression induced by LPS and its regulation in PAMs of rat. METHOD: In Sprague-Dawley rats, PAMs obtained by broncholaveolar lavage were purified by adherence to plastic plate. To study the effect of LPS on the SOD gene expression of PAMs, they were stimulated with different doses of LPS(0.01microg/ml ~ 10microg/ml) and for different intervals(0, 2, 4, 8, 24hrs). Also for evaluating the level of SOD gene regulation actinomycin D(AD) or cyclo- heximide(CHX) were added respectively. To assess whether LPS altered SOD mRNA stability, the rate of mRNA decay was determined in control group and LPS-treated group. Total cellular RNA extraction by guanidinium thiocyanate/phenol/chloroform method and Northern blot analysis by using a 32P-labelled rat MnSOD and CuZnSOD cDNAs were performed.
RESULTS
The expression of mRNA in MnSOD increased dose-dependently, but not in CuZnSOD. MnSOD mRNA expression peaked at 8 hours after LPS treatment. Upregulation of MnSOD mRNA expression induced by LPS was suppressed by adding AD or CHX respectively. MnSOD mRNA stability was not altered by LPS.
CONCLUSION
These findings show that PAMs of rat could be an important source of SOD in response to LPS, and suggest that their MnSOD mRNA expression may be regulated transcriptionally and require de novo protein synthesis without affecting mRNA stability.

Keyword

MnSOD; CuZnSOD; mRNA; Pulmonary alveolar macrophage; Lipopolysaccaharide

MeSH Terms

Acute Lung Injury
Animals
Blotting, Northern
Cytosol
Dactinomycin
DNA, Complementary
Eukaryotic Cells
Gene Expression*
Guanidine
Hydrogen Peroxide
Macrophages, Alveolar*
Oxygen
Plastics
Rats*
Rats, Sprague-Dawley
RNA
RNA Stability
RNA, Messenger
Superoxide Dismutase*
Superoxides*
Therapeutic Irrigation
Up-Regulation
DNA, Complementary
Dactinomycin
Guanidine
Hydrogen Peroxide
Oxygen
Plastics
RNA
RNA, Messenger
Superoxide Dismutase
Superoxides