Down-regulation of manganese-superoxide dismutase gene expression in idiopathic nephrotic syndrome.
An oxidant stress has been shown to prevail in experimental and clinical nephrotic syndrome. Such oxidant stress may be induced by a reduced activity of antioxidant systems. We examined the altered expression of manganese-superoxide dismutase (Mn-SOD), an antioxidant enzyme, in patients with idiopathic nephrotic syndrome, in whom an increased oxidant stress had been demonstrated. The Mn-SOD activities in peripheral blood mononuclear cells obtained from 12 patients with active nephrotic syndrome (6.0 +/- 1.1 years of age, mean +/- SE) and hypoproteinemia were 42% lower (p < 0.05) than in 12 control subjects (5.5 +/- 0.5 years of age) with normal serum total protein concentrations. Reverse-transcriptase polymerase chain reaction also demonstrated that Mn-SOD messenger RNA expression in the patients with nephrotic syndrome was, on average, 59% lower than in control subjects. Because expressions of some genes are sensitive to serum, the serum dependency of Mn-SOD gene transcription was studied in glomerular endothelial cells transfected with a luciferase reporter gene fused with a rat Mn-SOD DNA fragment of -806 to +22 bp of the transcription initiation site (-806:+22). When these cells were exposed to different concentrations of fetal bovine serum (0.5% to 15%), the transcriptional activities determined by luciferase activities were proportional to serum concentrations. This serum-dependent transcriptional activation was also demonstrated by the fragment (-220:+22) but not by the fragment (-220:-20). When glomerular endothelial cells transfected with the fragment (-220:+22) were treated with 5% serum from patients with active nephrotic syndrome, transcriptional activation was more than 80% less than that by 5% serum from control subjects without nephrosis. These results indicate that Mn-SOD gene transcription is regulated at least in part by serum, and that the serum-dependent transcription of the gene is diminished in patients with idiopathic nephrotic syndrome. The regulatory region of serum-dependent gene transcription resides within its early promoter region. Our findings suggest that down-regulation of antioxidant enzyme transcription may contribute increased oxidant stress in idiopathic nephrotic syndrome.
Yoshioka
T
T
Department of Pediatric Nephrology, Tokyo Women's Medical College, Japan.
Iwamoto
N
N
Tsunoda
Y
Y
Higuchi
C
C
Kawaguchi
H
H
Ito
K
K
D000818:Animals; D002648:Child; D015536:Down-Regulation; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008297:Male; D009404:Nephrotic Syndrome / Q000201:enzymology / Q000235:genetics*; D016133:Polymerase Chain Reaction; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D017382:Reactive Oxygen Species; D008156:Luciferases; D013482:Superoxide Dismutase