The regulation of glutathione peroxidase gene expression relevant to species difference and the effects of dietary selenium manipulation.
Glutathione peroxidase (GSH-Px) contains selenium (Se) as selenocysteine in the active site of the enzyme. GSH-Px activities in the cytosol of all guinea-pig tissues examined were extremely low compared with those in mice and rats, while Se concentrations in tissues were almost the same among three animal species. In addition, no GSH-Px mRNA was detectable in any tissues of guinea-pigs, although the guinea-pig had the same copy number (probably a single copy) of the GSH-Px gene in its genomic DNA as that of the mouse and rat, suggesting that the species difference of GSH-Px activity observed in rodents might be due to incapability of gene transcription. On the other hand, feeding of mice with Se-deficient diet for 6 weeks resulted in a remarkable decrease in GSH-Px mRNA as well as GSH-Px activity both in the liver and kidneys. The detailed time-course experiment revealed that the drop in GSH-Px activity preceded the decrease in the mRNA level in Se-depleted mice and the mRNA level recovered rapidly in contrast to the slow rate of increase in the enzyme activity in Se-repleted mice. These results suggested that the alteration in GSH-Px activity in mice subjected to dietary Se manipulation is attributable not only to transcriptional but also to post-transcriptional regulation.
Toyoda
H
H
Department of Public Health, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
Himeno
S
S
Imura
N
N
D000818:Animals; D001665:Binding Sites; D015139:Blotting, Southern; D004032:Diet; D005786:Gene Expression Regulation; D005979:Glutathione Peroxidase / Q000235:genetics* / Q000378:metabolism; D006168:Guinea Pigs; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009206:Myocardium / Q000201:enzymology; D012313:RNA / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012643:Selenium / Q000008:administration & dosage* / Q000032:analysis / Q000172:deficiency; D013045:Species Specificity
D012333:RNA, Messenger; D012313:RNA; D005979:Glutathione Peroxidase; D012643:Selenium