Regulation of glutathione peroxidase mRNA level by dietary selenium manipulation.

Glutathione peroxidase (GSH-Px) contains selenium at its active site as a selenocysteine moiety. We have shown that feeding mice a selenium-deficient diet for a long period caused a large decrease in the GSH-Px mRNA level as well as in GSH-Px activity both in the liver and kidneys (Toyoda, H., Himeno, S. and Imura, N. (1989) Biochim. Biophys. Acta 1008, 301-308). In the present study, the transcription rate of the GSH-Px gene was determined by a nuclear run-on assay using liver nuclei of mice fed a selenium-deficient or selenium-adequate diet. The results clearly demonstrate that the transcription rate of the GSH-Px gene was not changed by dietary selenium manipulation, indicating that dietary selenium regulates the level of GSH-Px mRNA in the post-transcriptional step.