Dietary selenium stabilizes glutathione peroxidase mRNA in rat liver.
The objective of these studies was to determine the step at which dietary selenium (Se) regulates the pre-translational expression of the gene for cytosolic Se-glutathione peroxidase (Se-GPX) in rat liver. Weanling male Sprague-Dawley rats were fed a Torula yeast-based Se-deficient diet, or the same diet supplemented with 0.5 mg/kg as Na2SeO3, for at least 40 d. Livers were excised and divided into three portions for isolation of nuclei, for purification of total RNA and for assay of Se-GPX activity. Nuclei were used in run-on transcription assays and for isolation of total nuclear RNA. Nuclear RNA and total liver RNA were probed with segments from a rat Se-GPX cDNA in Northern blot and slot blot assays. Despite marked differences in Se-GPX activity, there were no significant differences between dietary groups in the transcription rates of the Se-GPX gene. Species hybridizing to Se-GPX were not detected in nuclear RNA. However, steady state levels of Se-GPX mRNA were markedly reduced by Se deficiency. These results suggest that dietary Se exerts its effect on pretranslational Se-GPX gene expression at the level of cytosolic mRNA stabilization.
Christensen
M J
MJ
Department of Food Science and Nutrition, Brigham Young University, Provo, UT 84602.
Burgener
K W
KW
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002467:Cell Nucleus / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D004032:Diet; D005786:Gene Expression Regulation / Q000187:drug effects*; D005979:Glutathione Peroxidase / Q000235:genetics*; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012643:Selenium / Q000008:administration & dosage / Q000172:deficiency / Q000494:pharmacology*; D014158:Transcription, Genetic
D012333:RNA, Messenger; D004247:DNA; D005979:Glutathione Peroxidase; D012643:Selenium