Selenium toxicity but not deficient or super-nutritional selenium status vastly alters the transcriptome in rodents

Protein and mRNA levels for several selenoproteins, such as glutathione peroxidase-1 (Gpx1), are down-regulated dramatically by selenium (Se) deficiency. Selenoprotein levels in rats increase sigmoidally with increasing dietary Se and reach defined plateaus at the Se requirement, making them sensitive biomarkers for Se deficiency, but not high for Se status. Biomarkers for high Se status are needed as super-nutritional Se intakes are associated with beneficial and adverse health outcomes, but conventional biomarkers are not especially useful above the Se requirement. To characterize Se regulation of the transcriptome, we conducted 3 microarray experiments in weanling mice and rats fed Se-deficient diets supplemented with levels of Se up to 5 µg Se/g diet. Rats or mice were fed Se-deficient diets supplemented with sodium selenite up to 5 ug Se/g diet for 28 or 35 days. Affymetrix Rat 230 2.0 and Mouse 430 2.0 Genome Arrays were used to analyze gene expression in liver in all studies plus kidney in the mouse study.