SELENIUM DEFICIENCY DECREASES EXPRESSION OF THE GENES FOR TRANSTHYRETIN AND CITRATE TRANSPORT PROTEIN IN RAT-LIVER

Dietary intake of the essential trace element selenium (Se) regulates expression of genes for selenoproteins, including the gene for type I iodothyronine 5'-deiodinase. However, regulation of these genes does n ot account for all of Se's biological effects. To define additional me chanisms for Se's effects, these experiments aimed to identify other g enes also regulated by Se intake in rats. Weanling male Sprague-Dawley rats were fed a Torula yeast-based Se deficient diet, or the same die t supplemented with 0.5 mg Se/kg diet for 13 weeks. Differential displ ay of mRNA was used to identify cDNAs reverse transcribed from mRNAs p resent at different levels in the livers of the two groups of rats. No rthern blots, probed with these cDNAs, were used to quantitate differe nces in mRNA levels between the two dietary groups. Those cDNA probes detecting differential expression in Northern blots were sequenced. Ho mology searches in DNA sequence data bases were conducted to identify the differentially expressed genes. This analysis revealed that mRNA l evels for transthyretin and citrate transport protein are both reduced in the livers of Se-deficient rats. Reductions averaged 44.7% (p=0.00 09) for transthyretin and 42.8% (p=0.0032) for citrate transport prote in. These results suggest a coordinated regulation of thyroid hormone metabolism in rats by dietary Se intake. Copyright (C) 1997 Elsevier S cience Inc.