RAT SKELETAL-MUSCLE SELENOPROTEIN-W - CDNA CLONE AND MESSENGER-RNA MODULATION BY DIETARY SELENIUM

Rat skeletal muscle selenoprotein W cDNA was isolated and sequenced. T he isolation strategy involved design of degenerate PCR primers from r everse translation of a partial Peptide sequence. A reverse transcript ion-coupled PCR product from rat muscle mRNA was used to screen a musc le cDNA library prepared from selenium-supplemented rats. The cDNA seq uence confirmed the known protein primary sequence, including a seleno cysteine residue encoded by TGA, and identified residues needed to com plete the protein sequence. RNA folding algorithms predict a stem-loop structure in the 3' untranslated region of the selenoprotein W mRNA t hat resembles selenocysteine insertion sequence (SECIS) elements ident ified in other selenocysteine coding cDNAs. Dietary regulation of sele noprotein W mRNA was examined in rat muscle. Dietary selenium at 0.1 p pm as selenite increased muscle mRNA 4-fold relative to a selenium-def icient diet. Higher dietary selenium produced no further increase in m RNA levels.