Molecular cloning, chromosomal localization and expression profiling of porcine selenoprotein M gene

Selenoprotein M may regulate a myriad of biological processes through its redox function. In pigs, neither the nucleotide sequence nor the amino acid sequence is known. Furthermore, patterns of tissue expression and regulation by dietary selenium (Se) have not been examined. We determined the full coding sequence (CDS) and the chromosomal location of the porcine gene, SELM, and described its expression profile in vivo under different dietary Se concentrations. The cDNA sequence of porcine SELM from the start codon to the poly(A) tail was cloned by reverse transcription PCR. The CDS contained 429 bases with a typical mammalian selenocysteine insertion sequence of form 2 (F2) located in the 3′-untranslated region. The gene was mapped to chromosome 14q21, where porcine SELM and its neighboring genes exhibited a similar organization to human homologues on chromosome 22q12.2. The expression pattern of SELM mRNA in muscle, thyroid, cerebral cortex, pituitary, testis, liver, and kidney was analyzed with real-time quantitative PCR in young male pigs fed a Se-deficient corn-soybean meal basal diet supplemented with 0.0, 0.3, or 3.0 mg Se/kg in the form of Se-rich yeast. Though the SELM mRNA abundance in each of the 7 tissues was not affected by the dietary Se concentrations, it was significantly higher in thyroid (P < 0.01) than in cerebral cortex, pituitary, testis, liver, and kidney at all of the 3 dietary Se concentrations.