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

Abstract

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.

Characterization of Selenoprotein M and Its Response to Selenium Deficiency in Chicken Brain

“…The observed highly homology of SelM indicates that chicken SelM was derived from a common ancestor. Our 3D structural analysis demonstrated that chicken SelM was similar to that of pig SelM [9], chicken SelW [10,11], and chicken SelT [12], suggesting that they might exhibit similar functions.…”

“…However, the substitution of adenosines (A) for cytidines (C) shows no observable effect on Sec insertion into SelM. Pervious study has demonstrated that the SECIS element with -CC-motif appears to be universal in the Selm genes of mammalian animals [9]. In order to understand the evolutionary meaning of forms and motifs in the Selm SECIS element, we did a phylogenetic analysis encompassing a greater number of species.…”

“…In pig, SelM is ubiquitously expressed in many tissues, including muscle, liver, kidney, cerebral cortex, pituitary, thyroid, and testis. In human, it is expressed in many tissues with the highest levels in the brain [9], supporting its possible function in AD. Although the distribution, function, and structure of SelM in mammals have been well studied, studies of SelM in chicken remain very limited.…”

“…However, the biological functions of some selenoproteins identified recently remain largely unknown, including some redox (Rdx) proteins containing a diselenide bond in a common redox motif [8]. This motif that consist of CxxU (U designates selenocysteine) has been identified in a subset of selenoproteins, including selenoprotein M (SelM) [9], selenoprotein W (SelW) [10,11], and selenoprotein T (SelT) [12]. It has been proposed that these Rdx proteins exhibit a thioredoxin-like fold and a conserved CxxU motif, suggesting a redox function.…”

“…SelM was first reported as a new selenoprotein using bioinformatics methods [9,17]. It is highly conserved from plants to humans and localizes to the endoplasmic reticulum.…”