Cloning Of The Porcine Selenoprotein V Gene And The Effect Of Dietary Selenium On Its MRNA Abundance In Different Tissues

Selenium's function is performed in the form of selenoprotein in vivo. Studies on the expression of selenoprotein to dietary Se concentrations are popular these years. Until now there are 25 selenoprotein in mammals but most of which have unidentified functions. SelV was one of them found recently. Since there are limited informations on Porcine selenoprotein V (SelV) gene sequence and effects of different levels of dietary Se on its expression. The present study was conducted to investigate the responses of SelV mRNA abundance to dietary Se concentrations based on the clone of porcine SelV gene in the swine.In this trial, by means of RACE technology we cloned overall length porcine SelV gene at first, including initiation codon, UGA codon and 3'untranslation region. And then 24 weanling male pigs were fed a Se-deficient corn-soy diet (0.03 mg Se/kg) or the diet supplemented with 0.3 or 3.0 mg Se/kg (as Se-enriched yeast) diet (extra yeast selenium) for 16w. A set of 8 pigs. Blood sample were collected at 0w,8w and 16w. After 16w on the diet, pigs were sacrificed to collect liver, kidney, loin, hypothalamus, testis, heart, spleen, pituitary, and thyroid tissues. SelV mRNA abundance in different tissues were determined with the use of Real-time PCR.As the results showed, we first cloned a 1,233 base pair cDNA coding for the porcine SelV gene and found that this cDNA fragment shared 97% of sequence homology in the coding region to the human SelV gene. The high similarity of porcine SelV deduced amino acid sequence with the SelV in other organisms, such as mouse, rabbit, human and so on. Dietary Se supplement resulted in higher GPX activities in blood and liver of 16-week pigs compared with the Se-deficient group (P<0.05), but showed no effect on the activities of GPX in blood of 8-week pigs fed diets with 0.3 and 3.0 mg Se/kg. Quantitative real-time RT-PCR analysis indicated that the level of the SelV mRNA was highest in testis and it higher than other analyzed tissues 30-1000 times. Besides testis, the level of the SelV mRNA was higher in liver, thyroid, pituitary, hypothalamus and kidney, and was lower in heart, blood and spleen, lowest in muscle. With the dietary selenium increasing, the SelV mRNA level decreased in kidney(P<0.05). Compared with the two dietary Se supplemental levels (0.3 and 3.0 mg Se/kg), dietary Se deficiency resulted in a higher (P<0.05) SelV mRNA levels in hypothalamus and muscle. Thyroid had the highest SelV mRNA level in pigs fed 0.3 mg Se/kg (P<0.05). In conclusion, the level of the SelV mRNA was highest in testis, the SelV mRNA level decreased in kidney, heart and liver, So effects of dietary Se on SelV gene expression varied with tissues in weanling pigs.