Effects of Dietary Selenium Deficiency or Excess on Gene Expression of Selenoprotein N in Chicken Muscle Tissues

Previous studies have determined the effects of dietary selenium (Se) supplementation on selenoprotein N (SelN, SEPN1), selenophosphate synthetase-1 (SPS1), and selenocysteine-synthase (SecS) mRNA abundance in chicken skeletal and cardiac muscles. To investigate collective responses of these genes to dietary Se concentrations ranging from deficiency to moderately high level in muscle tissues of chicken, 1-day-old chickens were exposed to a diet of deficient Se and supplemented with Se (0.15 mg Se/kg and 1.50 mg Se/kg) as sodium selenite in the feed for 35 days. Muscle tissues (flight, breast, leg, and cardiac muscles) were collected and examined for Se content and mRNA levels of SelN on days 1, 15, 25, and 35 days, respectively. Moreover, SPS1 and SecS mRNA levels were analyzed. The results showed that the expression of SelN gene in cardiac muscle responded to dietary Se concentrations. SelN gene was downregulated in the Se deficiency group (L group), and upregulated in the Se excess group (H group) compared with the moderate Se group (M group) (P < 0.05) in cardiac muscle. Se deficiency mainly unregulated SelN mRNA level in skeletal muscles compared with M group. Excess dietary Se mainly resulted in the upregulation of SelN mRNA level in skeletal muscles compared with the M group. SecS mRNA levels responded to dietary Se concentrations showed a similar change compared with SelN in cardiac muscle. SPS1 mRNA levels responded to dietary Se concentrations showed a downregulation in L group and upregulation in H group. However, SelN mRNA levels displayed a different expression pattern in different skeletal and cardiac muscles. Moreover, Se also regulated the levels of SPS1 and SecS mRNAs. In summary, Se regulated the expression of SelN gene and affected the mRNA levels of SecS and SPS1. The level of Se in the feed may regulate SelN biosynthesis by affecting the levels of SPS1 and SecS mRNA.