Chicken 15-kDa selenoprotein plays important antioxidative function in splenocytes.

The 15-kDa selenoprotein (Sep15) is a thioredoxin-like protein. The expression of Sep15 is regulated by dietary selenium (Se) and plays important roles in mammals. However, the structure and function of chicken Sep15 and its response to Se are still unclear. In the present study, we replicated the chicken Se deficiency models and Sep15 deficiency models in splenocytes. Then, the homology, structure analysis, and levels of Sep15 were analyzed. In addition, the oxidative stress levels were examined in Sep15 deficiency splenocytes. The results indicated that chicken Sep15 preserved high similarity with that of other 14 animals in the coding nucleotide sequences (CDS) and deduced amino acid sequence, which suggested that chicken Sep15 may be derived from the same ancestor with other animals. The predicted structure and function showed that chicken Sep15 preserved the conserved thioredoxin-like fold CxU, which suggested an antioxidative function. Chicken Sep15 was also decreased by Se deficiency in immune organs (P < 0.05). In addition, Sep15 deficiency induced the occurrence of higher oxidative stress and enhanced the sensitivity of cells to H2O2 (P < 0.05). So the in vitro study further verified its antioxidative function. Thus, similar to its mammal homolog, chicken Sep15 preserves the typical characteristic of selenoprotein and may play some roles in the redox regulation.