Antioxidative role of selenoprotein W in oxidant-induced chicken splenic lymphocyte death

To verify the antioxidative role of SelW in oxidant-induced chicken splenic lymphocyte, in this report, the influence of selenite supplementation and SelW gene silence on H₂O₂-mediated cell viability and cell apoptosis in cultured splenic lymphocyte derived from spleen of chicken were examined. The cultured cells were treated with sodium selenite and H₂O₂, or knocked down SelW with small interfering RNAs (siRNAs). The lymphocytes were examined for cell viability, cell apoptosis and mRNA expression levels of SelW and apoptosis-related genes (Bcl-2, Bax, Bak-1, caspase-3 and p53). The results show that the mRNA expression of SelW were effectively increased after treatment with sodium selenite, and H₂O₂-induced cell apoptosis was significantly decreased and cell viability was significantly increased. 20 μM H₂O₂ was found to induce cell apoptosis and decrease cell viability, which was alleviated obviously when cells were pretreated with sodium selenite before exposure to 20 μM H₂O₂. Meanwhile, H₂O₂ induced a significantly up-regulation of the Bax/Bcl-2 ratio, Bax, Bak-1, caspase-3 and p53 and down-regulation of Bcl-2 (P < 0.05). When lymphocytes were pretreated with Se before treated with H₂O₂, the Bax/Bcl-2 ratio and mRNA expression of those genes were significantly decreased, and Bcl-2 was increased (P < 0.05). SelW siRNA-transfected cells were more sensitive to the oxidative stress induced by treatment of H₂O₂ than control cells. Silencing of the lymphocyte SelW gene decreased their cell viability, and increased their apoptosis rate and susceptibility to H₂O₂. Silencing of SelW significantly up-regulated the Bax/Bcl-2 ratio, Bax, Bak-1, caspase-3 and p53 and down-regulated Bcl-2 (P < 0.05). The present study demonstrates that SelW plays an important role in protection of splenic lymphocyte of birds from oxidative stress.