Transcriptome analysis of the Tan sheep testes: Differential expression of antioxidant enzyme-related genes and proteins in response to dietary vitamin E supplementation

Abstract

Gene-chip technology was employed to study the effect of dietary vitamin E on gene expression in sheep testes based on our previous research. Thirty-five male Tan sheep (20–30days after weaning) with similar body weight were randomly allocated into five groups and supplemented 0, 20, 100, 200 and 2000IUsheep−1day−1 vitamin E (treatments denoted as E0, E20, E100, E200, and E2000, respectively) for 120days. At the end of the study the sheep were slaughtered and the testis samples were immediately collected and stored in liquid nitrogen. Differences in gene expression between different treated groups were identified. Based on GO enrichment analysis and the KEGG database to evaluate the gene expression data we found that vitamin E might affect genes in the testes by modulating the oxidation level, by affecting the expression of various receptors and transcription factors in biological pathways, and by regulating the expression of metabolism-associated genes. The effect of vitamin E supplementation on the expression of oxidative enzyme-related genes was detected by quantitative real-time PCR (qRT-PCR) and Western blot. The results show that dietary vitamin E, at various doses, can significantly increase (P<0.05) the mRNA and protein expression of Glutathione peroxidase 3 and Glutathione S-transferase alpha 1. In addition, the results of qRT-PCR of the antioxidant enzyme genes were consistent with those obtained using the gene chip microarray analysis. In summary, the dietary vitamin E treatment altered the expression of a number of genes in sheep testes. The increase in the mRNA and protein levels of antioxidant enzyme genes, coupled with the elevation in the activity of the antioxidant enzymes were primarily responsible for the improved reproductive performance promoted by dietary vitamin E.