Core Promoters of Pig SOD2 Gene and Its Expression Regulation by DNA Methylation

In pig production, oxidative stress in the placentas of pregnant sows is one of the most important factors affecting reproductive performance. Superoxide dismutase SOD2 is a critical component of the antioxidant system and determines the antioxidant capacity of cells. The expression of the SOD2 gene is reportedly regulated by DNA methylation. At present, there are abundant reports on the function and structure of SOD2, but how DNA methylation affects the expression of SOD2 in pigs is still unclear. In this study, we identified the core promoters of SOD2 gene and verified the important transcription factor binding sites. Treatment of porcine placental trophoblast cells with a DNA methyltransferase (DNMT) inhibitor reduced promoter methylation and increased SOD2 expression. Treatment of SOD2 promoter fragments with CpG methyltransferase M.SssI reduced promoter activity. In summary, the SOD2 core promoter is located at -275/-66 bp. Hypomethylation of the core promoter promotes the expression of SOD2, while hypermethylation reduces promoter activity. This study provides a theoretical basis for further investigation into the regulation of porcine SOD2 gene by DNA methylation.