Enhanced GSH synthesis by Bisphenol A exposure promoted DNA methylation process in the testes of adult rare minnow Gobiocypris rarus

DNA methylation is a commonly studied epigenetic modification. The mechanism of BPA on DNA methylation is poorly understood. The present study aims to explore whether GSH synthesis affects DNA methylation in the testes of adult male rare minnow Gobiocypris rams in response to Bisphenol A (BPA). Male G. rams was exposed to 1, 15 and 225 mu g L-1 BPA for 7 days. The levels of global DNA methylation, hydrogen peroxide (H2O2) and glutathione (GSH) in the testes were analyzed. Meanwhile, the levels of enzymes involved in DNA methylation and de novo GSH synthesis, and the substrate contents for GSH production were measured. Furthermore, gene expression profiles of the corresponding genes of all studied enzymes were analyzed. Results indicated that BPA at 15 and 225 mu g L-1 caused hypermethylation of global DNA in the testes. The 15 mu g L-1 BPA resulted in significant decrease of ten-eleven translocation proteins (TETs) while 225 mu g L-1 BPA caused significant increase of DNA methyltransferase proteins (DNMTs). Moreover, 225 mu g L-1 BPA caused significant increase of H2O2 and GSH levels, and the de novo GSH synthesis was enhanced. These results indicated that the significant decrease of the level of TETs may be sufficient to cause the DNA hypermethylation by 15 mu g L-1 BPA. However, the significantly increased of DNMTs contributed to the significant increase of DNA methylation levels by 225 mu g L-1 BPA. Moreover, the elevated de novo GSH synthesis may promote the DNA methylation process. (C) 2016 Elsevier B.V. All rights reserved.