Epi-mutations for spermatogenic defects by maternal exposure to Di (2-ethylhexyl) phthalate

Exposure to environmental factors during fetal development may lead to epigenomic modifications in fetal germ cells, altering gene expression and promoting diseases in successive generations. In mouse, maternal exposure to Di (2-ethylhexyl) phthalate (DEHP) is known to induce defects in spermatogenesis in successive generations, but the mechanism(s) of impaired spermatogenesis are unclear. Here, we showed that maternal DEHP exposure results in DNA hypermethylation of promoters of spermatogenesis-related genes in fetal testicular germ cells in F1 mice, and hypermethylation of Hist1h2ba, Sycp1 and Taf7l, which are crucial for spermatogenesis, persisted from fetal testicular cells to adult spermatogonia, resulting in the downregulation of expression of these genes. Forced methylation of these gene promoters silenced expression of these loci in a reporter assay. Expression and methylation of those genes tended to be downregulated and increased, respectively in F2 spermatogonia following maternal DEHP exposure. These results suggested that DEHP-induced hypermethylation of Hist1h2ba, Sycp1 and Taf7l in fetal germ cells results in downregulation of these genes in spermatogonia and subsequent defects in spermatogenesis, at least in the F1 generation.