A lack of contact of sperm with accessory sex gland secretions deregulates DNA methylation and imprinted gene expression in rodent embryos

Abstract

Increased oxidative DNA damage is observed in sperm devoid of contact with accessory sex gland (ASG) secretion. After fertilization, these sperm may produce abnormal embryos. In this study, we investigated the possibility that the pattern of DNA methylation and imprinted gene expression in these embryos may be perturbed. Epididymal sperm, uterine sperm, and embryonic day 13 (E13) embryos were collected from hamster and mouse. The extent of global DNA methylation was determined with an antibody against methylcytosine using an embryo DNA dot. The sperm and embryo Gtl2 promoter and H19 differential methylated region (DMR) were subject to bisulfite sequencing. Expression of their reciprocally activated genes Dlk1 and Igf2 was quantified by real-time PCR. Genome-wide DNA hypo-methylation in both hamster and mouse embryos sired by males without ASG was observed. The imprinting pattern of fetal mouse Gtl2 promoter and fetal hamster H19 DMR were also disrupted while the expression of Dlk1 and Igf2 was dysregulated in the hamster embryo. This study suggests that a lack of contact of sperm with the ASG secretion disrupts genome-wide DNA methylation and also affects the DNA methylation pattern of imprinted genes in embryos. © 2009 Informa UK Ltd.