Genome-wide assessment of DNA methylation alterations induced by superovulation, sexual immaturity and in vitro follicle growth in mouse blastocysts

Abstract

Background In their attempt to fulfill the wish of having children, women who suffer from fertility issues often undergo assisted reproductive technologies such as ovarian stimulation, which has been associated with adverse health outcomes and imprinting disorders in children. However, given the crucial role of exogenous hormone stimulation in improving human infertility treatments, a more comprehensive analysis of the potential impacts on DNA methylation in embryos following ovarian stimulation is needed. Here, we provide genome-wide DNA methylation profiles of blastocysts generated after superovulation of prepubertal or adult mice, compared with blastocysts derived from non-stimulated adult mice. Additionally, we assessed the impact of the in vitro growth and maturation of oocytes on methylation in blastocysts. Results Neither hormone stimulation nor sexual maturity had an impact on the low global methylation levels characteristic of the blastocyst stage or was associated with extensive DNA methylation alterations. However, we found hormone- and age-associated changes at specific positions but dispersed throughout the genome. In particular, we detected anomalous methylation at a limited number of CpG islands. Additionally, superovulation in adult mice was associated with alterations at the Sgce and Zfp777 imprinted genes. On the other hand, in vitro culture of follicles from the early pre-antral stage was associated with globally reduced methylation and increased variability at imprinted loci in blastocysts. Conclusions Our results indicate a minimal effect of ovarian stimulation of adult and prepubertal mice on the DNA methylation landscape attained at the blastocyst stage, but potentially greater impacts of in vitro growth and maturation of oocytes. These findings have potential significance for the improvement of assisted reproductive techniques, in particular for those related to treatments in prepubertal females, which could be crucial for improving human fertility preservation strategies.

Cardiovascular health of offspring conceived by assisted reproduction technology: a comprehensive review

“…In addition, in the hearts of ART offspring, the expression of imprinted genes Dhcr7, Igf2, Mest, and Smoc1 was found to be reduced, whereas the DNA methylation levels of the Igf2- and Mest-imprinting control regions (ICRs) were abnormally increased ( 19 ). Superovulation in adult mice has also been linked to alterations in Sgce and Zfp777 imprinted genes, whereas in vitro culture of follicles from the early pre-antral stage resulted in globally reduced methylation and heightened variability at imprinted loci in blastocysts ( 48 ).…”