Oxygen concentration affects de novo DNA methylation and transcription in in vitro cultured oocytes

• DOI: 10.1186/s13148-021-01116-3
• Publication Date: 2021-06-28T12:02:47Z
• Authors: Florence Naillat; Heba Saadeh; Joanna Nowacka-Wo...; Lenka Gahurova; Fatima Santos; Shin-ichi Tomizawa; Gavin Kelsey
• Keywords: Human genetics; Transcription

Reproductive biology methods rely on in vitro follicle cultures from mature follicles obtained by hormonal stimulation for generating metaphase II oocytes to be fertilised and developed into a healthy embryo. Such techniques are used routinely both rodent human species. DNA methylation is dynamic process that plays role epigenetic regulation of gametogenesis development. In mammalian oocytes, establishment regulates gene expression the embryos. This particularly important class genes, imprinted whose patterns crucial next generation. The aim this work was establish an culture system immature mouse will allow manipulation specific factors deeper analysis regulatory mechanisms establishing transcription regulation-associated patterns. An were grown germinal vesicles (GV) under two different conditions: normoxia (20% oxygen, 20% O2) hypoxia (5% 5% O2). cultured sorted based their sizes. Reduced representative bisulphite sequencing (RRBS) RNA-seq libraries generated compared vivo-grown oocytes. global CpG-island (CGI) increased gradually along with oocyte growth, genes similar Transcriptomes revealed chromatin reorganisation enriched female reproductive whereas O2 condition, transcripts biased towards cellular stress responses. To further confirm results, we functional assay our model characterising using drugs reduce transcription. When histone processes reduced, at CGIs bodies presented lower profile. Our observations reveal changes between oxygen concentrations murine Oocytes had higher correlation vivo demonstrating concentration beneficial maturation ex condition. results shed light development GV model.