Acute irradiation induces a senescence-like chromatin structure in mammalian oocytes

We used RNA-seq to investigate mechanisms leading to changes in epigenetics and chromatin organization during irradiation. Purpose: Use of next-generation sequencing (NGS) to investigate the changes in transcriptional (RNAseq) profiles in mouse oocyte after irradiation. Methods: Oocyte collection was carried out on non-primed day 16 female mice. Collected cells are maintained in minimal essential medium (MEM) supplemented with 3mg/ml bovine serum albumin (Sigma Aldrich, St. Louis, MO) and milrinone (Sigma; 1 μg/ml) to prevent meiotic resumption. These cells are either directly sequenced or treated with γ-irradiation before sequencing. Results: Transcriptomics analyses reveal that the effects of genotoxic stress induced by γ-irradiation in mammalian oocytes are mediated by signaling pathways associated with the activation of senescence and repair from DNA damage and provide the first evidence for a mechanistic link between the DNA damage response and the regulation of PCH structure in the oocyte genome.