Single cell RNA-Seq of Hira-KO and control MII oocytes [Gdf9-Cre+]

The integrity of chromatin, which provides a dynamic template for all DNA related processes in eukaryotes, is maintained through replication dependent and independent assembly pathways. To address the role of replication independent histone deposition, we deleted the histone H3.3 chaperone Hira in developing mouse oocytes. We show that chromatin of non-replicative developing oocytes is highly dynamic, and that lack of continuous H3.3/H4 deposition alters chromatin structure, resulting in increased DNase I sensitivity, the accumulation of DNA damage, and, ultimately, a severe fertility phenotype. On the molecular level, abnormal chromatin structure leads to a dramatic decrease in the dynamic range of gene expression, the appearance of spurious transcripts, and inefficient de novo DNA methylation. In contrast to the only minor transcriptional phenotype observed in mouse pluripotent cells, we unequivocally show the importance of histone replacement and chromatin homeostasis for transcriptional regulation and normal developmental progression in an in vivo context. Overall design: RNA-Seq on 4 Hiraf/f and 4 Hiraf/f, Gdf9-Cre+ single MII oocytes