Premium
Integrative Genomic Analysis of Ribosomal DNA in the Mouse Oocyte and Early Embryo
Author(s) -
Garner Tyler B,
Diaz Francisco J
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.474.5
Subject(s) - biology , chromatin , epigenetics , genetics , histone , dna methylation , zygote , microbiology and biotechnology , transcriptome , oocyte , transcription (linguistics) , gene , gene expression , embryo , embryogenesis , linguistics , philosophy
Ribosomal RNAs compose the majority of the total transcripts present in cells and their expression is tightly controlled through changes in epigenetic modifications, chromatin structure, and DNA accessibility. These mechanisms conserve translational capacity for homeostatic maintenance and survival or stimulate ribosome biogenesis for growth and proliferation, such as in the maturing oocyte where gene expression is virtually arrested until after fertilization when transcription is upregulated to promote embryonic development. Next‐generation sequencing technologies have vastly improved our understanding of gene regulation during the egg to embryo transition, however most studies thus far have neglected rDNA. Here, we have integrated genomic analyses of histone modifications (ChIP‐seq), DNA methylation (RBBS‐seq), chromatin accessibility (ATAC‐seq and DNase‐seq), and transcriptome profiling (RNA‐seq) in oocytes and pre‐implantation embryos to the mouse rDNA repeat. We observed both low chromatin accessibility and enrichment of the active transcription markers H3K4me3 and H3K27ac in oocytes which increase significantly at the 2‐cell and 8‐cell stages, particularly along specific loci within the intergenic spacer (IGS). Conversely, repressive histone patterns associated with heterochromatin and Polycomb silencing (H3K9me3 and H3K27me3 respectively) were reduced from the oocyte to zygote and nearly abolished by the 8‐cell stage. Consistent with these findings, RNA‐seq coverage along the 18S, 5.8S, and 28S coding regions increased throughout development in addition to the appearance of signals in the external and internal transcribed spacers at the 2‐cell and 8‐cell stages, indicative of active rRNA transcription. Interestingly, uniquely‐aligned transcripts were detected at distinct loci along the IGS and promoter regions in 2‐cell and 8‐cell embryos that were absent in oocytes and zygotes. The significance of these stage‐specific, non‐coding transcripts in embryogenesis will be a focus of further investigations. Together, these analyses detail the rDNA genomic landscape from the egg to early embryo and present novel avenues for exploration of ribosomal regulation during this critical period of development. Support or Funding Information NIHT32GM108563‐01A1 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .