Tight gene co-expression between oocyte and surrounding cumulus is critical for oocyte developmental competence

ABSTRACT: Cytoplasmic and nuclear maturation of oocytes as well as interaction with the surrounding cumulus cells are important features relevant to the acquisition of developmental competence. We used brilliant cresyl blue (BCB) to distinguish oocytes with low activity of the enzyme Glucose-6-Phosphate Dehydrogenase, and thus separated fully grown (BCB+) oocytes from those in the growing phase (BCB-). The BCB+ oocytes are twice as likely to produce a blastocyst in vitro compared to BCB- oocytes (P<0.01). We analyzed mitochondrial DNA (mtDNA) copy number in single oocytes and determined that BCB- oocytes have 1.3-fold more copies than BCB+ oocytes (P=0.004). We also interrogated the transcriptome of oocytes and surrounding cumulus cells of BCB+ versus BCB- oocytes. There was no differential transcript abundance of genes expressed in oocytes, but we identified 172 genes in cumulus cells with differential transcript abundance (FDR<0.05) based on the BCB staining of their oocyte. Differential gene co-expression analysis between BCB+ and BCB- oocytes and their surrounding cumulus cells revealed dynamic coordination of transcript abundance between both compartments of the cumulus-oocyte complex. We identified a subset of genes whose co-expression in fully grown oocytes (n=75) and their surrounding cumulus cells (n=108) compose a unique profile of the cumulus-oocyte complex. In conclusion, as oocytes transition from growing to fully grown, there is an increase in the likelihood of producing a blastocyst, a reduction of mtDNA copies and no systematic variation of transcript abundance. Cumulus cells present changes in transcript abundance, which reflects in a dynamic co-expression between oocyte and cumulus cells.

ORGANISM(S): Bos taurus

PROVIDER: GSE199210 | GEO | 2022/03/28

REPOSITORIES: GEO