Characterization of the human cumulus cell transcriptome during final follicular maturation and ovulation

Abstract

Cumulus expansion and oocyte maturation are central processes in ovulation. Knowledge gained from rodent and other mammalian models has revealed some of the molecular pathways associated with these processes. However, the equivalent pathways in humans have not been thoroughly studied and remain unidentified. Compact cumulus cells (CCs) from germinal vesicle cumulus oocyte complexes (COCs) were obtained from patients undergoing in vitro maturation (IVM) procedures. Expanded CCs from metaphase 2 COC were obtained from patients undergoing IVF/ICSI. Global transcriptome profiles of the samples were obtained using state-of-the-art RNA sequencing techniques. We identified 1746 differentially expressed (DE) genes between compact and expanded CCs. Most of these genes were involved in cellular growth and proliferation, cellular movement, cell cycle, cell-to-cell signaling and interaction, extracellular matrix and steroidogenesis. Out of the DE genes, we found 89 long noncoding RNAs, of which 12 are encoded within introns of genes known to be involved in granulosa cell processes. This suggests that unique noncoding RNA transcripts may contribute to the regulation of cumulus expansion and oocyte maturation. Using global transcriptome sequencing, we were able to generate a library of genes regulated during cumulus expansion and oocyte maturation processes. Analysis of these genes allowed us to identify important new genes and noncoding RNAs potentially involved in COC maturation and cumulus expansion. These results may increase our understanding of the process of oocyte maturation and could ultimately improve the efficacy of IVM treatment.

A maternal deletion upstream of the imprint control region 2 in 11p15 causes loss of methylation and familial Beckwith–Wiedemann syndrome

“…That KCNQ1 is expressed in human and murine oocytes has already been shown. 28,29 Furthermore, Chotalia et al 24 also detected oocyte-specific start sites for Kcnq1.…”

Karyomapping and how is it improving preimplantation genetics?

“…At the same time, Verlinsky and colleagues described a protocol for polar body testing for patients at risk of transmitting PI type ZZ alpha-1-antitrypsin deficiency (AATD). Although no pregnancies were established, this study showed that proof of principle for polar body testing for monogenic disease [7]. Later…”

Non-coding RNAs in the Ovarian Follicle

“…The cellular and molecular pathways involved in these processes are today poorly understood and lncRNAs could play a major role (De La Fuente et al, 2004). Recently, lncRNAs were identified in granulosa and cumulus cells, oocytes and early embryos, and their role in oocyte and early embryo development has been suggested (Yan et al, 2013; Yerushalmi et al, 2014; Hamazaki et al, 2015; Xu et al, 2015). A comprehensive review on lncRNA functions in mammalian and in different species has been recently published (Taylor et al, 2015).…”