Identification of Potential Markers of Oocyte Competence Expressed in Bovine Cumulus Cells Matured with Follicle-Stimulating Hormone and/or Phorbol Myristate Acetate In Vitro

Abstract

Oocyte competence is the ability of the oocyte to complete maturation, undergo successful fertilization, and reach the blastocyst stage. Cumulus cells are indispensable for this process. Their removal significantly affects the blastocyst rates. Moreover, the properties and functions of cumulus cells are regulated by the oocyte. They also reflect the oocyte's degree of maturation. Our study was aimed at identifying markers of oocyte competence that are expressed in bovine cumulus cells. In a previous study in our laboratory, the blastocyst yield following FSH or phorbol myristate acetate (PMA) treatment was 45%%. Therefore, we tested four sets of conditions during the first 6 h of in vitro maturation (IVM): FSH (0.1 microg/ml), PMA (0.1 microM), FSH ++ PMA, and negative control. Extracts from each IVM treatment were hybridized against the same negative control on a microarray containing a partial library of differentially expressed transcripts in the cumulus of competent oocytes collected at 6 h after LH in vivo. Common positive clones between diffrentially treated cells were selected, and 15 candidates were validated by real-time PCR. Based on this, the main candidates expressed in cumulus cells and that could be valuable and indirect markers of oocyte competence are hyaluronan synthase 2 (HAS2), inhibin betaA (INHBA), epidermal growth factor receptor (EGFR), gremlin 1 (GREM1), betacellulin (BTC), CD44, tumor necrosis factor-induced protein 6 (TNFAIP6), and prostaglandin-endoperoxide synthase 2 (PTGS2). These biomarkers could be potential candidates to predict oocyte competence and to select higher-quality embryos for transfer. Additionally, these indirect predictors of oocyte competence and follicular health could improve our knowledge of gene expression patterns in the cumulus and yield insights into the molecular pathways controlling oocyte competence.

Changes in granulosa cells' gene expression associated with increased oocyte competence in bovine

“…In parallel, we and others have observed that granulosa/follicular gene expression may be associated with developmental competence of the enclosed oocyte in bovines (Robert et al 2001), rats (Jiang et al 2010), and humans (Assidi et al 2008, 2010, 2010. In our previous experiment, it was observed that an improved developmental rate was obtained with a hormonal treatment consisting of 3 days of stimulation using FSH plus a coasting period of 44 h (Blondin et al 2002).…”

Age-associated changes in bovine oocytes and granulosa cell complexes collected from early antral follicles

“…Of the apoptosis related genes, CCDC80, COL1A1, CTGF, DNAJB1, LGALS9, LTF, LNM, MT2A, MTH11, SOX4, and TIMP2 showed significant differences in expression levels between the two age groups (Supplementary Table 2). Table 3 lists the marker genes for the largest healthy follicles and the subordinate follicles in cows [31][32][33][34][35][36][37], and shows the expression levels of these genes in aged and young cows. All genes associated with subordinate follicles were expressed at lower levels in young cows.…”

Role of PTGS2-generated PGE2 during gonadotrophin-induced bovine oocyte maturation and cumulus cell expansion

“…Many pathways including cAMP and cAMP-dependent protein kinase A are reported to be involved in regulating this process (Downs et al, 2002;Homa, 1988). FSH stimulates germinal-vesicle breakdown (GVBD) and resumption of oocyte maturation both in vitro and in vivo (Assidi et al, 2008(Assidi et al, , 2010Sirard et al, 2007) through binding to FSH receptors on granulosa cells or cumulus cells which are G-protein-coupled receptors (Heitman and Ijzerman, 2008;Segaloff et al, 1990) and results in a signalling cascade involving increasing intracellular cAMP concentrations (Dekel, 1988) and stimulation of prostaglandin E synthesis (Shimada et al, 2006;Yamashita et al, 2011).…”