Effects of FSH on the expression of receptors for oocyte-secreted factors and members of the EGF-like family during in vitro maturation in cattle

Abstract

FSH induces expansion of bovine cumulus-oocyte complexes (COCs) in cattle, which can be enhanced by oocyte-secreted factors (OSFs). In this study it was hypothesised that FSH stimulates COC expansion in part from direct stimulation of the epidermal growth factor (EGF)-like ligands amphiregulin (AREG), epiregulin (EREG) and betacellulin (BTC), but also in part through regulation of OSFs or their receptors in cumulus cells. Bovine COCs were cultured in defined medium with graded doses of FSH. In the absence of FSH, COCs did not expand. FSH caused cumulus expansion, and increased the abundance of AREG and EREG mRNA in a time- and dose-dependent manner, but decreased BTC mRNA levels. FSH had modest stimulatory effects on the levels of mRNA encoding the bone morphogenetic protein 15 (BMP15) receptor, BMPR1B, in cumulus cells, but did not alter mRNA expression of the growth and differentiation factor 9 (GDF9) receptor, TGFBR1. More interestingly, FSH dramatically stimulated levels of mRNA encoding two receptors for fibroblast growth factors (FGF), FGFR2C and FGFR3C, in cumulus cells. FSH also stimulated mRNA expression of FGFR1B, but not of FGFR2B in cumulus cells. Based on dose-response studies, FGFR3C was the receptor most sensitive to the influence of FSH. This study demonstrates that FSH stimulates the expression of EGF-like factors in bovine cumulus cells, and provides evidence that FSH differently regulates the expression of distinct receptors for OSFs in cumulus cells.

Bone morphogenetic protein 15 and fibroblast growth factor 10 enhance cumulus expansion, glucose uptake, and expression of genes in the ovulatory cascade during in vitro maturation of bovine cumulus–oocyte complexes

“…In association with this enhancement in cumulus expansion, BMP15 stimulated the expression of genes critical for this process. BMP15 increased abundance of mRNA encoding AREG, EREG, PTGS2, PTX3, and TNFAIP6 as previously observed in the mouse (Yoshino et al 2006, Li et al 2009a, although BMP15 had no effect on BTC mRNA levels in cattle unlike the situation in mice (Yoshino et al 2006); this is probably because of the marked species differences in the regulation of BTC expression (Caixeta et al 2012). Most interesting however, is the stimulatory action of BMP15 on mRNA expression of ADAM10 and ADAM17 in the present study.…”

“…All treatments were tested after 4, 12, and 22 h of culture; these time points were chosen based on a previous time-course study (Caixeta et al 2012). Different times of culture were assessed in different experiments and thus treatments were compared within each time point but not between time points.…”

“…The preovulatory LH surge induces COC expansion in vivo (reviewed by Richards et al (2002)), and studies on mice and rats indicate that the effect of LH on the COC is mediated by the epidermal growth factor (EGF)-like family members, amphiregulin (AREG), epiregulin (EREG), and betacellulin (BTC), that are secreted by mural granulosa cells and act upon cumulus cells (Park et al 2004, Ashkenazi et al 2005, Conti et al 2006. FSH can also stimulate the expression/ synthesis of EGF-like growth factors in murine and bovine cumulus cells (Downs & Chen 2008, Caixeta et al 2012. EGF-like growth factors are synthesized as transmembrane precursors and must undergo proteolytic cleavage ('shedding') by members of the disintegrin and metalloproteinase (ADAM) family (reviewed by Ben-Ami et al (2006)).…”

Standard human chorionic gonadotropin versus double trigger for final oocyte maturation results in different granulosa cells gene expressions: a pilot study

“…Follicle-stimulating hormone has been shown previously to initiate the synthesis of hyaluronic acid, cumulus expansion, and the resumption of meiosis (12,13,43), and FSH has also been shown to directly increase the mRNA expression of amphiregulin and epiregulin in the GCs (43).…”

FSH in vitro versus LH in vivo: similar genomic effects on the cumulus

“…This de novo gene expression is indispensable for gonadotropin-induced oocyte maturation in murine and feline species [75,76] and was shown to involve the MAPK downstream of the cAMP-dependent PKA pathway in most mammals including mouse [77,78], rat [79] and cow [80]. In fact, it was shown that PKA phosphorylation and, EGF-like factors overexpression and secretion are both required to the FSH activation of ERK1/2 in pig and mice cumulus cells [61,81-83]. Additional signaling cross-talk events between the cAMP/PKA and the EGFR-MAPKs cascades were shown to up-regulate the PKA pathway via the synthesis of PGE2 [84-86].…”