Expression of genes involved in prostaglandin E2 and progesterone production in bovine cumulus–oocyte complexes during in vitro maturation and fertilization

Abstract

Prostaglandin E 2 (PGE 2 ) and progesterone appear to be critical mediators of cumulus expansion and the resumption of oocyte meiosis. The aim of this study was to identify the types of prostaglandin E synthase (PTGES) expressed in the bovine cumulus-oocyte complex (COC), to characterize their temporal expression during the periconceptional interval using an in vitro model of maturation (IVM) and fertilization (IVF), and to compare their expression with the level of steroidogenic gene expression. Real-time RT-PCR analysis revealed that enzymes related to the PGE 2 biosynthesis pathway were mainly expressed during IVM. Transcripts encoding PTGES1-3 were detected in bovine COCs. Only the expression of PTGES1 significantly increased during IVM whereas that of PTGES2 and PTGES3 remained unchanged. The induction of PTGES1 expression paralleled the induction of prostaglandin G/H synthase-2 (PTGS2) expression and the amounts of PGE 2 secreted by maturing COCs. Concomitantly, cholesterol side chain cleavage cytochrome P450 expression was significantly upregulated in maturing COCs and the high level of expression persisted in fertilized COCs. The expression of the StAR protein remained constant during IVM and then decreased significantly during IVF. Expression of the progesterone catabolic-related enzyme, 20a-hydroxysteroid dehydrogenase significantly decreased throughout the periconceptional interval. This was associated with a rising level of progesterone released by COCs in the culture media. In conclusion, our results suggest that the periconceptional differentiation of the bovine COC includes the transient induction of PGE 2 biosynthetic activity via the PTGS2/PTGES1 pathway during the maturation period and the increasing ability to produce progesterone from the immature to the fertilized stages. Reproduction (2008) 135 593-603

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

“…Among the three PTGES isoforms, only PTGES1 was responsive to Gn stimulation during maturation. This finding is in agreement with a previous report where only PTGES1 of the three isoforms of PTGES detected was found to increase during bovine oocyte maturation, paralleling the induction of PTGS2 enzyme (Nuttinck et al, 2008). This is not only observed in COC, as it was shown that while all PTGES isoforms were expressed in the bovine oviduct (Gauvreau et al, 2010) and endometrium , PTGES1 was reported to be the main enzyme associated with PGE 2 production .…”

The Effect of Linolenic Acid on Bovine Oocyte Maturation and Development1

“…Inhibition of PGE production using PTGS2 inhibitors was found to attenuate cumulus expansion and GVBD of mouse oocytes [17][18][19]43]. In cattle, the mRNAs of PTGS2 and PGE 2 receptors (PTGER2 and PTGER3) were expressed in COCs, and PGE 2 was found to induce moderate cumulus cell expansion [41,44,45], which suggests that PGs may have an important role in oocyte maturation. In the studies presented here, inhibition of PTGS2 by NS-398 resulted in a significant reduction in oocyte nuclear maturation.…”

Impact of linoleic acid on bovine oocyte maturation and embryo development

“…It acts through G-protein coupled receptors (PTGER) on cumulus cells (Calder et al 2001). Linoleic acid influences oocyte development mRNA for PTGS2 and PGE 2 receptors (PTGER2 and PTGER3) are expressed in bovine COCs (Nuttinck et al 2002(Nuttinck et al , 2008, and PGE 2 was also shown to induce moderate expansion of cumulus cells (Calder et al 2001). This suggests that PGE may have a role in oocyte maturation.…”