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

Abstract

(AA Fouladi-Nashta).Waleed Fawzy A Marei is a veterinarian and graduated from Cairo University, Egypt in 2001. He started his academic career in theriogenology in 2002 and obtained his MSc degree in 2005. He joined the reproduction research group at the Royal Veterinary College, London, UK and investigated the effects of fatty acids on oocyte quality and early embryo development for his PhD, awarded in 2010. He then pursued post-doctoral research in the same group, working on early embryo development and implantation. Currently, he is a lecturer on theriogenology at Cairo University. His interests are clinical applications of assisted reproduction technologies and feed additives to improve reproductive performance in farm animals.Abstract Prostaglandin E 2 (PGE 2 ) is an autocrine/paracrine factor which mediates gonadotrophin (Gn) stimulation of cumulus expansion and oocyte maturation in rodents. Its role in bovine oocyte maturation is less characterized. This study detected PTGS2 (COX2) and PGE synthases (PTGES1, PTGES2 and PTGES3) in bovine cumulus-oocyte complexes (COC). Only PTGS2 and PTGES1 expression changed during maturation. In Gn-free media, no cumulus expansion and $45% nuclear maturation was achieved, while Gn-induced maturation showed full cumulus expansion (score 3) and $87% maturation. PGE 2 supplementation without Gn induced mild cumulus expansion (score 0.5-1) but increased nuclear maturation to levels similar to those obtained with Gn alone. In the presence of Gn, exogenous PGE 2 did not affect expansion or nuclear maturation and subsequent embryo development. Treatment with PTGS2 selective inhibitor (NS398), PTGS2-specific siRNA or PTGER2-receptor antagonist (AH6809) resulted in $20-25% reduction in nuclear maturation. NS398 and AH6809 did not affect cumulus expansion. Most oocytes not reaching metaphase of second meiosis (MII) following NS398, AH6809 and PTGS2-specific siRNA treatments were at MI. After longer maturation, NS398-treated oocytes had normal MII rate and uncompromised embryo development. PGE 2 has a limited role in cumulus expansion in bovine COC but is important for the timing of Gn-induced nuclear maturation. RBMOnline

Effects of Essential Fatty Acids during In Vitro Maturation of Porcine Oocytes: Hormone Synthesis and Embryonic Developmental Potential

“…Similar result was reported that LA significantly inhibits GV breakdown (35% in LA vs. 81% in control) in cumulusfree oocytes (Homa et al, 1992). (Marei et al, 2014). In mammals, LA can be transformed to DGLA and AA, and ALA can be transformed to EPA, and specifically, DGLA is a precursor for 1-series PG synthesis (PGF 1 or PGE 1 ), AA is a precursor for 2-series PG synthesis (PGF 2 or PGE 2 ), and EPA is a precursor for 3-series PG synthesis (PGF 3 or PGE 3 ) (Wathes et al, 2007).…”

CK1 inhibitor affects in vitro maturation and developmental competence of bovine oocytes

“…The results showed that 5 μM D4476 significant inhibited cumulus cell apoptosis, and promoted cumulus cell proliferation and expansion. Furthermore, expansion genes PTGS‐2, PTX‐3 and TGS‐6 were marker genes for oocyte maturation quality (Maina et al, ; Marei, Abayasekara, Wathes, & Fouladi‐Nashta, ; Salustri et al, ; Wisniewski & Vilček, ). Consequently, we speculated that D4476 improved developmental competence of oocytes by promoting proliferation and expansion of CCs.…”

Analysis of gene expression in granulosa cells post‐maturation to evaluate oocyte culture systems in the domestic cat

“…Expression and enzyme activity of aromatase CYP19A1, responsible for the conversion of androgens into oestrogens, for example, are regulated by FSH as demonstrated in bovine granulosa cells (Gutierrez, Campbell, & Webb, ). Genes regulating cumulus expansion by prostaglandin synthesis such as prostaglandin‐endoperoxide synthase 2 (PTGS2 or COX2), and PTGES, depend also on gonadotropin stimulation (Marei, Abayasekara, Wathes, & Fouladi‐Nashta, ).…”