The prostaglandin E₂ receptor PTGER2 and prostaglandin F_2α receptor PTGFR mediate oviductal glycoprotein 1 expression in bovine oviductal epithelial cells

Abstract

Oviductal glycoprotein 1 (OVGP1), an oviductin, is involved in the maintenance of sperm viability and motility and contributes to sperm capacitation in the oviduct. In this study, the regulatory effects exerted by prostaglandin E₂ (PGE₂) and F_2α (PGF_2α) on OVGP1 expression via their corresponding receptors in bovine oviductal epithelial cells (BOECs) were investigated. BOECs were cultured in vitro, and their expression of receptors of PGE₂ (PTGER1, PTGER2, PTGER3, and PTGER4) and PGF_2α (PTGFR) was measured using RT-qPCR. Ca²⁺ concentration was determined with a fluorescence-based method and cAMP was quantified by enzyme-linked immunosorbent assays to verify activation of PTGER2 and PTGFR by their corresponding agonists in these cells. OVGP1 mRNA and protein expression was measured using RT-qPCR and western blotting, respectively, following PTGER2 and PTGFR agonist-induced activation. PTGER1, PTGER2, PTGER4, and PTGFR were found to be present in BOECs; however, PTGER3 expression was not detected. OVGP1 expression was significantly promoted by 10^–6 M butaprost (a PTGER2 agonist) and decreased by 10^–6 M fluprostenol (a PTGFR agonist). In addition, 3 μM H-89 (a PKA inhibitor) and 3 μM U0126 (an ERK inhibitor) effectively inhibited PGE₂-induced upregulation of OVGP1, and 5 μM chelerythrine chloride (a PKC inhibitor) and 3 μM U0126 negated OVGP1 downregulation by PGF_2α. In conclusion, this study demonstrates that OVGP1 expression in BOECs is enhanced by PGE₂ via PTGER2-cAMP-PKA signaling, and reduced by PGF_2α through the PTGFR-Ca²⁺-PKC pathway.