1. Canine placental prostaglandin E2 synthase (PTGES): Expression, localization and biological functions in providing substrates for prepartum PGF2alpha synthesis
- Author
-
Gram, Aykut, Fox, Barbara, Büchler, Urs, Boos, Alois, Hoffmann, Bernd, Kowalewski, Mariusz P, University of Zurich, and Kowalewski, Mariusz P
- Subjects
1307 Cell Biology ,endocrine system ,10077 Institute of Veterinary Anatomy ,570 Life sciences ,biology ,lipids (amino acids, peptides, and proteins) ,2743 Reproductive Medicine - Abstract
The prepartum output of PGF2alpha in the bitch is associated with increased placental PGE2 synthase (PTGES) mRNA levels. Contrasting with this is a decreased expression of PGF2alpha synthase (PGFS/AKR1C3) in utero placental compartments during prepartum luteolysis suggesting an involvement of alternative synthetic pathways in PGF2alpha synthesis e.g. conversion of PGE2 to PGF2alpha. However since the expression and possible functions of the respective PTGES protein remained unknown no further conclusion could be drawn. Therefore a canine specific PTGES antibody was generated and used to investigate the expression cellular localization and biochemical activities of canine utero placental PTGES throughout pregnancy and at prepartum luteolysis. Additionally the biochemical activities of these tissues involved in the conversion of PGE2 to PGF2alpha were investigated. The endometrial PTGES was localized in the uterine surface epithelium pre implantation and in superficial and deep uterine glands endothelial cells and myometrium throughout pregnancy and at parturition. Placental signals were mostly in the trophoblast. The biochemical properties of recombinant PTGES protein were confirmed. Additionally expression of two PGE2 receptors PTGER2/EP2 and PTGER4/EP4 revealed their decreasing expression during luteolysis. In contrast the utero placental expression of prostaglandin transporter (PGT) was strongly elevated prior to parturition. These localization patterns resembled that of PTGES. The increased expression of PTGES and PGT at parturition together with the accompanying decreased levels of PGE2 receptors and the capability of canine uterine and placental homogenates to take part in the conversion of PGE2 to PGF2alpha as found in this study suggest that PGE2 could be utilized locally as a substrate for prepartum PGF2alpha synthesis in the dog.
- Published
- 2014