Expression of prostaglandin F2α (PGF2α) receptor and its isoforms in the bovine corpus luteum during the estrous cycle and PGF2α-induced luteolysis

Prostaglandin F-2 alpha (PGF(2 alpha)) induces luteolysis via a specific receptor. PTGFR. Although PTGFR mRNA expression in the bovine corpus luteum (CL) has been studied previously, changes in PTGFR protein and its localization are not fully understood during, the life span of the CL. In addition to full-length PTGFR, several types of PTGFR isoforms, such as PTGFR alpha (type I) and PTGFR zeta (type 11). were reported in the bovine CL, suggesting isoform-specific lineal action. Full-length PTGFR mRNA in the bovine CL increased from the early to the mid-luteal phase and decreased during luteolysis, whereas PTGFR protein remained stable. PTGFR protein was localized to both luteal and endothelial cells and was expressed similarly during the life span of the CL. Like full-length PTGFR mRNA. PTGFR alpha and PTGFR zeta mRNA also increased from the early to mid-luteal phases, and mRNA of PTGFR zeta, but not PTGFR alpha, decreased in the regressing CL. During PGF(2 alpha)-induced lnteolysis. the mRNAs of full-length PTGFR. PTGFR alpha and PTGFR zeta decreased rapidly (from 5 or 15 min after PGF(2 alpha), injection). but PTGFR protein decreased only 12 h later. Silencing full-length PTGFR using small interfering RNA prevented PGF(2 alpha)-stimulated cyclooxygenase-2 (PTGS2) mRNA induction. By contrast, PGF(2 alpha), could stimulate vascular endothelial growth factor A (VEGFA) mRNA even when full-length PTGFR was knocked clown, thus suggesting that PGF(2 alpha), may stimulate PTGS2 via full-length PTGFR, whereas VEGFA is stimulated via other PTGFR isoforms. Collectively, PTGFR protein was expressed continually in the bovine CL during the estrous cycle, implying that PGF(2 alpha) could function throughout this period. Additionally, the bovine CL expresses different PTGFR isoforms, and thus PGF(2 alpha) may have different effects when acting via full-length PTGFR or via PTGFR isoforms. (C) 2012 Elsevier Inc. All rights reserved.