Quantitative analysis throughout pregnancy of placentomal and interplacentomal expression of pregnancy-associated glycoproteins-1 and -9 in the cow

Abstract

The multigenic pregnancy-associated glycoproteins (PAG) exhibit spatially and temporally distinct pattern across gestation in the bovine. The majority of the bovine bPAG are localized to the binucleate cells (BNC) while some are expressed throughout the trophectoderm. Bovine (b)PAG-1 and -9 are both localized to the BNC but are differentially transcribed. In addition, the anatomical location of BNC does influence protein expression in the ungulates. Therefore, the objective of the present study was to compare and contrast bPAG-1 and -9 transcriptions in the placentomal (cotyledonary, caruncular) and interplacentomal (intercotyledonary, intercaruncular) tissues throughout pregnancy in the bovine using real-time reverse transcription PCR (RT-PCR) and by in-situ hybridization. The levels of bPAG-9 transcription in the fetal membrane at peri-implantation were significantly (P<0.01) higher than bPAG-1. The expression of bPAG-9 in the placentomal and interplacentomal tissues were significantly (P<0.01) higher than bPAG-1 during the first trimester of gestation. The transcription of bPAG-1 in the placentomal and interplacentomal tissues were significantly (P<0.01) higher than bPAG-9 from mid-gestation to peripartum. The expression of bPAG-1 and -9 throughout gestation were significantly (P<0.01) affected by the anatomical location of BNC. In situ analysis paralleled the expression patterns of bPAG-1 and -9 across gestation. These findings indicate that bPAG-9 expression in the placentomal and interplacentomal tissues predominates in the first trimester of gestation while bPAG-1 transcription was primarily higher in the last two trimesters of gestation. The cellular location had significant effect on bPAG-1 and -9 transcription.