Bovine pregnancy associated glycoproteins can alter selected transcripts in bovine endometrial explants

This study was designed to examine changes in target transcript abundance in endometrial explants exposed to pregnancy-associated glycoproteins (PAGs). Endometrial explants from pregnant and non-pregnant heifers collected on day18 (day 0: day of insemination) were incubated in the absence or presence of PAGs (15 μg/ml). The PAGs represented a mixture comprised of approximately equal amounts of bovine PAGs 4, 6, and 9. Samples were harvested for RNA extraction after 24 h or 96 h of incubation. Transcript abundance for target genes related to prostaglandin synthesis (PTGES), a chemokine (CXCL5) and tissue remodeling (EMMPRIN; MMPs 1, 2, 3, 7, 8, and 9; PLAU; SPP1; TIMP1 and TIMP2) were analyzed by quantitative PCR. Changes in relative transcript abundance for MMP1, MMP3, MMP7, PLAU, EMMPRIN and SPP1 were observed after PAG exposure in both non-pregnant and pregnant endometrium (P < 0.05). However, some of the transcripts associated with tissue remodeling were altered only at certain time points (either 24 h or 96 h). The transcript for bovine CXCL5 was increased in non-pregnant endometrium four- and six-fold at 24 h and 96 h of PAG exposure, respectively (P < 0.05); in pregnant endometrium, only the 24 h incubation period exhibited an elevation in CXCL5 (P < 0.05). In non-pregnant endometrium, both PTGES and MMP9 were elevated after exposure to PAGs for 24 h (P < 0.05) but not in the other samples. Some interferon-responsive transcripts (IFI6, ISG15) were found to be more abundant (P < 0.05) in pregnant endometrium after 96 h exposure to PAGs compared to endometrium that had not been exposed to the PAGs. Likewise, ISG15 message was elevated (P = 0.06) in non-pregnant endometrium after 24 h incubation with PAGs. These results indicate that the PAGs used in this experiment were able to induce changes in endometrial transcripts encoding for proteins associated with matrix remodeling as well as chemokine production and prostaglandin release.