Influence of estradiol on bovine trophectoderm and uterine gene transcripts around maternal recognition of pregnancy.

Embryo survival and pregnancy success is increased among animals that exhibit estrus prior to fixed time artificial insemination (AI), but there are no differences in conceptus survival to d16. The objective of this study was to determine effects of preovulatory estradiol on uterine transcriptomes, select trophectoderm transcripts, and uterine luminal fluid (ULF) proteins. Beef cows/heifers were synchronized, artificially inseminated (d0), and grouped into either high (highE2) or low (lowE2) preovulatory estradiol. Uteri were flushed (d16); conceptuses and endometrial biopsies (n = 29) were collected. RNA sequencing was performed on endometrium. Real-Time PCR (RT-PCR) was performed on trophectoderm (TE; n = 21) RNA to measure relative abundance of IFNT, PTGS2, TM4SF1, C3, FGFR2, and GAPDH. Uterine fluid was analyzed using 2D LC-MS/MS based iTRAQ method. RT-PCR data were analyzed using the MIXED procedure in SAS. There were no differences in mRNA abundances in TE, but there were 432 differentially expressed genes (DEGs) (253 downregulated, 179 upregulated) in highE2/conceptus versus lowE2/conceptus groups. There were also 48 differentially expressed proteins (DEPs; 19 upregulated, 29 downregulated), 6 of these were differentially expressed (FDR < 0.10) at the mRNA level. Similar pathways for mRNA and proteins included: calcium signaling, protein kinase A signaling, and corticotropin releasing hormone (CRH) signaling. These differences in uterine function, may be preparing the conceptus for improved likelihood of survival after d16 among highE2 animals.