Differential Endometrial Gene Expression in Pregnant and Nonpregnant Sows1

Abstract

In an attempt to unveil molecular processes controlling the porcine placentation, we have investigated the pregnancy-induced gene expression in the endometrium using the Affymetrix GeneChip Porcine Genome Array. At Day 14 after insemination, at the time of initial placentation, samples were obtained from the endometrium of pregnant sows and sows inseminated with inactivated semen. Analysis of the microarray data revealed 263 genes to be significantly differentially expressed between the pregnant and nonpregnant sows. Most gene ontology terms significantly enriched at pregnancy had allocated more up-regulated genes than down-regulated genes. These terms included developmental process, transporter activity, calcium ion binding, apoptosis, cell motility, enzyme-linked receptor protein signaling pathway, positive regulation of cell proliferation, ion homeostasis, and hormone activity. Only the three terms oxidoreductase activity, lipid metabolic process, and organic acid metabolic process had an overrepresentation of down-regulated genes. A gene interaction network based on the genes identified in the gene ontology term developmental processes identified genes likely to be involved in the process of placentation. Pregnancy-specific localization of IL11RA to the surface epithelium of the endometrium suggests a role of interleukin 11 signaling in formation of the porcine epitheliochorial placenta. Furthermore, up-regulation of FGF9 mRNA in pregnant endometrium and localization of FGF9 to the apical cell domain of the glandular epithelium suggest the concept of endometrial FGF9 acting as an embryonic growth factor in the pig.

Differential expression of genes linked to the leukemia inhibitor factor signaling pathway during the estrus cycle and early pregnancy in the porcine endometrium

“…Although LIFR mRNA was previously demonstrated to be expressed in the porcine endometrium on Days 11,18,30, and 60 of gestation [4], our results are the first to compare the profiles of LIFR expression in cyclic and pregnant gilts on the corresponding days after estrus. Profile of endometrial expression of LIFR mRNA on Day 14 of pregnancy vs. the estrous cycle is in agreement with the results of the recently performed microarray analysis of the endometrial transcriptomes [14]. The increased expression of the LIF and LIFR in the porcine endometrium on Days 12-16 of pregnancy (present data) coincides with elevated LIF content in the uterine lumen (Day 12) and abundant expression of LIFR mRNA in the porcine conceptuses (Day 14) [3], which confirms the important role of this system during maternal recognition of pregnancy and implantation.…”

“…The present results are the first to compare the pattern of IL6R mRNA expression in the porcine endometrium during the estrous cycle and early pregnancy. Recent report showed a similar expression pattern of IL6R mRNA in the endometrium of pregnant animals on Day 14 [14]. The increased IL6 protein content in endometrium of pregnant animals [3] and upregulated expression of IL6R in the endometrium on Day 14 of pregnancy (the current study) and conceptuses (Days 10-12) [3] suggest that IL6 is substantial component of embryo-maternal crosstalk required for successful implantation.…”

Proteomic analysis of porcine endometrial tissue during peri-implantation period reveals altered protein abundance

“…These efforts, along with global gene expression studies, have tremendously advanced our understanding of porcine pregnancy and endometrial biology. In recent years, while many global gene expression studies in the porcine endometrium have been conducted on differential gene expression during pregnancy [11][12][13][14], there are very few reports regarding global changes in porcine endometrial proteome during pregnancy [6,15]. Kayser et al [6] reported changes in uterine fluid proteome during early porcine pregnancy and some proteins reported by them are common to this study.…”

“…ALDR (or AKR1B1) levels changed only with the progression of pregnancy with a~9-fold increase in Day 12 versus Day 9. The AKR1B1 gene has previously been shown to have a specific expression on Days 12 and 13 of porcine pregnancy [12,65]. Besides countering oxidative stress [66], in endometrium members of the aldo-keto reductase family, including ALDR, play an important role in the biosynthesis of prostaglandins [13,67], participating in pregnancy recognition and conceptus development in pigs [68].…”

Uterine Responses to the Preattachment Embryo in Domestic Ungulates: Recognition of Pregnancy and Preparation for Implantation

“…To elucidate endometrial responses at the level of gene expression, or more specifically, changes in mRNA concentrations, several microarray and RNA-seq studies have been performed for Day 12 as the time of MRP (57) and for Day 14 (58,59) and as the time of beginning of conceptus implantation. Particularly in the RNA-seq studies, a plethora of transcriptome changes in porcine endometrium during the preimplantation period were observed.…”