Deep Sequencing of the Porcine Endometrial Transcriptome on Day 14 of Pregnancy1

Abstract

In pigs, conceptus attachment to the uterine surface epithelium starts around Day 14 of pregnancy preceded by a pronounced vascularization at the implantation zones, initiating the epitheliochorial placentation. To characterize the complex transcriptome changes in the endometrium in the course of initial conceptus attachment, deep sequencing of endometrial RNA samples of pregnant animals (n = 4) and corresponding cyclic controls (n = 4) was performed using Illumina RNA-Seq. The obtained sequence reads were mapped to the porcine genome, and relative expression values were calculated for the analysis of differential gene expression. Statistical analysis revealed 1933 differentially expressed genes (false discovery rate 1%), 1229 with higher and 704 with lower mRNA concentration, in the samples from pregnant animals. Expression of selected genes was validated by the use of quantitative real-time RT-PCR. The RNA-Seq data were compared to results of a microarray study of bovine endometrium on Day 18 of pregnancy and additional related data sets. Bioinformatics analysis revealed for the genes with higher mRNA concentration in pregnant samples strong overrepresentation, particularly for immune-related functional terms but also for apoptosis and cell adhesion. Overrepresented terms for the genes with lower mRNA concentration in pregnant samples were related to extracellular region, ion transport, cell adhesion, and lipid and steroid metabolic process. In conclusion, RNA-Seq analysis revealed comprehensive transcriptome differences in porcine endometrium between Day 14 of pregnancy and corresponding cyclic endometrium and highlighted new processes and pathways probably involved in regulation of noninvasive implantation 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

“…Deep sequencing analysis of porcine endometrium showed up-regulation of both proapoptotic and antiapoptotic genes on Day 14 in pregnant animals. Among the antiapoptotic genes, those belonging to BCL2 family (BCL2A1, BCL2L14) were identified in that study [15]. Because Bcl-2 is considered to be an important antiapoptotic …”

Proteomes of the Female Genital Tract During the Oestrous Cycle

“…The regulation of the uterine transcriptome during the preimplantation phase has been intensively studied in several species (sheep (73), bovine (74,75), horse (21,76), and pig (77)(78)(79)) and the proteome of uterine fluid during the early stages of pregnancy was analyzed in cattle and sheep (80 -82). Several proteins we found more abundant in the uterine luminal fluid during the luteal phase were also described as uterine markers of early pregnancy with an increased production in the presence of an embryo.…”

Differential Gene Expression in Uterine Endometrium During Implantation in Pigs1

“…Multiparous Large White sows (fifth parity) were observed daily for standing heat in the presence of a boar. The sows of the pregnant group were inseminated twice, 12 and 24 h after heat detection [14]. The sows of the nonpregnant group were treated with inactivated sperm from the same boar [14].…”

“…The sows of the pregnant group were inseminated twice, 12 and 24 h after heat detection [14]. The sows of the nonpregnant group were treated with inactivated sperm from the same boar [14]. Nine pregnant sows were slaughtered by electrocution on Days 13,18, and 24 after insemination (the pregnant group, three sows every period).…”

“…We expect that these differences in gene expression patterns to help identify candidate genes that contribute to differences in litter size. There have been some expression studies carried out in pigs looking at changes in endometria [14][15][16][17][18], ovaries [3], and placentas [19], and genes differently expressed at one stage of pregnancy have been identified. Furthermore, important biological processes and pathways were identified.…”