Transcriptome Changes in the Porcine Endometrium During the Preattachment Phase1

Abstract

The porcine conceptus undergoes rapid differentiation and expansion of its trophoblastic membranes between Days 11 and 12 of gestation. Concomitant with trophoblast elongation, production of conceptus estrogen, the porcine embryonic pregnancy recognition signal, increases. Conceptus attachment to the uterine surface epithelium starts after Day 13, initiating epitheliochorial placentation. To analyze the transcriptome changes in the endometrium in the course of maternal recognition of pregnancy, deep sequencing of endometrial RNA samples of Day 12 pregnant animals (n = 4) and corresponding nonpregnant controls (n = 4) was performed using RNA sequencing (RNA-Seq). Between 30 000 000 and 35 000 000 sequence reads per sample were produced and mapped to the porcine genome (Sscrofa10.2). Analysis of read counts revealed 2593 differentially expressed genes (DEGs). Expression of selected genes was validated by the use of quantitative real-time RT-PCR. Bioinformatics analysis identified several functional terms specifically overrepresented for up-regulated or down-regulated genes. Comparison of the RNA-Seq data from Days 12 and 14 of pregnancy was performed at the level of all expressed genes, the level of the DEG, and the level of functional categories. This revealed specific gene expression patterns reflecting the different functions of the endometrium during these stages (i.e., recognition of pregnancy and preparation for conceptus attachment). Genes related to mitosis, immune response, epithelial cell differentiation and development, proteolysis, and prostaglandin signaling and metabolism are discussed in detail. This study identified comprehensive transcriptome changes in porcine endometrium associated with establishment of pregnancy and could be a resource for targeted studies of genes and pathways potentially involved in regulation of this process.

Implantation and Establishment of Pregnancy in the Pig

“…5 ). Changes in endometrial transcriptome during early stages of conceptus attachment to uterine LE are just beginning to widen our understanding of the critical factors involved with establishment and maintenance of pregnancy in the pig (Samborski et al 2013 ;Chen et al 2015 ;Kiewisz et al 2014 ). The emergence of microRNAs as posttranscriptional players in regulating gene function has added a new area of investigation to enhance understanding of conceptus-endometrial interactions (Krawczynski et al 2015 ).…”

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.…”

Association of non-synonymous SNPs of <i>OPN</i> gene with litter size traits in pigs

“…Furthermore, the OPN gene corresponds to the location with the QTL regions for reproductive traits, such as ovulation rate (Rathje et al, 1997), uterine capacity (Rohrer et al, 1999), age of puberty (Cassady et al, 2001), litter size and embryosurvival rate (King et al, 2003), on SSC8 in pigs. Moreover, the function genomic analysis showed that the differential expression levels of the OPN gene were found in the ovarian follicles, ovaries, myometrium and endometrium (Caetano et al, 2004;Fernandez-Roddriguez et al, 2011;Sun et al, 2011;Wang et al, 2013;Samborski et al, 2013). Therefore the OPN gene can be regarded as a candidate gene for the determination of reproductive traits in pigs.…”

“…Several genes have been discovered. One of these genes is osteopontin (OPN) which can be differentially expressed in various reproductive tissues, e.g., ovarian follicles, ovaries, myometrium and endometrium (Caetano et al, 2004;Fernandez-Roddriguez et al, 2011;Sun et al, 2011;Wang et al, 2013;Samborski et al, 2013).…”