Endometrial gene expression profile of pregnant sows with extreme phenotypes for reproductive efficiency

Abstract

Prolificacy can directly impact porcine profitability, but large genetic variation and low heritability have been found regarding litter size among porcine breeds. To identify key differences in gene expression associated to swine reproductive efficiency, we performed a transcriptome analysis of sows’ endometrium from an Iberian x Meishan F2 population at day 30–32 of gestation, classified according to their estimated breeding value (EBV) as high (H, EBV > 0) and low (L, EBV < 0) prolificacy phenotypes. For each sample, mRNA and small RNA libraries were RNA-sequenced, identifying 141 genes and 10 miRNAs differentially expressed between H and L groups. We selected four miRNAs based on their role in reproduction, and five genes displaying the highest differences and a positive mapping into known reproductive QTLs for RT-qPCR validation on the whole extreme population. Significant differences were validated for genes: PTGS2 (p = 0.03; H/L ratio = 3.50), PTHLH (p = 0.03; H/L ratio = 3.69), MMP8 (p = 0.01; H/L ratio = 4.41) and SCNN1G (p = 0.04; H/L ratio = 3.42). Although selected miRNAs showed similar expression levels between H and L groups, significant correlation was found between the expression level of ssc-miR-133a (p < 0.01) and ssc-miR-92a (p < 0.01) and validated genes. These results provide a better understanding of the genetic architecture of prolificacy-related traits and embryo implantation failure in pigs.

Whole genome sequence analysis to detect signatures of positive selection for high fecundity in sheep

“…Krueppel‐like factor 5 is a protein encoded by the KLF5 gene mapped to sheep chromosome 10. Some previous studies have indicated that KLF5 has potential important pleiotropic effect on regulating several cellular processes (development, differentiation, proliferation and apoptosis) and also has a significant role in regulation of embryo pre‐implantation litter size and prolificacy levels in pigs (Córdoba et al, ; Dang, Pevsner, & Yang, ). Another reproduction‐related gene, PDGFRL , was found to be under selection (top 1% F ST ) on sheep chromosome 26.…”

Insertion/Deletion Within the KDM6A Gene Is Significantly Associated With Litter Size in Goat

“…As one of the most important factors restricting female fertility, increasing litter size has received much more consideration (Naicy et al, 2016 ; Yang et al, 2017 ). However, litter size is a trait with low heritability in many livestock animals, including pigs (Córdoba et al, 2015 ) and goats (Shaat and Mäki-Tanila, 2009 ); therefore, traditional direct selection is ineffective. At present, marker-assisted selection (MAS), based on relevant genetic variants, is used extensively to improve traits with low heritability, such as those associated with growth and reproduction (Sharma et al, 2013 ; An et al, 2015 ; Tomas et al, 2016 ).…”

Defining age- and lactocrine-sensitive elements of the neonatal porcine uterine microRNA–mRNA interactome†,‡

“…Integrated analysis of miRNA–mRNA networks in placental tissues of Large White and Qingping sows revealed mRNAs and miRNAs associated with onset of labor, as well as a subset of genes that may play a role in regulation of gestation length [ 18 ]. Endometrial mRNAs and miRNAs in pregnant sows were also associated with extreme prolificacy phenotypes [ 17 ]. Present results now implicate miRNA–mRNA interactions in neonatal porcine uterine development.…”

“…In pigs, miRNAs were identified in adult endometrium [ 12 – 14 ] and in placental tissues [ 12 , 15 , 16 ] during early pregnancy. Endometrial [ 17 ] and placental [ 18 ] miRNA–mRNA interactions during pregnancy were also characterized. Little is known about miRNA expression in the developing uterus, or the roles of miRNAs in regulation of uterine gene expression during the perinatal period.…”