Spatial Transcriptomic and miRNA Analyses Revealed Genes Involved in the Mesometrial-Biased Implantation in Pigs.

Huang Huang,Yang Yang,Tian Tian,Deng Deng,Yu Yu

doi:10.3390/genes10100808

Abstract

Implantation failure is a major cause of early embryonic loss. Normally, the conceptus attachment is initiated at mesometrial side of the uterus and then spread to the anti-mesometrial side in pigs, however, the mechanisms that direct the mesometrial-biased attachment are largely unknown. In this study, the histological features of the entire uterine cross-section from gestational days 12 (pre-attachment stage) and 15 (post-attachment stage) were investigated and the differences in histological features between the mesometrial and anti-mesometrial side of the uterus were observed. Then, transcriptomic and miRNA analyses were performed on mesometrial and anti-mesometrial endometrium obtained from gestational days 12 and 15, respectively. Differentially expressed genes (DEGs) and miRNAs (DE-miRs) that were common to both or unique to either of the two anatomical locations of uterus were identified, respectively, indicating that differences in molecular response to the implanting conceptus exist between the two anatomical locations. In addition, we detected DEGs and DE-miRs between the two anatomical locations on the two gestational days, respectively. Of these DEGs, a number of genes, such as chemokine and T cell surface marker genes, were found to be significantly up-regulated mesometrially. Furthermore, we detected the interaction of CXCR4, CXCL11 and miR-9 using dual luciferase reporter assay. Taken together, this study revealed genes and pathways that might play the role of creating a receptive microenvironment at the mesometrial side, which is required to guide a proper positioning of conceptus in the uterus in pigs.

Highlights

Failure in conceptus implantation is a major cause for the decrease in litter size in pigs
Transcriptome analysis revealed that a total of 1753 genes were differentially expressed (DEGs) between gestational days 12 and 15 in the mesometrial endometrium
The results indicate that during the early gestational stages, regulation of immune related genes was required for endometrial remodeling at both the mesometrial and anti-mesometrial side of the uterus, and gene expression patterns before and after conceptus attachment were different between the mesometrial and anti-mesometrial endometrium in the uterus

Summary

Introduction

Failure in conceptus implantation is a major cause for the decrease in litter size in pigs. The initial attachment of porcine conceptus to the endometrium takes place around day 13 of gestation, forming a non-invasive epitheliochorial placenta [1,2,3]. A recent study conducted by using laser capture microdissection (LCM) determined the gene expression changes in different types of endometrial cells between day 12 of pregnant and non-pregnant cyclic gilts [9]. These findings identified genes and regulatory pathways that are associated with embryo implantation in pigs [10,11,12,13,14,15]

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Results

Discussion

Conclusion