RNA-Sequencing based analysis of bovine endometrium during the maternal recognition of pregnancy

Abstract

Background Maternal recognition is the crucial step for establishing pregnancy in cattle. This study aims to identify endometrial genes and biological pathways involved in the maternal recognition of pregnancy. Caruncular endometrial tissues were collected from Day 15–17 of gestation (pregnant), non-pregnant (absence of conceptus), and cyclic (non-bred) heifers. Results Total RNAs were isolated from the caruncular endometrial tissues of pregnant, non-pregnant, and cyclic heifers, and were subjected to high-throughput RNA-sequencing. The genes with at least two-fold change and Benjamini and Hochberg p-value ≤ 0.05 were considered differentially expressed genes and further confirmed with quantitative real-time PCR. A total of 107 genes (pregnant vs cyclic) and 98 genes (pregnant vs non-pregnant) were differentially expressed in the pregnant endometrium. The most highly up-regulated genes in the pregnant endometrium were MRS2, CST6, FOS, VLDLR, ISG15, IFI6, MX2, C15H11ORF34, EIF3M, PRSS22, MS4A8, and TINAGL1. Interferon signaling, immune response, nutrient transporter, synthesis, and secretion of proteins are crucial pathways during the maternal recognition of pregnancy. Conclusions The study demonstrated that the presence of conceptus at Day 15–17 of gestation affects the endometrial gene expression related to endometrial remodeling, immune response, nutrients and ion transporters, and relevant signaling pathways in the caruncular region of bovine endometrium during the maternal recognition of pregnancy.

Transcriptomics analysis of the bovine endometrium during the perioestrus period

“…COL6A6 was upregulated at all time points, displaying the largest log 2 fold-change at Day 7 post-oestrus (luteal phase) (+9.05). Collagens are diverse and are involved in organizing the extracellular matrix in the endometrium of pregnant bovines, as well as participating in signalling and adhesion [ 46 ]. Collagen VI forms a subepithelial and pericellular fibril sheet in both superficial and deep bovine endometrium, linking cells to the collagen fibril network and localizing around capillaries and smooth muscle cells [ 71 ]: therefore, in this case it could have a function in reorganizing cells, particularly the vasculature of the endometrium during this period.…”

“…The quality of the individual 29 raw RNA-seq sample library files was assessed with the FastQC software (version 0.11.5) [ 44 ]. Paired-end reads from each individual library were aligned to the Bos taurus reference genome (UMD3.1.1 –GCF_000003055.6; [ 45 , 46 ], from the NCBI RefSeq database [ 47 ], using the STAR aligner software (version 2.5.1b) [ 48 ]. Following this, the aligned SAM files were quality-assessed with FastQC.…”

Identification and characterization of circRNAs in peri-implantation endometrium between Yorkshire and Erhualian pigs

“…Further, we found that the host genes of these DEcircRNAs are also involved in multiple pregnancy-related biological processes, including " biological adhesion “, “reproductive process” and “growth”. Previous studies have found that MRS2 (ssc_circ:chr7:19265492_19273195(+) host gene) is up-regulated in bovine pregnant endometrium and may be involved in the regulation of maternal recognition of pregnancy [ 66 ]. Studies have shown that CDH13(ssc_circ:chr6:5297087_5377909(-) host gene) is up-regulated in the porcine endometrium during implantation and is a gene related to implantation and pregnancy establishment in pigs [ 67 ].…”

Single-cell transcriptomics reveals striking heterogeneity and functional organization of dendritic and monocytic cells in the bovine mesenteric lymph node

“…Notably, while MS4A8 was found to be highly expressed selectively in cDC2 (c5, c9) and putative inflammatory cDC2 (c3, left part), it appeared to be absent from putative moDC (c3, right part). The function of MSA48 is poorly characterized, but it was recently found to be highly upregulated in bovine pregnant endometrium (55) and in blood of Salmonella-infected pigs (56).…”