Analysis of the Uterine Epithelial and Conceptus Transcriptome and Luminal Fluid Proteome During the Peri-Implantation Period of Pregnancy in Sheep

Abstract

Studies support the idea that uterine epithelia and their secretions have important biological roles in conceptus survival, elongation, and implantation in sheep. The present study evaluated the transcriptome of the uterine luminal epithelium (LE) and glandular epithelium (GE) and the conceptus and proteome of uterine luminal fluid (ULF) during the peri-implantation period of pregnancy. Transcriptome (RNA-sequencing) analysis was conducted in LE and GE isolated from uteri of Day 10, 12, 14, 16, and 20 pregnant sheep by laser capture microdissection. In the LE, the total number of expressed genes increased between Days 10 and 20, whereas expressed genes in the GE increased from Days 10 to 14 and then decreased to Day 20. Most of the expressed genes in LE and GE from Days 10 to 14 are involved in cell survival and growth, whereas genes involved in cell organization and protein synthesis were most abundant on Days 16 and 20. Total expressed genes in the conceptus was greatest on Day 12, decreased to Day 16, and then increased to Day 20. Genes abundantly expressed in the elongating conceptus included IFNT, PTGS2, MGST1, FADS1, and FADS2, whereas SERPINA1, CSH1, and PLET1 were most abundant in the Day 20 conceptus. Proteins, identified by mass spectrometry, increased in the ULF from Days 10 to 16 and are involved in cellular reorganization or are proteases or chaperone proteins. These results support the idea that conceptus elongation and implantation is regulated by both extrinsic and intrinsic factors. This study provides critical information that serves as a foundation to discover new regulatory pathways governing uterine receptivity, conceptus elongation, trophectoderm differentiation, conceptus-endometrial interactions, and pregnancy establishment in ruminants.

Trophectoderm-Specific Knockdown of LIN28 Decreases Expression of Genes Necessary for Cell Proliferation and Reduces Elongation of Sheep Conceptus

“…Many studies have reported the role of IGF2BPs in cell proliferation, cell invasion, tumorigenesis, and embryogenesis [40][41][42][43][44][45][46][47][48][49][50][51]. IGF2BPs have also been found in sheep trophoblast cells suggesting their role in rapid proliferation of these cells [52]. HMGA1 promotes invasion of trophoblast cells and reduced levels of HMGA1 has been linked to pathogenesis of preeclampsia [53,54].…”

Hormone regulates endometrial function via cooperation of endoplasmic reticulum stress and mTOR‐autophagy

“…The first important step in pregnancy recognition and implantation is interaction between the endometrial luminal epithelium (LE) and the blastocyst (Greening, Nguyen, Elgass, Simpson, & Salamonsen, ). In ruminant, the receptive endometrium and the elongation of the hatched blastocyst are required to complete the process of implantation (Brooks, Burns, Moraes, & Spencer, ). In particular, two‐thirds of failure pregnancy are due to abnormal uterine receptivity (Chen et al, ).…”

“…Also, IFNT induces or substantially stimulates expression of several IFN‐stimulated genes (ISGs) which are speculated to involved in elongation and implantation of the conceptus in the ovine uterus, including ISG15 and chemokine (C‐X‐C motif) ligand 10 ( CXCL10 ) (Sakumoto et al, ). A recent study reports that the transcriptome of the uterine LE and GE was evaluated by laser capture microdissection in sheep, and genes abundantly expressed in the LE and GE during the peri‐implantation period of pregnancy included the radical S‐adenosylcontaining domain 2 ( RSAD2 ) and Osteopontin ( SPP1 ) (Brooks et al, ). With the development of blastocysts into filamentous conceptus during days 12–17, the conceptus of ovine gradually contact with LE and adhere firmly to LE on day 16 (Wan et al, ).…”

Transcriptome Analysis of Three Sheep Intestinal Regions reveals Key Pathways and Hub Regulatory Genes of Large Intestinal Lipid Metabolism

“…Recently, several studies have reported the successful transcriptome sequencing of multiple tissues in sheep brain 15 , uterus 16 , skeletal muscle 17–19 , mammary gland 20 , milk 21 , rumen 22 , and skin 23 tissues. To the best of our knowledge, only two transcriptomic studies on sheep have recently been conducted on large intestine metabolism.…”