Transcriptomic Analysis of STAT1/3 in the Goat Endometrium During Embryo Implantation.

Haokun Liu,Zuhui Li,Caixia Wang,Ruixue Zhang,Pengfei Lin,Chunmei Shang,Yaping Jin,Xinyan Zhang,Aihua Wang

doi:10.3389/fvets.2021.757759

Abstract

Interferon tau (IFNT), a pregnancy recognition signal in ruminants, promotes the establishment of embryo implantation by inducing the expression of interferon-stimulated genes (ISGs) via the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway. However, the precise regulatory mechanism of IFNT in goat embryo implantation remains largely unknown. In this study, we performed RNA sequencing of goat endometrial epithelial cells (gEECs) with or without 20 ng/mL IFNT treatment. Differential comparison showed that there were 442 upregulated differentially expressed genes (DEGs) and 510 downregulated DEGs. Bioinformatic analyses revealed that DEGs were significantly enriched in immune-related functions or pathways. The qRT-PCR validation results showed that the expression levels of STAT family members (STAT1, STAT2, and STAT3) were significantly upregulated in gEECs after IFNT treatment, which is in agreement with the RNA-seq data. Meanwhile, the protein levels of p-STAT1 and p-STAT3 increased significantly in gEECs after 6 and 24 h of IFNT treatment, respectively. Further in vivo experiments also confirmed that both mRNA and protein phosphorylation levels of STAT1 and STAT3 in the uterus on day 18 of pregnancy (P18) were significantly increased compared to those on day 5 (P5) and day 15 of pregnancy (P15). On P5, STAT1 and STAT3 proteins were primarily located in the uterine luminal epithelium (LE) and glandular epithelium (GE), and were also detected in the stromal cells. The intense immunostaining of STAT1 and STAT3 proteins were decreased on P15 and then increased on P18, especially in the superficial GE and subepithelial stromal cells. Moreover, p-STAT1 and p-STAT3 were highly expressed in the deep GE on P18. Collectively, these results highlight the role of IFNT in regulating endometrial receptivity in gEECs and uncover the temporal and spatial changes in the expression of STAT1/3 during embryo implantation in the goat endometrium.

Highlights

Embryo implantation is crucial for successful pregnancy
The phosphorylated-STAT1/STAT2 heterodimer forms the interferon-stimulated gene factor 3 (ISGF3) complex with interferon regulatory factor 9 (IRF9) and translocates to the nucleus, which binds to IFN-stimulated response elements (ISREs) in the promoter region of a group of interferon-stimulated genes (ISGs), leading to the transcription of ISGs [13]
Based on the RNA-seq results, we found that the expression and localization of STAT1 and STAT3, which are downstream components of the JAK-STAT signaling pathway, showed spatiotemporal changes during embryo implantation process

Summary

Introduction

Embryo implantation is crucial for successful pregnancy During this period, the elongated conceptus and receptive endometrium recognize each other and have complex interactions, which change the expression of a number of genes, resulting in promotion of embryo implantation and placenta formation, eventually leading to the establishment of pregnancy [1, 2]. In addition to its anti-luteolytic action, IFNT regulates the function of the receptive endometrium and the elongation of the conceptus to facilitate the establishment of pregnancy [10]. The phosphorylated-STAT1/STAT2 heterodimer forms the interferon-stimulated gene factor 3 (ISGF3) complex with interferon regulatory factor 9 (IRF9) and translocates to the nucleus, which binds to IFN-stimulated response elements (ISREs) in the promoter region of a group of interferon-stimulated genes (ISGs), leading to the transcription of ISGs [13]. Similar to other STATs, STAT3 forms complexes with other transcription factors, including the STAT3 homodimer [15] and STAT1/STAT3 heterodimer [16], and translocates to the nucleus for signal transduction

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Results

Conclusion