Tissue expression of EphB2 and RNA-seq analysis during embryo im-plantation in Meishan pigs

Embryo implantation is a key step affecting swine litter size, which is an important economic and reproduction trait in pigs. In order to investigate the effect of erythropoietin-producing hepatocellular receptor B2 (EphB2) on endometrium migration and attachment during swine embryo implantation, the mRNA and protein expression levels of EphB2 in endometrium implantation sites, endometrium non-implantation sites and ovary were detected in Meishan sows during pre-implantation, mid-implantation and post-implantation period using real-time quantitative PCR and Western blot. Differential expression genes were also analyzed in endometrium implantation sites and ovary during different implantation periods by RNA sequencing (RNA-seq) technology. The qRT-PCR and Western blot results showed that EphB2 mRNA and protein expression curve was the same in endomtrium implantation sites and endometrium non-implantation sites during pre-implantation, mid-implantation and post-implantation period, with a first increase followed by a decrease, and its expression level during mid-implantation was significantly higher than pre-implantation and post-implantation (P<0.01). In contrast, EphB2 mRNA and protein expression curve in ovary during pre-implantation, mid-implantation and post-implantation period showed a first decrease followed by an increase, and the expression levels were significantly different among different implantation periods (P<0.05). RNA-seq results indicated that EphB2 mRNA expression during mid-implantation was higher than that of pre-implantation extremely significantly in endometrium implantation sites (P<0.01), and was significantly higher than that of post-implantation in ovary (P<0.05). By and large, EphB2 might play an important role in swine embryo implantation, and it's a potential candidate gene for litter size in pigs.