SOX2 plays a crucial role in cell proliferation and lineage segregation during porcine pre‐implantation embryo development

Abstract

Objectives Gene regulation in early embryos has been widely studied for a long time because lineage segregation gives rise to the formation of a pluripotent cell population, known as the inner cell mass (ICM), during pre‐implantation embryo development. The extraordinarily longer pre‐implantation embryo development in pigs leads to the distinct features of the pluripotency network compared with mice and humans. For these reasons, a comparative study using pre‐implantation pig embryos would provide new insights into the mammalian pluripotency network and help to understand differences in the roles and networks of genes in pre‐implantation embryos between species. Materials and methods To analyse the functions of SOX2 in lineage segregation and cell proliferation, loss‐ and gain‐of‐function studies were conducted in pig embryos using an overexpression vector and the CRISPR/Cas9 system. Then, we analysed the morphological features and examined the effect on the expression of downstream genes through immunocytochemistry and quantitative real‐time PCR. Results Our results showed that among the core pluripotent factors, only SOX2 was specifically expressed in the ICM. In SOX2‐disrupted blastocysts, the expression of the ICM‐related genes, but not OCT4, was suppressed, and the total cell number was also decreased. Likewise, according to real‐time PCR analysis, pluripotency‐related genes, excluding OCT4, and proliferation‐related genes were decreased in SOX2‐targeted blastocysts. In SOX2‐overexpressing embryos, the total blastocyst cell number was greatly increased but the ICM/TE ratio decreased. Conclusions Taken together, our results demonstrated that SOX2 is essential for ICM formation and cell proliferation in porcine early‐stage embryogenesis.

Species-Specific Enhancer Activity of OCT4 in Porcine Pluripotency: The Porcine OCT4 Reporter System Could Monitor Pluripotency in Porcine Embryo Development and Embryonic Stem Cells

“…The expression of DE-GFP and PE-GFP in the pooled embryos was highest at the 8-cell stage, and expression decreased through 5-day-old (D5, early) and 7-day-old (D7, late) blastocysts (BL) ( Figure 2(a) ). This is consistent with the highest expression of OCT4 at the 6–8-cell stage and decreases at later stages in preimplantation porcine embryos [ 34 ]. When comparing the expression of DE-GFP and PE-GFP, there was no difference in expression at the 6–8-cell stage, but at the D5 BL stage and D7 BL stage, the expression of DE-GFP was significantly increased compared with that of PE-GFP ( Figure 2(b) ).…”

“…and expression decreased through 5-day-old (D5, early) and 7-day-old (D7, late) blastocysts (BL) (Figure 2(a)). This is consistent with the highest expression of OCT4 at the 6-8cell stage and decreases at later stages in preimplantation porcine embryos [34]. When comparing the expression of DE-GFP and PE-GFP, there was no difference in expression at the 6-8-cell stage, but at the D5 BL stage and D7 BL stage, the expression of DE-GFP was significantly increased com-pared with that of PE-GFP (Figure 2 To determine the difference in expression in ICM and TE of the reporter system, the preimplantation porcine ICM marker SOX2 was stained but there was no difference (Figure 2(e)).…”

Molecular Mechanisms Underlying the Inhibition of Proliferation and Differentiation by Florfenicol in P19 Stem Cells: Transcriptome Analysis

“…In this study, we find that FLO decreases the expression of Oct4 and Sox2 ( Figure 1C ), which implies that FLO represses the pluripotency of P19SCs. Moreover, given the essential roles of Oct4 and Sox2 in regulating cell cycle and proliferation of stem cells ( Lee et al, 2016 ; Lee et al, 2021 ), we speculate that FLO-induced downregulation of pluripotent factors and proliferation inhibition in ESCs might be key reasons for poor embryo quality and early embryonic death post FLO treatment.…”

“…Sox2 is a target gene of Oct4 and is also essential for pluripotent cell development. Loss of Oct4 or Sox2 is reported to cause loss of pluripotency of ESCs and embryonic lethality ( Boyer et al, 2006 ; Lee et al, 2021 ). In this study, we find that FLO decreases the expression of Oct4 and Sox2 ( Figure 1C ), which implies that FLO represses the pluripotency of P19SCs.…”

Changes in OCT4 expression play a crucial role in the lineage specification and proliferation of preimplantation porcine blastocysts

“…The disruption of OCT4 expression in mammalian embryos prevents ICM formation and the maintenance of pluripotency 28–30 . SOX2 is known to play an important role in the formation of ICM or intact blastocysts 18,31 . In NANOG knockout embryos, epiblast formation is disturbed, and the ICM differentiates into the primitive endoderm 32,33 .…”