ESRRB Facilitates the Conversion of Trophoblast-Like Stem Cells From Induced Pluripotent Stem Cells by Directly Regulating CDX2

Distinct properties of putative trophoblast stem cells established from somatic cell nuclear-transferred pig blastocysts

BACKGROUND

Genetically modified pigs are considered ideal models for studying human diseases and potential sources for xenotransplantation research. However, the somatic cell nuclear transfer (SCNT) technique utilized to generate these cloned pig models has low efficiency, and fetal development is limited due to placental abnormalities.

RESULTS

In this study, we unprecedentedly established putative porcine trophoblast stem cells (TSCs) using SCNT and in vitro-fertilized (IVF) blastocysts through the activation of Wing-less/Integrated (Wnt) and epidermal growth factor (EGF) pathways, inhibition of transforming growth factor-β (TGFβ) and Rho-associated protein kinase (ROCK) pathways, and supplementation with ascorbic acid. We also compared the transcripts of putative TSCs originating from SCNT and IVF embryos and their differentiated lineages. A total of 19 porcine TSCs exhibiting typical characteristics were established from SCNT and IVF blastocysts (TSCsNT and TSCsIVF). Compared with the TSCsIVF, TSCsNT showed distinct expression patterns suggesting unique TSCsNT characteristics, including decreased mRNA expression of genes related to apposition, steroid hormone biosynthesis, angiopoiesis, and RNA stability.

CONCLUSION

This study provides valuable information and a powerful model for studying the abnormal development and dysfunction of trophoblasts and placentas in cloned pigs.

Enhancement of Chromatin and Epigenetic Reprogramming in Porcine SCNT Embryos—Progresses and Perspectives

Over the last 25 years, cloned animals have been produced by transferring somatic cell nuclei into enucleated oocytes (SCNT) in more than 20 mammalian species. Among domestic animals, pigs are likely the leading species in the number of clones produced by SCNT. The greater interest in pig cloning has two main reasons, its relevance for food production and as its use as a suitable model in biomedical applications. Recognized progress in animal cloning has been attained over time, but the overall efficiency of SCNT in pigs remains very low, based on the rate of healthy, live born piglets following embryo transfer. Accumulating evidence from studies in mice and other species indicate that new strategies for promoting chromatin and epigenetic reprogramming may represent the beginning of a new era for pig cloning.

KDM4C Contributes to Trophoblast-Like Stem Cell Conversion from Porcine-Induced Pluripotent Stem Cells (piPSCs) Via Regulating CDX2

Studies on ESRRB-regulating porcine-induced pluripotent stem cells (piPSCs) converted to trophoblast-like stem cells (TLSCs) contribute to the understanding of early embryo development. However, the epigenetic modification regulation network during the conversion is poorly understood. Here, the global change in histone H3 Lysine 4, 9, 27, 36 methylation and Lysine 27 acetylation was investigated in piPSCs and TLSCs. We found a high modification profile of H3K36me2 in TLSCs compared to that of piPSCs, whereas the profiles of other modifications remained constant. KDM4C, a H3K36me3/2 demethylase, whose gene body region was combined with ESRRB, was upregulated in TLSCs. Moreover, KDM4 inhibitor supplementation rescued the AP-negative phenotype observed in TLSCs, confirming that KDM4C could regulate the pluripotency of TLSCs. Subsequently, KDM4C replenishment results show the significantly repressed proliferation and AP-positive staining of TLSCs. The expressions of CDX2 and KRT8 were also upregulated after KDM4C overexpression. In summary, these results show that KDM4C replaced the function of ESRRB. These findings reveal the unique and crucial role of KDM4C-mediated epigenetic chromatin modifications in determination of piPSCs’ fate and expand the understanding of the connection between piPSCs and TSCs.

AXIN2 Reduces the Survival of Porcine Induced Pluripotent Stem Cells (piPSCs)

The establishment of porcine pluripotent stem cells (piPSCs) is critical but remains challenging. All piPSCs are extremely sensitive to minor perturbations of culture conditions and signaling network. Inhibitors, such as CHIR99021 and XAV939 targeting the WNT signaling pathway, have been added in a culture medium to modify the cell regulatory network. However, potential side effects of inhibitors could confine the pluripotency and practicability of piPSCs. This study aimed to investigate the roles of AXIN, one component of the WNT pathway in piPSCs. Here, porcine AXIN1 and AXIN2 genes were knocked-down or overexpressed. Digital RNA-seq was performed to explore the mechanism of cell proliferation and apoptosis. We found that (1) overexpression of the porcine AXIN2 gene significantly reduced survival and negatively impacted the pluripotency of piPSCs, and (2) knockdown of AXIN2, a negative effector of the WNT signaling pathway, enhanced the expression of genes involved in cell cycle but reduced the expression of genes related to cell differentiation, death, and apoptosis.