Histone H3 lysine 27 trimethylation acts as an epigenetic barrier in porcine nuclear reprogramming

Abstract

Aberrant epigenetic reprogramming is the main obstacle to the development of somatic cell nuclear transfer (SCNT) embryos and the generation of induced pluripotent stem (iPS) cells, which results in the low reprogramming efficiencies of SCNT and iPS. Histone H3 lysine 27 trimethylation (H3K27me3), as a repressive epigenetic mark, plays important roles in mammalian development and iPS induction. However, the reprogramming of H3K27me3 in pig remains elusive. In this study, we showed that H3K27me3 levels in porcine early cloned embryos were higher than that in IVF embryos. Then GSK126 and GSK-J4, two small molecule inhibitors of H3K27me3 methylase (EZH2) and demethylases (UTX/JMJD3), were used to regulate the H3K27me3 level. The results showed that H3K27me3 level was reduced in cloned embryos after treatment of PEF with 0.75 mM GSK126 for 48 h, incubation of one-cell reconstructed oocytes with 0.1 mM GSK126 and injection of antibody for EZH2 into oocyte. Meanwhile, the development of the cloned embryos was significantly improved after these treatments. On the contrary, GSK-J4 treatment increased the H3K27me3 level in cloned embryos and decreased the cloned embryonic development. Furthermore, iPS efficiency was both increased after reducing the H3K27me3 level in donor cells and in early reprogramming phase. In summary, our results suggest that H3K27me3 acts as an epigenetic barrier in SCNT and iPS reprogramming, and reduction of H3K27me3 level in donor cells and in early reprogramming phase can enhance both porcine SCNT and iPS efficiency.

KDM 6A and KDM 6B play contrasting roles in nuclear transfer embryos revealed by MERVL reporter system

“…Our scRNA-seq transcriptome also demonstrated that ZGArelated genes failed to be properly activated in MERVL À SCNT compared with normal fertilization embryos. Furthermore, a high H3K27me3 level is detrimental to bovine SCNT embryonic development, consistent with porcine SCNT reprogramming [52]. Collectively, these results suggested that SCNT embryos are H3K27me3-defective at the ZGA stage, which serves as another barrier to murine, bovine, and porcine SCNT reprogramming.…”

Transcriptional memory inherited from donor cells is a developmental defect of bovine cloned embryos

“…5,[10][11][12] Histone H3 lysine 27 trimethylation (H3K27me3) [13][14][15] and 5-methylcytosine (5-mC), 16,17 both of which are repressive markers, have also been revealed as an obstacle for SCNT reprogramming in mammals. Previous studies have shown that the persistence of histone H3 lysine 9 trimethylation (H3K9me3) in SCNT embryos is an important barrier for nuclear reprogramming, which is responsible for abnormal embryonic genome activation (EGA), and that ectopic expression of H3K9me3 demethylase can restore the EGA defects and significantly improve the cloning efficiency.…”

Injury Induces Endogenous Reprogramming and Dedifferentiation of Neuronal Progenitors to Multipotency

“…Importantly, these factors, starting with Ascl1, followed by Neurog1 and NeuroD1, have been shown to indicate neuronal specification in the epithelium, as in the central nervous system (CNS) (Chen et al, 2014; Goldstein et al, 2015; Huard et al, 1998; Jang et al, 2003; Joiner et al, 2015; Krolewski et al, 2012; Leung et al, 2007; Manglapus et al, 2004; Packard et al, 2011a, 2016; Shaker et al, 2012; Xie et al, 2016). These neurogenic factors act in opposition to drivers of non-neuronal cell differentiation such as Hes1, which directs the formation of Sus cells(Cau et al, 1997; Guillemot and Joyner, 1993; Krolewski et al, 2012; Packard et al, 2011a).…”