Enhancement of epigenetic reprogramming status of porcine cloned embryos with zebularine, a DNA methyltransferase inhibitor

Abstract Aberrant epigenetic reprogramming is known to be a major cause of inefficient somatic cell nuclear transfer (SCNT) in pigs, and use of epigenetic modification agents, such as DNA methyltransferase inhibitors (DNMTis), is a promising approach for enhancing SCNT efficacy. Here, we attempted to find the optimal condition of zebularine (Zb), a DNMTi, treatment on porcine SCNT embryos during in vitro culture (IVC). As results, treatment with 5 nM Zb for 24 hr showed the highest rate of embryo development to blastocyst compared to other groups ( p < .05). Also, the relative intensities of global DNA methylation levels of anti‐5‐methylcytosine in pseudo‐pronuclear (PNC), 2‐cell and 4‐cell stages were significantly lower in the Zb‐treated group ( p < .05), however, changes in methylation levels of centromeric satellite repeat were noted only in PNC and blastocyst stages. In addition, significant positive alterations in the relative expression of genes related to pluripotency ( OCT4 and SOX2 ), histone acetylation ( HAT1 , HDAC1 , HDAC2 , and HDAC3 ) and DNA methylation ( DNMT1 and DNMT3a ) were observed compared to the control ( p < .05). In conclusion, we found that Zb could modify DNA methylation levels in the early stages of porcine SCNT embryos and promote their developmental competence.