Significant improvement of somatic reprogramming efficiency by transient overexpression of ZGA inducer Dux

Cloned animals generated by somatic cell nuclear transfer (SCNT) have been reported for many years; however, SCNT is extremely inefficient, and zygotic genome activation (ZGA) is required for SCNT-mediated somatic cell reprogramming. To identify candidate factors that facilitate ZGA in SCNT-mediated reprogramming, we performed siRNA-repressor and mRNA-inducer screening, which revealed Dux, Dppa2, and Dppa4 as key factors enhancing the ZGA in SCNT. We found that direct injection of ZGA-inducers showed no significant effect on SCNT blastocyst formation; however, following the establishment of an inducible Dux transgenic mouse model, we demonstrated that transient overexpression of Dux not only improved SCNT efficiency but also increased that of chemical-induced pluripotent stem cell reprogramming. Moreover, transcriptome profiling revealed that Dux treated SCNT embryos were similar to fertilized embryos. Furthermore, transient overexpression of Dux combined with inactivation of DNA methyltransferases (Dnmts) further promoted the overall development of SCNT-derived animals. These findings enhanced our understanding of ZGA-regulators in somatic reprogramming.