Overcoming Intrinsic H3K27me3 Imprinting Barriers Improves Post-implantation Development after Somatic Cell Nuclear Transfer

Successful cloning by somatic cell nuclear transfer (SCNT) requires overcoming significant epigenetic barriers. Genomic imprinting is not generally regarded as such a barrier, although H3K27me3-dependent imprinting is differentially distributed in E6.5 epiblast and extraembryonic tissues. Here we report significant enhancement of SCNT efficiency by deriving somatic donor cells carrying simultaneous monoallelic deletion of four H3K27me3-imprinted genes from haploid mouse embryonic stem cells. Quadruple monoallelic deletion of Sfmbt2, Jade1, Gab1, and Smoc1 normalized H3K27me3-imprinted expression patterns and increased fibroblast cloning efficiency to 14% compared with a 0% birth rate from wild-type fibroblasts while preventing the placental and body overgrowth defects frequently observed in cloned animals. Sfmbt2 deletion was the most effective of the four individual gene deletions in improving SCNT. These results show that lack of H3K27me3 imprinting in somatic cells is an epigenetic barrier that impedes post-implantation development of SCNT embryos and can be overcome by monoallelic imprinting gene deletions in donor cells. [Display omitted] •Increased SCNT cloning by monoallelic deletion of four H3K27me3-imprinted genes•H3K27me3-imprinted gene deletion normalized body and placental weights in cloned pups•Sfmbt2 deletion is the most effective monoallelic deletion for improving SCNT Wang et al. report significantly increased cloning efficiencies from fibroblasts by engineering monoallelic deletions of four placenta-specific H3K27me3 imprinting genes. Editing in and deriving donor cells from haploid embryonic stem cells enabled derivation of cloned pups with normalized body and placental weights.