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.

通过体细胞核移植（SCNT）成功克隆需要克服重要的表观遗传障碍。尽管依赖H3K27me3的印迹在E6.5外胚层和胚外组织中差异分布，但基因组印迹通常不被视为此类障碍。在这里我们报告通过从单倍体小鼠胚胎干细胞中同时携带四个H3K27me3印迹基因的单等位基因缺失体细胞供体细胞，SCNT效率显着提高。Sfmbt2，Jade1，Gab1和Smoc1的四个单等位基因缺失与野生型成纤维细胞的0％出生率相比，H3K27me3印迹的表达模式正常化，成纤维细胞克隆效率提高到14％，同时防止了在克隆动物中经常观察到的胎盘和身体过度生长缺陷。在改善SCNT方面，Sfmbt2缺失是四个单独基因缺失中最有效的。这些结果表明，体细胞中缺乏H3K27me3印迹是表观遗传障碍，阻碍了SCNT胚胎植入后的发育，可以通过供体细胞中的单等位基因印迹基因缺失来克服。