RNA sequencing revealed abnormal gene expression and benefits of vitamin C treatment in cloned bovine embryos

Somatic cell nuclear transfer (SCNT) in mammals has been mostly unsuccessful. In this study, we measured and compared transcription profiles of cloned and fertilized embryos using RNA sequencing. Before zygotic genome activation (ZGA), fewer genes were activated in the cloned embryos than in vitro fertilization (IVF), leading to insufficient activation of protein transport and degradation functions. In blastocysts, terms of “embryo development” and “adherens junction” represented major differences for repressed genes in SCNT compared to IVF. Vitamin C (Vc) was found to relax donor cell chromatin and promote cloned embryo development. RNA sequencing indicated that Vc treatment restored some abnormal genes and processes in the cloned embryos. Processes of autophagy, RNA-editing and cell junction were not fully established, but they were improved by Vc treatment. Overexpression of ZNF641, one of the completely restored genes by Vc treatment, improved the cloned embryos’ potential. Finally, Vc treatment rescued some long non-coding RNAs that were aberrantly expressed in the cloned embryos. Collectively, many important genes and biological processes were abnormal in the cloned embryos, some of which can be improved by Vc treatment. This investigation provides several practical aspects that could be useful for improving cloning efficiency and its future applications. Comparison of gene expression in preimplantation embryos derived from IVF, SCNT and Vc-treated SCNT,respectively.