Aberrant DNA methylation reprogramming in bovine SCNT preimplantation embryos

<jats:title>Abstract</jats:title><jats:p>DNA methylation reprogramming plays important roles in mammalian embryogenesis. Mammalian somatic cell nuclear transfer (SCNT) embryos with reprogramming defects fail to develop. Thus, we compared DNA methylation reprogramming in preimplantation embryos from bovine SCNT and <jats:italic>in vitro</jats:italic> fertilization (IVF) and analyzed the influence of vitamin C (VC) on the reprogramming of DNA methylation. The results showed that global DNA methylation followed a typical pattern of demethylation and remethylation in IVF preimplantation embryos; however, the global genome remained hypermethylated in SCNT preimplantation embryos. Compared with the IVF group, locus DNA methylation reprogramming showed three patterns in the SCNT group. First, some pluripotency genes (<jats:italic>POU5F1</jats:italic> and <jats:italic>NANOG</jats:italic>) and repeated elements (satellite I and α-satellite) showed insufficient demethylation and hypermethylation in the SCNT group. Second, a differentially methylated region (DMR) of an imprint control region (ICR) in <jats:italic>H19</jats:italic> exhibited excessive demethylation and hypomethylation. Third, some pluripotency genes (<jats:italic>CDX2</jats:italic> and <jats:italic>SOX2</jats:italic>) were hypomethylated in both the IVF and SCNT groups. Additionally, VC improved the DNA methylation reprogramming of satellite I, α-satellite and <jats:italic>H19</jats:italic> but not that of <jats:italic>POU5F1</jats:italic> and <jats:italic>NANOG</jats:italic> in SCNT preimplantation embryos. These results indicate that DNA methylation reprogramming was aberrant and that VC influenced DNA methylation reprogramming in SCNT embryos in a locus-specific manner.</jats:p>