Evaluation of porcine urine-derived cells as nuclei donor for somatic cell nuclear transfer

Molecular characterizations and functional roles of NANOG in early development of porcine embryos

Nanog homeobox (NANOG) is the gateway to the pluripotent ground state in mouse embryonic stem cells and early embryos. However, understanding of the molecular signatures and functional characteristics of porcine NANOG remains limited. In this study, we analyzed the gene structure and sequence characteristics of porcine NANOG and found that the porcine NANOG gene is localized on chromosome 5, while NANOG sequence on chromosome 1 is the processed pseudogene. We explored the expression pattern of NANOG in porcine early embryos by immunofluorescence staining and Realtime-PCR and RNA-seq, the results showed that transcription of porcine NANOG commences at the 4-cell stage, while expression of the NANOG protein is initially observed in the inner cell mass of blastocysts. Furthermore, we identified a NANOG splicing variant in porcine early embryos, which maintain the overall structure of the original NANOG mRNA, except for a deletion of 38 base pairs in the second exon. To further investigate the function of NANOG in early embryo development in pigs, we employed siRNA-mediated deletion of the two specific transcripts on porcine zygotes. The results showed that blastocyst rate was significantly reduced after NANOG deleting. A significant decrease in the expression of DNA methylation-related gene DNMT3B was also observed in D3 embryo from the NANOG deleting group. In conclusion, the porcine NANOG gene, accompanied by a single-exon processed pseudogene, exhibits two transcripts and plays a pivotal role in the development of early-stage embryos.

Molecular Mechanism and Application of Somatic Cell Cloning in Mammals-Past, Present and Future

Thus far, nearly 25 mammalian species have been cloned by intra- or interspecies somatic cell nuclear transfer (SCNT) [...].

Epigenetic manipulation to improve mouse SCNT embryonic development

Cloned mammals can be achieved through somatic cell nuclear transfer (SCNT), which involves reprogramming of differentiated somatic cells into a totipotent state. However, low cloning efficiency hampers its application severely. Cloned embryos have the same DNA as donor somatic cells. Therefore, incomplete epigenetic reprogramming accounts for low development of cloned embryos. In this review, we describe recent epigenetic barriers in SCNT embryos and strategies to correct these epigenetic defects and avoid the occurrence of abnormalities in cloned animals.