cd26 Knockdown Negatively Affects Porcine Parthenogenetic Preimplantation Embryo Development

SIMPLE SUMMARY: The cd26 gene is known to be significantly involved in immune responses. However, there are very few studies that have used cd26 siRNA in porcine embryos and no available information regarding its role during this pre-implantation development in in vitro. In the present study, the cd26 siRNA-injected oocytes showed significantly lower blastocyst development than control groups and we confirmed aberrant gene expression patterns of the porcine parthenogenetic embryo development. This study showed the possibility that the cd26 plays an important role in in vitro development of the porcine pre-implantation embryo. ABSTRACT: cd26 is ubiquitously distributed in the body, particularly in the endothelial and epithelial cells, with the highest expression in the kidney, liver, and small intestine. In humans, cd26 serves as a marker for the embryo implantation phase. However, little is known about the role of cd26 in porcine pre-implantation embryo development. Here, we aimed to examine siRNA-induced cd26 downregulation in the cytoplasm of MII oocytes, to determine whether cd26 is involved in the regulation of porcine pre-implantation embryonic development. The cd26 siRNA was micro-injected into the cytoplasm of MII oocytes, which were then parthenogenetically activated electrically in a medium containing 0.3M Mannitol. Inhibition of the cd26 expression did not affect cleavage but stopped development in the blastocyst stage. Additionally, the cd26 siRNA-treated blastocysts had significantly more apoptotic cells than the untreated blastocysts. Among the 579 transcripts evaluated with transcriptome resequencing, 38 genes were differentially expressed between the treatment and control blastocysts (p < 0.05). Twenty-four genes were upregulated in cd26 siRNA-injected blastocysts, whereas 14 were downregulated. These genes are involved in apoptosis, accumulation of reactive oxygen species, and aberrant expression of ribosomal protein genes. Our results indicate that cd26 is required for proper porcine parthenogenetic activation during embryonic development.