Homologous recombination (HR) plays a critical role in facilitating replication fork progression when the polymerase complex encounters a blocking DNA lesion, and it also serves as the primary mechanism for error-free DNA repair of double-stranded breaks. DNA repair protein RAD51 homolog 1 (RAD51) plays a central role in HR. However, the role of RAD51 during porcine early embryo development is unknown. In the present study, we examined whether RAD51 is involved in the regulation of early embryonic development of porcine parthenotes. We found that inhibition of RAD51 delayed cleavage and ceased development before the blastocyst stage. Disrupting RAD51 activity with RNAi or an inhibitor induces sustained DNA damage, as demonstrated by the formation of distinct γH2AX foci in nuclei of four-cell embryos. Inhibiting RAD51 triggers a DNA damage checkpoint by activating the ataxia telangiectasia mutated (ATM)–p53–p21 pathway. Furthermore, RAD51 inhibition caused apoptosis, reactive oxygen species accumulation, abnormal mitochondrial distribution and decreased pluripotent gene expression in blastocysts. Thus, our results indicate that RAD51 is required for proper porcine parthenogenetic activation (PA) embryo development.
Zhe-Long Jin, Xing-Hui Shen, Liang Shuang, Jeong-woo Kwon, Min-Jeong Seong and Nam-Hyung Kim
Xue Li, Zhi-Yan Shan, Yan-Shuang Wu, Xing-Hui Shen, Chun-Jia Liu, Jing-Ling Shen, Zhong-Hua Liu and Lei Lei
Pig pluripotent cells may represent an advantageous experimental tool for developing therapeutic application in the human biomedical field. However, it has previously been proven to be difficult to establish from the early embryo and its pluripotency has not been distinctly documented. In recent years, induced pluripotent stem (iPS) cell technology provides a new method of reprogramming somatic cells to pluripotent state. The generation of iPS cells together with or without certain small molecules has become a routine technique. However, the generation of iPS cells from pig embryonic tissues using viral infections together with small molecules has not been reported. Here, we reported the generation of induced pig pluripotent cells (iPPCs) using the iPS technology in combination with valproic acid (VPA). VPA treatment significantly increased the expression of pluripotent genes and played an important role in early reprogramming. We showed that iPPCs resembled pig epiblast cells in their morphology and pluripotent markers, such as OCT4, NANOG, and SSEA1. It had a normal karyotype and could form embryoid bodies, which express three germ layer markers in vitro. In addition, the iPPCs might directly differentiate into neural progenitors after being induced with the retinoic acid and extracellular matrix. Our study established a reasonable method to generate pig pluripotent cells, which might be a new donor cell source for human neural disease therapy.