RAD51 maintains chromosome integrity and mitochondrial distribution during porcine oocyte maturation in vitro

DNA repair protein RAD51 homolog 1 (RAD51) plays a central role in homologous recombination (HR) repair of DNA breaks. HR depends on the formation of a RAD51 recombinase filament that facilitates strand invasion. However, the role of RAD51 during porcine oocyte maturation is unknown. The objective of this study was to investigate the expression and function of RAD51 during porcine oocyte maturation in vitro. RAD51 was mainly localized to the nucleus at the germinal vesicle (GV) stage, and was widely distributed in the cytoplasm between the GV breakdown (GVBD) and metaphase II stage. DNA damage induced by etoposide was accompanied by the formation of RAD51 foci that were colocalized with γH2AX. Inhibition of RAD51 increased DNA damage and induced metaphase I arrest along with spindle defects, chromosomal misalignment, and abnormal spindle assembly checkpoint (SAC) activity. Inhibition of RAD51 also increased ROS levels and led to an abnormal mitochondrial distribution. Our results indicate that RAD51 plays a critical role in maintaining chromosome integrity and mitochondrial activity during porcine oocyte maturation.