CDCA8 regulates meiotic spindle assembly and chromosome segregation during human oocyte meiosis

As a member of the chromosomal passenger complex, CDCA8 (cell division cycle associated 8) plays an important role in human mitosis, but its roles in human meiosis are unknown. Here, we show that CDCA8 expression is increased and its encoded protein has dynamic localization in human oocytes from germinal vesicle breakdown (GVBD) to metaphase Ⅱ (MⅡ), and that there are multipolar spindles, disordered chromosomes, and that microtubule assembly is affected after CDCA8 RNA interference (RNAi) in GV-stage oocytes. The GVBD and polar body extrusion (PBE) rates were not affected following CDCA8 depletion, but the PBE time was extended. There was no statistical difference between CDCA8 expression of oocytes from older and younger women, but the first polar body from older women was prone to chromosome abnormalities, and oocytes with such abnormalities had lower CDCA8 expression than oocytes with normal polar bodies. These results indicate that CDCA8 is associated with bipolar spindle formation, chromosome segregation, PBE during human oocyte meiosis, and that it may affect the incidence of aneuploidy embryos in older women.