Survivin is a critical regulator of spindle organization and chromosome segregation during rat oocyte meiotic maturation.

Survivin is a novel member of the inhibitor of apoptosis gene family that bear baculoviral IAP repeats (BIRs), whose physiological roles in regulating meiotic cell cycle need to be determined. Confocal microscopy was employed to observe the localization of survivin in rat oocytes. At the germinal vesicle (GV) stage, survivin was mainly concentrated in the GV. At the prometaphase I (pro-MI) and metaphase I (MI) stage, survivin was mainly localized at the kinetochores, with a light staining detected on the chromosomes. After transition to anaphase I or telophase I stage, survivin migrated to the midbody, and signals on the kinetochores and chromosomes disappeared. At metaphase II (MII) stage, survivin became mainly localized at the kinetochores again. Microinjection of oocytes with anti-survivin antibodies at the beginning of the meiosis, thus blocking the normal function of survivin, resulted in abnormal spindle assembly, chromosome segregation and first polar body emission. These results suggest that survivin is involved in regulating the meiotic cell cycle in rat oocytes.