MKlp2 inhibitior paprotrain affects polar body extrusion during mouse oocyte maturation

BACKGROUND Mammalian oocyte meiotic maturation involves a number of important processes, including spindle assembly and migration, cortical reorganization and polar body extrusion. Numerous proteins contribute to these processes, but it is unknown whether MKlp2 (mitotic kinesin-like protein 2; also called KIF20A), a microtubule-associated protein that regulates cytokinesis during mitosis, is involved in oocyte maturation. METHODS Confocal microscopy, time lapse microscopy, inhibitor treatment were adopted to examine the roles of MKlp2 in mouse oocyte. RESULTS Immunostaining results showed that MKlp2 localized to oocyte microtubules. Time-lapse microscopy showed that disrupting MKlp2 expression with paprotrain, a specific inhibitor of MKlp2, resulted in polar body extrusion failure. This could be rescued after rescuing oocytes from paprotrain in fresh medium. Cell cycle analysis showed that most oocytes were arrested at metaphase I or telophase I. However, oocyte spindle structure and chromosome alignment were not disrupted after the inhibition of MKlp2 by paprotrain. CONCLUSIONS This study demonstrated that MKlp2 is crucial for oocyte maturation by regulating polar body extrusion.