Aurora-C Kinase Deficiency Causes Cytokinesis Failure in Meiosis I and Production of Large Polyploid Oocytes in Mice

We previously isolated Aurora-C/Aie1 in a screen for kinases expressed in mouse sperm and eggs. Here, we show the localization of endogenous Aurora-C and examine its roles during female mouse meiosis. Aurora-C was detected at the centromeres and along the chromosome arms in prometaphase I-metaphase I and was concentrated at centromeres at metaphase II, in which Aurora-C also was phosphorylated at Thr171. During the anaphase I-telophase I transition, Aurora-C was dephosphorylated and relocalized to the midzone and midbody. Microinjection of the kinase-deficient Aurora-C (AurC-KD) mRNA into mouse oocytes significantly inhibited Aurora-C activity and caused multiple defects, including chromosome misalignment, abnormal kinetochore-microtubule attachment, premature chromosome segregation, and cytokinesis failure in meiosis I. Furthermore, AurC-KD reduced Aurora-C and histone H3 phosphorylation and inhibited kinetochore localization of Bub1 and BubR1. Similar effects also were observed in the oocytes injected with INCNEP-delIN mRNAs, in which the Aurora-C binding motif was removed. The most dramatic effect observed in AurC-KD-injected oocytes is cytokinesis failure in meiosis I, resulting in producing large polyploid oocytes, a pattern similar to Aurora-C deficiency human spermatozoa. Surprisingly, we detected no Aurora-B protein in mouse oocytes. We propose that Aurora-C, but not Aurora-B, plays essential roles in female mouse meiosis.