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.

Kisspeptin, encoded by the Kiss1 gene, has many forms including kisspeptin54, kisspeptin14, kisspeptin13, and kisspeptin10, and all these peptides have the same affinity to their receptor KISS1R encoded by the Kiss1r gene. The KISS1-KISS1R system was discovered in neurons, and many reports stress on their function in the brain. However, recent studies have shown that Kiss1 and Kiss1r are expressed in the testes. The goal of this study was to demonstrate the roles of Kiss1 and Kiss1r in testicular function, especially their steroidogenic activity. Kisspeptin10 and the kisspeptin10 antagonist peptide234 were used to determine their effect on testosterone production. Moreover, expression of steroidogenic genes in mouse testes and their gonadosomatic index (weight of the testes divided by the total body weight) and also serum testosterone level were studied between the ages of 2 weeks and 15 weeks. Kisspeptin10 and peptide234 did not affect testosterone production in primary Leydig cells from adult mice. Kiss1 and Esr1 expression also increased during puberty. The peak gonadosomatic index occurred at 4 weeks of age, and serum testosterone levels plateaued after the age of 4 weeks. Our results suggest that kisspeptin10 does not affect steroidogenesis in adult Leydig cells, but its pattern of expression follows the stages of testicular development. Future studies should determine if kisspeptin regulates testicular development during puberty.