Unlike somatic cells mitosis, germ cell meiosis consists of two consecutive rounds of divisions that segregate homologous chromosomes and sister chromatids, respectively. The meiotic oocyte is characterized by an absence of centrioles and asymmetric divisions. Centriolin is a relatively novel centriolar protein that functions in mitotic cell cycle progression and cytokinesis. Here, we explored the function of centriolin in meiosis and showed that it was localized to meiotic spindles, and concentrated at the spindle poles and midbody during oocyte meiotic maturation. Unexpectedly, knockdown of centriolin in oocytes with either siRNA or Morpholino micro-injection, did not affect meiotic spindle organization, cell cycle progression, or cytokinesis (as indicated by polar body emission), but led to a failure of peripheral meiotic spindle migration; and symmetric division or large polar body emission. These data suggest that, unlike in mitotic cells, the centriolar protein centriolin does not regulate cytokinesis, but plays an important role in regulating asymmetric division of meiotic oocytes.

Zinc (Zn2+) is one of essential factors during mammalian oocyte maturation and fertilization. Previous studies showed that depletion of cellular Zn by metalion chelator impair asymmetric division of oocyte. But the detailed mechanism of these phenomena is unclear. We found that depletions of zinc by cell-permeable heavy metal chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethane-1,2-diamine (TPEN) caused the decrease of cytoplasmic actin mesh level. Spire2-GFP is co-localized with zinc at the cortex and intracellular vesicle. By the treatment of TPEN, number of Spire2-GFP decorated vesicle is drastically decreased, indicating that Zn2+is essential for the localization of the spire in mouse oocyte. Two putative zinc-binding regions were located in the C-terminal part of Spire2. Mutations of zinc binding site on spire abolish its localization at the intracellular vesicle. Over expression of C-terminal region containing zinc binding site of spire impair oocyte maturations and decrease cytoplasmic actin mesh. Taken together, these results suggest that intracellular zinc is crucial for the proper localizations of spire in the mouse oocyte, and unraveling the novel regulatory mode of actin nucleator spire by Zn2+.