Inhibition of meiosis in mouse oocytes by CphX siRNA

Specific aim：CphX (Cytoplasmic polyadnylated homeobox) gene has been known to expressed in the embryonic stem cells, oocytes and preimplantation embryos. Significant decrease of oocyte number and female offspring has been demonstrated in the CphX knockout mice. The aim of this study is to explore the function of CphX in murine oocyte meiosis.

Materials and Methods：Immature oocytes were obtained from the overies of 5-week-old female B6CBF1 mice 44 hour after i.p. injection of 10 IU PMSG. The follicles were punctured with a needle for the collection of immature oocytes. After Wash, the oocytes were cultured in the pre-buffered human oviduct culture medium in the 37oC incubator equilibrated with 5% CO2. C-mos and CphX siRNA were microinjected into oocytes, 24 or 48 hours after injection, oocyte morphology were recorded as GV phase, meiosis I or meiosis II. Statistical analysis was carried out and p<0.05 was considered significant.

Results：After 24 hour culture, the ratio of oocytes with meiosis progression into meiosis II is 3.6% (3/83), 1.3% (1/77), 18.8% (15/80) and 52.4% (22/24) in the CphX, c-mos, control, and uninjected group, respectively. CphX siRNA injection significantly down-regulated the number of oocytes reaching meiosis II as compared to that in the control group (p<0.05).

CONCLUSION：Resultsin this study show that microinjection of CphX siRNA significantly inhibited meiosis progression of oocytes and suggest CphX as an important factor during meiosis in mice.