Cyclin G1在小鼠卵巢的表达及其与卵泡发育的关系

Cyclin G1 Expressing in Mouse Ovary and Relating to Follicular Development

目的观察细胞周期素G1(CyclinG1)在小鼠卵巢中各级卵泡的表达及其与卵泡发育的关系。方法性成熟前小鼠用孕马血清促性腺激素(PMSG)刺激卵泡生长,用绒毛膜促性腺激素(hCG)刺激卵泡排卵及向黄体转化。于给药后不同时间取出卵巢,用免疫组化方法检测不同发育阶段卵泡CyclinG1蛋白的表达和分布;用细胞免疫荧光方法检测不同成熟阶段的卵细胞中CyclinG1蛋白表达。结果免疫组化染色结果显示,颗粒细胞中Cy-clinG1的表达水平随卵泡发育成熟而逐渐增强,且一直定位在胞核;CyclinG1在各个时期卵泡的卵母细胞中均有表达,该表达的定位与卵泡生长发育的不同阶段有关,随着卵泡的发育,CyclinG1在卵母细胞的表达由胞核转至胞浆。至排卵前卵泡颗粒细胞,CyclinG1表达水平减弱,当颗粒细胞分化为黄体细胞后表达水平进一步减弱。闭锁卵泡中CyclinG1的表达水平很弱。细胞免疫荧光染色结果显示,处于生发泡时期(GV)卵母细胞仅有较弱的CyclinG1表达,当卵母细胞生发泡破裂(GVBD)后,该表达增强;与处于第二次减数分裂中期(M)的卵母细胞相比,受精卵的CyclinG1表达明显增强。结论CyclinG1在小鼠卵泡发育及卵母细胞成熟过程中的表达具有时空特异性,可能作为细胞周期的正调节因子参与了卵泡生长发育和卵母细胞成熟过程的调控。

Objective In this experiment, we investigated the expression of Cyclin G1 in mouse ovaries and explored the role of Cyclin G1 during ovarian folicular development and oocyte maturation. Methods Immature female Kunming mice were treated with Pregnant Mare Serum Gonadotropin （PMSG） to induce the follicular development, with PMSG/human Chorionic Gonadotropin （hCG） to promote the ovulation and luteinization. The expression pattern of Cyclin G1 in ovary sections was determined by immunohistochemical analysis. The expression and localization of Cyclin G1 in isolated oocytes were evaluated by indirect immunofluorescence analyses. Results The immunohistochemical staining showed that with the development of follicles, granulose cells showed to have the gradually increased Cyclin G1 levels and the expressing protein G1 localized clearly in cell nuclei. The Cyclin G1 was observed to express at all stage follicles of oocytes by immunohistochemical analysis. The localization of Cyclin G1 in oocytes was related to the developing stage of follicle. With the development of follicle, Cyclin G1 protein in the oocytes was transferred from the cell nucleus to the cytoplasm. Following anovulatory dose of hCG, the positive reactivity of Cyclin G1 in preovulatory granulosa cells was decreased. Furthermore, the luteinized granulosa cells showed the weak staining. And the expression of Cyclin G1 in atretic follicles was very low. Indirect immunofluorescence analyses demonstrated that Cyclin G1 was present in both GV （germinal vesicle） oocytes and those after GVBD （germinal vesicle breakdown）, with increasing expression in oocytes after GVBD. Cyclin G1 was also present in both metaphase Ⅱ （M Ⅱ ） eggs and fertilized eggs. Comparing with M Ⅱeggs, the positive immunostaining was increased in fertilized eggs. Conclusion The expression of Cyclin G1 in mouse ovary is in spatiotemporal pattern, which indicates that Cyclin G1 may play the role as a positive modulator of cell cycle in ovarian follicular development and oocyte maturation.