Xiang Cheng, Li Jia, Hu Liaoliao, Huang Jian, Luo Tao, Zhong Zhisheng, Zheng Yuehui, Zheng Liping
Medical Teaching Laboratory Center, Jiangxi Medical College, Nanchang University, Nanchang, China.
Cell Physiol Biochem. 2015;35(3):957-68. doi: 10.1159/000369752. Epub 2015 Feb 2.
The Hippo signaling pathway, a highly conserved cell signaling system, exists in most multicellular organisms and regulates cell proliferation, differentiation, and apoptosis. It has been reported that the members of Hippo signaling are expressed in mammalian ovaries, but the exact functions of this pathway in primordial follicle development remains unclear.
To analyze the spatio-temporal correlation between the core component of Hippo pathway and the size of primordial follicle pool, Western blot, Real-time PCR and immunohistochemistry were used, and the expression and localization of MST1, LATS2 and YAP1 mRNA and protein were examined in 3 d, 1 m, 5 m, 16 m postnatal mice ovary and the culture model of mice primordial follicle in vitro.
Both the protein and mRNA expression of the MST1 and LATS2 were decreased significantly as mouse age increased (p < 0.05), however, the mRNA expression of them increased significantly in 16 m compared with 5 m as well as the protein expression of LATS2.The expression of YAP showed the opposite trend, and the significant protein expression of pYAP was increased before 1 m, after which no significant change was observed. Moreover, the ratio of pYAP/YAP decreased significantly. Culturing ovaries for 8 d in vitro resulted in the activation of primordial follicles in 3 d postnatal mice ovaries, and these developed into primary follicles with the expression of PCNA increasing significantly (p < 0.05). The mRNA and protein expression of MST and LATS decreased significantly (p < 0.05), and the expression of YAP increased significantly (p < 0.05, p < 0.01), whereas the ratio of pYAP/YAP decreased significantly (p < 0.05).
The above results reveal that the expression of the core components of Hippo pathway changed during mouse follicular development, especially before and after primordial follicle activation in vitro. The primordial follicle activation may be related to the significant decrease of the ratio of pYAP1/YAP1. In conclusion, Hippo signaling pathway expressed in mice ovaries and have spatio-temporal correlation with the size of primordial follicle pool.
河马信号通路是一种高度保守的细胞信号系统，存在于大多数多细胞生物中，可调节细胞增殖、分化和凋亡。据报道，河马信号通路的成员在哺乳动物卵巢中表达，但其在原始卵泡发育中的具体功能仍不清楚。
为分析河马信号通路核心成分与原始卵泡库大小之间的时空相关性，采用蛋白质免疫印迹法、实时荧光定量PCR和免疫组织化学方法，检测出生后3天、1个月、5个月、16个月小鼠卵巢以及体外小鼠原始卵泡培养模型中MST1、LATS2和YAP1 mRNA和蛋白的表达及定位。
随着小鼠年龄增长，MST1和LATS2的蛋白及mRNA表达均显著降低（p<0.05），然而，16个月时它们的mRNA表达与5个月相比显著增加，LATS2的蛋白表达也增加。YAP的表达呈现相反趋势，1个月前pYAP的显著蛋白表达增加，之后未观察到显著变化。此外，pYAP/YAP的比值显著降低。体外培养卵巢8天可激活出生后3天小鼠卵巢中的原始卵泡，这些卵泡发育为初级卵泡，增殖细胞核抗原（PCNA）的表达显著增加（p<0.05）。MST和LATS的mRNA和蛋白表达显著降低（p<0.05），YAP的表达显著增加（p<0.05，p<0.01），而pYAP/YAP的比值显著降低（p<0.05）。
上述结果表明，河马信号通路核心成分的表达在小鼠卵泡发育过程中发生变化，尤其是在体外原始卵泡激活前后。原始卵泡激活可能与pYAP1/YAP1比值的显著降低有关。总之，河马信号通路在小鼠卵巢中表达，并与原始卵泡库大小存在时空相关性。
