Challenging research for functional analyses of piRNA/PIWI in mammalian female germ cells

猪卵母细胞中至少存在PIWIL1和PIWIL2两种PIWImRNA，抑制PIWIL1和PIWIL2的表达可导致高cAMP浓度下卵母细胞减数分裂的恢复，提示PIWI参与了猪卵巢卵母细胞减数分裂停滞的生理过程。这种PIWI功能是通过抑制细胞周期蛋白B的积聚来实现的，并且可能影响细胞周期蛋白B降解的APC功能，因为在翻译调控方面没有发现差异，如细胞周期蛋白B的mRNA水平、极光A和CPEB状态。

At least two PIWI mRNA, PIWIL1 and PIWIL2, are present in porcine oocytes and the inhibition of these protein expression results in the meiotic resumption of oocytes under a high cAMP concentration, suggesting the physiological involvement of PIWI in the meiotic arrest of porcine ovarian oocytes. This PIWI function is mediated by the inhibition of cyclin B accumulation and might affect on the APC function, which works on the cyclin B degradation, as no differences are detected in the translational regulations, such as cyclin B mRNA level, Aurora A and CPEB status.