mTORC2/Akt/Girdin信号通过介导调控微丝骨架影响小鼠受精卵早期发育

In mouse fertilized eggs, the proper assembly and distribution of actin cytoskeleton is intimately related with the cleavage of early-stage embryo..However, in mammals, especially in mouse fertilized eggs, the mechanisms and involved factors responsible for regulating the actin cytoskeleton are poorly defined. In our preliminary work, Both mTORC2 and PKB/Akt were found to modulate the division of mouse fertilized eggs through regulating the distribution of actin cytoskeleton. PKB/Akt has been proved to be a downstream target of the mTORC2 signaling pathway. Girdin, the newly found actin-cross linker, has been proved to be a downstream target of the Akt signaling pathway. Therefore, in this application, the expression of Girdin and its effect on F-actin organization in mouse fertilized eggs under the regulation of PKB/Akt will be tested by biological techniques..Collectively, this study aimed to prove the participation of mTORC2/Akt in F-actin assembling in early-stage cleavage of mouse fertilized eggs via the function of Girdin, which will provide novel thoughts and experimental basis for further clarifying the molecular mechanism(s) of actin dynamics in the development of mouse embryo.

小鼠受精卵中微丝骨架的正确聚集和分布与早期细胞分裂关系密切。在此过程中参与的调控因子及信号调控机制目前尚不清楚。申请者研究发现过表达或敲低mTORC2和PKB/Akt都会影响小鼠受精卵微丝骨架聚集。结合文献报道PKB/Akt为mTORC2的底物蛋白。申请者分析mTORC2可能通过PKB/Akt蛋白发挥对微丝骨架分布的调控作用。而Girdin(girders of actin filaments)是一个新近发现参与微丝交联的PKB/Akt下游作用分子。研究显示PKB/Akt能够磷酸化Girdin蛋白，使其通过细胞骨架的重构在细胞迁移过程中扮演重要角色。综上分析如能证明mTORC2对Girdin蛋白的作用，则可提出：在小鼠受精卵早期发育中mTORC2通过PKB/Akt依赖的Girdin途径导致微丝骨架分布改变，促进受精卵早期分裂。为进一步阐明小鼠受精卵早期发育的分子机理提供新的思路和实验基础。

在小鼠受精卵细胞的分裂及早期发育过程中，微丝骨架形成和变化受多种因子的调控，其中mTORC2、Akt及Girdin对小鼠受精卵微丝聚集的作用显著，它们对微丝聚集的调控机理及相互作用是本课题研究的主要目标。通过实验我们明确了mTORC2、Akt可影响小鼠受精卵微丝的正确聚集与分布，接下来又明确了Akt通过磷酸化Girdin蛋白改变微丝的聚集，影响正常的小鼠卵细胞的分裂。进而提出在小鼠受精卵早期细胞分裂中微丝骨架的聚集与分布受mTORC2/Akt/Girdin信号途径的调节。一方面为受精卵早期细胞的正常分裂、发育机理提供理论依据。另一方面对小鼠受精卵发育早期中出现的异常胚胎现象进行合理解释。此研究有助于解决人类的不孕不育。

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