FOXO3a介导PTEN对DNA修复基因RAD51表达的调节作用

FOXO3a serves as an effector on the signaling pathway of PTEN regulating RAD51 expression

目的探讨转录因子FOXO3a在PTEN调节RAD51表达中的作用。方法利用Western印迹技术分析PTEN缺陷与否时,总FOXO3a以及细胞核内FOXO3a磷酸化的情况;转染外源AKT到PTEN野生型细胞或外源PTEN和失去激酶活性的AKT(AKT-DN)到PTEN缺陷型细胞,Western印迹检测核内FOXO3a的磷酸化情况。结果 PTEN缺失导致细胞核内FOXO3a磷酸化水平增高;外源PTEN可以降低PTEN缺陷型细胞核内FOXO3a的磷酸化水平,外源AKT可以增加PTEN野生型细胞核内FOXO3a的磷酸化水平;沉默FOXO3a在一定程度上导致RAD51表达水平下降。结论 FOXO3a可以结合到RAD51基因的启动子区,PI3K/AKT/FOXO3a信号通路是PTEN调节RAD51表达的重要方式之一。

Objective To explore the effect of transcription factor FOXO3a on the signaling pathway of PTEN regulating the expression of RAD51.Methods Western blotting was used both to determine the phosphorylation of FOXO3a in both Pten＋/＋ and Pten-/-MEFs cells and to detect the phosphorylation of FOXO3a in Pten＋/＋ MEFs cells transfected with Flag-Akt WT or Flag-Akt AC（activated Akt）,and Pten-/-MEFs cells transfected with Flag-PtEN WT or Flag-Akt DN（inactivated Akt）.Results Higher phosphorylation of FOXO3a was found in Pten-/-MEFs cells compared to Pten＋/＋ MEFs cells,and the increased level of phosphorylated Akt was mainly found in the nuclei of Pten-/-MEFs cells.Transfection of exogenous Pten gene into Pten-/-MEFs resulted in a decreased phosphorylation of FOXO3a in the nucleus.In contrast,Pten＋/＋ MEFs transfected with exogenous akt gene showed a rising phosphorylation of FOXO3a in the nucleus.siRNA-mediated knockdown of FOXO3a gene resulted in a decreased expression of RAD51 protein in Pten＋/＋MEFs cells.Conclusion FOXO3a can bind to the transcriptional region of RAD51 gene,through which PTEN/ PI3K/Akt/FOXO3a signaling pathway regulates the expression of RAD51.