缺氧影响PTEN磷酸化和核定位

目的观察缺氧(hypoxia)对第10号染色体缺失并与张力蛋白同源的磷酸酶(phosphatase and tension homolog deleted onchromosome ten,PTEN)磷酸化及核定位的影响。方法以1%O2条件下培养的COS-7细胞为缺氧模型,在缺氧处理不同时间点0、1、8、24、32 h收集细胞,应用Western blotting方法检测PTEN磷酸化水平及其下游信号分子磷酸化蛋白激酶B(phosphorylatedprotein kinase B,p-Akt)的表达变化;分别应用细胞核、质分离技术,共聚焦显微镜观察缺氧24 h前后PTEN亚细胞定位的变化。结果 COS-7细胞缺氧处理24 h与未缺氧对照细胞相比,PTEN磷酸化水平显著降低,p-Akt亦明显减少;细胞核中PTEN表达量则显著升高。结论 PTEN磷酸化水平和核质分布受到细胞缺氧的调节。在细胞缺氧反应中,PTEN去磷酸化而活化,通过抑制其下游分子Akt磷酸化,从而抑制缺氧诱导的细胞增殖信号通路活化;并且部分入核发挥核内PTEN功能。

Effects of Hypoxia on PTEN Phosphorylation and Nuclear Localization

Objective To investigate the effects of hypoxia on endogenous phosphatase and tension homolog deleted on chromosome ten(PTEN) phosphorylation and nuclear localization. Methods COS-7 cells were cultured in hypoxic condition(1% O₂) and harvested at 0, 1, 8, 24, 32 h. Each lysate was used to detect p-PTEN and PTEN downstream molecule p-Akt expression by Western blotting. Subcellular localization of PTEN was observed at 0, 24 h with hypoxic treatment by nucleus and plasma separation method and confocal microscopy respectively. Results Upon hypoxic treatment for 24 h, phosphorylated PTEN level decreased significantly，accompanied by p-Akt expression level decrease; and nuclear PTEN level increase. Conclusion In response to hypoxia treatment, PTEN was activated due to decrease of phosphorylated PTEN level, then PTEN inhibited downstream Akt activation. Under hypoxic condition, PTEN was promoted to enter nucleus.