Salsman S, Felts N, Pye Q N, Floyd R A, Hensley K
Department of Biochemistry and Molecular Biology, Oklahoma University Health Sciences Center, Oklahoma City 73104, USA.
Arch Biochem Biophys. 2001 Feb 15;386(2):275-80. doi: 10.1006/abbi.2000.2202.
Phosphorylation of the serine/threonine kinase Akt has previously been shown to be increased by treatment of cells with H2O2; the target of H2O2 has not been clearly identified. Here we show that treatment of rat primary astrocytes with H2O2 resulted in increased Akt phosphorylation that was blocked by wortmannin. The thiol-reducing agent N-acetylcysteine had only a slight inhibitory effect. Treatment with rotenone or antimycin A also resulted in increased wortmannin-sensitive Akt phosphorylation, probably by increasing intracellular H2O2 generation by blocking mitochondrial electron transport. Addition of phosphatidylinositol 3,4-bisphosphate to cells also resulted in an increase in Akt phosphorylation. This increase was additive to that induced by H2O2 and was also blocked by wortmannin. These results suggest that activation of Akt by H2O2 occurs upstream of phosphatidylinositol 3-kinase (PI 3-K) activity in astrocytes. The data indicate that major oxidative effects do not occur at the level of the PI 3-K-antagonizing phosphatase PTEN.
先前的研究表明，用H2O2处理细胞会使丝氨酸/苏氨酸激酶Akt的磷酸化增加；H2O2的作用靶点尚未明确。在此我们发现，用H2O2处理大鼠原代星形胶质细胞会导致Akt磷酸化增加，而渥曼青霉素可阻断这一过程。硫醇还原剂N-乙酰半胱氨酸仅有轻微的抑制作用。用鱼藤酮或抗霉素A处理也会导致渥曼青霉素敏感的Akt磷酸化增加，这可能是通过阻断线粒体电子传递增加细胞内H2O2的生成所致。向细胞中添加磷脂酰肌醇3,4-二磷酸也会导致Akt磷酸化增加。这种增加与H2O2诱导的增加具有累加效应，并且也被渥曼青霉素阻断。这些结果表明，在星形胶质细胞中，H2O2对Akt的激活发生在磷脂酰肌醇3激酶（PI 3-K）活性的上游。数据表明，主要的氧化作用并非发生在PI 3-K拮抗磷酸酶PTEN水平。
