Han Mijin, Im Dong-Soon
Laboratory of Pharmacology, College of Pharmacy (BK21 Project) and Longevity Life Science and Technology Institutes, Pusan National University, Busan, 609-735, Korea.
Arch Pharm Res. 2008 Jun;31(6):749-57. doi: 10.1007/s12272-001-1222-5. Epub 2008 Jun 19.
We studied cytotoxic mechanism of mitochondrial inhibitors in U937 cells. U937 cells were sensitive to cytotoxicity of mitochondrial inhibitors under glucose deprivation condition, whereas PC12 neuronal cells were not. In glucose deprivation condition, intracellular ATP content is decreased and thereby AMP-activated protein kinase (AMPK) is activated. And also activation of JNK, inactivation of ERK, and enhanced expression of Bcl-2 were observed. Mitochondrial inhibitors such as rotenone, TTFA, antimycin A, sodium azide, oligomycin, and valinomycin were used in this study. Inhibitors did not much influence intracellular ATP contents and activity of AMPK under glucose deprivation condition. Activities of Akt and p38 MAPK, however, were decreased by the inhibitors under glucose deprivation condition except TTFA. Furthermore, intracellular Ca2+ concentration was also greatly increased by the inhibitors. Finally, mitochondrial membrane potential was decreased by the inhibitors but TTFA increase the potential and oligomycin maintains it. In the present study, results suggest that under glucose deprivation condition mitochondrial inhibitors may induce severe cytotoxicity of U937 cells through inhibition of Akt and p38 MAPK, increase of [Ca2+]i, and decrease of MMP, but not through inhibition of ATP production and activation of AMPK.
我们研究了线粒体抑制剂在U937细胞中的细胞毒性机制。在葡萄糖剥夺条件下,U937细胞对线粒体抑制剂的细胞毒性敏感,而PC12神经元细胞则不敏感。在葡萄糖剥夺条件下,细胞内ATP含量降低,从而激活AMP激活的蛋白激酶(AMPK)。同时还观察到JNK的激活、ERK的失活以及Bcl-2表达的增强。本研究使用了鱼藤酮、TTFA、抗霉素A、叠氮化钠、寡霉素和缬氨霉素等线粒体抑制剂。在葡萄糖剥夺条件下,抑制剂对细胞内ATP含量和AMPK活性影响不大。然而,除TTFA外,在葡萄糖剥夺条件下,抑制剂会降低Akt和p38 MAPK的活性。此外,抑制剂还会使细胞内Ca2+浓度大幅升高。最后,抑制剂会降低线粒体膜电位,但TTFA会增加膜电位,寡霉素则使其维持稳定。在本研究中,结果表明在葡萄糖剥夺条件下,线粒体抑制剂可能通过抑制Akt和p38 MAPK、增加[Ca2+]i以及降低MMP来诱导U937细胞产生严重的细胞毒性,而不是通过抑制ATP生成和激活AMPK来实现。