Yoon So-Young, Oh Young J
Department of Systems Biology, Yonsei University College of Life Science and Biotechnology, Seoul 03722, Korea.
Exp Neurobiol. 2015 Sep;24(3):197-205. doi: 10.5607/en.2015.24.3.197. Epub 2015 Sep 2.
We previously demonstrated that 1-methyl-4-phenylpyridinium (MPP(+)) causes caspase-independent, non-apoptotic death of dopaminergic (DA) neuronal cells. Here, we specifically examined whether change of glucose concentration in culture medium may play a role for determining cell death modes of DA neurons following MPP(+) treatment. By incubating MN9D cells in medium containing varying concentrations of glucose (535 mM), we found that cells underwent a distinct cell death as determined by morphological and biochemical criteria. At 510 mM glucose concentration (low glucose levels), MPP(+) induced typical of the apoptotic dell death accompanied with caspase activation and DNA fragmentation as well as cell shrinkage. In contrast, MN9D cells cultivated in medium containing more than 17.5 mM (high glucose levels) did not demonstrate any of these changes. Subsequently, we observed that MPP(+) at low glucose levels but not high glucose levels led to ROS generation and subsequent JNK activation. Therefore, MPP(+)-induced cell death only at low glucose levels was significantly ameliorated following co-treatment with ROS scavenger, caspase inhibitor or JNK inhibitor. We basically confirmed the quite similar pattern of cell death in primary cultures of DA neurons. Taken together, our results suggest that a biochemically distinct cell death mode is recruited by MPP(+) depending on extracellular glucose levels.
我们之前证明，1-甲基-4-苯基吡啶离子（MPP(+)）可导致多巴胺能（DA）神经元细胞发生不依赖于半胱天冬酶的非凋亡性死亡。在此，我们专门研究了培养基中葡萄糖浓度的变化是否可能在决定MPP(+)处理后DA神经元的细胞死亡模式中发挥作用。通过在含有不同浓度葡萄糖（535 mM）的培养基中培养MN9D细胞，我们发现根据形态学和生化标准，细胞经历了明显不同的细胞死亡。在葡萄糖浓度为510 mM（低葡萄糖水平）时，MPP(+)诱导典型的凋亡性细胞死亡，伴有半胱天冬酶激活、DNA片段化以及细胞萎缩。相反，在含有超过17.5 mM（高葡萄糖水平）的培养基中培养的MN9D细胞未表现出任何这些变化。随后，我们观察到低葡萄糖水平而非高葡萄糖水平下的MPP(+)会导致活性氧（ROS）生成及随后的JNK激活。因此，在与ROS清除剂、半胱天冬酶抑制剂或JNK抑制剂联合处理后，仅在低葡萄糖水平下MPP(+)诱导的细胞死亡得到显著改善。我们在DA神经元原代培养中基本证实了非常相似的细胞死亡模式。综上所述，我们的结果表明，MPP(+)根据细胞外葡萄糖水平引发了一种生化上不同的细胞死亡模式。
