TNF-α Induces Apoptosis Through JNK/Bax-Dependent Pathway in Differentiated, but not Naïve PC12 Cells
TNF-α Induces Apoptosis Through JNK/Bax-Dependent Pathway in Differentiated, but not Naïve PC12 Cells
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DOI：
10.4161/cc.6.12.4302
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发表时间：
2007-06
期刊：
影响因子：
4.3
通讯作者：
Lan Zhang;D. Xing;Lei Liu;Xuejuan Gao;Miaojuan Chen
中科院分区：
文献类型：
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作者：
Lan Zhang;D. Xing;Lei Liu;Xuejuan Gao;Miaojuan Chen
分化的 PC12 细胞已广泛用作分析神经元变性的模型。一些证据表明，分化的 PC12 细胞比初始 PC12 对细胞凋亡刺激更敏感。然而，两种类型PC12细胞的凋亡机制尚不完全清楚。在这项研究中，首次使用共聚焦显微镜研究了肿瘤坏死因子-α (TNF-α) 诱导活分化和幼稚 PC12 细胞凋亡的信号通路。我们的结果表明，在 TNF-α 诱导的细胞凋亡过程中，在分化的 PC12 细胞中观察到 Bax 易位至线粒体，并观察到细胞色素 C (Cyt c) 从线粒体释放，但在初始 PC12 细胞中未观察到。此外，bim、c-Jun N 端蛋白激酶 1 和 2（JNK1 和 JNK2）的 mRNA 水平在分化的 PC12 细胞中显着增加。在初始 PC12 细胞中，TNF-α 诱导的细胞凋亡被 Z-IETD-fmk（caspase-8 特异性抑制剂）抑制，但 SP600125（JNK 特异性抑制剂）不被抑制。而在分化的PC12细胞中，只有Z-IETD-fmk和SP600125共同处理才能有效抑制细胞凋亡过程，并且SP600125抑制Bax向线粒体的易位，表明JNK介导了Bax的激活。实验数据有力地证明，TNF-α 通过 JNK/Bax 依赖性途径诱导分化的 PC12 细胞凋亡，但不是幼稚的 PC12 细胞。
Differentiated PC12 cells have been used widely as a model for the analysis of neuronal degeneration. Some evidences showed that differentiated PC12 cells were more sensitive than naïve PC12 against apoptosis stimuli. However, the apoptosis mechanism of both types of PC12 cells was not fully known. In this study, the signaling pathways involved in tumor necrosis factor-α (TNF-α)-induced apoptosis in living differentiated and naïve PC12 cells were investigated using confocal microscope for the first time. Our results showed that during TNF-α-induced apoptosis, Bax translocation to mitochondria and cytochrome C (Cyt c) release from mitochondria were observed in differentiated PC12 cells, but not in naïve PC12 cells. Furthermore, the mRNA levels of bim, c-Jun N-terminal protein kinase 1 and 2 (JNK1 and JNK2) increased noticeably in differentiated PC12 cells. The apoptosis induced by TNF-α was inhibited by Z-IETD-fmk (specific inhibitor of caspase-8) but not SP600125 (specific inhibitor of JNK) in naïve PC12 cells. While in differentiated PC12 cells, the process of apoptosis could only be inhibited effectively by Z-IETD-fmk and SP600125 co-treatment, and SP600125 inhibited the Bax translocation to mitochondria implying that JNK mediated activation of Bax. The experimental data strongly demonstrated that TNF-α induced apoptosis through JNK/Bax-dependent pathway in differentiated, but not naïve PC12 cells.