Activation mechanism of c-Jun amino-terminal kinase in the course of neural differentiation of P19 embryonic carcinoma cells
Activation mechanism of c-Jun amino-terminal kinase in the course of neural differentiation of P19 embryonic carcinoma cells
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DOI：
10.1074/jbc.m406610200
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发表时间：
2004-08-27
影响因子：
4.8
通讯作者：
Kobayashi, T
中科院分区：
文献类型：
--
作者：
Akiyama, S;Yonezawa, T;Kobayashi, T
P19胚胎癌细胞是研究早期发育和分化的模型系统，取决于培养条件，其可以分化为神经元和原始内胚层样细胞。我们以前曾报道，c-Jun氨基末端激酶（JNK）的激活是必需的维甲酸诱导的P19细胞的神经分化。然而，负责激活JNK的信号传导途径尚不清楚。在这项研究中，我们证明了MAPK激酶4（MKK 4）和TAK 1（MKK 4的上游激酶之一）的活性在神经分化细胞中增强。神经分化的抑制蛋白磷酸酶2C激酶，一个灭活剂的TAK 1的过表达，建议在分化过程中的TAK 1信号通路的关键作用。共聚焦显微镜分析表明，TAK 1，磷酸-MKK 4，磷酸-JNK共定位与微管蛋白的神经突和本地化也在细胞核的分化。与此相反，两个TAK 1结合蛋白，TAB 1和TAB 2，这是参与TAK 1的激活，分别定位于神经突和细胞核的分化细胞。提示TAK 1-MKK 4-JNK信号通路在P19细胞内不同部位分别被激活，并可能参与P19细胞神经分化的调控。
P19 embryonic carcinoma cells, a model system for studying early development and differentiation, can differentiate into neurons and primitive endoderm-like cells depending on the culture conditions. We have previously reported that the activation of c-Jun amino-terminal kinase (JNK) is required for the retinoic acid-induced neural differentiation of P19 cells. However, the signaling pathway(s) responsible for the activation of JNK has not been known. In this study, we demonstrated that activities of MAPK kinase 4 (MKK4) and TAK1, one of the upstream kinases of MKK4, were enhanced in the neurally differentiating cells. Inhibition of the neural differentiation by an overexpression of protein phosphatase 2Cepsilon, an inactivator of TAK1, suggested a critical role of the TAK1 signaling pathway during the differentiation. Confocal microscopic analysis indicated that TAK1, phospho-MKK4, and phospho-JNK were colocalized with tubulin in the neurites and localized also in the nuclei of the differentiating cells. In contrast, two TAK1-binding proteins, TAB1 and TAB2, which are involved in the activation of TAK1, were localized in the neurites and the nuclei of the differentiating cells, respectively. These results suggest that two distinct TAK1-MKK4-JNK signaling pathways are independently activated at the different intracellular locations and may participate in the regulation of the neural differentiation of P19 cells.