Ganglioside GM3 promotes cell migration by regulating MAPK and c-Fos/AP-1
Ganglioside GM3 promotes cell migration by regulating MAPK and c-Fos/AP-1
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DOI：
10.1038/sj.onc.1209416
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发表时间：
2006-06-01
期刊：
影响因子：
8
通讯作者：
Yamashita, T.
中科院分区：
文献类型：
--
作者：
Hashiramoto, A.;Mizukami, H.;Yamashita, T.
已经提出神经节苷脂作为跨膜信号传导的调节剂。GM 3是一种含有单水杨酸的鞘糖脂，近年来被认为是哺乳动物细胞信号转导的关键分子之一。在这项研究中，我们使用小鼠胚胎成纤维细胞系（MEFs）建立从sialyltransferase-I敲除小鼠（GM 3 synthase KO小鼠），以评估神经节苷脂的有丝分裂信号的调节。细胞增殖试验显示GM 3 KO MEFs具有更高的生长潜力。免疫印迹结果显示GM 3 KO MEFs中Ras/Raf/MEK/ERK信号通路表达上调，这些信号导致ERK向细胞核的转位增强。此外，外源性和内源性GM 3的加回均降低了GM 3 KO MEFs中MAPK的活性。此外，GM 3 KO MEFs在高密度培养条件下形成灶，细胞周期调节剂的分析揭示了GM 3 KO MEFs对进入细胞周期阻滞的抗性。最后，GM 3 KO MEFs中c-Fos的持续表达与c-Fos和AP-1之间的DNA结合活性相关。这些结果表明，唾液酸转移酶-I的缺失改变MEFs的特性，使其处于MAPK通路的高度活化状态，表明GM 3作为膜传递信号的调节剂的关键作用。
Gangliosides have been proposed as modulators of transmembrane signaling. Recently, GM3, a glycosphingolipid containing monosaialic acids, is thought to be one of the key molecules of signal transduction in mammalian cells. In this study, we used mouse embryonic fibroblast cell lines (MEFs) established from sialyltransferase-I knockout mice (GM3 synthase KO mice) to evaluate the regulation of mitogenic signals by gangliosides. Cell proliferation assay revealed a higher growth potential of GM3 KO MEFs. Immunoblots showed upregulation of Ras/Raf/MEK/ERK pathway in GM3 KO MEFs, and these signals resulted in enhanced translocation of ERK into the nuclei. Further, both exogenous and endogenous add-back of GM3 decreased the activities of MAPK in GM3 KO MEFs. In addition, GM3 KO MEFs formed foci in high-density culture condition, and analyses of cell cycle modulators revealed the resistance of GM3 KO MEFs for entering cell cycle arrest. Finally, sustained expressions of c-Fos in GM3 KO MEFs were shown to correlate with DNA-binding activity between c-Fos and AP-1. These results demonstrate that the deletion of sialyltransferase-I changes the character of MEFs to a highly activated state of the MAPK pathway, indicating the critical role of GM3 as a regulator of membrane-transmitted signals.