Nuclear translocation of p42/p44 mitogen-activated protein kinase is required for growth factor-induced gene expression and cell cycle entry
Nuclear translocation of p42/p44 mitogen-activated protein kinase is required for growth factor-induced gene expression and cell cycle entry
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DOI：
10.1093/emboj/18.3.664
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发表时间：
1999-02-01
期刊：
影响因子：
11.4
通讯作者：
Pouysségur, J
中科院分区：
文献类型：
--
作者：
Brunet, A;Roux, D;Pouysségur, J
丝裂原激活蛋白激酶 (MAPK) 模块由连续磷酸化激活的三种蛋白激酶组成，参与多种细胞外因子的信号转导。在哺乳动物细胞中，促有丝分裂刺激触发 p42/p44MAPK 从细胞质易位到细胞核，而该模块的其他蛋白激酶仍保留在细胞质中。由于 MAPK 已被证明可以磷酸化和激活核靶标，例如转录因子 Elk1，因此有人提出，但尚未证明，MAPK 核转位可能代表信号转导中的关键步骤。在这项研究中，我们通过表达催化失活形式的细胞质 MAP 激酶磷酸酶，将 p42/p44MAPK 隔离在细胞质中 （MKP-3/Pyst-1）。将 MAPK 隔离在细胞质中并不会改变其激活或其磷酸化 MAPK 细胞质底物（p90RSK1 或 Elk1 的工程细胞质形式）的能力。相比之下，阻止 MAPK 核易位会强烈抑制 Elk1 依赖性基因转录以及细胞响应生长因子而重新启动 DNA 复制的能力。因此，MAPK 重新定位到细胞核似乎是有丝分裂原诱导的基因表达和细胞周期重新进入的重要调节步骤。
Mitogen-activated protein kinase (MAPK) modules, composed of three protein kinases activated by successive phosphorylation, are involved in the signal transduction of a wide range of extracellular agents. In mammalian cells, mitogenic stimulation triggers the translocation of p42/p44MAPK from the cytoplasm to the nucleus, whereas the other protein kinases of the module remain cytosolic. Since MAPK has been shown to phosphorylate and activate nuclear targets, such as the transcription factor Elk1, it has been proposed, but not yet demonstrated, that MAPK nuclear translocation could represent a critical step in signal transduction, In this study, we sequestered p42/p44MAPK in the cytoplasm by the expression of a catalytically inactive form of cytoplasmic MAP kinase phosphatase (MKP-3/Pyst-1). Sequestering MAPK in the cytoplasm did not alter its activation or its ability to phosphorylate cytoplasmic substrates of MAPK (p90RSK1 or an engineered cytoplasmic form of Elk1). In contrast, prevention of MAPK nuclear translocation strongly inhibited Elk1-dependent gene transcription and the ability of cells to reinitiate DNA replication in response to growth factors. Thus the relocalization of MAPK to the nucleus appears to be an important regulatory step for mitogen-induced gene expression and cell cycle re-entry.