Epidermal growth factor receptor-mediated cell motility: phospholipase C activity is required, but mitogen-activated protein kinase activity is not sufficient for induced cell movement.
Epidermal growth factor receptor-mediated cell motility: phospholipase C activity is required, but mitogen-activated protein kinase activity is not sufficient for induced cell movement.
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DOI：
10.1083/jcb.127.3.847
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发表时间：
1994-11
期刊：
影响因子：
--
通讯作者：
Wells A
中科院分区：
文献类型：
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作者：
Chen P;Xie H;Sekar MC;Gupta K;Wells A
我们最近证明，EGF 受体 (EGFR) 诱导的细胞运动需要受体激酶活性和自磷酸化（P. Chen、K. Gupta 和 A. Wells. 1994. J. Cell Biol. 124:547-555）。这表明直接下游效应分子含有 src 同源-2 结构域。磷脂酶 C gamma (PLC gamma) 是该信号的候选传感器之一，因为它在调节细胞骨架动力学方面具有潜在作用。我们利用缺乏受体的 NR6 细胞中表达的信号传导受限 EGFR 突变体来确定 PLC 激活对于 EGFR 介导的细胞运动是否是必需的。暴露于 EGF (25 nM) 增强了所有五种 EGFR 突变细胞系中的 PLC 活性，这些细胞系也通过增加细胞运动做出反应。在不表现出增强的运动反应的品系中，基础磷酸肌醇周转不受EGF的影响。 EGFR 介导的细胞运动与 PLC 活性之间的相关性表明，但并未证明存在因果关系。 PLC 的特异性抑制剂 U73122 (1 microM) 可减弱 EGF 诱导的运动和 PLC 反应，而其无活性类似物 U73343 对这些反应没有影响。在 EGF 反应性感染系中，显性失活 PLC gamma-1 片段的表达会降低 PLC 和运动反应。最后，PLC gamma-1 的反义寡核苷酸 (20 microM) 降低了表达野生型 EGFR 的 NR6 细胞中的两种反应。这些发现强烈支持 PLC gamma 作为该运动途径中的紧邻后受体效应器。我们之前已经证明 EGFR 介导的细胞运动和促有丝分裂信号通路是可分离的。分歧点未定义。所有激酶活性 EGFR 突变体都会诱导有丝分裂反应，而只有那些自磷酸化的突变体才能诱导 PLC 活性。 U73122 不影响这些运动响应感染细胞系中 EGF 诱导的胸苷掺入。此外，显性失活PLC gamma-1片段不会减少EGF诱导的胸苷掺入。所有激酶活性 EGFR 都会刺激丝裂原激活蛋白 (MAP) 激酶活性，无论受体是否诱导细胞运动；在抑制运动反应的浓度下，这种 EGF 诱导的 MAP 激酶活性不受 U73122 的影响。因此，导致运动和细胞增殖的信号传导途径在紧接受体后阶段出现分歧，我们认为这是通过效应分子的差异激活来实现的。
We recently have demonstrated that EGF receptor (EGFR)-induced cell motility requires receptor kinase activity and autophosphorylation (P. Chen, K. Gupta, and A. Wells. 1994. J. Cell Biol. 124:547-555). This suggests that the immediate downstream effector molecule contains a src homology-2 domain. Phospholipase C gamma (PLC gamma) is among the candidate transducers of this signal because of its potential roles in modulating cytoskeletal dynamics. We utilized signaling-restricted EGFR mutants expressed in receptor devoid NR6 cells to determine if PLC activation is necessary for EGFR-mediated cell movement. Exposure to EGF (25 nM) augmented PLC activity in all five EGFR mutant cell lines which also responded by increased cell movement. Basal phosphoinositide turnover was not affected by EGF in the lines which do not present the enhanced motility response. The correlation between EGFR-mediated cell motility and PLC activity suggested, but did not prove, a causal link. A specific inhibitor of PLC, U73122 (1 microM) diminished both the EGF- induced motility and PLC responses, while its inactive analogue U73343 had no effect on these responses. Both the PLC and motility responses were decreased by expression of a dominant-negative PLC gamma-1 fragment in EGF-responsive infectant lines. Lastly, anti-sense oligonucleotides (20 microM) to PLC gamma-1 reduced both responses in NR6 cells expressing wild-type EGFR. These findings strongly support PLC gamma as the immediate post receptor effector in this motogenic pathway. We have demonstrated previously that EGFR-mediated cell motility and mitogenic signaling pathways are separable. The point of divergence is undefined. All kinase-active EGFR mutants induced the mitogenic response while only those which are autophosphorylated induced PLC activity. U73122 did not affect EGF-induced thymidine incorporation in these motility-responsive infectant cell lines. In addition, the dominant-negative PLC gamma-1 fragment did not diminish EGF-induced thymidine incorporation. All kinase active EGFR stimulated mitogen-activated protein (MAP) kinase activity, regardless of whether the receptors induced cell movement; this EGF-induced MAP kinase activity was not affected by U73122 at concentrations that depressed the motility response. Thus, the signaling pathways which lead to motility and cell proliferation diverge at the immediate post-receptor stage, and we suggest that this is accomplished by differential activation of effector molecules.