Epidermal growth factor receptor is modulated by redox through multiple mechanisms -: Effects of reductants and H2O2
Epidermal growth factor receptor is modulated by redox through multiple mechanisms -: Effects of reductants and H2O2
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DOI：
10.1046/j.1432-1327.2000.01194.x
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发表时间：
2000-04-01
期刊：
影响因子：
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通讯作者：
Hirata, H
中科院分区：
文献类型：
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作者：
Kamata, H;Shibukawa, Y;Hirata, H
细胞氧化还原状态已被证明在细胞信号系统中起重要作用。本文研究了还原剂和H2O2对细胞中表皮生长因子（EGF）信号传导的影响。H2O2诱导EGF受体磷酸化，形成由Shc、Grb2、Sos和EGF受体组成的受体复合物。H2O2不诱导EGF受体的二聚化或寡聚化。蛋白酪氨酸磷酸酶（PTP）实验显示H2O2抑制细胞裂解物中EGF受体的去磷酸化，表明PTP失活参与H2O2诱导的EGF受体活化。相比之下，还原剂n -乙酰- l-半胱氨酸[Cys(Ac)]和二硫苏糖醇明显抑制EGF诱导的细胞中EGF受体的二聚化和激活。与抑制EGF受体一致，Cys（Ac）抑制了EGF诱导的Ras、磷脂酰肌醇3-激酶和丝裂原活化蛋白激酶的活化。二硫苏糖醇在体外和体内完全抑制EGF结合和EGF受体的激酶激活。相比之下，Cys（Ac）抑制细胞上高亲和力的egf结合位点，但对低亲和力的结合位点没有影响。此外，Cys（Ac）在体外不抑制EGF诱导的激酶激活或EGF受体的二聚化，表明它通过氧化还原敏感的细胞过程或过程抑制EGF受体。因此，EGF受体通过多个步骤被氧化还原调节，包括PTP的去磷酸化、配体结合和一个或多个Cys（Ac）敏感的细胞过程。
The cellular redox state has been shown to play an essential role in cellular signaling systems. Here we investigate the effects of reductants and H2O2 on the signaling of epidermal growth factor (EGF) in cells. H2O2 induced the phosphorylation of the EGF receptor and the formation of a receptor complex comprising Shc, Grb2, Sos, and the EGF receptor. Dimerization or oligomerization of the EGF receptor was not induced by H2O2. Protein tyrosine phosphatase (PTP) assay showed that H2O2 suppressed dephosphorylation of the EGF receptor in cell lysates, suggesting that inactivation of PTP was involved in H2O2-induced activation of the EGF receptor. In contrast, the reductants N-acetyl-L-cysteine [Cys(Ac)] and dithiothreitol markedly suppressed EGF-induced dimerization and activation of the EGF receptor in cells. In accordance with suppression of the EGF receptor, Cys(Ac) suppressed EGF-induced activation of Ras, phosphatidylinositol 3-kinase and mitogen-activated protein kinase. Dithiothreitol completely inhibited EGF binding and kinase activation of the EGF receptor both in vitro and in vivo. In contrast, Cys(Ac) suppressed high-affinity EGF-binding sites on the cells, but had no effect on low-affinity binding sites. Furthermore, Cys(Ac) did not suppress EGF-induced kinase activation or dimerization of the EGF receptor in vitro, indicating that it suppressed the EGF receptor through a redox-sensitive cellular process or processes. Thus, the EGF receptor is regulated by redox through multiple steps including dephosphorylation by PTP, ligand binding, and a Cys(Ac)-sensitive cellular process or processes.