Downregulation of epidermal growth factor receptor signaling by singlet oxygen through activation of caspase-3 and protein phosphatases.
Downregulation of epidermal growth factor receptor signaling by singlet oxygen through activation of caspase-3 and protein phosphatases.
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单线态氧通过激活 caspase-3 和蛋白磷酸酶下调表皮生长因子受体信号传导。
DOI：
10.1038/sj.onc.1206604
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Kochevar,IreneE
中科院分区：
文献类型：
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作者：
Zhuang,Shougang;Ouedraogo,GladysD;Kochevar,IreneE
生存信号通路的下调会导致活性氧（ROS）的细胞毒性，并可能成为某些过度增殖性疾病治疗的基础。我们研究了单线态氧（一种由光敏作用形成的 ROS）在通过表皮生长因子受体 (EGFR) 调节生存信号中的作用。人角质形成细胞暴露于单线态氧会导致 EGFR 快速丢失，而抑制受体内化或中断主要蛋白水解途径（蛋白酶体、溶酶体或钙蛋白酶）都不能阻止这种损失。然而，用 caspase-3 抑制剂 DEVD-FMK 进行预处理可抑制 EGFR 降解。单线态氧处理后 5 分钟即可检测到 Caspase-3 裂解，重组活性 caspase-3 完全裂解角质形成细胞膜组分中的 EGFR。单线态氧诱导的 EGFR 丢失伴随着 EGFR 以及 Akt 和细胞外信号调节激酶 1/2 (ERK) 1/2 的去磷酸化。单线态氧诱导的蛋白质去磷酸化不依赖于 caspase-3 的激活。相反，用冈田酸抑制蛋白磷酸酶（PP）完全阻断 EGFR、ERK1/2 和 Akt 的去磷酸化以及 EGFR 的降解。这些结果表明，单线态氧产生的氧化应激通过降低蛋白质水平及其磷酸化来快速破坏 EGFR 介导的信号传导。这些反应取决于 caspase-3 和 PP 的相互交织的激活。
Downregulation of survival signaling pathways contributes to the cytotoxicity of reactive oxygen species (ROS) and may underlie certain therapies for hyperproliferative diseases. We have investigated the role of singlet oxygen, an ROS formed by photosensitization, in the regulation of survival signaling via the epidermal growth factor receptor (EGFR). Exposure of human keratinocytes to singlet oxygen resulted in rapid loss of EGFR, which was not blocked by either inhibition of receptor internalization or by interrupting the major proteolytic pathways (proteasome, lysosome or calpain). However, pretreatment with a caspase-3 inhibitor, DEVD-FMK, inhibited EGFR degradation. Caspase-3 cleavage was detected as early as 5 min after singlet oxygen treatment, and recombinant active caspase-3 completely cleaved EGFR in a keratinocyte membrane fraction. The singlet oxygen-induced loss of EGFR was accompanied by dephosphorylation of EGFR as well as of Akt and extracellular signal-regulated kinase 1/2 (ERK) 1/2. Singlet oxygen-induced protein dephosphorylation was not dependent on activation of caspase-3. In contrast, inhibition of protein phosphatases (PPs) with okadaic acid completely blocked dephosphorylation of EGFR, ERK1/2 and Akt as well as degradation of EGFR. These results indicate that the oxidative stress produced by singlet oxygen rapidly disrupts EGFR-mediated signaling by decreasing both the protein level and its phosphorylation. These responses depended on intertwined activation of caspase-3 and PPs.