NADPH oxidase and ERK signaling regulates hyperoxia-induced Nrf2-ARE transcriptional response in pulmonary epithelial cells
NADPH oxidase and ERK signaling regulates hyperoxia-induced Nrf2-ARE transcriptional response in pulmonary epithelial cells
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DOI：
10.1074/jbc.m408275200
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发表时间：
2004-10-01
影响因子：
4.8
通讯作者：
Reddy, SP
中科院分区：
文献类型：
--
作者：
Papaiahgari, S;Kleeberger, SR;Reddy, SP
氧化应激在高氧诱导的急性肺损伤中起主要作用。我们以前已经表明，缺乏Nrf 2的小鼠比野生型小鼠更容易受到高氧的影响。Nrf 2激活抗氧化反应元件（ARE）介导的基因表达，参与细胞对毒性损伤的保护。本研究的目的是调查的机制，控制高氧激活Nrf 2使用非恶性小鼠肺泡上皮细胞系，C10。高氧暴露后Nrf 2 mRNA和蛋白水平无明显变化。与此相反，高氧引起的易位Nrf 2从细胞质到细胞核内的30-60分钟的曝光。与这些观察结果一致，凝胶位移和报告分析表明，高氧增强的ARE DNA结合活性的Nrf 2和ARE驱动的转录上调之间的相关性。用二苯基碘鎓（DPI）抑制NADPH氧化酶可阻断Nrf 2易位和ARE介导的转录。抑制MEK/ERK通路也产生类似的效果。与这一发现一致，高氧刺激ERK-1和ERK-2磷酸化，而DPI或N-乙酰-L-半胱氨酸阻断这种激活。高氧刺激内源性Nrf 2的磷酸化，但不存在U 0126，这表明ERK信号在Nrf 2的激活中起着关键作用。与这一观点一致，高氧不刺激缺乏ERK-1的成纤维细胞中Nrf 2的磷酸化。总的来说，我们的研究结果表明，高氧诱导的，ARE驱动的，Nrf 2依赖的转录是由NADPH氧化酶和ERK-1信号转导控制。
Oxidative stress plays a major role in hyperoxia-induced acute lung injury. We have shown previously that mice lacking the Nrf2 are more susceptible to hyperoxia than are wild-type mice. Nrf2 activates antioxidant response element (ARE)-mediated gene expression involved in cellular protection against toxic insults. The present study was designed to investigate the mechanisms that control the activation of Nrf2 by hyperoxia using a non-malignant murine alveolar epithelial cell line, C10. No significant alteration in the levels of Nrf2 mRNA and protein was found following exposure to hyperoxia. In contrast, hyperoxia caused the translocation of Nrf2 from the cytoplasm to the nucleus within 30-60 min of exposure. Consistent with these observations, gel shift and reporter analyses demonstrated a correlation between the hyperoxia-enhanced ARE DNA-binding activity of Nrf2 and an up-regulation of ARE-driven transcription. Inhibition of NADPH oxidase with diphenyleneiodonium (DPI) blocked both Nrf2 translocation and ARE-mediated transcription. Inhibition of the MEK/ERK pathway caused a similar effect. Consistent with this finding, hyperoxia stimulated ERK-1 and ERK-2 phosphorylation, whereas DPI or N-acetyl-L-cysteine blocked such activation. Hyperoxia stimulated the phosphorylation of endogenous Nrf2, but not in the presence of U0126, suggesting a critical role for ERK signaling in the activation of Nrf2. Consistent with this notion, hyperoxia did not stimulate the phosphorylation of Nrf2 in fibroblasts lacking the ERK-1. Collectively, our findings suggest that hyperoxia-induced, ARE-driven, Nrf2-dependent transcription is controlled by NADPH oxidase and ERK-1 signaling.