Characterization of Nrf2 activation and heme oxygenase-1 expression in NIH3T3 cells exposed to aqueous extracts of cigarette smoke
Characterization of Nrf2 activation and heme oxygenase-1 expression in NIH3T3 cells exposed to aqueous extracts of cigarette smoke
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DOI：
10.1016/j.freeradbiomed.2005.07.003
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发表时间：
2005-12-01
影响因子：
7.4
通讯作者：
Müller, T
中科院分区：
文献类型：
--
作者：
Knörr-Wittmann, C;Hengstermann, A;Müller, T
香烟烟雾（CS）是一种复杂的化学混合物，估计由多达5000种不同的化学物质组成，其中许多是促氧化剂。在这里，我们表明，至少在体外，旨在打击氧化应激CS曝光所造成的细胞反应主要是由转录因子Nrf 2，抗氧化剂和II期相关基因的主要诱导剂控制。Nrf 2在细胞对CS的反应中的突出作用通过以下观察得到证实：在暴露于CS的水提取物的NIH 3 T3细胞中，（i）Nrf 2被强烈地稳定化并且在核提取物中变得可检测。(ii)Nrf 2的核定位与推定的Nrf 2/MafK异源二聚体与其同源顺式调节位点的DNA结合增加相一致，即，抗氧化反应元件（antioxidant-responsive element，ARE）(iii)使用各种hmox 1启动子/荧光素酶报告基因构建体对氧化应激诱导基因血红素加氧酶-1（hmox 1）的调控元件的研究揭示，该基因的强CS依赖性表达主要由远端增强子I（“E1”）和2（“E2”）控制，其均包含三个典型的ARE样应激响应元件（StRE）。值得注意的是，RNA干扰引起的Nrf 2水平的耗竭显着损害CS诱导的hmox 1启动子激活，基于E1和E2所表现出的不同的Nrf 2敏感性。最后，（iv）Nrf 2的siRNA依赖性敲低完全废除了CS诱导的II期相关基因的表达。总之，这些结果证实了Nrf 2在感知（氧化剂）应激和协调旨在解决应激条件的有效转录反应中的突出作用。(c)2005年爱思唯尔公司All rights reserved.
Cigarette smoke (CS) is a complex chemical mixture estimated to be composed of up to 5000 different chemicals, many of which are prooxidant. Here we show that, at least in vitro, the cellular response designed to combat oxidative stress resulting from CS exposure is primarily controlled by the transcription factor Nrf2, a principal inducer of antioxidant and phase II-related genes. The prominent role of Nrf2 in the cellular response to CS is substantiated by the following observations: In NIH3T3 cells exposed to aqueous extracts of CS (i) Nrf2 is strongly stabilized and becomes detectable in nuclear extracts. (ii) Nuclear localization of Nrf2 coincides with increased DNA binding of a putative Nrf2/MafK heterodimer to its cognate cis-regulatory site, i.e., the antioxidant-responsive element (ARE). (iii) Studies on the regulatory elements of the oxidative stress-inducible gene heme oxygenase-1 (hmox1) using various hmox1 promoter/luciferase reporter constructs revealed that the strong CS-dependent expression of this gene is primarily governed by the distal enhancers I ("E1") and 2 ("E2"), which both contain three canonical ARE-like stress-responsive elements (StREs). Notably, depletion of Nrf2 levels caused by RNA interference significantly compromised CS-induced hmox1 promoter activation, based on the distinct Nrf2 sensitivity exhibited by E1 and E2. Finally, (iv) siRNA-dependent knock-down of Nrf2 completely abrogated CS-induced expression of phase II-related genes. Taken together, these results confirm the outstanding role of Nrf2 both in sensing (oxidant) stress and in orchestrating an efficient transcriptional response aimed at resolving the stressing conditions. (c) 2005 Elsevier Inc. All rights reserved.