Differential responses of the Nrf2-Keap1 system to laminar and oscillatory shear stresses in endothelial cells
Differential responses of the Nrf2-Keap1 system to laminar and oscillatory shear stresses in endothelial cells
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DOI：
10.1074/jbc.m502551200
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发表时间：
2005-07-22
影响因子：
4.8
通讯作者：
Yamamoto, M
中科院分区：
文献类型：
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作者：
Hosoya, T;Maruyama, A;Yamamoto, M
Nrf 2-Keap 1系统通过抗氧化反应元件（ARE）协调调节细胞保护基因的表达。几个ARE调控基因的表达被发现在内皮细胞中被层流剪切应力上调，表明Nrf 2有助于通过ARE的抗动脉粥样硬化反应。为了进一步了解Nrf 2在动脉粥样硬化发展中的作用，我们研究了Nrf 2如何调节基因表达以响应抗动脉粥样硬化层流（L-flow）或促动脉粥样硬化振荡流（O-flow）。人主动脉内皮细胞（HAECs）暴露于L-流，而不是O-流，诱导细胞保护基因的表达，如NAD（P）H醌氧化还原酶1（NQO 1）的5倍和血红素加氧酶-1的8倍。在siRNA介导的敲低实验中确定了Nrf 2对L-flow诱导的表达的关键贡献。两种环氧合酶-2（考克斯-2）特异性抑制剂可减弱L-flow暴露急性期Nrf 2核蓄积。考克斯的下游产物-2，15-脱氧-δ（12，14）-前列腺素J（2）（15 d-PGJ（2））通过与Keap 1的半胱氨酸结合激活HAEC中的Nrf 2调节途径。这些结果表明，15 d-PGJ（2）是L-flow激活Nrf 2和诱导抗动脉粥样硬化基因表达所必需的。而L-流和O-流诱导的Nrf 2的核积累到相当的水平，染色质免疫沉淀分析显示，Nrf 2结合NQO 1 ARE显着减少的情况下，O-流相比，L-流。这些结果表明，O-flow在DNA结合步骤抑制Nrf 2活性，从而抑制动脉粥样硬化保护基因的表达，从而使血管易于形成动脉粥样硬化。
The Nrf2-Keap1 system coordinately regulates cytoprotective gene expression via the antioxidant responsive element (ARE). The expression of several ARE-regulated genes was found to be up-regulated in endothelial cells by laminar shear stress, suggesting that Nrf2 contributes to the anti-atherosclerosis response via the ARE. To gain further insight into the roles that Nrf2 plays in the development of atherosclerosis, we examined how Nrf2 regulates gene expression in response to anti-atherogenic laminar flow (L-flow) or pro-atherogenic oscillatory flow (O-flow). Exposure of human aortic endothelial cells (HAECs) to L-flow, but not to O-flow, induced the expression of cytoprotective genes, such as NAD(P)H quinone oxidoreductase 1 (NQO1) by 5-fold and heme oxygenase-1 by 8-fold. The critical contribution of Nrf2 to the expression induced by L-flow was ascertained in siRNA-mediated knockdown experiments. Two cyclooxygenase-2 (COX-2) specific inhibitors attenuated Nrf2 nuclear accumulation in the acute phase of L-flow exposure. A downstream product of COX-2, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), activated the Nrf2 regulatory pathway in HAECs through binding to the cysteines of Keap1. These results demonstrate that 15d-PGJ(2) is essential for L-flow to activate Nrf2 and induce anti-atherosclerotic gene expression. Whereas both L-flow and O-flow induced the nuclear accumulation of Nrf2 to comparable levels, chromatin immunoprecipitation analysis revealed that Nrf2 binding to the NQO1 ARE was significantly diminished in the case of O-flow compared with that of L-flow. These results suggest that O-flow inhibits Nrf2 activity at the DNA binding step, thereby suppressing atheroprotective gene expression and hence predisposing the blood vessels to the formation of atherosclerosis.