Chen Xi-Lin, Varner Signe E, Rao Anjali S, Grey Janice Y, Thomas Suzanne, Cook Christopher K, Wasserman Martin A, Medford Russell M, Jaiswal Anil K, Kunsch Charles
Discovery Research, AtheroGenics, Inc., Alpharetta, Georgia 30004, USA.
J Biol Chem. 2003 Jan 10;278(2):703-11. doi: 10.1074/jbc.M203161200. Epub 2002 Oct 4.
Atherosclerotic lesions preferentially develop in areas of the vasculature exposed to nonlaminar blood flow and low fluid shear stress, whereas laminar flow and high fluid shear stress are athero-protective. We have identified a set of genes including NAD(P)H:quinone oxidoreductase-1 (NQO1), heme oxygenase-1 (HO-1), ferritin (heavy and light chains), microsomal epoxide hydrolase, glutathione S-transferase, and gamma-glutamylcysteine synthase, whose expression is induced by exposure to prolonged physiological levels of steady laminar flow (shear stress = 20 dyn/cm(2)) in endothelial cells (EC). These genes contain an antioxidant response element (ARE) or ARE-like transcriptional regulatory sequence in their promoters and generally function to protect cells against oxidant stress. We demonstrate that exposure of EC to laminar flow activates ARE-mediated transcriptional activity. Mutation of the ARE from either the NQO1 or HO-1 promoter abolished laminar flow-induced NQO1 and HO-1 transcriptional activation. Expression of antisense Nrf2 (a transcriptional factor for ARE), a dominant negative Nrf2, or the cytoplasmic inhibitor of Nrf2 (Keap1/INrf2) inhibited laminar flow-induced NQO1 promoter activation in EC. In addition, expression of NQO1 or Nrf2 inhibited tumor necrosis factor-alpha-induced activation of VCAM-1 (vascular cell adhesion molecule-1) gene expression in EC. These data define the ARE as a novel endothelial shear stress response element. Furthermore, laminar flow activation of antioxidant genes via an ARE-dependent transcriptional mechanism may represent a novel athero-protective and anti-inflammatory mechanism in the vasculature.
动脉粥样硬化病变优先发生在血管系统中暴露于非层流血液和低流体剪切应力的区域，而层流和高流体剪切应力具有抗动脉粥样硬化作用。我们已经鉴定出一组基因，包括NAD(P)H:醌氧化还原酶-1（NQO1）、血红素加氧酶-1（HO-1）、铁蛋白（重链和轻链）、微粒体环氧化物水解酶、谷胱甘肽S-转移酶和γ-谷氨酰半胱氨酸合成酶，其表达在内皮细胞（EC）中通过暴露于长时间生理水平的稳定层流（剪切应力=20达因/平方厘米）而被诱导。这些基因在其启动子中含有抗氧化反应元件（ARE）或ARE样转录调控序列，并且通常起到保护细胞免受氧化应激的作用。我们证明将EC暴露于层流可激活ARE介导的转录活性。来自NQO1或HO-1启动子的ARE突变消除了层流诱导的NQO1和HO-1转录激活。反义Nrf2（ARE的转录因子）、显性负性Nrf2或Nrf2的细胞质抑制剂（Keap1/INrf2）的表达抑制了EC中层流诱导的NQO1启动子激活。此外，NQO1或Nrf2的表达抑制了肿瘤坏死因子-α诱导的EC中VCAM-1（血管细胞黏附分子-1）基因表达的激活。这些数据将ARE定义为一种新型的内皮剪切应力反应元件。此外，通过ARE依赖性转录机制对抗氧化基因的层流激活可能代表了血管系统中一种新型的抗动脉粥样硬化和抗炎机制。
