Laminar flow induction of antioxidant response element-mediated genes in endothelial cells. A novel anti-inflammatory...

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.