title: Laminar flow induction of antioxidant response element-mediated genes in endothelial cells. A novel anti-inflammatory mechanism.
abstract: 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.
authors.affiliation: Discovery Research, AtheroGenics, Inc., Alpharetta, Georgia 30004, USA. xchen@atherogenics.com
authors.forename: Xi-Lin
authors.initials: XL
authors.lastname: Chen
authors.forename: Signe E
authors.initials: SE
authors.lastname: Varner
authors.forename: Anjali S
authors.initials: AS
authors.lastname: Rao
authors.forename: Janice Y
authors.initials: JY
authors.lastname: Grey
authors.forename: Suzanne
authors.initials: S
authors.lastname: Thomas
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Cook
authors.forename: Martin A
authors.initials: MA
authors.lastname: Wasserman
authors.forename: Russell M
authors.initials: RM
authors.lastname: Medford
authors.forename: Anil K
authors.initials: AK
authors.lastname: Jaiswal
authors.forename: Charles
authors.initials: C
authors.lastname: Kunsch
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001161:Arteriosclerosis / Q000517:prevention & control; D001775:Blood Circulation; D002352:Carrier Proteins / Q000502:physiology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics; D051547:Heme Oxygenase-1; D018056:Hemorheology; D006801:Humans; D007249:Inflammation / Q000517:prevention & control*; D008565:Membrane Proteins; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics; D051267:NF-E2-Related Factor 2; D020218:Response Elements / Q000502:physiology*; D013314:Stress, Mechanical; D015534:Trans-Activators / Q000502:physiology; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics
chemical_list: D000975:Antioxidants; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human