Laminar flow induction of antioxidant response element-mediated genes in endothelial cells. A novel anti-inflammatory mechanism.
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.
Chen
Xi-Lin
XL
Discovery Research, AtheroGenics, Inc., Alpharetta, Georgia 30004, USA. xchen@atherogenics.com
Varner
Signe E
SE
Rao
Anjali S
AS
Grey
Janice Y
JY
Thomas
Suzanne
S
Cook
Christopher K
CK
Wasserman
Martin A
MA
Medford
Russell M
RM
Jaiswal
Anil K
AK
Kunsch
Charles
C
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
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