Bach1 differentially regulates distinct Nrf2-dependent genes in human venous and coronary artery endothelial cells adapted to physiological oxygen levels

• Published in: Free radical biology & medicine 2016-03, Vol.92, p.152-162
• Main Authors: Chapple, Sarah J., Keeley, Thomas P., Mastronicola, Daniela, Arno, Matthew, Vizcay-Barrena, Gema, Fleck, Roland, Siow, Richard C.M., Mann, Giovanni E.
• Format: Article
• Language: English
• Subjects: Amino Acid Transport System y+ - metabolism; Antioxidants - metabolism; Bach1; Basic-Leucine Zipper Transcription Factors - genetics; Basic-Leucine Zipper Transcription Factors - metabolism; Coronary artery; Coronary Vessels - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Endothelial cells; Endothelial Cells - metabolism; Fanconi Anemia Complementation Group Proteins - genetics; Fanconi Anemia Complementation Group Proteins - metabolism; GCL; Glutamate-Cysteine Ligase - metabolism; Glutathione; Glutathione - metabolism; Glutathione reductase GR; Heme Oxygenase-1 - genetics; Heme Oxygenase-1 - metabolism; HO-1; Humans; Hypoxia-Inducible Factor 1, alpha Subunit - genetics; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; Kelch-Like ECH-Associated Protein 1 - genetics; Kelch-Like ECH-Associated Protein 1 - metabolism; Mitochondria; NAD(P)H Dehydrogenase (Quinone) - genetics; NAD(P)H Dehydrogenase (Quinone) - metabolism; NF-E2-Related Factor 2 - genetics; NF-E2-Related Factor 2 - metabolism; Normoxia; NQO1; Nuclear Factor-E2-Related Factor 2, Nrf2; Oxygen - metabolism; Physiological oxygen tension; Reactive Oxygen Species - metabolism; Redox signaling; Sequestosome-1; Solute Carrier Family 7-anionic amino acid transporter light chain xCT; Thioredoxin reductase-1; Veins - metabolism
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2015.12.013

The effects of physiological oxygen tension on Nuclear Factor-E2-Related Factor 2 (Nrf2)-regulated redox signaling remain poorly understood. We report the first study of Nrf2-regulated signaling in human primary endothelial cells (EC) adapted long-term to physiological O2 (5%). Adaptation of EC to 5% O2 had minimal effects on cell ultrastructure, viability, basal redox status or HIF1-α expression. Affymetrix array profiling and subsequent qPCR/protein validation revealed that induction of select Nrf2 target genes, HO-1 and NQO1, was significantly attenuated in cells adapted to 5% O2, despite nuclear accumulation and DNA binding of Nrf2. Diminished HO-1 induction under 5% O2 was stimulus independent and reversible upon re-adaptation to air or silencing of the Nrf2 repressor Bach1, notably elevated under 5% O2. Induction of GSH-related genes xCT and GCLM were oxygen and Bach1-insensitive during long-term culture under 5% O2, providing the first evidence that genes related to GSH synthesis mediate protection afforded by Nrf2–Keap1 defense pathway in cells adapted to physiological O2 levels encountered in vivo. [Display omitted] •Physiological normoxia alters the redox phenotype in human endothelial cells.•Induction of selected Nrf2 target genes, HO-1 and NQO1, is attenuated under 5% O2.•Diminished HO-1 induction is stimulus independent and reversible on readaptation to air.•Bach1 mRNA and protein expression are elevated in cells adapted to 5% O2.•Glutathione synthesis related genes are Bach1 and oxygen insensitive.•Nrf2 confers vascular protection via GCLM and the xCT under physiological normoxia.