Redox and metal profiles in human coronary endothelial and smooth muscle cells under hyperoxia, physiological normoxia and hypoxia: Effects of NRF2 signaling on intracellular zinc
Matthew J. Smith,
Fan Yang,
Alexander Griffiths,
Alexander Morrell,
Sarah J. Chapple,
Richard C.M. Siow,
Theodora Stewart,
Wolfgang Maret,
Giovanni E. Mann
Affiliations
Matthew J. Smith
King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK
Fan Yang
King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK
Alexander Griffiths
London Metallomics Facility, Faculty of Life Sciences & Medicine, King's College London, UK
Alexander Morrell
London Metallomics Facility, Faculty of Life Sciences & Medicine, King's College London, UK
Sarah J. Chapple
King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK
Richard C.M. Siow
King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK
Theodora Stewart
Research Management & Innovation Directorate (RMID), King's College London, UK
Wolfgang Maret
Departments of Biochemistry and Nutritional Sciences, School of Life Course & Population Sciences, Faculty of Life Sciences & Medicine, King's College London, UK
Giovanni E. Mann
King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK; Corresponding author. King's BHF Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK.
Zinc is an important component of cellular antioxidant defenses and dysregulation of zinc homeostasis is a risk factor for coronary heart disease and ischemia/reperfusion injury. Intracellular homeostasis of metals, such as zinc, iron and calcium are interrelated with cellular responses to oxidative stress. Most cells experience significantly lower oxygen levels in vivo (2–10 kPa O2) compared to standard in vitro cell culture (18kPa O2). We report the first evidence that total intracellular zinc content decreases significantly in human coronary artery endothelial cells (HCAEC), but not in human coronary artery smooth muscle cells (HCASMC), after lowering of O2 levels from hyperoxia (18 kPa O2) to physiological normoxia (5 kPa O2) and hypoxia (1 kPa O2). This was paralleled by O2-dependent differences in redox phenotype based on measurements of glutathione, ATP and NRF2-targeted protein expression in HCAEC and HCASMC. NRF2-induced NQO1 expression was attenuated in both HCAEC and HCASMC under 5 kPa O2 compared to 18 kPa O2. Expression of the zinc efflux transporter ZnT1 increased in HCAEC under 5 kPa O2, whilst expression of the zinc-binding protein metallothionine (MT) decreased as O2 levels were lowered from 18 to 1 kPa O2. Negligible changes in ZnT1 and MT expression were observed in HCASMC. Silencing NRF2 transcription reduced total intracellular zinc under 18 kPa O2 in HCAEC with negligible changes in HCASMC, whilst NRF2 activation or overexpression increased zinc content in HCAEC, but not HCASMC, under 5 kPa O2. This study has identified cell type specific changes in the redox phenotype and metal profile in human coronary artery cells under physiological O2 levels. Our findings provide novel insights into the effect of NRF2 signaling on Zn content and may inform targeted therapies for cardiovascular diseases.
