Increasing Intracellular Levels of Iron with Ferric Ammonium Citrate Leads to Reduced P-glycoprotein Expression in Human Immortalised Brain Microvascular Endothelial Cells
- 1 January 2021
- journal article
- research article
- Published by Springer Science and Business Media LLC in Pharmaceutical Research
- Vol. 38 (1), 97-111
- https://doi.org/10.1007/s11095-021-03006-y
Abstract
Purpose P-glycoprotein (P-gp) at the blood-brain barrier (BBB) precludes the brain penetration of many xenobiotics and mediates brain-to-blood clearance of β-amyloid, which accumulates in the Alzheimer’s disease (AD) brain. Zinc and copper are reported to modulate BBB expression and function of P-gp; however, the impact of exogenous iron, which accumulates in AD, on P-gp dynamics remains unknown. Methods P-gp protein and MDR1 transcript levels were assessed in immortalised human cerebral microvascular endothelial (hCMEC/D3) cells treated with ferric ammonium citrate (FAC; 250 μM, 72 h), by Western blotting and RT-qPCR, respectively. P-gp function was assessed using rhodamine-123 and [3H]-digoxin accumulation. Intracellular reactive oxygen species (ROS) levels were determined using 2′,7′-dichlorofluorescin diacetate and intracellular iron levels quantified using a ferrozine assay. Results FAC treatment significantly reduced P-gp protein (36%) and MDR1 mRNA (16%) levels, with no significant change in rhodamine-123 or [3H]-digoxin accumulation. While P-gp/MDR1 downregulation was associated with elevated ROS and intracellular iron, MDR1 downregulation was not attenuated with the antioxidant N-acetylcysteine nor the iron chelators desferrioxamine and deferiprone, suggesting the involvement of a ROS-independent mechanism or incomplete iron chelation. Conclusions These studies demonstrate that iron negatively regulates P-gp expression at the BBB, potentially impacting CNS drug delivery and brain β-amyloid clearance.Keywords
Funding Information
- Judith Jane Mason and Harold Stannett Williams Memorial Foundation (Mason Foundation National Medical Program (MAS2017F035))
This publication has 55 references indexed in Scilit:
- Treatment of heart failure in adults with thalassemia major: response in patients randomised to deferoxamine with or without deferiproneJournal of Cardiovascular Magnetic Resonance, 2013
- Intracellular trafficking of P-glycoproteinThe International Journal of Biochemistry & Cell Biology, 2012
- Polarized Distribution of Heme Transporters in Retinal Pigment Epithelium and Their Regulation in the Iron-Overload Disease HemochromatosisInvestigative Ophthalmology & Visual Science, 2011
- ABC efflux transporters in brain vasculature of Alzheimer's subjectsBrain Research, 2010
- Structure and function of the blood–brain barrierNeurobiology of Disease, 2010
- Restoring Blood-Brain Barrier P-Glycoprotein Reduces Brain Amyloid-β in a Mouse Model of Alzheimer's DiseaseMolecular Pharmacology, 2010
- Diesel exhaust particles induce oxidative stress, proinflammatory signaling, and P‐glycoprotein up‐regulation at the blood‐brain barrierThe FASEB Journal, 2008
- N‐tert‐butyl hydroxylamine, a mitochondrial antioxidant, protects human retinal pigment epithelial cells from iron overload: relevance to macular degenerationThe FASEB Journal, 2007
- Zip14 (Slc39a14) mediates non-transferrin-bound iron uptake into cellsProceedings of the National Academy of Sciences of the United States of America, 2006
- Analysis of Relative Gene Expression Data Using Real-Time Quantitative PCR and the 2−ΔΔCT MethodMethods, 2001