title: Increased mitochondrial ROS formation by acetaminophen in human hepatic cells is associated with gene expression changes suggesting disruption of the mitochondrial electron transport chain.
abstract: Acetaminophen (APAP) overdosage results in hepatotoxicity, but the underlying molecular mechanisms are still not completely understood. In the current study, we focused on mitochondrial-specific oxidative liver injury induced by APAP exposure. Owning to genetic polymorphisms in the CYP2E1 gene or varying inducibility by xenobiotics, the CYP2E1 mRNA level and protein activity vary extensively among individuals. As CYP2E1 is a known ROS generating enzyme, we chose HepG2 to minimize CYP2E1-induced ROS formation, which will help us better understand the APAP induced mitochondrial-specific hepatotoxicity in a subpopulation with low CYP2E1 activity. HepG2 cells were exposed to a low and toxic dose (0.5 and 10mM) of APAP and analyzed at four time points for genome-wide gene expression. Mitochondria were isolated and electron spin resonance spectroscopy was performed to measure the formation of mitochondrial ROS. The yield of ATP was measured to confirm the impact of the toxic dose of APAP on cellular energy production. Our results indicate that 10mM APAP significantly influences the expression of mitochondrial protein-encoding genes in association with an increase in mitochondrial ROS formation. Additionally, 10mM APAP affects the expression of genes encoding the subunits of electron transport chain (ETC) complexes, which may alter normal mitochondrial functions by disrupting the assembly, stability, and structural integrity of ETC complexes, leading to a measurable depletion of ATP, and cell death. The expression of mitochondrium-specific antioxidant enzyme, SOD2, is reduced which may limit the ROS scavenging ability and cause imbalance of the mitochondrial ROS homeostasis. Overall, transcriptome analysis reveals the molecular processes involved in the observed APAP-induced increase of mitochondrial ROS formation and the associated APAP-induced oxidative stress.
authors.affiliation: Department of Toxicogenomics, School of Oncology and Developmental Biology (GROW), Maastricht University, 6200 MD Maastricht, the Netherlands. Electronic address: j.jiang@maastrichtuniversity.nl.
authors.forename: Jian
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Department of Toxicogenomics, School of Oncology and Developmental Biology (GROW), Maastricht University, 6200 MD Maastricht, the Netherlands.
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Briedé
authors.affiliation: Department of Toxicogenomics, School of Oncology and Developmental Biology (GROW), Maastricht University, 6200 MD Maastricht, the Netherlands.
authors.forename: Danyel G J
authors.initials: DG
authors.lastname: Jennen
authors.affiliation: Department of Toxicogenomics, School of Oncology and Developmental Biology (GROW), Maastricht University, 6200 MD Maastricht, the Netherlands.
authors.forename: Anke
authors.initials: A
authors.lastname: Van Summeren
authors.affiliation: Department of Toxicogenomics, School of Oncology and Developmental Biology (GROW), Maastricht University, 6200 MD Maastricht, the Netherlands.
authors.forename: Karen
authors.initials: K
authors.lastname: Saritas-Brauers
authors.affiliation: Department of Human Movement Sciences, School of nutrition, Toxicology and metabolism (NUTRIM) Maastricht University Medical Centre, 6200 MD Maastricht, the Netherlands.
authors.forename: Gert
authors.initials: G
authors.lastname: Schaart
authors.affiliation: Department of Toxicogenomics, School of Oncology and Developmental Biology (GROW), Maastricht University, 6200 MD Maastricht, the Netherlands.
authors.forename: Jos C S
authors.initials: JC
authors.lastname: Kleinjans
authors.affiliation: Department of Toxicogenomics, School of Oncology and Developmental Biology (GROW), Maastricht University, 6200 MD Maastricht, the Netherlands.
authors.forename: Theo M C M
authors.initials: TM
authors.lastname: de Kok
mesh_terms: D000082:Acetaminophen / Q000633:toxicity*; D000255:Adenosine Triphosphate / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D056486:Chemical and Drug Induced Liver Injury / Q000201:enzymology / Q000209:etiology* / Q000235:genetics / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D045222:Electron Transport Chain Complex Proteins / Q000235:genetics / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D043922:Toxicogenetics / Q000379:methods; D000099156:Superoxide Dismutase 2
chemical_list: D000082:Acetaminophen; D000255:Adenosine Triphosphate; D045222:Electron Transport Chain Complex Proteins; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D000099156:Superoxide Dismutase 2
keywords: Acetaminophen; ESR; HepG2; Microarray; Mitochondrial ROS; Toxicogenomics