51. Disruption of canonical AHR-mediated induction of hepatocyte PKM2 expression compromises antioxidant defenses and increases TCDD-induced hepatotoxicity.
- Author
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Orlowska K, Nault R, Ara J, LaPres JJ, Harkema J, Demireva EY, Xie H, Wilson RH, Bradfield CA, Yap D, Joshi A, Elferink CJ, and Zacharewski T
- Subjects
- Animals, Mice, Antioxidants metabolism, Mice, Knockout, Oxidative Stress drug effects, Chemical and Drug Induced Liver Injury metabolism, Chemical and Drug Induced Liver Injury pathology, Chemical and Drug Induced Liver Injury etiology, Humans, Thyroid Hormones metabolism, Liver metabolism, Liver drug effects, Liver pathology, Basic Helix-Loop-Helix Transcription Factors metabolism, Basic Helix-Loop-Helix Transcription Factors genetics, Thyroid Hormone-Binding Proteins, Male, Glutathione metabolism, Receptors, Aryl Hydrocarbon metabolism, Receptors, Aryl Hydrocarbon genetics, Polychlorinated Dibenzodioxins toxicity, Hepatocytes metabolism, Hepatocytes drug effects, Pyruvate Kinase metabolism, Pyruvate Kinase genetics, Reactive Oxygen Species metabolism
- Abstract
Metabolic reprogramming by the pyruvate kinase M2 isoform is associated with cell proliferation and reactive oxygen species (ROS) defenses. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), an environmental contaminant that induces ROS and hepatotoxicity, dose-dependently induces pyruvate kinase muscle isoform M2 (PKM2) in the liver. To further investigate its role in combating TCDD hepatotoxicity, a Pkm
ΔDRE mouse was constructed lacking the dioxin response element mediating aryl hydrocarbon receptor (AHR) induction. TCDD failed to induce hepatic PKM2 in PkmΔDRE mice and in primary hepatocytes isolated from an AHR knockout model (AHRV375Afl/fl Alb-CreERT2 ), demonstrating induction is AHR dependent. Both wild-type (WT) and PkmΔDRE mice exhibited dose-dependent increases in liver weight after treatment with TCDD every 4 days for 28 days. Glutathione (GSH) levels increased in WT mice while oxidized glutathione (GSSG) levels increased in both models with a 24-fold decrease in the GSH/GSSG ratio in PkmΔDRE mice suggesting lower antioxidant and recycling capacity. Moreover, TCDD-induced fibrosis was more severe in PkmΔDRE mice while PkmΔDRE hepatocytes exhibited greater cytotoxicity following co-treatment with TCDD and hydrogen peroxide. TCDD also induced PKM2 in human HepaRG™ cells with AHR enrichment at a conserved DRE core within the locus. These results suggest AHR-mediated PKM2 induction is a novel antioxidant response to TCDD., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2024
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