Disruption of canonical AHR-mediated induction of hepatocyte PKM2 expression compromises antioxidant defenses and increases TCDD-induced hepatotoxicity
Karina Orlowska,
Rance Nault,
Jesmin Ara,
John J. LaPres,
Jack Harkema,
Elena Y. Demireva,
Huirong Xie,
Rachel H. Wilson,
Christopher A. Bradfield,
Dianne Yap,
Aditya Joshi,
Cornelis J. Elferink,
Tim Zacharewski
Affiliations
Karina Orlowska
Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA; Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, 48824, USA
Rance Nault
Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA; Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, 48824, USA; Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, 48824, USA
Jesmin Ara
Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
John J. LaPres
Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA; Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, 48824, USA
Jack Harkema
Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, 48824, USA; Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, 48824, USA
Elena Y. Demireva
Transgenic and Genome Editing Facility, Michigan State University, East Lansing, MI, 48824, USA; Institute for Quantitative Health Science & Engineering, Michigan State University, East Lansing, MI, 48824, USA
Huirong Xie
Transgenic and Genome Editing Facility, Michigan State University, East Lansing, MI, 48824, USA; Institute for Quantitative Health Science & Engineering, Michigan State University, East Lansing, MI, 48824, USA
Rachel H. Wilson
McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI, 53706, USA
Christopher A. Bradfield
McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI, 53706, USA
Dianne Yap
Department of Pharmacology and Toxicology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
Aditya Joshi
Department of Pharmacology and Toxicology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
Cornelis J. Elferink
Department of Pharmacology and Toxicology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
Tim Zacharewski
Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA; Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, 48824, USA; Corresponding author. Michigan State University, Department of Biochemistry & Molecular Biology, Biochemistry Building, 603 Wilson Road, East Lansing, MI, 48824, USA.
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 PkmΔDRE 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/flAlb-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.
