Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA; Institute for Integrative Toxicology, Michigan State University, East Lansing, MI, 48824, USA.
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.
Redox Biol. 2024 Nov;77:103405. doi: 10.1016/j.redox.2024.103405. Epub 2024 Oct 22.
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 mouse was constructed lacking the dioxin response element mediating aryl hydrocarbon receptor (AHR) induction. TCDD failed to induce hepatic PKM2 in Pkm mice and in primary hepatocytes isolated from an AHR knockout model (AHRAlb-Cre), demonstrating induction is AHR dependent. Both wild-type (WT) and Pkm 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 Pkm mice suggesting lower antioxidant and recycling capacity. Moreover, TCDD-induced fibrosis was more severe in Pkm mice while Pkm 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.
丙酮酸激酶 M2 同工型的代谢重编程与细胞增殖和活性氧（ROS）防御有关。2,3,7,8-四氯二苯并对二恶英（TCDD）是一种环境污染物，可诱导 ROS 和肝毒性，可剂量依赖性地诱导肝脏中的丙酮酸激酶肌肉同工型 M2（PKM2）。为了进一步研究其在对抗 TCDD 肝毒性中的作用，构建了缺乏介导芳香烃受体（AHR）诱导的二恶英反应元件的 Pkm 小鼠。TCDD 未能诱导 Pkm 小鼠和从 AHR 敲除模型（AHRAlb-Cre）分离的原代肝细胞中的肝 PKM2，表明诱导是 AHR 依赖性的。WT 和 Pkm 小鼠在 28 天内每 4 天用 TCDD 处理后，肝脏重量均呈剂量依赖性增加。WT 小鼠中的谷胱甘肽（GSH）水平增加，而两种模型中的氧化谷胱甘肽（GSSG）水平均增加，GSH/GSSG 比值在 Pkm 小鼠中降低了 24 倍，表明抗氧化和回收能力降低。此外，TCDD 在 Pkm 小鼠中诱导的纤维化更为严重，而在用 TCDD 和过氧化氢共同处理后，Pkm 肝细胞表现出更大的细胞毒性。TCDD 还在具有 AHR 富集的人 HepaRG™细胞中诱导 PKM2，在基因座内的保守 DRE 核心内。这些结果表明，AHR 介导的 PKM2 诱导是 TCDD 的一种新型抗氧化反应。
