芳烃受体维持小鼠肝脏线粒体的动态平衡。
Aryl hydrocarbon receptor maintains hepatic mitochondrial homeostasis in mice.
机构信息
Department of Anesthesiology, Critical Care and Pain Medicine and Center for Perioperative Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
College of Pharmacy and Research Institute of Pharmaceutical Sciences, Chonnam National University, Gwangju 61186, South Korea.
出版信息
Mol Metab. 2023 Jun;72:101717. doi: 10.1016/j.molmet.2023.101717. Epub 2023 Mar 31.
OBJECTIVE
Mitophagy removes damaged mitochondria to maintain cellular homeostasis. Aryl hydrocarbon receptor (AhR) expression in the liver plays a crucial role in supporting normal liver functions, but its impact on mitochondrial function is unclear. Here, we identified a new role of AhR in the regulation of mitophagy to control hepatic energy homeostasis.
METHODS
In this study, we utilized primary hepatocytes from AhR knockout (KO) mice and AhR knockdown AML12 hepatocytes. An endogenous AhR ligand, kynurenine (Kyn), was used to activate AhR in AML12 hepatocytes. Mitochondrial function and mitophagy process were comprehensively assessed by MitoSOX and mt-Keima fluorescence imaging, Seahorse XF-based oxygen consumption rate measurement, and Mitoplate S-1 mitochondrial substrate utilization analysis.
RESULTS
Transcriptomic analysis indicated that mitochondria-related gene sets were dysregulated in AhR KO liver. In both primary mouse hepatocytes and AML12 hepatocyte cell lines, AhR inhibition strongly suppressed mitochondrial respiration rate and substrate utilization. AhR inhibition also blunted the fasting response of several essential autophagy genes and the mitophagy process. We further identified BCL2 interacting protein 3 (BNIP3), a mitophagy receptor that senses nutrient stress, as an AhR target gene. AhR is directly recruited to the Bnip3 genomic locus, and Bnip3 transcription was enhanced by AhR endogenous ligand treatment in wild-type liver and abolished entirely in AhR KO liver. Mechanistically, overexpression of Bnip3 in AhR knockdown cells mitigated the production of mitochondrial reactive oxygen species (ROS) and restored functional mitophagy.
CONCLUSIONS
AhR regulation of the mitophagy receptor BNIP3 coordinates hepatic mitochondrial function. Loss of AhR induces mitochondrial ROS production and impairs mitochondrial respiration. These findings provide new insight into how endogenous AhR governs hepatic mitochondrial homeostasis.
目的
自噬作用清除受损的线粒体，以维持细胞内的平衡。肝脏中芳烃受体（AhR）的表达对支持正常的肝脏功能起着至关重要的作用，但它对线粒体功能的影响尚不清楚。在这里，我们确定了 AhR 在调控自噬以控制肝能量平衡中的新作用。
方法
在这项研究中，我们利用 AhR 敲除（KO）小鼠和 AhR 敲低 AML12 肝细胞的原代肝细胞。内源性 AhR 配体犬尿氨酸（Kyn）被用于激活 AML12 肝细胞中的 AhR。通过 MitoSOX 和 mt-Keima 荧光成像、基于 Seahorse XF 的耗氧率测量和 Mitoplate S-1 线粒体底物利用分析，全面评估线粒体功能和自噬过程。
结果
转录组分析表明，AhR KO 肝中的线粒体相关基因集发生了失调。在原代小鼠肝细胞和 AML12 肝细胞系中，AhR 抑制强烈抑制线粒体呼吸率和底物利用。AhR 抑制也减弱了几种必需自噬基因的禁食反应和自噬过程。我们进一步鉴定了 BCL2 相互作用蛋白 3（BNIP3），作为一种感知营养应激的自噬受体，是 AhR 的靶基因。AhR 被直接募集到 Bnip3 基因组位置，并且 AhR 内源性配体处理增强了野生型肝中的 Bnip3 转录，并完全消除了 AhR KO 肝中的 Bnip3 转录。在 AhR 敲低细胞中过表达 Bnip3 减轻了线粒体活性氧（ROS）的产生，并恢复了功能性自噬。
结论
AhR 调节自噬受体 BNIP3 协调肝线粒体功能。AhR 的缺失会导致线粒体 ROS 产生增加，并损害线粒体呼吸。这些发现为内源性 AhR 如何调节肝线粒体内稳态提供了新的见解。
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