Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
Department of Pathology, McGill University, Montreal, QC, Canada.
Sci Rep. 2021 Nov 30;11(1):23189. doi: 10.1038/s41598-021-02339-3.
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor known to mediate toxic responses to dioxin. However, the role of the AhR in the regulation of cellular physiology has only recently been appreciated, including its ability to control cell cycle progression and apoptosis by unknown mechanisms. We hypothesized that the AhR enhances the activation of the AKT serine/threonine kinase (Akt) pathway to promote cell survival. Utilizing AhR knock-out (Ahr) and wild-type (Ahr) mouse lung fibroblasts (MLFs), we found that Ahr MLFs have significantly higher basal Akt phosphorylation but that AhR did not affect Akt phosphorylation in MLFs exposed to growth factors or AhR ligands. Basal Akt phosphorylation was dependent on PI3K but was unaffected by changes in intracellular glutathione (GSH) or p85α. There was no significant decrease in cell viability in Ahr MLFs treated with LY294002-a PI3K inhibitor-although LY294002 did attenuate MTT reduction, indicating an affect on mitochondrial function. Using a mass spectrometry (MS)-based approach, we identified several proteins that were differentially phosphorylated in the Ahr MLFs compared to control cells, including proteins involved in the regulation of extracellular matrix (ECM), focal adhesion, cytoskeleton remodeling and mitochondrial function. In conclusion, Ahr ablation increased basal Akt phosphorylation in MLFs. Our results indicate that AhR may modulate the phosphorylation of a variety of novel proteins not previously identified as AhR targets, findings that help advance our understanding of the endogenous functions of AhR.
芳香烃受体 (AhR) 是一种配体激活的转录因子，已知可介导二恶英的毒性反应。然而，AhR 调节细胞生理的作用最近才被认识到，包括其通过未知机制控制细胞周期进程和细胞凋亡的能力。我们假设 AhR 增强 AKT 丝氨酸/苏氨酸激酶 (Akt) 途径的激活，以促进细胞存活。利用 AhR 敲除 (Ahr) 和野生型 (Ahr) 小鼠肺成纤维细胞 (MLFs)，我们发现 Ahr MLFs 具有明显更高的基础 Akt 磷酸化，但 AhR 不会影响暴露于生长因子或 AhR 配体的 MLFs 中的 Akt 磷酸化。基础 Akt 磷酸化依赖于 PI3K，但不受细胞内谷胱甘肽 (GSH) 或 p85α 变化的影响。Ahr MLFs 用 PI3K 抑制剂 LY294002 处理时，细胞活力没有明显下降-尽管 LY294002 确实减弱了 MTT 减少，表明对线粒体功能有影响。使用基于质谱 (MS) 的方法，我们鉴定出 Ahr MLFs 与对照细胞相比差异磷酸化的几种蛋白质，包括参与细胞外基质 (ECM)、焦点黏附、细胞骨架重塑和线粒体功能调节的蛋白质。总之，Ahr 缺失增加了 MLFs 中的基础 Akt 磷酸化。我们的结果表明，AhR 可能调节以前未被鉴定为 AhR 靶标的多种新型蛋白质的磷酸化，这一发现有助于我们深入了解 AhR 的内源性功能。
