AIMS Mitochondrial dysfunction is an early prominent feature of Alzheimer's disease (AD). In the present study, we sought to investigate whether defective mitophagy is tightly related to amyloid-β (Aβ)-induced mitochondrial dysfunction. MAIN METHODS Immunofluorescence, western blot and transmission electron microscopy were used to examine mitophagy. Mitochondrial membrane potential was assessed using the JC-1 dye. Mitochondrial ROS was detected using MitoSOX™ Red staining. KEY FINDINGS Aβ induced mitochondrial dysfunction in HEK293 cells. Moreover, Aβ induced an increase in parkin translocation to mitochondria and led to a drastic reduction in cytosolic parkin. Furthermore, Aβ-treated cells displayed a microtubule-associated protein 1 light chain 3 (LC3) punctate pattern and elevated mitochondrial LC3-II levels, suggesting the upregulation of mitophagy. Notably, Aβ induced the accumulation of mitochondrial p62, which was associated with impaired mitophagy. In addition, Aβ-treated cells exhibited fragmented or swollen mitochondria with severely decreased cristae. We then investigated whether overexpression of parkin could protect cells against Aβ-induced mitochondrial dysfunction. Interestingly, parkin overexpression inhibited Aβ-induced mitochondrial dysfunction. Besides, parkin overexpression increased cytosolic and mitochondrial parkin levels as well as mitochondrial LC3-II levels in Aβ-treated cells. Additionally, parkin overexpression reversed the accumulation of p62 in mitochondria, indicating that parkin overexpression restored impaired mitophagy in Aβ-treated cells. Importantly, parkin overexpression remarkably reversed Aβ-induced mitochondrial fragmentation. SIGNIFICANCE Our data demonstrate that overexpression of parkin ameliorates impaired mitophagy and promotes the removal of damaged mitochondria in Aβ-treated cells, indicating that upregulation of parkin-mediated mitophagy may be a potential strategy for the therapy of AD.

中文翻译：

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Parkin的过表达通过恢复受损的线粒体吞噬来减轻HEK293细胞中Aβ诱导的线粒体功能障碍。

AIMS线粒体功能障碍是阿尔茨海默氏病（AD）的早期突出特征。在本研究中，我们试图调查是否有缺陷的自噬与淀粉样β（Aβ）诱导的线粒体功能障碍密切相关。主要方法免疫荧光，免疫印迹和透射电镜检查线粒体。使用JC-1染料评估线粒体膜电位。使用MitoSOX™Red染色检测线粒体ROS。主要发现Aβ诱导HEK293细胞线粒体功能异常。此外，Aβ诱导了帕金森向线粒体易位的增加，并导致胞浆帕金森的急剧减少。此外，经Aβ处理的细胞显示出微管相关蛋白1轻链3（LC3）的点状模式，并增加了线粒体LC3-II的水平，提示线粒体上调。值得注意的是，Aβ诱导线粒体p62的积累，这与线粒体受损有关。另外，经Aβ处理的细胞表现出线粒体破碎或肿胀，cr的严重减少。然后，我们研究了Parkin的过表达是否可以保护细胞免受Aβ诱导的线粒体功能障碍。有趣的是，Parkin过表达抑制了Aβ诱导的线粒体功能障碍。此外，帕金森蛋白的过度表达增加了Aβ处理细胞的胞质和线粒体帕金蛋白水平以及线粒体LC3-II水平。另外，Parkin的过表达逆转了线粒体中p62的积累，表明Parkin的过表达恢复了Aβ处理细胞中受损的线粒体。重要的，派克蛋白的过表达显着逆转了Aβ诱导的线粒体片段化。意义我们的数据表明，Parkin的过表达改善了线粒体受损，并促进了Aβ处理的细胞中线粒体受损的清除，表明Parkin介导的线粒体上调可能是AD治疗的潜在策略。