The purpose of our study is to determine the protective effects of mitophagy enhancers against mutant APP and amyloid beta (Aβ)-induced mitochondrial and synaptic toxicities in Alzheimer’s disease (ad). Over two decades of research from our lab and others revealed that mitochondrial abnormalities are largely involved in the pathogenesis of both early-onset and late-onset ad. Emerging studies from our lab and others revealed that impaired clearance of dead or dying mitochondria is an early event in the disease process. Based on these changes, it has been proposed that mitophagy enhancers are potential therapeutic candidates to treat patients with ad. In the current study, we optimized doses of mitophagy enhancers urolithin A, actinonin, tomatidine, nicotinamide riboside in immortalized mouse primary hippocampal (HT22) neurons. We transfected HT22 cells with mutant APP cDNA and treated with mitophagy enhancers and assessed mRNA and protein levels of mitochondrial dynamics, biogenesis, mitophagy and synaptic genes, cell survival; assessed mitochondrial respiration in mAPP-HT22 cells treated and untreated with mitophagy enhancers. We also assessed mitochondrial morphology in mAPP-HT22 cells treated and untreated with mitophagy enhancers. Mutant APP-HT22 cells showed increased fission, decreased fusion, synaptic & mitophagy genes, reduced cell survival and defective mitochondrial respiration, and excessively fragmented and reduced length of mitochondria. However, these events were reversed in mitophagy-enhancers-treated mutant mAPP-HT22 cells. Cell survival was significantly increased, mRNA and protein levels of mitochondrial fusion, synaptic and mitophagy genes were increased, mitochondrial number is reduced, and mitochondrial length is increased, and mitochondrial fragmentation is reduced in mitophagy-enhancers-treated mutant APP-HT22 cells. Further, urolithin A showed strongest protective effects against mutant APP and Aβ-induced mitochondrial and synaptic toxicities in ad. Based on these findings, we cautiously propose that mitophagy enhancers are promising therapeutic drugs to treat mitophagy in patients with ad.

中文翻译：

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线粒体自噬增强剂对阿尔茨海默病中β淀粉样蛋白诱导的线粒体和突触毒性的保护作用

我们研究的目的是确定线粒体自噬增强剂对阿尔茨海默病 (ad) 中突变 APP 和淀粉样蛋白 (Aβ) 诱导的线粒体和突触毒性的保护作用。我们实验室和其他实验室二十多年的研究表明，线粒体异常在很大程度上参与了早发型和晚发型 AD 的发病机制。我们实验室和其他实验室的最新研究表明，死亡或垂死线粒体的清除受损是疾病过程中的早期事件。基于这些变化，有人提出线粒体自噬增强剂是治疗 AD 患者的潜在治疗候选者。在当前的研究中，我们优化了永生化小鼠原代海马 (HT22) 神经元中线粒体自噬增强剂尿石素 A、放线菌素、番茄碱、烟酰胺核苷的剂量。我们用突变型 APP cDNA 转染 HT22 细胞，并用线粒体自噬增强剂处理，并评估线粒体动力学、生物合成、线粒体自噬和突触基因、细胞存活的 mRNA 和蛋白质水平；评估了用线粒体自噬增强剂处理和未处理的 mAPP-HT22 细胞的线粒体呼吸。我们还评估了用线粒体自噬增强剂处理和未处理的 mAPP-HT22 细胞的线粒体形态。突变的 APP-HT22 细胞表现出裂变增加、融合减少、突触和线粒体自噬基因减少、细胞存活率降低和线粒体呼吸缺陷，以及线粒体过度破碎和长度缩短。然而，这些事件在线粒体自噬增强剂处理的突变 mAPP-HT22 细胞中发生逆转。线粒体自噬增强剂处理的突变APP-HT22细胞中，细胞存活率显着增加，线粒体融合、突触和线粒体自噬基因的mRNA和蛋白质水平增加，线粒体数量减少，线粒体长度增加，线粒体碎片减少​​。此外，尿石素 A 对 AD 中突变 APP 和 Aβ 诱导的线粒体和突触毒性表现出最强的保护作用。基于这些发现，我们谨慎地提出线粒体自噬增强剂是治疗 AD 患者线粒体自噬的有前途的治疗药物。