Mechanism of ZCCHC6 Regulation of Mitochondrial Dysfunction In Alzheimer's Disease

项目总结 线粒体功能障碍是脑内易感神经元的早期显著特征 阿尔茨海默病(AD)，它可能在AD的发病机制中发挥关键作用。线粒体是动态的 细胞器经历不断的分裂和融合事件。最近的进展表明，过度 线粒体分裂(分裂)与功能缺陷有关，并与多种人类疾病有关 包括神经退行性疾病。氧化应激已被认为是导致衰老的一个因素 以及多种神经退行性疾病的进展，包括阿尔茨海默病。增加反应性产品的产量 氧物种(ROS)和疾病相关的线粒体功能丧失可能是导致丢失的原因 阿尔茨海默病患者的海马神经元功能。然而，氧化应激诱导的分子机制 线粒体的异常动力学还有待确定。线粒体动力学和功能可能是 受与线粒体分裂相关的因子的失调调节。核裂变的主要执行者是 动力蛋白相关蛋白1(Drp1)是一种主要的胞浆蛋白，在体内转运到线粒体表面 调停核裂变的命令。Mff和Mid49/51是线粒体膜蛋白，可将Drp1招募到 用于分裂的线粒体。众所周知，MFF和Mid49的表达是转录后的 由特定的miRNAs调控，但目前尚不清楚为什么这种调控失败，导致线粒体增加 公元后的裂变。重要的是，我们的初步数据表明，在神经细胞中，氧化应激诱导 我们和其他人已经发现的ZCCHC6的表达，使miRNAs尿苷化，使其无效 在调控基因表达方面。在我们的初步研究中，我们还发现线粒体网络在 具有诱导氧化应激的N2a神经元和调节线粒体分裂的基因(Mff，Mid49)是 上调和预测调节其表达的miRNAs下调。因此，我们的基本 假设“氧化应激诱导的神经元Zcchc6通过以下途径参与AD的发病 通过尿苷基化使调节线粒体分裂因子的特定miRNAs失效 促进线粒体分裂，抑制ZCCHC6有可能抑制和/或逆转 阿尔茨海默病患者的线粒体功能障碍。为了检验这一假设，我们将详细描述 ZCCHC6的异常表达在介导氧化应激诱导的神经元线粒体断裂中的作用 两种临床前模型中Zcchc6在体外和体内缺失对AD和AD发生发展的影响 认知障碍。我们的发现将使我们了解氧化的生物学和临床相关性。 应激诱导Zcchc6和miRNA尿苷基化上调以调节信号基因的表达 与阿尔茨海默病的线粒体损伤和分裂有关。因此，我们的研究结果很可能是 对AD研究设计新的预防和/或治疗策略的重大影响。

PROJECT SUMMARY Mitochondrial dysfunction is an early prominent feature in susceptible neurons in the brain of patients with Alzheimer's disease (AD), which likely plays a critical role in the pathogenesis of AD. Mitochondria are dynamic organelles that undergo continual fission and fusion events. Recent advances indicate that excessive mitochondrial division (fission) is associated with functional defects and is implicated in multiple human diseases including neurodegenerative diseases. Oxidative stress has been recognized as a contributing factor in aging and in the progression of multiple neurodegenerative diseases including AD. Increased production of reactive oxygen species (ROS) and disease-dependent loss of mitochondrial function are likely causally involved in loss of hippocampal neuronal function in AD. However, molecular mechanisms underlying oxidative stress-induced abnormal mitochondrial dynamics are yet to be determined. Mitochondrial dynamics and function may be modulated by dysregulation of factors associated with mitochondrial fission. The major executor of fission is the dynamin related protein 1 (DRP1), a mainly cytosolic protein which translocates to the mitochondrial surface in order to mediate fission. Mff and Mid49/51 are mitochondrial membrane proteins that recruit DRP1 to the mitochondria for fission. It is well established that expression of Mff and Mid49 are post-transcriptionally regulated by specific miRNAs but it is not known why this regulation fails resulting in the increased mitochondrial fission in AD. Importantly, our preliminary data demonstrated that in neuronal cells oxidative stress induce the expression of ZCCHC6 which has been shown by us, and others, to uridylate miRNAs rendering them ineffective in regulating gene expression. In our preliminary studies we also found mitochondrial network fragmentation in N2a neurons with induced oxidative stress and that genes that regulate mitochondrial fission (Mff, Mid49) were upregulated and miRNAs predicted to regulate their expression were downregulated. Therefore, our basic hypothesis is that “Oxidative stress induced Zcchc6 in neurons contributes to AD pathogenesis by rendering specific miRNAs that regulate mitochondrial fission factors ineffective by uridylation which enhance mitochondrial fission and that inhibiting ZCCHC6 has the potential to inhibit and/or reverse mitochondrial dysfunction in AD”. To test this hypothesis, we will characterize in detail the causal role of aberrant ZCCHC6 expression in mediating oxidative stress-induced mitochondrial fragmentation in neurons in vitro and the impact of in vivo depletion of Zcchc6 in two preclinical models on the development of AD and cognitive impairment. Our findings will allow us to understand the biological and clinical relevance of oxidative stress-induced upregulation of Zcchc6 and miRNA uridylation to regulate expression of signature genes associated with mitochondrial impairment and fission in AD. Therefore, the results of our study would likely have a major impact on AD research toward designing novel preventive and/or therapeutic strategies.