Compensatory Mitochondrial Protective Mechanisms Against Oxidative Stress in PD

摘要 帕金森病（PD）表现出的复杂而漫长的病程首先始于非运动性 运动障碍，然后慢慢发展为轻度至中度运动障碍，最终造成严重的运动障碍。 和认知缺陷尽管疾病的各个阶段的病理生理机制已经被证实， 线粒体功能障碍（MD）和神经氧化应激（OS）尚未被表征， 被确定为PD中进行性神经退行性过程中的关键病理学相关因素。学习Key 调节黑质纹状体多巴胺（DA）能系统对MD易感性的氧化信号传导机制 和氧化损伤，我们意外地发现蛋白激酶D1（PKD 1）在黑质中高度表达， DA能神经元和激酶在氧化损伤的早期阶段被迅速激活，以保护DA能神经元。 DA能神经元抗氧化损伤。我们的机制研究表明，激活PKD 1迅速， 易位到DA能神经元的线粒体和细胞核。我们的初步研究表明， 活化的PKD 1可能增强关键神经适应性氧化机制的转录， 增强PGC 1-α、TFAM和BDNF信号通路。因此，本研究的目的是阐明 线粒体/核事件控制PKD 1介导的代偿性保护反应， PD动物模型。我们的建议的首要假设是，促生存激酶PKD 1是迅速 在氧化损伤的初始阶段在黑质DA能神经元中激活，并迅速易位到 线粒体和细胞核启动细胞存活信号通路。它的核转位启动了关键的亲- 负责PGC 1-α，TFAM和BDNF上调的存活转录机制，导致增强的 DA能神经元的线粒体生物发生和神经营养支持。PKD 1的线粒体易位 通过调节线粒体质量控制（MQC）改善线粒体功能。因此，PKD 1作为一个关键， 黑质DA能神经元中的“补偿适应开关”。为了验证这一点，我们将系统地进行以下工作： 具体目标：（i）表征PKD 1活化和核/线粒体易位及其功能 在细胞培养和PD动物模型中的相关性;（ii）表征下游促存活信号传导 DA能神经元中PKD 1线粒体/核易位激活的通路;和（iii）验证PKD 1作为 PD的治疗靶点，并检查新型PKD 1激活剂的翻译潜力。我们将使用多个 模型系统和最先进的细胞，组织学和神经化学方法，以实现这些特定的 目标。我们利用PKD 1适应性信号传导机制的多方面方法， 神经元存活将使我们能够设计一种新的翻译策略，能够在病程早期进行干预， PD的疾病进展。

Abstract The complex and prolonged disease course exhibited by Parkinson’s disease (PD) first starts with non-motor disturbances and then slowly progresses to mild-to-moderate motor deficits, ultimately inflicting severe motor and cognitive deficits. Although pathophysiological mechanisms underlying various stages of the disease have yet to be characterized, both mitochondrial dysfunction (MD) and neural oxidative stress (OS) have been identified as key pathological correlates in the progressive neurodegenerative process in PD. While studying key oxidative signaling mechanisms that regulate susceptibility of the nigrostriatal dopamin(DA)ergic system to MD and oxidative damage, we unexpectedly discovered that protein kinase D1 (PKD1) is highly expressed in nigral DAergic neurons and that the kinase is rapidly activated during the early stages of oxidative insult to protect DAergic neurons against oxidative damage. Our mechanistic studies revealed that activated PKD1 rapidly translocates to both mitochondria and the nucleus of DAergic neurons. Our preliminary studies show that activated PKD1 likely enhances the transcription of key neuro-adaptive oxidative mechanisms involving enhanced PGC1-α, TFAM and BDNF signaling pathways. Thus, the goal of this study is to elucidate mitochondrial/nuclear events governing the PKD1-mediated compensatory protective response using cell and animal models of PD. The overarching hypothesis of our proposal is that the pro-survival kinase PKD1 is rapidly activated in nigral DAergic neurons during the initial stage of an oxidative insult and quickly translocates to mitochondria and nuclei to initiate cell survival signaling pathways. Its nuclear translocation initiates key pro- survival transcriptional machinery responsible for PGC1-α, TFAM and BDNF upregulation, leading to enhanced mitochondrial biogenesis and neurotrophic support in DAergic neurons. Mitochondrial translocation of PKD1 improves mitochondrial function by regulating mitochondrial quality control (MQC). Thus, PKD1 serves as a key ‘compensatory adaptive switch’ in nigral DAergic neurons. To test this, we will systematically pursue the following specific aims: (i) characterize PKD1 activation and nuclear/mitochondrial translocation and its functional relevance in cell culture and animal models of PD; (ii) characterize the downstream pro-survival signaling pathways activated by PKD1 mitochondrial/nuclear translocation in DAergic neurons; and (iii) validate PKD1 as a therapeutic target of PD and examine the translational potential of a novel PKD1 activator. We will use multiple model systems and state-of-the-art cellular, histological and neurochemical approaches to achieve these specific aims. Our multifaceted approach to harness the PKD1 adaptive signaling mechanisms that promote DAergic neuronal survival will enable us to devise a novel translational strategy capable of intervening early in the course of disease progression in PD.