Role of NADPH oxidase 1-derived ROS in the pathogenesis of Parkinson's disease

描述(由申请人提供)：氧化应激是帕金森氏病(PD)发病的一个主要因素。长期以来，线粒体一直被认为是帕金森病患者氧化应激的罪魁祸首。然而，帕金森病中活性氧物种(ROS)的分子来源尚不清楚。NADPH氧化酶家族(NOX)是第一个被发现的专门产生超氧化物的酶复合体。在这里，我们首先证明了在体内和体外，氧化应激(如6-OHDA)增加了Nox同源物Nox1在DA细胞中的表达。Nox1系统的关键组件rac1也被激活。散发性帕金森病患者死后脑多巴胺能神经元中Nox1表达增加。新发现的帕金森病的致病基因亮氨酸富含重复蛋白激酶2(LRRK2)的突变也增加了DA细胞中Nox1的表达和ROS的产生。有趣的是，Nox1的诱导受到线粒体呼吸链抑制物的影响，这表明线粒体功能障碍和Nox1激活之间存在相互作用。最近的研究还表明，线粒体功能障碍在Nox1介导的超氧化物生成中起着重要作用。最后，抑制NOx1介导的超氧化物产生保护黑质DA神经元免受6-OHDA诱导的变性。这些研究将探讨1)线粒体ROS是否在Nox1的诱导和激活中起关键作用，2)Nox1/rac1系统通过AAV2介导的基因转导抑制或激活该系统在黑质纹状体通路退化中的作用，以及3)LRRK2突变是否影响Nox1介导的ROS产生的激活和随后的DA神经变性。公共卫生相关性：线粒体功能障碍和氧化应激与帕金森病的发病密切相关。这项拟议研究的总体目标是确定NADPH氧化酶1和rac1，一种专门的超氧化物生成系统在多巴胺能黑质纹状体通路退化中的作用。我们将研究线粒体是否在NOx1诱导中起关键作用，以及NOx系统的干预是否可以防止DA神经退变。此外，研究LRRK2突变与Nox1/rac1激活之间的相互作用可能会发现参与帕金森病发病的共同分子途径。综上所述，这些结果将有助于我们理解控制黑质纹状体通路对氧化应激易感性的细胞机制，并导致新的治疗靶点的开发。

DESCRIPTION (provided by applicant): Oxidative stress is a major contributing factor in the pathogenesis of Parkinson's disease (PD). Mitochondria have long been implicated as the culprit for oxidative stress in PD. However, molecular sources for reactive oxygen species (ROS) in PD have not been clearly elucidated. A family of NADPH oxidase (NOX) is the first enzyme complex discovered which is specialized to generate superoxide. Here, we first demonstrate that the expression of Nox1, a Nox homologue, is increased in DA cells by oxidative stress such as 6-OHDA both in vivo and in vitro. Rac1, a key component of the Nox1 system, is also activated. Nox1 expression is increased in DA neurons of postmortem human brains from sporadic PD patients. Mutations in Leucine-rich-repeat-kinase 2 (LRRK2), the newly identified causative gene for PD also increase Nox1 expression and ROS generation in DA cells. Interestingly, Nox1 induction is affected by mitochondrial respiratory chain inhibitors, suggesting the interplay between mitochondrial dysfunction and Nox1 activation. Recent studies also suggest a prominent role of mitochondrial dysfunction in Nox1-mediated superoxide generation. Finally, inhibition of Nox1-mediated superoxide generation protects substantia nigra DA neurons from 6-OHDA- induced degeneration. These proposed studies will investigate 1) whether mitochondrial ROS plays a key role in Nox1 induction and activation, 2) the role of the Nox1/Rac1 system in degeneration of the nigrostriatal pathway by inhibition or activation of this system using AAV2-mediated gene transduction, and 3) whether LRRK2 mutations affect the activation of Nox1-mediated ROS production and consequential DA neurodegeneration. PUBLIC HEALTH RELEVANCE: Mitochondrial dysfunction and oxidative stress are strongly implicated in the pathogenesis of PD. The overall goal of this proposed study is to define the role of NADPH oxidase 1 and Rac1, the specialized superoxide generation system in degeneration of the dopaminergic nigrostriatal pathway. We will investigate whether mitochondria play a key role in the Nox1 induction and the intervention of the Nox system prevents DA neurodegeneration. Additionally, the study on the interaction between LRRK2 mutations and the Nox1/Rac1 activation may identify common molecular pathways involved in the pathogenesis of PD. Collectively, these results will help us to understand cellular mechanism governing the vulnerability of the DA nigrostriatal pathway to oxidative stress and lead to the development of novel therapeutic target.