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

描述（由申请人提供）：氧化应激是帕金森病（PD）发病机制的主要影响因素。线粒体长期以来被认为是PD中氧化应激的罪魁祸首。然而，PD中活性氧（ROS）的分子来源尚未明确阐明。NADPH氧化酶（NOX）家族是第一个被发现的专门产生超氧化物的酶复合物。在这里，我们首先证明，Nox 1，一个Nox同源物的表达，增加DA细胞的氧化应激，如6-OHDA在体内和体外。Nox 1系统的关键组成部分Rac 1也被激活。Nox 1在散发性PD患者死后人脑DA神经元中的表达增加富含亮氨酸重复序列激酶2（LRRK 2）的突变，新发现的PD致病基因也增加了DA细胞中Nox 1的表达和ROS的产生。有趣的是，Nox 1诱导受线粒体呼吸链抑制剂的影响，这表明线粒体功能障碍和Nox 1激活之间的相互作用。最近的研究还表明，线粒体功能障碍在Nox 1介导的超氧化物生成中起着重要作用。最后，抑制Nox 1介导的超氧化物生成保护黑质DA神经元免受6-OHDA诱导的变性。这些拟议的研究将调查1）线粒体ROS是否在Nox 1诱导和激活中起关键作用，2）Nox 1/Rac 1系统在黑质纹状体通路变性中的作用，通过使用AAV 2介导的基因转导抑制或激活该系统，以及3）LRRK 2突变是否影响Nox 1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PD的发病机制密切相关。这项研究的总体目标是确定NADPH氧化酶1和Rac 1的作用，专门的超氧化物生成系统在多巴胺能黑质纹状体通路的退化。我们将研究线粒体是否在Nox 1诱导中起关键作用，以及Nox系统的干预是否可以预防DA神经变性。此外，研究LRRK 2突变与Nox 1/Rac 1激活之间的相互作用可能会发现参与PD发病机制的共同分子途径。总的来说，这些结果将帮助我们了解控制DA黑质纹状体通路对氧化应激的脆弱性的细胞机制，并导致新型治疗靶点的开发。

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.