Peroxiredoxin 6 as an anti-oxidant enzyme

描述（由申请人提供）：本项目将评价一种新型谷胱甘肽过氧化物酶的性质，该酶在肺中大量富集，在肺抗氧化防御和肺表面活性物质代谢中发挥重要作用。这种最近描述的蛋白质称为过氧化物酶6（Prdx 6或1-cys Peroxiredoxin）代表了唯一具有相对高比活性的非硒谷胱甘肽过氧化物酶。这种酶的活性谱中的一个重要特征是，与经典的谷胱甘肽过氧化物酶不同，它能够减少磷脂氢过氧化物，例如，在氧化应激期间膜磷脂的过氧化。在过去4年的支持作为一个组成项目的P-01赠款，我们已经证明，Prdx 6发挥了开创性的作用，在防御肺对氧化应激（高氧，百草枯），该基因的启动子含有对转录因子Nrf 2敏感的抗氧化反应元件，并开发了一种基于脂质结合研究的模型，用于蛋白质的过氧化物酶（Prx）和磷脂酶（PLA 2）活性的协调。我们现在正在寻求5年的支持，以延长这些研究。具体目标1将在Prdx 6无效细胞中利用“敲入”技术，以评价2种活性（Prx、PLA 2）对抗氧化保护的各自贡献。这一目标也将直接比较Prdx 6和其他主要谷胱甘肽过氧化物酶（GPx 1）在抗氧化保护中的相对作用。具体目标2将研究通过组合KGF和地塞米松处理对Prdx 6的诱导，我们的初步数据表明其对Prdx 6表达具有协同作用。具体目标3将继续研究，以评价蛋白质的结构-功能特征，特别关注磷脂结合（作为磷脂氢过氧化物酶活性的要求）和Prdx 6翻译后修饰的作用。具体目标4将利用细胞系统分析pGST在Prdx 6活性活化中的作用。拟议的研究将提供一个协调的努力，调查这种新的抗氧化酶在肺防御氧化应激的作用，并将提供有关其酶活性的生化调节的新信息。这一信息可能会导致新的方法来增加肺耐受氧化应激的能力。 公共卫生相关性：我们已经表征了一种新的酶，其具有两种重要的活性，其用于保护肺免受氧化应激并且还调节肺表面活性剂的代谢。该计划的目标是评估酶的两种活性，以确定它们在抗氧化防御中的相对重要性，研究蛋白质的结构如何影响活性，并确定增加肺细胞中蛋白质表达的方法。了解peroxiredoxin 6的这种作用将有助于将其作为增加肺细胞在氧化应激中生存能力的新靶点。

DESCRIPTION (provided by applicant): This project will evaluate the properties of a novel glutathione peroxidase enzyme that is considerably enriched in lungs and plays an important role in lung antioxidant defense and lung surfactant metabolism. This recently described protein called peroxiredoxin 6 (Prdx6 or 1-cys Peroxiredoxin) represents the only non-selenium glutathione peroxidase of relatively high specific activity. An important characteristic in the activity spectrum for this enzyme is its ability, unlike classical glutathione peroxidase, to reduce phospholipid hydroperoxides as, for example, peroxidation of membrane phospholipids during oxidant stress. During the past 4 years of support as a component project of a P-01 grant, we have demonstrated that Prdx6 plays a seminal role in defense of lungs against oxidant stress (hyperoxia, paraquat), that the promoter of the gene contains an antioxidant response element that is sensitive to the transcription factor Nrf2, and have developed a model based on lipid binding studies for the coordination of the peroxidase (Prx) and phospholipase (PLA2) activities of the protein. We are now seeking 5 years of support to extend these studies. Specific Aim 1 will utilize "knock-in" technology in the Prdx6 null cells to evaluate the respective contributions of the 2 activities (Prx, PLA2) to antioxidant protection. This aim will also directly compare the relative roles of Prdx6 and the other major glutathione peroxidase (GPx1) in antioxidant protection. Specific Aim 2 will study induction of Prdx6 by combined KGF and dexamethasone treatment, which our preliminary data indicate have a synergistic effect on Prdx6 expression. Specific Aim 3 will continue studies to evaluate structure-function characteristics of the protein with a special focus on phospholipid binding as a requirement for the phospholipid hydroperoxide peroxidase activity and the role of Prdx6 post-translational modifications. Specific Aim 4 will utilize cellular systems for analysis of the role of pGST in activation of Prdx6 activity. The proposed studies will provide a coordinated effort to investigate the role of this novel antioxidant enzyme in lung defense against oxidant stress and will provide new information concerning the biochemical regulation of its enzymatic activity. This information could lead to new approaches to increasing the ability of the lung to tolerate oxidant stress. PUBLIC HEALTH RELEVANCE: We have characterized a novel enzyme which has two important activities that serve to protect the lungs against oxidant stress and also regulate metabolism of the lung surfactant. Our goals for the program are to evaluate the two activities of the enzyme to determine their relative importance in antioxidant defense, to investigate how the structure of the protein influences activity, and to determine methods for increasing the expression of the protein in lung cells. Understanding this role of peroxiredoxin 6 will facilitate this as a new target for increasing the ability of the lung cells to survive oxidant stress.