Peroxiredoxin 6 as an anti-oxidant enzyme

描述（由申请人提供）：本项目将评估一种新型谷胱甘肽过氧化物酶的特性，该酶在肺中相当丰富，在肺抗氧化防御和肺表面活性物质代谢中起重要作用。这种最近被描述的蛋白质称为过氧化物还蛋白6 （Prdx6或1-cys过氧化物还蛋白），是唯一具有相对高比活性的非硒谷胱甘肽过氧化物酶。与经典的谷胱甘肽过氧化物酶不同，该酶活性谱的一个重要特征是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。在过去的4年里，作为P-01资助的一个组成部分项目，我们已经证明Prdx6在抗氧化应激（高氧，百草枯）的肺防御中起着重要作用，该基因的启动子包含一个对转录因子Nrf2敏感的抗氧化反应元件，并开发了一个基于脂质结合研究的模型，用于协调蛋白质的过氧化物酶（Prx）和磷脂酶（PLA2）活性。我们现在正在寻求5年的支持来扩展这些研究。Specific Aim 1将利用“敲入”技术在Prdx6空细胞中评估两种活性（Prx, PLA2）对抗氧化保护的各自贡献。这一目的也将直接比较Prdx6和其他主要谷胱甘肽过氧化物酶（GPx1）在抗氧化保护中的相对作用。Specific Aim 2将研究KGF和地塞米松联合治疗对Prdx6的诱导作用，我们的初步数据表明，KGF和地塞米松联合治疗对Prdx6的表达有协同作用。Specific Aim 3将继续研究评估该蛋白的结构-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以及Prdx6翻译后修饰的作用。Specific Aim 4将利用细胞系统分析pGST在Prdx6活性激活中的作用。这些研究将为研究这种新型抗氧化酶在肺抗氧化应激中的作用提供协调的努力，并将为其酶活性的生化调节提供新的信息。这一信息可能会导致新的方法来提高肺耐受氧化应激的能力。

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.