Peroxiredoxin 6 as an anti-oxidant enzyme

描述(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性质，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发挥重要作用。这种最近被称为过氧化还蛋白6(Prdx6或1-cys peroxiredosin)的蛋白质是唯一一种具有相对较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，该酶活性谱中的一个重要特征是它能够还原磷脂氢过氧化，例如，在氧化胁迫期间膜磷脂的过氧化。在过去的四年里，作为P-01拨款的一个组成部分，我们证明了Prdx6在保护肺免受氧化应激(高氧，百草枯)方面发挥了重要作用，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，并建立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，以延长这些研究。具体目标1将利用Prdx6缺失细胞中的“敲入”技术来评估这2种活性(PRX、PLA2)对抗氧化保护的各自贡献。这一目标还将直接比较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。具体目标2将研究KGF和地塞米松联合治疗对Prdx6的诱导，我们的初步数据表明这对Prdx6的表达具有协同作用。具体目标3将继续研究以评估蛋白质的结构-功能特征，特别关注磷脂结合作为磷脂过氧化氢过氧化物酶活性的要求以及Prdx6翻译后修饰的作用。具体目标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的抗氧化酶在肺对氧化应激防御中的作用提供协调的努力，并将提供关于其酶活性的生化调节的新信息。这些信息可能会导致新的方法来提高肺耐受氧化应激的能力。 与公众健康相关：我们已经确定了一种新型酶的特征，该酶具有两种重要的活性，可以保护肺免受氧化应激的影响，并调节肺表面活性物质的代谢。我们计划的目标是评估该酶的两种活性，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，并确定增加该蛋白质在肺细胞中表达的方法。了解过氧化还蛋白6的这一作用将有助于将其作为提高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.