Gpx3 Targeting and Extracellular Oxidative Stress

描述(申请人提供)：细胞外谷胱甘肽过氧化物酶(Gpx3)主要由肾脏近端曲管(PCT)细胞产生。Gpx3以GSH为还原底物，在细胞外分解过氧化氢和其他过氧化氢。因此，Gpx3起到了细胞外抗氧化剂的作用。我们已经发展了免疫细胞化学方法来检测Gpx3，并用它们来表明Gpx3特异性地结合到肾小管、小肠、结肠和其他吸收上皮的基底膜。在大多数组织中，它不与基底膜结合。我们还获得了Gpx3基因缺失的小鼠。利用这些小鼠，我们发现Gpx3缺失严重影响了细胞外谷胱甘肽代谢，血浆谷胱甘肽浓度几乎增加了两倍。这一发现支持GSH是Gpx3的还原底物。我们还发现Gpx3不参与硒的调节转运。我们假设Gpx3保护肾和肠的基底膜及其相关的上皮细胞免受氧化应激的损害。我们建议表征Gpx3与基底膜的关系，并评估其对肠道、肾脏和肝脏氧化应激的影响。我们还建议表征肾脏对Gpx3在其他组织中的存在和功能的影响。这些研究旨在提供对Gpx3功能的洞察，并评估肾脏疾病如何剥夺其他组织的Gpx3，从而使它们容易受到氧化应激的伤害。与公共健康相关：细胞外谷胱甘肽过氧化物酶(Gpx3)是一种抗氧化酶。我们的初步数据显示，Gpx3与肠道和其他组织中的基底膜结合。我们产生了Gpx3缺失的小鼠，并将评估这些小鼠对氧化应激的Gpx3保护作用，以阐明一些疾病。

DESCRIPTION (provided by applicant): Extracellular glutathione peroxidase (Gpx3) is produced primarily by the proximal convoluted tubule (PCT) cells of the kidney. Gpx3 catabolizes H2O2 and other hydroperoxides outside cells using GSH as its reducing substrate. Thus, Gpx3 functions as an extracellular antioxidant. We have developed immunocytochemistry methods to detect Gpx3 and have used them to show that Gpx3 binds specifically to the basement membranes of kidney tubules, small intestine, colon, and other absorptive epithelia. It does not bind to basement membranes in most tissues. We have also acquired mice with the Gpx3 gene deleted. Using these mice, we have found that extracellular glutathione metabolism is sharply affected by Gpx3 deletion with plasma glutathione concentration being almost tripled. This finding supports GSH as being the reducing substrate of Gpx3. We have also shown that Gpx3 is not involved in the regulated transport of selenium. We hypothesize that Gpx3 protects basement membranes and their associated epithelial cells in kidney and intestine from damage by oxidative stresses. We propose to characterize the relationship of Gpx3 with basement membranes and to assess its effect on oxidative stresses in intestine, kidney, and liver. We also propose to characterize the effect of the kidney on the presence and function of Gpx3 in other tissues. These studies are designed to provide insight into Gpx3 function and to assess how kidney disease might deprive other tissues of Gpx3 and thereby render them susceptible to injury from oxidative stress. PUBLIC HEALTH RELEVANCE: Extracellular glutathione peroxidase (Gpx3) is an antioxidant enzyme. Our preliminary data show that Gpx3 binds to basement membranes in the intestine and in other tissues. We produced mice with Gpx3 deleted and will assess Gpx3 protection against oxidative stress in those mice to shed light on some diseases.