Gpx3 Targeting and Extracellular Oxidative Stress

描述（由申请人提供）：细胞外谷胱甘肽过氧化物酶（Gpx3）主要由肾近曲小管（PCT）细胞产生。Gpx3利用谷胱甘肽作为还原性底物，分解细胞外的H2O2和其他氢过氧化物。因此，Gpx3作为细胞外抗氧化剂起作用。我们已经开发了检测Gpx3的免疫细胞化学方法，并使用它们表明Gpx3特异性地结合肾小管、小肠、结肠和其他吸收性上皮的基底膜。在大多数组织中，它不与基底膜结合。我们也获得了Gpx3基因缺失的小鼠。通过这些小鼠，我们发现细胞外谷胱甘肽代谢受到Gpx3缺失的严重影响，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。我们还表明Gpx3不参与硒的调节运输。我们假设Gpx3保护肾和肠基底膜及其相关上皮细胞免受氧化应激损伤。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。这些研究旨在深入了解Gpx3的功能，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损伤。公共卫生相关性：细胞外谷胱甘肽过氧化物酶（Gpx3）是一种抗氧化酶。我们的初步数据表明，Gpx3与肠和其他组织的基底膜结合。我们制造了Gpx3缺失的小鼠，并将评估Gpx3对这些小鼠氧化应激的保护作用，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.