Laboratory of Nephrology, Department of Medicine Specialties and PHYM department, University Hospital and University of Geneva, Switzerland.
Department of Biology, Institute of Molecular Health Sciences, ETH Zurich, Switzerland.
Sci Rep. 2016 Dec 7;6:38598. doi: 10.1038/srep38598.
NADPH oxidase 4 (NOX4) is highly expressed in kidney proximal tubular cells. NOX4 constitutively produces hydrogen peroxide, which may regulate important pro-survival pathways. Renal ischemia reperfusion injury (IRI) is a classical model mimicking human ischemic acute tubular necrosis. We hypothesized that NOX4 plays a protective role in kidney IRI. In wild type (WT) animals subjected to IRI, NOX4 protein expression increased after 24 hours. NOX4 KO (knock-out) and WT littermates mice were subjected to IRI. NOX4 KO mice displayed decreased renal function and more severe tubular apoptosis, decreased Bcl-2 expression and higher histologic damage scores compared to WT. Activation of NRF2 was decreased in NOX4 KO mice in response to IRI. This was related to decreased KEAP1 oxidation leading to decreased NRF2 stabilization. This resulted in decreased glutathione levels. In vitro silencing of NOX4 in cells showed an enhanced propensity to apoptosis, with reduced expression of NRF2, glutathione content and Bcl-2 expression, similar to cells derived from NOX4 KO mice. Overexpression of a constitutively active form of NRF2 (caNRF2) in NOX4 depleted cells rescued most of this phenotype in cultured cells, implying that NRF2 regulation by ROS issued from NOX4 may play an important role in its anti-apoptotic property.
NADPH 氧化酶 4（NOX4）在肾脏近端肾小管细胞中高度表达。NOX4 持续产生过氧化氢，这可能调节重要的生存相关途径。肾缺血再灌注损伤（IRI）是一种模拟人类缺血性急性肾小管坏死的经典模型。我们假设 NOX4 在肾 IRI 中发挥保护作用。在经历 IRI 的野生型（WT）动物中，NOX4 蛋白表达在 24 小时后增加。NOX4 KO（敲除）和 WT 同窝小鼠经历 IRI。与 WT 相比，NOX4 KO 小鼠的肾功能下降更严重，肾小管凋亡增加，Bcl-2 表达减少，组织学损伤评分更高。NOX4 KO 小鼠中 NRF2 的激活在 IRI 时减少。这与 KEAP1 氧化减少导致 NRF2 稳定性降低有关。这导致谷胱甘肽水平降低。在细胞中沉默 NOX4 显示出增强的凋亡倾向，NRF2、谷胱甘肽含量和 Bcl-2 表达减少，与来自 NOX4 KO 小鼠的细胞相似。在耗尽 NOX4 的细胞中过表达一种组成型激活形式的 NRF2（caNRF2）可挽救培养细胞中大部分这种表型，这意味着来自 NOX4 的 ROS 对 NRF2 的调节可能在其抗凋亡特性中发挥重要作用。
