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Updated: Mar 10, 2026
Modeling Hypoxia/Reoxygenation Injury in Proximal Tubular Epithelial Cells
Published on: November 21, 2025
NADPH oxidase 4 deficiency increases tubular cell death during acute ischemic reperfusion injury
Stellor Nlandu-Khodo1, Romain Dissard1, Udo Hasler1
1Laboratory of Nephrology, Department of Medicine Specialties and PHYM department, University Hospital and University of Geneva, Switzerland.
Abstract:
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.
Insights
NADPH oxidase 4 (NOX4) protects kidneys from injury by producing hydrogen peroxide. Loss of NOX4 worsens kidney damage and apoptosis by impairing the NRF2 survival pathway.
Area of Science:
- Nephrology
- Cell Biology
- Biochemistry
Background:
- NADPH oxidase 4 (NOX4) is abundant in kidney proximal tubules and produces hydrogen peroxide.
- NOX4-derived reactive oxygen species (ROS) may influence cell survival pathways.
- Renal ischemia reperfusion injury (IRI) is a model for acute tubular necrosis.
Purpose of the Study:
- To investigate the protective role of NOX4 in kidney IRI.
- To elucidate the molecular mechanisms underlying NOX4's function in renal injury.
Main Methods:
- Comparison of wild-type (WT) and NOX4 knockout (KO) mice subjected to IRI.
- Assessment of renal function, tubular apoptosis, histological damage, and protein expression (NOX4, Bcl-2, NRF2, KEAP1).
- In vitro studies using cell cultures with NOX4 silencing and NRF2 overexpression.
Main Results:
- NOX4 protein expression increased post-IRI in WT mice.
- NOX4 KO mice showed worsened renal function, increased tubular apoptosis, and higher damage scores compared to WT.
- NOX4 deficiency led to reduced NRF2 activation, decreased KEAP1 oxidation, and lower glutathione levels, mimicking in vitro findings.
Conclusions:
- NOX4 plays a crucial protective role in kidney IRI.
- NOX4-mediated ROS production is vital for NRF2 activation and stabilization, contributing to cell survival.
- Targeting the NOX4-ROS-NRF2 axis may offer therapeutic strategies for preventing renal IRI.
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