NADPH Oxidases Mediate Zinc Deficiency‐Induced Oxidative Stress in Mouse Kidneys

Abstract

Zn2+ deficiency (ZnD) is common in diabetes. Experimental studies show that ZnD worsens diabetic complications, including diabetic kidney disease. Oxidative stress caused by increased reactive oxygen species (ROS) plays a role in the harmful effects of ZnD. However, the sources of oxidative stress continue to be identified. In diabetes, NADPH oxidases (Nox) are enzymes that promote oxidative stress in the kidneys. This study seeks to determine the role of Nox enzymes in ZnD‐induced oxidative stress in mouse kidneys. WT mice were pair‐fed a ZnD or control diet for 6 weeks. After collecting kidneys and urine, kidney damage (BCA Protein Assay), ROS levels (Amplex Red) and Nox enzymes expression (qRT‐PCR and Western blot) were examined. To further investigate the effect of Zn2+ bioavailability on Nox enzymes, mouse distal convoluted tubule (mDCT) cells were exposed to a Zn2+ chelator (TPEN) or vehicle (DMSO) for 48 hours with or without Zn2+ supplementation for the last 24 hours. Findings show that a Zn2+ restricted diet induces urinary protein that is accompanied by elevated Nox2 expression and ROS levels in mice kidneys. In mDCT cells, inhibition of Nox enzymes with DPI blocks Zn2+ depletion‐induced ROS levels. Zn2+ depletion increases ROS levels and Nox2 and Nox4 expression. Furthermore, Zn2+ supplementation reduces Zn2+ depletion‐induced Nox2 increases. These findings suggest that Nox enzymes mediate ZnD‐induced oxidative stress and kidney damage. Understanding how ZnD causes kidney injury can have an important impact on the treatment of diabetic kidney disease.R25DK101390 (MSL), VA‐MERIT (JLG), R01DK085097 (RSH), T32‐DK00756 (CRW)