Mechanisms of Podocyte Injury in Diabetes
Role of Cytochrome P450 and NADPH Oxidases
- Assaad A. Eid1,
- Yves Gorin1,
- Bridget M. Fagg1,
- Rita Maalouf1,
- Jeffrey L. Barnes1,2,
- Karen Block1,2 and
- Hanna E. Abboud1,2
- 1University of Texas Health Science Center, Department of Medicine, San Antonio, Texas; and the
- 2South Texas Veterans Healthcare System, San Antonio, Texas.
- Corresponding author: Hanna E. Abboud, abboud{at}uthscsa.edu.
Abstract
OBJECTIVE We investigated the role of cytochrome P450 of the 4A family (CYP4A), its metabolites, and NADPH oxidases both in reactive oxygen species (ROS) production and apoptosis of podocytes exposed to high glucose and in OVE26 mice, a model of type 1 diabetes.
RESEARCH DESIGN AND METHODS Apoptosis, albuminuria, ROS generation, NADPH superoxide generation, CYP4A and Nox protein expression, and mRNA levels were measured in vitro and in vivo.
RESULTS Exposure of mouse podocytes to high glucose resulted in apoptosis, with approximately one-third of the cells being apoptotic by 72 h. High-glucose treatment increased ROS generation and was associated with sequential upregulation of CYP4A and an increase in 20-hydroxyeicosatetraenoic acid (20-HETE) and Nox oxidases. This is consistent with the observation of delayed induction of NADPH oxidase activity by high glucose. The effects of high glucose on NADPH oxidase activity, Nox proteins and mRNA expression, and apoptosis were blocked by N-hydroxy-N′-(4-butyl-2-methylphenol) formamidine (HET0016), an inhibitor of CYP4A, and were mimicked by 20-HETE. CYP4A and Nox oxidase expression was upregulated in glomeruli of type 1 diabetic OVE26 mice. Treatment of OVE26 mice with HET0016 decreased NADPH oxidase activity and Nox1 and Nox4 protein expression and ameliorated apoptosis and albuminuria.
CONCLUSIONS Generation of ROS by CYP4A monooxygenases, 20-HETE, and Nox oxidases is involved in podocyte apoptosis in vitro and in vivo. Inhibition of selected cytochrome P450 isoforms prevented podocyte apoptosis and reduced proteinuria in diabetes.
Footnotes
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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- Received November 4, 2008.
- Accepted February 5, 2009.
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Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.
- © 2009 by the American Diabetes Association.
