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Oxidative Medicine and Cellular Longevity
Volume 2 (2009), Issue 2, Pages 93-98
http://dx.doi.org/10.4161/oxim.2.2.8372

Urate Oxidase Knockdown Decreases Oxidative Stress in a Murine Hepatic Cell Line

1Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV, USA
2Health Effects Laboratory Division, National Institute of Occupational Safety and Health, Morgantown, WV, USA
3West Virginia University, PO Box 6108, Morgantown, WV 26506, USA
4USDA, Agricultural Research Service, National Center for Cool and Cold Water Aquaculture, Leetown, WV, USA

Received 23 February 2009; Revised 10 March 2009; Accepted 10 March 2009

Copyright © 2009 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Humans, birds, and some primates do not express the uric acid degrading enzyme urate oxidase (UOX) and, as a result, have plasma uric acid concentrations higher than UOX expressing animals. Although high uric acid concentrations are suggested to increase the antioxidant defense system and provide a health advantage to animals without UOX, knockout mice lacking UOX develop pathological complications including gout and kidney failure. As an alternative to the knockout model, RNA interference was used to decrease UOX expression using stable transfection in a mouse hepatic cell line (ATCC, FL83B). Urate oxidase mRNA was reduced 66% (p < 0.05) compared to wild type, as measured by real time RT-PCR. To determine if UOX knockdown resulted in enhanced protection against oxidative stress, cells were challenged with hexavalent chromium (Cr(VI)) or 3-morpholinosydnonimine hydrochloride (SIN-1). Compared to wild type, cells with UOX knockdown exhibited a 37.2 ± 3.5% reduction (p < 0.05) in the electron spin resonance (ESR) signal after being exposed to Cr(VI) and displayed less DNA fragmentation (p < 0.05) following SIN-1 treatment. Cell viability decreased in wild type cells (p < 0.05), but not cells with UOX knockdown, after treatment with SIN-1. These results are consistent with an increased intracellular uric acid concentration and an increased defense against oxidative stress.