Xanthine Oxidoreductase-Mediated Superoxide Production Is Not Involved in the Age-Related Pathologies in Sod1-Deficient Mice |
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Authors: | Shuichi Shibuya Kenji Watanabe Yusuke Ozawa Takahiko Shimizu |
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Affiliation: | 1.Aging Stress Response Research Project Team, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8511, Japan; (S.S.); (K.W.);2.Department of Endocrinology, Hematology, and Geriatrics, Chiba University Graduate School of Medicine, Chiba, Chiba 260-8670, Japan; |
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Abstract: | Reactive oxygen species (ROS) metabolism is regulated by the oxygen-mediated enzyme reaction and antioxidant mechanism within cells under physiological conditions. Xanthine oxidoreductase (XOR) exhibits two inter-convertible forms (xanthine oxidase (XO) and xanthine dehydrogenase (XDH)), depending on the substrates. XO uses oxygen as a substrate and generates superoxide (O2•−) in the catalytic pathway of hypoxanthine. We previously showed that superoxide dismutase 1 (SOD1) loss induced various aging-like pathologies via oxidative damage due to the accumulation of O2•− in mice. However, the pathological contribution of XO-derived O2•− production to aging-like tissue damage induced by SOD1 loss remains unclear. To investigate the pathological significance of O2•− derived from XOR in Sod1−/− mice, we generated Sod1-null and XO-type- or XDH-type-knock-in (KI) double-mutant mice. Neither XO-type- nor XDH-type KI mutants altered aging-like phenotypes, such as anemia, fatty liver, muscle atrophy, and bone loss, in Sod1−/− mice. Furthermore, allopurinol, an XO inhibitor, or apocynin, a nicotinamide adenine dinucleotide phosphate oxidase (NOX) inhibitor, failed to improve aging-like tissue degeneration and ROS accumulation in Sod1−/− mice. These results showed that XOR-mediated O2•− production is relatively uninvolved in the age-related pathologies in Sod1−/− mice. |
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Keywords: | superoxide SOD1 xanthine oxidoreductase aging oxidative stress |
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