1. Defective biosynthesis of ascorbic acid in Sod1-deficient mice results in lethal damage to lung tissue
- Author
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Daisuke Kinoshita, Kaoru Goto, Yuji Takeda, Junichi Fujii, Toshihiro Kurahashi, Shinya Akatsuka, Hironobu Asao, Masafumi Watanabe, Takujiro Homma, Shinichi Saitoh, Ken Ichi Yamada, Tetsu Watanabe, Satoshi Miyata, Tomoyuki Nakano, and Shinya Toyokuni
- Subjects
0301 basic medicine ,medicine.medical_specialty ,SOD1 ,Ascorbic Acid ,Biochemistry ,Superoxide dismutase ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,Superoxide Dismutase-1 ,0302 clinical medicine ,Immune system ,In vivo ,Physiology (medical) ,Internal medicine ,medicine ,Animals ,Lung ,Mice, Knockout ,chemistry.chemical_classification ,Reactive oxygen species ,biology ,Superoxide Dismutase ,Superoxide ,Ascorbic acid ,Pathophysiology ,Mice, Inbred C57BL ,030104 developmental biology ,Endocrinology ,chemistry ,biology.protein ,030217 neurology & neurosurgery - Abstract
Superoxide dismutase 1 (Sod1) plays pivotal roles in antioxidation via accelerating the conversion of superoxide anion radicals into hydrogen peroxide, thus inhibiting the subsequent radical chain reactions. While Sod1 deficient cells inevitably undergo death in culture conditions, Sod1-knockout (KO) mice show relatively mild phenotypes and live approximately two years. We hypothesized that the presence of abundant levels of ascorbic acid (AsA), which is naturally produced in mice, contributes to the elimination of reactive oxygen species (ROS) in Sod1-KO mice. To verify this hypothesis, we employed mice with a genetic ablation of aldehyde reductase (Akr1a), an enzyme that is involved in the biosynthesis of AsA, and established double knockout (DKO) mice that lack both Sod1 and Akr1a. Supplementation of AsA (1.5 mg/ml in drinking water) was required for the DKO mice to breed, and, upon terminating the AsA supplementation, they died within approximately two weeks regardless of age or gender. We explored the etiology of the death from pathophysiological standpoints in principal organs of the mice. Marked changes were observed in the lungs in the form of macroscopic damage after the AsA withdrawal. Histological and immunological analyses of the lungs indicated oxidative damage of tissue and activated immune responses. Thus, preferential oxidative injury that occurred in pulmonary tissues appeared to be primary cause of the death in the mice. These collective results suggest that the pivotal function of AsA in coping with ROS in vivo, is largely in pulmonary tissues that are exposed to a hyperoxygenic microenvironment.
- Published
- 2021