title: Sod1 loss induces intrinsic superoxide accumulation leading to p53-mediated growth arrest and apoptosis.
abstract: Oxidative damages induced by a redox imbalance cause age-related changes in cells and tissues. Superoxide dismutase (SOD) enzymes play a major role in the antioxidant system and they also catalyze superoxide radicals (O2·-). Since the loss of cytoplasmic SOD (SOD1) resulted in aging-like phenotypes in several types of mouse tissue, SOD1 is essential for the maintenance of tissue homeostasis. To clarify the cellular function of SOD1, we investigated the cellular phenotypes of Sod1-deficient fibroblasts. We demonstrated that Sod1 deficiency impaired proliferation and induced apoptosis associated with O2·- accumulation in the cytoplasm and mitochondria in fibroblasts. Sod1 loss also decreased the mitochondrial membrane potential and led to DNA damage-mediated p53 activation. Antioxidant treatments effectively improved the cellular phenotypes through suppression of both intracellular O2·- accumulation and p53 activation in Sod1-deficient fibroblasts. In vivo experiments revealed that transdermal treatment with a vitamin C derivative significantly reversed the skin thinning commonly associated with the upregulated p53 action in the skin. Our findings revealed that intrinsic O2·- accumulation promoted p53-mediated growth arrest and apoptosis as well as mitochondrial disfunction in the fibroblasts.
authors.affiliation: Department of Advanced Aging Medicine, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. shimizut@chiba-u.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Shuichi
authors.initials: S
authors.lastname: Shibuya
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Koyama
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ozawa
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Toda
authors.forename: Koutaro
authors.initials: K
authors.lastname: Yokote
authors.forename: Takahiko
authors.initials: T
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001205:Ascorbic Acid / Q000494:pharmacology; D001284:Atrophy; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D020405:Dermis / Q000166:cytology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010641:Phenotype; D013482:Superoxide Dismutase / Q000172:deficiency* / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D016159:Tumor Suppressor Protein p53; D013481:Superoxides; D013482:Superoxide Dismutase; D001205:Ascorbic Acid