title: Hyperoxia exposure induced hormesis decreases mitochondrial superoxide radical levels via Ins/IGF-1 signaling pathway in a long-lived age-1 mutant of Caenorhabditis elegans.
abstract: The hormetic effect, which extends the lifespan by various stressors, has been confirmed in Caenorhabditis elegans (C. elegans). We have previously reported that oxidative stress resistance in a long-lived mutant age-1 is associated with the hormesis. In the age-1 allele, which activates an insulin/insulin-like growth factor-1 (Ins/IGF-1) signaling pathway, the superoxide dismutase (SOD) and catalase activities increased during normal aging. We now demonstrate changes in the mitochondrial superoxide radical (*O(2)(-)) levels of the hormetic conditioned age-related strains. The *O(2)(-) levels in age-1 strain significantly decreased after intermittent hyperoxia exposure. On the other hand, this phenomenon was not observed in a daf-16 null mutant. This hormesis-dependent reduction of the *O(2)(-) levels was observed even if the mitochondrial Mn-SOD was experimentally reduced. Therefore, it is indicated that the hormesis is mediated by events that suppress the mitochondrial *O(2)(-) production. Moreover, some SOD gene expressions in the hormetic conditioned age-1 mutant were induced over steady state mRNA levels. These data suggest that oxidative stress-inducible hormesis is associated with a reduction of the mitochondrial *O(2)(-) production by activation of the antioxidant system via the Ins/IGF-1 signaling pathway.
authors.affiliation: Department of Health Science, Daito Bunka University School of Sports & Health Science, Iwadono, Saitama, Japan.
authors.forename: Sumino
authors.initials: S
authors.lastname: Yanase
authors.forename: Naoaki
authors.initials: N
authors.lastname: Ishii
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D007328:Insulin / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D008136:Longevity / Q000502:physiology; D008928:Mitochondria / Q000737:chemistry*; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*; D015398:Signal Transduction / Q000502:physiology*; D013481:Superoxides / Q000032:analysis*
chemical_list: D029742:Caenorhabditis elegans Proteins; D007328:Insulin; D013481:Superoxides; D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases; C100662:AGE-1 protein, C elegans