title: Mitochondria-targeted catalase reverts the neurotoxicity of hSOD1G⁹³A astrocytes without extending the survival of ALS-linked mutant hSOD1 mice.
abstract: Dominant mutations in the Cu/Zn-superoxide dismutase (SOD1) cause familial forms of amyotrophic lateral sclerosis (ALS), a fatal disorder characterized by the progressive loss of motor neurons. The molecular mechanism underlying the toxic gain-of-function of mutant hSOD1s remains uncertain. Several lines of evidence suggest that toxicity to motor neurons requires damage to non-neuronal cells. In line with this observation, primary astrocytes isolated from mutant hSOD1 over-expressing rodents induce motor neuron death in co-culture. Mitochondrial alterations have been documented in both neuronal and glial cells from ALS patients as well as in ALS-animal models. In addition, mitochondrial dysfunction and increased oxidative stress have been linked to the toxicity of mutant hSOD1 in astrocytes and neurons. In mutant SOD1-linked ALS, mitochondrial alterations may be partially due to the increased association of mutant SOD1 with the outer membrane and intermembrane space of the mitochondria, where it can affect several critical aspects of mitochondrial function. We have previously shown that decreasing glutathione levels, which is crucial for peroxide detoxification in the mitochondria, significantly accelerates motor neuron death in hSOD1G93A mice. Here we employed a catalase targeted to the mitochondria to investigate the effect of increased mitochondrial peroxide detoxification capacity in models of mutant hSOD1-mediated motor neuron death. The over-expression of mitochondria-targeted catalase improved mitochondrial antioxidant defenses and mitochondrial function in hSOD1G93A astrocyte cultures. It also reverted the toxicity of hSOD1G93A-expressing astrocytes towards co-cultured motor neurons, however ALS-animals did not develop the disease later or survive longer. Hence, while increased oxidative stress and mitochondrial dysfunction have been extensively documented in ALS, these results suggest that preventing peroxide-mediated mitochondrial damage alone is not sufficient to delay the disease.
authors: Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina, United States of America.
authors: Mariana
authors: M
authors: Pehar
authors: SCCP Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, United States of America.
authors: Gyda
authors: G
authors: Beeson
authors: SCCP Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, United States of America.
authors: Craig C
authors: CC
authors: Beeson
authors: Division of Pharmaceutical Sciences, Waisman Center, Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, Wisconsin, United States of America.
authors: Jeffrey A
authors: JA
authors: Johnson
authors: Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina, United States of America.
authors: Marcelo R
authors: MR
authors: Vargas
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology; D009154:Mutation; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D015854:Up-Regulation
chemical_list: D017382:Reactive Oxygen Species; C000606290:SOD1 protein, human; D002374:Catalase; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1