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Pro-Oxidant Activity of an ALS-Linked SOD1 Mutant in Zn-Deficient Form.

ABSTRACT: Cu, Zn superoxide dismutase (SOD1) is a representative antioxidant enzyme that catalyzes dismutation of reactive oxygen species in cells. However, (E,E)-SOD1 mutants in which both copper and zinc ions were deleted exhibit pro-oxidant activity, contrary to their antioxidant nature, at physiological temperatures, following denaturation and subsequent recombination of Cu2+. This oxidative property is likely related to the pathogenesis of amyotrophic lateral sclerosis (ALS); however, the mechanism by which Cu2+ re-binds to the denatured (E,E)-SOD1 has not been elucidated, since the concentration of free copper ions in cells is almost zero. In this study, we prepared the (Cu,E) form in which only a zinc ion was deleted using ALS-linked mutant H43R (His43?Arg) and found that (Cu,E)-H43R showed an increase in the pro-oxidant activity even at physiological temperature. The increase in the pro-oxidant activity of (Cu,E)-H43R was also observed in solution mimicking intracellular environment and at high temperature. These results suggest that the zinc-deficient (Cu,E) form can contribute to oxidative stress in cells, and that the formation of (E,E)-SOD1 together with the subsequent Cu2+ rebinding is not necessary for the acquisition of the pro-oxidant activity.

SUBMITTER: Nagao C

PROVIDER: S-EPMC7464938 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Pro-Oxidant Activity of an ALS-Linked SOD1 Mutant in Zn-Deficient Form.

Nagao Chise C Kuroi Kunisato K Wakabayashi Taiyu T Nakabayashi Takakazu T

Molecules (Basel, Switzerland) 20200807 16

Cu, Zn superoxide dismutase (SOD1) is a representative antioxidant enzyme that catalyzes dismutation of reactive oxygen species in cells. However, (E,E)-SOD1 mutants in which both copper and zinc ions were deleted exhibit pro-oxidant activity, contrary to their antioxidant nature, at physiological temperatures, following denaturation and subsequent recombination of Cu<sup>2+</sup>. This oxidative property is likely related to the pathogenesis of amyotrophic lateral sclerosis (ALS); however, the ...[more]

PMID: 32784718

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Project description:Amyotrophic lateral sclerosis (ALS) is caused by the progressive degeneration of motor neurons. Mutations in the Cu/Zn superoxide dismutase (SOD1) are found in about 20% of patients with familial ALS. Mutant SOD1 causes motor neuron death through an acquired toxic property. Although, molecular mechanism underlying this toxic gain-of-function remains unknown, evidence support the role of mutant SOD1 expression in non-neuronal cells in shaping motor neuron degeneration. We have previously found that in contrast to non-transgenic, SOD1G93A-expressing astrocytes induced apoptosis of co-cultured motor neurons. This prompted us to investigate whether the effect on motor neuron survival was related to a change in the gene expression profile. Through high-density oligonucletide microarrays we found changes in the expression of genes involved in transcription, signaling, cell proliferation, extracellular matrix construction, response to stress and steroid and lipid metabolism. Decorin, a small multifunctional proteoglycan, was the most up-regulated gene. Down-regulated genes included the insulin-like growth factor-1 receptor and the RNA binding protein ROD1. We also analyzed the expression of selected genes in purified motor neurons expressing SOD1G93A and in spinal cord of asymptomatic and early symptomatic ALS-rodent model. The expression of mutated SOD1 in astrocytes cause gene expression changes with potential consequences for its interaction with motor neurons. The astrocyte-specific gene expression profile contributes to the identification of possible candidates for cell type-specific therapies in ALS Keywords: Cell type comparison Astrocytes were plated at a density of 2x104 cells/cm2 and maintained as described in Cassina P, et al.J Neurosci Res. 2002;67(1):21-9. Confluent astrocytes monolayers were changed to supplemented L15 medium (Vargas et al., 2006) for 24h before RNA isolation. Total RNA was isolated with RNeasy kit/RNase-Free DNase Set (Qiagen, CA, USA). RNA quality was assessed with the A260/280 ratio and the 2100 Bioanalyzer (Agilent Technologies, CA, USA) to ensure integrity of the samples used for microarray analysis. Double-stranded cDNA was synthesized from 5 μg of total RNA and used for microarray analysis with the Rat Genome 230 2.0 array (Affymetrix, CA, USA). A total of six arrays divided in three control and three transgenic samples were used. Labeling was performed with one-cycle target labeling assay according to Affymetrix, including the eukaryotic poly-A RNA control and the eukaryotic hybridization control kit. Hybridization, washing and scanning were carried out as described in the Affymetrix GeneChip expression analysis technical manual at the Oregon State University’s Center for Genome Research and Biocomputing. Image processing was done using Affymetrix GCOS 1.4 software. The quality of hybridization and overall chip performance was determined by visual inspection of the raw scanned data and the GCOS-generated report file. Microarray data (.CEL files) was normalized using GC-RMA probe-level analysis in ArrayAssist 4.0 (Stratagene, CA, USA). Following variance stabilization and Log transformation, fold chance versus p-value was calculated using nontransgenic (NonTG) samples as base values.

Dataset Information

Pro-Oxidant Activity of an ALS-Linked SOD1 Mutant in Zn-Deficient Form.

Publications

Pro-Oxidant Activity of an ALS-Linked SOD1 Mutant in Zn-Deficient Form.

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