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Assay Development for High Content Quantification of Sod1 Mutant Protein Aggregate Formation in Living Cells
Published on: October 4, 2017
Mass spectrometry imaging of SOD1 protein-metal complexes in SOD1G93A transgenic mice implicates demetalation with
Oliver J Hale1, Tyler R Wells2, Richard J Mead3,4
1School of Biosciences, University of Birmingham, Birmingham, UK.
Abstract:
Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of motor neurons in the central nervous system (CNS). Mutations in the metalloenzyme SOD1 are associated with inherited forms of ALS and cause a toxic gain of function thought to be mediated by dimer destabilization and misfolding. SOD1 binds two Cu and two Zn ions in its homodimeric form. We have applied native ambient mass spectrometry imaging to visualize the spatial distributions of intact metal-bound SOD1G93A complexes in SOD1G93A transgenic mouse spinal cord and brain sections and evaluated them against disease pathology. The molecular specificity of our approach reveals that metal-deficient SOD1G93A species are abundant in CNS structures correlating with ALS pathology whereas fully metalated SOD1G93A species are homogenously distributed. Monomer abundance did not correlate with pathology. We also show that the dimer-destabilizing post-translational modification, glutathionylation, has limited influence on the spatial distribution of SOD1 dimers.
Insights
Metal-deficient SOD1 aggregates in the central nervous system correlate with amyotrophic lateral sclerosis (ALS) pathology, while fully metalated forms are evenly distributed. This finding offers new insights into ALS disease mechanisms.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- Amyotrophic lateral sclerosis (ALS) involves motor neuron degeneration in the central nervous system (CNS).
- Mutations in the copper-zinc superoxide dismutase 1 (SOD1) gene are linked to inherited ALS, causing a toxic gain of function.
- SOD1 is a metalloenzyme that binds copper and zinc ions in its homodimeric form.
Purpose of the Study:
- To investigate the spatial distribution of intact metal-bound SOD1 complexes in the context of ALS pathology.
- To determine the relationship between metalation status, aggregation, and disease progression in SOD1-linked ALS.
Main Methods:
- Native ambient mass spectrometry imaging was employed to visualize SOD1 complexes in transgenic mouse spinal cord and brain sections.
- Spatial distributions of metal-bound SOD1G93A species were evaluated against neuropathological markers.
- The influence of post-translational modifications like glutathionylation on SOD1 dimer distribution was assessed.
Main Results:
- Metal-deficient SOD1G93A species were found to be abundant in CNS regions exhibiting ALS pathology.
- Fully metalated SOD1G93A species showed homogenous distribution across the CNS, irrespective of pathology.
- Monomer abundance and glutathionylation did not significantly correlate with disease pathology or spatial distribution.
Conclusions:
- The spatial distribution of metal-deficient SOD1G93A is linked to ALS pathology, suggesting a role in disease pathogenesis.
- Metalation status, rather than monomer abundance or glutathionylation, appears critical for the pathological localization of SOD1 in ALS.
- Mass spectrometry imaging provides a powerful tool for understanding the molecular basis of neurodegenerative diseases like ALS.
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