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Wild-type and mutant SOD1 share an aberrant conformation and a common pathogenic pathway in ALS.

Bosco DA, Morfini G, Karabacak NM, Song Y, Gros-Louis F, Pasinelli P, Goolsby H, Fontaine BA, Lemay N, McKenna-Yasek D, Frosch MP, Agar JN, Julien JP, Brady ST, Brown RH - Nat. Neurosci. (2010)

Bottom Line: Using a conformation-specific antibody that detects misfolded SOD1 (C4F6), we found that oxidized wild-type SOD1 and mutant SOD1 share a conformational epitope that is not present in normal wild-type SOD1.In a subset of human sporadic ALS (SALS) cases, motor neurons in the lumbosacral spinal cord were markedly C4F6 immunoreactive, indicating that an aberrant wild-type SOD1 species was present.Recombinant, oxidized wild-type SOD1 and wild-type SOD1 immunopurified from SALS tissues inhibited kinesin-based fast axonal transport in a manner similar to that of FALS-linked mutant SOD1.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts, USA. daryl.bosco@umassmed.edu

ABSTRACT
Many mutations confer one or more toxic function(s) on copper/zinc superoxide dismutase 1 (SOD1) that impair motor neuron viability and cause familial amyotrophic lateral sclerosis (FALS). Using a conformation-specific antibody that detects misfolded SOD1 (C4F6), we found that oxidized wild-type SOD1 and mutant SOD1 share a conformational epitope that is not present in normal wild-type SOD1. In a subset of human sporadic ALS (SALS) cases, motor neurons in the lumbosacral spinal cord were markedly C4F6 immunoreactive, indicating that an aberrant wild-type SOD1 species was present. Recombinant, oxidized wild-type SOD1 and wild-type SOD1 immunopurified from SALS tissues inhibited kinesin-based fast axonal transport in a manner similar to that of FALS-linked mutant SOD1. Our findings suggest that wild-type SOD1 can be pathogenic in SALS and identify an SOD1-dependent pathogenic mechanism common to FALS and SALS.

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Related in: MedlinePlus

The structure of WT-SOD1The X-ray crystallographic structure of WT-SOD1 (pdb2C9V) 48 modeled in PyMOL. WT-SOD1 residues G93 and C111 within exon 2 are highlighted and labeled in purple. The zinc and copper atoms are shown in light cyan and orange, respectively. SOD1 conformation specific antibodies epitope map to the following regions: C4F6 to exon 4 (residues H80-V118 highlighted in red); A9G3 (Fig. 4c) to exons 1 and 2 (comprised of β-strands 1-4); SEDI 38 to β-strand 8; and USOD 33 to β-strand 4.
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Figure 2: The structure of WT-SOD1The X-ray crystallographic structure of WT-SOD1 (pdb2C9V) 48 modeled in PyMOL. WT-SOD1 residues G93 and C111 within exon 2 are highlighted and labeled in purple. The zinc and copper atoms are shown in light cyan and orange, respectively. SOD1 conformation specific antibodies epitope map to the following regions: C4F6 to exon 4 (residues H80-V118 highlighted in red); A9G3 (Fig. 4c) to exons 1 and 2 (comprised of β-strands 1-4); SEDI 38 to β-strand 8; and USOD 33 to β-strand 4.

Mentions: To test this hypothesis, WT-SOD1 was exposed to hydrogen peroxide (H2O2) to generate an oxidized form of WT-SOD1 (SOD1ox). Fourier-transform mass spectrometry (FT-MS) was employed to confirm the oxidation of WT-SOD1, as indicated by an increase of 48 Da for the predominant species in the spectrum of SOD1ox (monoisotopic mass of 15,892 Da; Fig. 1b) compared to unmodified WT-SOD1 (15,844 Da; Fig. 1a). SOD1ox was subjected to electron capture dissociation (ECD), which confirmed that the sulfhydryl group of Cys 111 encoded within exon 4 (Fig. 2) is fully and irreversibly oxidized to sulfonic acid 23 through the incorporation of 3 oxygens (Fig. 1c and Supplementary Table 1). No other oxidated forms of WT-SOD1 were observed.


Wild-type and mutant SOD1 share an aberrant conformation and a common pathogenic pathway in ALS.

Bosco DA, Morfini G, Karabacak NM, Song Y, Gros-Louis F, Pasinelli P, Goolsby H, Fontaine BA, Lemay N, McKenna-Yasek D, Frosch MP, Agar JN, Julien JP, Brady ST, Brown RH - Nat. Neurosci. (2010)

The structure of WT-SOD1The X-ray crystallographic structure of WT-SOD1 (pdb2C9V) 48 modeled in PyMOL. WT-SOD1 residues G93 and C111 within exon 2 are highlighted and labeled in purple. The zinc and copper atoms are shown in light cyan and orange, respectively. SOD1 conformation specific antibodies epitope map to the following regions: C4F6 to exon 4 (residues H80-V118 highlighted in red); A9G3 (Fig. 4c) to exons 1 and 2 (comprised of β-strands 1-4); SEDI 38 to β-strand 8; and USOD 33 to β-strand 4.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2967729&req=5

Figure 2: The structure of WT-SOD1The X-ray crystallographic structure of WT-SOD1 (pdb2C9V) 48 modeled in PyMOL. WT-SOD1 residues G93 and C111 within exon 2 are highlighted and labeled in purple. The zinc and copper atoms are shown in light cyan and orange, respectively. SOD1 conformation specific antibodies epitope map to the following regions: C4F6 to exon 4 (residues H80-V118 highlighted in red); A9G3 (Fig. 4c) to exons 1 and 2 (comprised of β-strands 1-4); SEDI 38 to β-strand 8; and USOD 33 to β-strand 4.
Mentions: To test this hypothesis, WT-SOD1 was exposed to hydrogen peroxide (H2O2) to generate an oxidized form of WT-SOD1 (SOD1ox). Fourier-transform mass spectrometry (FT-MS) was employed to confirm the oxidation of WT-SOD1, as indicated by an increase of 48 Da for the predominant species in the spectrum of SOD1ox (monoisotopic mass of 15,892 Da; Fig. 1b) compared to unmodified WT-SOD1 (15,844 Da; Fig. 1a). SOD1ox was subjected to electron capture dissociation (ECD), which confirmed that the sulfhydryl group of Cys 111 encoded within exon 4 (Fig. 2) is fully and irreversibly oxidized to sulfonic acid 23 through the incorporation of 3 oxygens (Fig. 1c and Supplementary Table 1). No other oxidated forms of WT-SOD1 were observed.

Bottom Line: Using a conformation-specific antibody that detects misfolded SOD1 (C4F6), we found that oxidized wild-type SOD1 and mutant SOD1 share a conformational epitope that is not present in normal wild-type SOD1.In a subset of human sporadic ALS (SALS) cases, motor neurons in the lumbosacral spinal cord were markedly C4F6 immunoreactive, indicating that an aberrant wild-type SOD1 species was present.Recombinant, oxidized wild-type SOD1 and wild-type SOD1 immunopurified from SALS tissues inhibited kinesin-based fast axonal transport in a manner similar to that of FALS-linked mutant SOD1.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts, USA. daryl.bosco@umassmed.edu

ABSTRACT
Many mutations confer one or more toxic function(s) on copper/zinc superoxide dismutase 1 (SOD1) that impair motor neuron viability and cause familial amyotrophic lateral sclerosis (FALS). Using a conformation-specific antibody that detects misfolded SOD1 (C4F6), we found that oxidized wild-type SOD1 and mutant SOD1 share a conformational epitope that is not present in normal wild-type SOD1. In a subset of human sporadic ALS (SALS) cases, motor neurons in the lumbosacral spinal cord were markedly C4F6 immunoreactive, indicating that an aberrant wild-type SOD1 species was present. Recombinant, oxidized wild-type SOD1 and wild-type SOD1 immunopurified from SALS tissues inhibited kinesin-based fast axonal transport in a manner similar to that of FALS-linked mutant SOD1. Our findings suggest that wild-type SOD1 can be pathogenic in SALS and identify an SOD1-dependent pathogenic mechanism common to FALS and SALS.

Show MeSH
Related in: MedlinePlus