Novel Antibodies Reveal Inclusions Containing Non-Native SOD1 in Sporadic ALS Patients

Abstract

Mutations in CuZn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) and are found in 6% of ALS patients. Non-native and aggregation-prone forms of mutant SOD1s are thought to trigger the disease. Two sets of novel antibodies, raised in rabbits and chicken, against peptides spaced along the human SOD1 sequence, were by enzyme-linked immunosorbent assay and an immunocapture method shown to be specific for denatured SOD1. These were used to examine SOD1 in spinal cords of ALS patients lacking mutations in the enzyme. Small granular SOD1-immunoreactive inclusions were found in spinal motoneurons of all 37 sporadic and familial ALS patients studied, but only sparsely in 3 of 28 neurodegenerative and 2 of 19 non-neurological control patients. The granular inclusions were by confocal microscopy found to partly colocalize with markers for lysosomes but not with inclusions containing TAR DNA binding protein-43, ubiquitin or markers for endoplasmic reticulum, autophagosomes or mitochondria. Granular inclusions were also found in carriers of SOD1 mutations and in spinobulbar muscular atrophy (SBMA) patients and they were the major type of inclusion detected in ALS patients homozygous for the wild type-like D90A mutation. The findings suggest that SOD1 may be involved in ALS pathogenesis in patients lacking mutations in the enzyme.

Extracellular wildtype and mutant SOD1 induces ER–Golgi pathology characteristic of amyotrophic lateral sclerosis in neuronal cells

“…Mutant SOD1 induces eR stress [6] and Golgi fragmentation [26] in neuronal cell cultures, and we now show that aggregated SOD1 Wt induces UPR and Golgi fragmentation similar to mutant SOD1. these findings are consistent with recent evidence for common pathogenic pathways shared by mutant SOD1 and SOD1 Wt , and the presence of misfolded SOD1 Wt in sporadic aLS tissues [4,5]. It is unclear how eR stress is triggered in aLS because SOD1 is normally located in the cytoplasm and reports that it is found in microsomes [47] have been subsequently challenged [23].…”

“…Mutations in SOD1 (Cu/Zn-superoxide dismutase) cause 20 % of familial aLS, and these cases display similar clinical features and pathogenesis to sporadic aLS, which accounts for 90 % of all aLS cases. Misfolded and aggregated SOD1 is present in both familial and sporadic aLS, but its pathobiology remains unclear [4,5].…”

“…Oxidized, misfolded SOD1 Wt is present in the intracellular inclusions in motor neurons of sporadic aLS patients [5,10]. Furthermore, recently it was shown that transgenic overexpression of SOD1 Wt causes aLS in mice [11].…”

Intercellular propagated misfolding of wild-type Cu/Zn superoxide dismutase occurs via exosome-dependent and -independent mechanisms

“…Whereas it is generally accepted SOD1 is not found in large perikaryal cytoplasmic inclusions outside of SOD1 FALS cases, misfolded SOD1 has been increasingly identified in SALS and non-SOD1 FALS (5,10,11). Indeed, we have reported that misfolded human wild-type SOD1 (HuWtSOD1) can be detected by spinal cord immunohistochemistry (IHC) in FALS secondary to FUS mutation, and in SALS patients with cytosolic WT TDP-43 accumulation (11).…”

Structural and kinetic analysis of protein-aggregate strains in vivo using binary epitope mapping

“…A conspicuous cause of ALS is a large number of structurally diverse mutations in SOD1 (7) (alsod.iop.kcl.ac.uk/), whose common denominator seems to be decreased structural stability and reduced repulsive charge (8). However, pathological aggregation of SOD1 need not always be triggered by mutation; it occurs also in ALS patients lacking SOD1 mutations (9)(10)(11). Consistently, it is also found that mice that are bred to express wild-type human SOD1 (hSOD1 wt ) at a high rate develop a fatal ALS-like disease, with accumulation of large amounts of hSOD1 aggregates in remaining motor neurons (12).…”