Localization of a toxic form of superoxide dismutase 1 protein to pathologically affected tissues in familial ALS

Brotherton, Terrell; Li, Yingjie; Cooper, Deborah S.; Gearing, Marla; Julien, Jean‐Pierre; Rothstein, Jeffrey D.; Boylan, Kevin B.; Glass, Jonathan D.

doi:10.1073/pnas.1115009109

Cited by 92 publications

(102 citation statements)

References 38 publications

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“…These small, soluble oligomers undergo aberrant interactions with cell machinery and activate cell death pathways, but their exact stoichiometry is not known and their properties have yet to be characterized. Recently, metastable soluble Cu,Zn superoxide dismutase (SOD1) oligomers have been identified that contain an epitope associated with disease-linked species of SOD1, mutants of which are implicated in a subset of ALS (15)(16)(17)(18). Size exclusion chromatography (SEC) of these oligomers revealed a size range of two to four monomers, consistent with previous findings of potentially cytotoxic SOD1 oligomers (19)(20)(21).…”

supporting

confidence: 69%

Nonnative SOD1 trimer is toxic to motor neurons in a model of amyotrophic lateral sclerosis

Proctor

Fee

Tao

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

109

146

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Since the linking of mutations in the Cu,Zn superoxide dismutase gene (sod1) to amyotrophic lateral sclerosis (ALS) in 1993, researchers have sought the connection between SOD1 and motor neuron death. Disease-linked mutations tend to destabilize the native dimeric structure of SOD1, and plaques containing misfolded and aggregated SOD1 have been found in the motor neurons of patients with ALS. Despite advances in understanding of ALS disease progression and SOD1 folding and stability, cytotoxic species and mechanisms remain unknown, greatly impeding the search for and design of therapeutic interventions. Here, we definitively link cytotoxicity associated with SOD1 aggregation in ALS to a nonnative trimeric SOD1 species. We develop methodology for the incorporation of low-resolution experimental data into simulations toward the structural modeling of metastable, multidomain aggregation intermediates. We apply this methodology to derive the structure of a SOD1 trimer, which we validate in vitro and in hybridized motor neurons. We show that SOD1 mutants designed to promote trimerization increase cell death. Further, we demonstrate that the cytotoxicity of the designed mutants correlates with trimer stability, providing a direct link between the presence of misfolded oligomers and neuron death. Identification of cytotoxic species is the first and critical step in elucidating the molecular etiology of ALS, and the ability to manipulate formation of these species will provide an avenue for the development of future therapeutic strategies.neurodegeneration | protein aggregation | protein misfolding | ALS | structural modeling P rotein misfolding and aggregation are linked to cell death and disease progression in neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS). In these diseases and others, the formation of amyloid plaques, often observed post mortem, has long been thought to play a role in neurodegeneration, but toxicity has never been confirmed (1-3). Recent research has shown that small, soluble oligomers, rather than insoluble amyloids, are likely to be the cytotoxic species causing neurodegeneration (4-14). These small, soluble oligomers undergo aberrant interactions with cell machinery and activate cell death pathways, but their exact stoichiometry is not known and their properties have yet to be characterized. Recently, metastable soluble Cu,Zn superoxide dismutase (SOD1) oligomers have been identified that contain an epitope associated with disease-linked species of SOD1, mutants of which are implicated in a subset of ALS (15-18). Size exclusion chromatography (SEC) of these oligomers revealed a size range of two to four monomers, consistent with previous findings of potentially cytotoxic SOD1 oligomers (19)(20)(21).Knowledge of the structures of these species would not only allow for definitive testing of their toxicity but could potentially lead to an understanding of disease mechanism and therapeutic strategies against diseases for which no ...

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supporting

confidence: 69%

Nonnative SOD1 trimer is toxic to motor neurons in a model of amyotrophic lateral sclerosis

Proctor

Fee

Tao

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

109

146

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“…Furthermore, we observed the formation of inclusions in a small proportion of Sh-SY5Y cells treated with native SOD1 Wt , which were never present in NSC-34 cells. Metal-free forms of SOD1 have been proposed to be the toxic precursor preceding aggregation in familial aLS [43,44]. the majority of aLS mutations affect the structural stability of SOD1, leading to the exposure of buried hydrophobic residues, thus resulting in aggregation [45].…”

Section: Discussionmentioning

confidence: 99%

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

Sundaramoorthy

Walker

Yerbury

et al. 2013

Cell. Mol. Life Sci.

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Amyotrophic lateral sclerosis (ALS) is a fatal and rapidly progressing neurodegenerative disorder and the majority of ALS is sporadic, where misfolding and aggregation of Cu/Zn-superoxide dismutase (SOD1) is a feature shared with familial mutant-SOD1 cases. ALS is characterized by progressive neurospatial spread of pathology among motor neurons, and recently the transfer of extracellular, aggregated mutant SOD1 between cells was demonstrated in culture. However, there is currently no evidence that uptake of SOD1 into cells initiates neurodegenerative pathways reminiscent of ALS pathology. Similarly, whilst dysfunction to the ERGolgi compartments is increasingly implicated in the pathogenesis of both sporadic and familial ALS, it remains unclear whether misfolded, wildtype SOD1 triggers ER-Golgi dysfunction. In this study we show that both extracellular, native wildtype and mutant SOD1 are taken up by macropinocytosis into neuronal cells. Hence uptake does not depend on SOD1 mutation or misfolding. We also demonstrate that purified mutant SOD1 added exogenously to neuronal cells inhibits protein transport between the ER-Golgi apparatus, leading to Golgi fragmentation, induction of ER stress and apoptotic cell death. Furthermore, we show that extracellular, aggregated, wildtype SOD1 also induces ER-Golgi pathology similar to mutant SOD1, leading to apoptotic cell death. Hence extracellular misfolded wildtype or mutant SOD1 induce dysfunction to ERGolgi compartments characteristic of ALS in neuronal cells, implicating extracellular SOD1 in the spread of pathology among motor neurons in both sporadic and familial ALS. Abstract amyotrophic lateral sclerosis (aLS) is a fatal and rapidly progressing neurodegenerative disorder and the majority of aLS is sporadic, where misfolding and aggregation of Cu/Zn-superoxide dismutase (SOD1) is a feature shared with familial mutant-SOD1 cases. aLS is characterized by progressive neurospatial spread of pathology among motor neurons, and recently the transfer of extracellular, aggregated mutant SOD1 between cells was demonstrated in culture. however, there is currently no evidence that uptake of SOD1 into cells initiates neurodegenerative pathways reminiscent of aLS pathology. Similarly, whilst dysfunction to the eR-Golgi compartments is increasingly implicated in the pathogenesis of both sporadic and familial aLS, it remains unclear whether misfolded, wildtype SOD1 triggers eR-Golgi dysfunction. In this study we show that both extracellular, native wildtype and mutant SOD1 are taken up by macropinocytosis into neuronal cells. hence uptake does not depend on SOD1 mutation or misfolding. We also demonstrate that purified mutant SOD1 added exogenously to neuronal cells inhibits protein transport between the eR-Golgi apparatus, leading to Golgi fragmentation, induction of eR stress and apoptotic cell death. Furthermore, we show that extracellular, aggregated, wildtype SOD1 also induces eR-Golgi pathology similar to mutant SOD1, leading to apoptotic cell death. hence extracellu...

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“…Finally, accumulation of misfolded SOD1 has been reported by several groups also in sporadic ALS (27,(41)(42)(43)(44)(45)(46)(47), although other groups have reached the opposite conclusion (48)(49)(50)(51). The identification of MIF as a cytosolic chaperone that stimulates the folding or refolding of misfolded SOD1 and inhibits the aggregation of mutant SOD1 in vivo suggests new avenues for therapy in ALS, mediated by increasing intracellular MIF levels in the nervous system.…”

Section: Discussionmentioning

confidence: 99%

Endogenous macrophage migration inhibitory factor reduces the accumulation and toxicity of misfolded SOD1 in a mouse model of ALS

Leyton-Jaimes

Benaim

Abu-Hamad

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Mutations in superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease characterized by the loss of upper and lower motor neurons in the brain and spinal cord. It has been suggested that the toxicity of mutant SOD1 results from its misfolding and accumulation on the cytoplasmic faces of intracellular organelles, including the mitochondria and endoplasmic reticulum (ER) of ALS-affected tissues. Recently, macrophage migration inhibitory factor (MIF) was shown to directly inhibit the accumulation of misfolded SOD1 and its binding to intracellular membranes, but the role of endogenous MIF in modulating SOD1 misfolding in vivo remains unknown. To elucidate this role, we bred MIF-deficient mice with SOD1 G85R mice, which express a dismutase-inactive mutant of SOD1 and are considered a model of familial ALS. We found that the accumulation of misfolded SOD1, its association with mitochondrial and ER membranes, and the levels of sedimentable insoluble SOD1 aggregates were significantly higher in the spinal cords of SOD1 G85R -MIF −/− mice than in their SOD1 G85R -MIF +/+ littermates. Moreover, increasing MIF expression in neuronal cultures inhibited the accumulation of misfolded SOD1 and rescued from mutant SOD1-induced cell death. In contrast, the complete elimination of endogenous MIF accelerated disease onset and late disease progression and shortened the lifespan of the SOD1 G85R mutant mice. These findings indicate that MIF plays a significant role in the folding and misfolding of SOD1 in vivo, and they have implications for the potential therapeutic role of upregulating MIF within the nervous system to modulate the selective accumulation of misfolded SOD1.ALS | mutant SOD1 mouse | mutant SOD1 | misfolded SOD1 | MIF

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Localization of a toxic form of superoxide dismutase 1 protein to pathologically affected tissues in familial ALS

Cited by 92 publications

References 38 publications

Nonnative SOD1 trimer is toxic to motor neurons in a model of amyotrophic lateral sclerosis

Nonnative SOD1 trimer is toxic to motor neurons in a model of amyotrophic lateral sclerosis

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

Endogenous macrophage migration inhibitory factor reduces the accumulation and toxicity of misfolded SOD1 in a mouse model of ALS

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