Impaired Extracellular Secretion of Mutant Superoxide Dismutase 1 Associates with Neurotoxicity in Familial Amyotrophic Lateral Sclerosis

Turner, Bradley J.; Atkin, Julie D.; Farg, Manal A.; Zang, Dawei; Rembach, Alan; Lopes, Elizabeth C; Patch, Justin D; Hill, Andrew F.; Cheema, Surindar S.

doi:10.1523/jneurosci.4253-04.2005

Cited by 174 publications

(158 citation statements)

References 55 publications

Supporting

Mentioning

142

Contrasting

Order By: Relevance

“…The A4V and G85R mutants of SOD1, both of which lead to a familial form of amyotrophic lateral sclerosis, have previously been reported to form inclusions (25,29,30). Inclusions formed by these proteins had an apparent porous, labyrinthine topology in a small proportion of the cells (ϳ10% of the transfected population) (Fig.…”

Section: Resultsmentioning

confidence: 98%

“…Mutations in SOD1 that lead to amyotrophic lateral sclerosis are also associated with the formation of inclusions (24). pEGFP-N1 vectors containing human SOD1 WT , SOD1 A4V , SOD1 G85R , and SOD1 G93A were generated as described (25). The pEGFP-C1 vectors containing polyalanine repeats of 7 alanines or 37 alanines were generated as described (22) and the mCherry versions made by swapping out EGFP using standard cloning procedures.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Misfolded Polyglutamine, Polyalanine, and Superoxide Dismutase 1 Aggregate via Distinct Pathways in the Cell

Polling

Mok

Ramdzan

et al. 2014

Journal of Biological Chemistry

View full text Add to dashboard Cite

Background: Protein aggregation is associated with neurodegenerative diseases. Results: We defined how the oligomeric state of disease-relevant mutant protein and homopolypeptides relate to clustering into inclusion subtypes IPOD and JUNQ. Conclusion: JUNQ protein and homopolypeptides relate to constitutively disrupted oligomeric states irrespective of inclusion formation. Significance: JUNQ inclusions may arise by cellular failure in degradation of abnormal oligomeric states.

show abstract

Section: Resultsmentioning

confidence: 98%

mentioning

confidence: 99%

Misfolded Polyglutamine, Polyalanine, and Superoxide Dismutase 1 Aggregate via Distinct Pathways in the Cell

Polling

Mok

Ramdzan

et al. 2014

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…VSVG-ts045 misfolds and is retained in the eR at 40 °C, but is transported to the Golgi apparatus at the permissive temperature of 32 °C [35]. We first examined eR-Golgi transport in Sh-SY5Y cells transfected with SOD1 proteins linked to eGFP [6,12] and VSVG-ts045 mCherry, to confirm that intracellular mutant SOD1 can inhibit eR-Golgi trafficking in this cell line. VSVG-ts045 was detected immunocytochemically using markers of the eR (calnexin) and Golgi (GM130) and its co-localization with each marker was quantified using Mander's coefficient [36].…”

Section: Uptake Of Extracellular Sod1 Wt and Sod1 G93a By Neuronal Cellsmentioning

confidence: 99%

“…there is accumulating evidence that secreted, extracellular SOD1, which is misfolded either due to mutation or cellular stress, could be a toxic factor spreading neurodegeneration among motor neurons in aLS. SOD1 is secreted by neuronal cells [12,13] and is present in the cerebrospinal fluid (CSF) of aLS patients [14,15]. aggregated mutant SOD1 can be taken up by cells via macropinocytosis which triggers subsequent aggregation of natively folded SOD1 [1].…”

Section: Introductionmentioning

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.

View full text Add to dashboard Cite

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...

show abstract

“…Moreover, both dimers exhibited the expected SOD activity, in accordance with the robust enzymatic activity of previously published EGFPtagged SOD1 fusion constructs. 35 Finally, we could demonstrate the formation of the conserved intramolecular SOD1 disulfide bond in the fusion proteins. This indicates proper processing by CCS, which inserts the catalytic copper cofactor and catalyzes the formation of the conserved disulfide bond.…”

Section: Discussionmentioning

confidence: 81%

Mutant SOD1 detoxification mechanisms in intact single cells

et al. 2007

View full text Add to dashboard Cite

Mutant superoxide dismutase 1 (mtSOD1) causes dominantly inherited amyotrophic lateral sclerosis (ALS). The mechanism for mtSOD1 toxicity remains unknown. Two main hypotheses are the impairment of proteasomal function and chaperone depletion by misfolded mtSOD1. Here, we employed FRET/FLIM and biosensor imaging to quantitatively localize ubiquitination, as well as chaperone binding of mtSOD1, and to assess their effect on proteasomal and protein folding activities. We found large differences in ubiquitination and chaperone interaction levels for wild-type (wt) SOD1 versus mtSOD1 in intact single cells. Moreover, SOD1 ubiquitination levels differ between proteasomal structures and cytoplasmic material. Hsp70 binding and ubiquitination of wt and mtSOD1 species are highly correlated, demonstrating the coupled upregulation of both cellular detoxification mechanisms upon mtSOD1 expression. Biosensor imaging in single cells revealed that mtSOD1 expression alters cellular protein folding activity but not proteasomal function in the neuronal cell line examined. Our results provide the first cellby-cell-analysis of SOD1 ubiquitination and chaperone interaction. Moreover, our study opens new methodological avenues for cell biological research on ALS. Amyotrophic lateral sclerosis (ALS) is a progressive fatal neurodegenerative disease caused by the selective loss of motoneurons. 1 While ALS mostly occurs sporadically, 5-10% of cases are hereditary. About 20% of familial and few sporadic cases show point or frameshift mutations within the superoxide dismutase 1 (SOD1) gene. 2 The principle underlying mutant superoxide dismutase 1 (mtSOD1) toxicity seems to be a toxic gain -rather than loss -of function, since symptomatic mtSOD1-transgenic mice still express wild-type (wt), SOD1, some SOD1 mutants retain their enzymatic activity, 2,3 and neither knockout of endogenous SOD1 nor transgenic overexpression of wtSOD1 affect the course of disease in mtSOD1-transgenic mice. 4 Nonetheless, the downstream events in mtSOD1-mediated motoneuron death have not yet been resolved, although several hypotheses have been proposed that are based on properties that are specific for mtSOD1: altered protein folding, decreased solubility, and the propensity to form cytoplasmic aggregates. 5-10 One of the major hypotheses states that misfolded mtSOD1, through binding, depletes neuroprotective chaperones. 5-7 Accordingly, recombinant mtSOD1 inhibited chaperone activity in vitro. 11 Moreover, expression of Hsp70, Hsp27, or Hsp40 decreased aggregation of mtSOD1 and protected against mtSOD1 toxicity in cell lines and primary motoneurons. 6,12 However, overexpression of Hsp70 alone did not improve motoneuron survival in mtSOD1-transgenic mice. 13 This is possibly explained by a requirement, in vivo, for correction of further cellular functions or the combined action of different chaperones in the prevention of motoneuron cell death. Indeed, arimoclomol treatment, known to upregulate both Hsp70 and Hsp90 in the spinal cord, extended the lifespan of SOD1 ...

show abstract

Impaired Extracellular Secretion of Mutant Superoxide Dismutase 1 Associates with Neurotoxicity in Familial Amyotrophic Lateral Sclerosis

Abstract: G93A rats. Collectively, these results suggest novel extracellular roles for SOD1 in ALS and support a causal relationship between mutant SOD1 secretion and intraneuronal toxicity.

Cited by 174 publications

References 55 publications

Misfolded Polyglutamine, Polyalanine, and Superoxide Dismutase 1 Aggregate via Distinct Pathways in the Cell

Misfolded Polyglutamine, Polyalanine, and Superoxide Dismutase 1 Aggregate via Distinct Pathways in the Cell

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

Mutant SOD1 detoxification mechanisms in intact single cells

Contact Info

Product

Resources

About