scholarly journals Bridging the Bridging Imidazolate in the Bimetallic Center of the Cu/Zn SOD1 and ALS

2021 ◽  
Vol 9 ◽  
Author(s):  
Ahmet Can Timucin ◽  
Suleyman Selim Cinaroglu ◽  
Osman Ugur Sezerman ◽  
Emel Timucin
Keyword(s):  
Metal Binding ◽  
Atomistic Simulations ◽  
Superoxide Dismutase 1 ◽  
Wild Type ◽  
Intramolecular Disulfide Bond ◽  
Two Temperatures ◽  
Dynamics Simulations ◽  
Potential Use ◽  
Mobility Fluctuations ◽  
Lateral Sclerosis

Metallation status of human Cu/Zn superoxide dismutase 1 (SOD1) plays a pivotal role in the pathogenesis of amyotrophic lateral sclerosis (ALS). All of the amino acids found in the bimetallic center have been associated with ALS except for two positions. H63 which forms the bridging imidazolate ion in the bimetallic center and K136 which is not directly involved in coordination but located in the bimetallic center were not reported to be mutated in any of the identified ALS cases. In this study, we investigated the structure and flexibility of five SOD1 variants by using classical molecular dynamics simulations. These variants include three substitutions on the non-ALS-linked positions; H63A, H63R, K136A and ALS-linked positions; G37R, H46R/H48D. We have generated four systems for each variant differing in metallation and presence of the intramolecular disulfide bond. Overall, a total of 24 different dimers including the wild-type were generated and simulated at two temperatures, 298 and 400 K. We have monitored backbone mobility, fluctuations and compactness of the dimer structures to assess whether the hypothetical mutations would behave similar to the ALS-linked variants. Results showed that particularly two mutants, H63R and K136A, drastically affected the dimer dynamics by increasing the fluctuations of the metal binding loops compared with the control mutations. Further, these variants resulted in demetallation of the dimers, highlighting probable ALS toxicity that could be elicited by the SOD1 variants of H63R and K136A. Overall, this study bridges two putative SOD1 positions in the metallic center and ALS, underlining the potential use of atomistic simulations for studying disease variants.

scholarly journals Mutant SOD1-expressing astrocytes release toxic factors that trigger motoneuron death by inducing hyperexcitability

2013 ◽  
Vol 109 (11) ◽  
pp. 2803-2814 ◽  
Author(s):  
Elsa Fritz ◽  
Pamela Izaurieta ◽  
Alexandra Weiss ◽  
Franco R. Mir ◽  
Patricio Rojas ◽  
...  
Keyword(s):  
Calcium Transients ◽  
Repetitive Firing ◽  
Critical Element ◽  
Superoxide Dismutase 1 ◽  
Wild Type ◽  
Mutant Sod1 ◽  
Site Of Action ◽  
Inward Currents ◽  
Als Patients ◽  
Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating paralytic disorder caused by dysfunction and degeneration of motoneurons starting in adulthood. Recent studies using cell or animal models document that astrocytes expressing disease-causing mutations of human superoxide dismutase 1 (hSOD1) contribute to the pathogenesis of ALS by releasing a neurotoxic factor(s). Neither the mechanism by which this neurotoxic factor induces motoneuron death nor its cellular site of action has been elucidated. Here we show that acute exposure of primary wild-type spinal cord cultures to conditioned medium derived from astrocytes expressing mutant SOD1 (ACM-hSOD1G93A) increases persistent sodium inward currents (PCNa), repetitive firing, and intracellular calcium transients, leading to specific motoneuron death days later. In contrast to TTX, which paradoxically increased twofold the amplitude of calcium transients and killed motoneurons, reduction of hyperexcitability by other specific (mexiletine) and nonspecific (spermidine and riluzole) blockers of voltage-sensitive sodium (Nav) channels restored basal calcium transients and prevented motoneuron death induced by ACM-hSOD1G93A. These findings suggest that riluzole, the only FDA-approved drug with known benefits for ALS patients, acts by inhibiting hyperexcitability. Together, our data document that a critical element mediating the non-cell-autonomous toxicity of ACM-hSOD1G93A on motoneurons is increased excitability, an observation with direct implications for therapy of ALS.

scholarly journals Tryptophan residues in TDP-43 and SOD1 mediate the cross-seeding and toxicity of SOD1

2020 ◽  
Author(s):  
Edward Pokrishevsky ◽  
Michèle G. DuVal ◽  
Luke McAlary ◽  
Sarah Louadi ◽  
Silvia Pozzi ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Inclusion Bodies ◽  
Dna Binding Protein ◽  
Effector Proteins ◽  
Superoxide Dismutase 1 ◽  
Wild Type ◽  
Reporter Protein ◽  
Sporadic Als ◽  
Tryptophan Residues ◽  
Lateral Sclerosis

ABSTRACTAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of motor neurons. Neuronal superoxide dismutase-1 (SOD1) inclusion bodies are characteristic of familial ALS with SOD1 mutations, while a hallmark of sporadic ALS is inclusions containing aggregated wild-type TAR DNA-binding protein 43 (TDP-43). Co-expression of mutant or wild-type TDP-43 with SOD1 leads to misfolding of endogenous SOD1 and aggregation of SOD1 reporter protein G85R-GFP in HEK293FT cells, and promotes synergistic axonopathy in zebrafish. This pathological interaction is dependent upon natively solvent-exposed tryptophans in SOD1 (tryptophan-32) and TDP-43 RRM1 (tryptophan-172), in concert with natively sequestered TDP-43 N-terminal domain tryptophan-68. TDP-43 RRM1 intrabodies reduce wild-type SOD1 misfolding in HEK293FT cells, via blocking tryptophan-172. Tryptophan-68 becomes antibody-accessible in aggregated TDP-43 in sporadic ALS motor neurons and cell culture. 5-fluorouridine inhibits TDP-43-induced G85R-GFP SOD1 aggregation in HEK293FT cells, and ameliorates axonopathy in zebrafish, via its interaction with SOD1 tryptophan-32. Collectively, our results establish a novel and potentially druggable tryptophan-mediated mechanism whereby two principal ALS disease effector proteins might directly interact in disease.

scholarly journals Misfolded SOD1 inclusions in patients with mutations in C9orf72 and other ALS/FTD-associated genes

2019 ◽  
Vol 90 (8) ◽  
pp. 861-869 ◽  
Author(s):  
Karin Forsberg ◽  
Karin Graffmo ◽  
Bente Pakkenberg ◽  
Markus Weber ◽  
Martin Nielsen ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Superoxide Dismutase 1 ◽  
Wild Type ◽  
Spinal Motor Neurons ◽  
Hexanucleotide Repeat ◽  
Cortical Motor ◽  
Spinal Motor ◽  
Repeat Expansions ◽  
Misfolded Sod1 ◽  
Lateral Sclerosis

ObjectiveA hallmark of amyotrophic lateral sclerosis (ALS) caused by mutations in superoxide dismutase-1 (SOD1) are inclusions containing SOD1 in motor neurons. Here, we searched for SOD1-positive inclusions in 29 patients carrying ALS-linked mutations in six other genes.MethodsA panel of antibodies that specifically recognise misfolded SOD1 species were used for immunohistochemical investigations of autopsy tissue.ResultsThe 18 patients with hexanucleotide-repeat-expansions in C9orf72 had inclusions of misfolded wild type (WT) SOD1WT in spinal motor neurons. Similar inclusions were occasionally observed in medulla oblongata and in the motor cortex and frontal lobe. Patients with mutations in FUS, KIF5A, NEK1, ALSIN or VAPB, carried similar SOD1WT inclusions. Minute amounts of misSOD1WT inclusions were detected in 2 of 20 patients deceased from non-neurological causes and in 4 of 10 patients with other neurodegenerative diseases. Comparison was made with 17 patients with 9 different SOD1 mutations. Morphologically, the inclusions in patients with mutations in C9orf72HRE, FUS, KIF5A, NEK1, VAPB and ALSIN resembled inclusions in patients carrying the wildtype-like SOD1D90A mutation, whereas patients carrying unstable SOD1 mutations (A4V, V5M, D76Y, D83G, D101G, G114A, G127X, L144F) had larger skein-like SOD1-positive inclusions.Conclusions and relevanceAbundant inclusions containing misfolded SOD1WT are found in spinal and cortical motor neurons in patients carrying mutations in six ALS-causing genes other than SOD1. This suggests that misfolding of SOD1WT can be part of a common downstream event that may be pathogenic. The new anti-SOD1 therapeutics in development may have applications for a broader range of patients.

scholarly journals Expression of wild-type human superoxide dismutase-1 in mice causes amyotrophic lateral sclerosis

2012 ◽  
Vol 22 (1) ◽  
pp. 51-60 ◽  
Author(s):  
K. S. Graffmo ◽  
K. Forsberg ◽  
J. Bergh ◽  
A. Birve ◽  
P. Zetterstrom ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Superoxide Dismutase ◽  
Superoxide Dismutase 1 ◽  
Wild Type ◽  
Lateral Sclerosis

scholarly journals Mutations in Superoxide Dismutase 1 (Sod1) Linked to Familial Amyotrophic Lateral Sclerosis Can Disrupt High-Affinity Zinc-Binding Promoted by the Copper Chaperone for Sod1 (Ccs)

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1086 ◽  
Author(s):  
Stefanie D. Boyd ◽  
Morgan S. Ullrich ◽  
Jenifer S. Calvo ◽  
Fatemeh Behnia ◽  
Gabriele Meloni ◽  
...  
Keyword(s):  
Amyotrophic Lateral Sclerosis ◽  
Superoxide Dismutase ◽  
Zinc Binding ◽  
Copper Chaperone ◽  
Superoxide Dismutase 1 ◽  
Wild Type ◽  
High Affinity ◽  
Familial Form ◽  
First Time ◽  
Lateral Sclerosis

Zinc (II) ions (hereafter simplified as zinc) are important for the structural and functional activity of many proteins. For Cu, Zn superoxide dismutase (Sod1), zinc stabilizes the native structure of each Sod1 monomer, promotes homo-dimerization and plays an important role in activity by “softening” the active site so that copper cycling between Cu(I) and Cu(II) can rapidly occur. Previously, we have reported that binding of Sod1 by its copper chaperone (Ccs) stabilizes a conformation of Sod1 that promotes site-specific high-affinity zinc binding. While there are a multitude of Sod1 mutations linked to the familial form of amyotrophic lateral sclerosis (fALS), characterizations by multiple research groups have been unable to realize strong commonalities among mutants. Here, we examine a set of fALS-linked Sod1 mutations that have been well-characterized and are known to possess variation in their biophysical characteristics. The zinc affinities of these mutants are evaluated here for the first time and then compared with the previously established value for wild-type Sod1 zinc affinity. Ccs does not have the same ability to promote zinc binding to these mutants as it does for the wild-type version of Sod1. Our data provides a deeper look into how (non)productive Sod1 maturation by Ccs may link a diverse set of fALS-Sod1 mutations.

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