ID: 23431152
Title: SOD1 exhibits allosteric frustration to facilitate metal binding affinity.
Abstract: Superoxide dismutase-1 (SOD1) is a ubiquitous, Cu and Zn binding, free-radical defense enzyme whose misfolding and aggregation play a potential key role in amyotrophic lateral sclerosis, an invariably fatal neurodegenerative disease. Over 150 mutations in SOD1 have been identified with a familial form of the disease, but it is presently not clear what unifying features, if any, these mutants share to make them pathogenic. Here, we develop several unique computational assays for probing the thermo-mechanical properties of both ALS-associated and rationally designed SOD1 variants. Allosteric interaction-free energies between residues and metals are calculated, and a series of atomic force microscopy experiments are simulated with variable tether positions to quantify mechanical rigidity "fingerprints" for SOD1 variants. Mechanical fingerprinting studies of a series of C-terminally truncated mutants, along with an analysis of equilibrium dynamic fluctuations while varying native constraints, potential energy change upon mutation, frustratometer analysis, and analysis of the coupling between local frustration and metal binding interactions for a glycine scan of 90 residues together, reveal that the apo protein is internally frustrated, that these internal stresses are partially relieved by mutation but at the expense of metal-binding affinity, and that the frustration of a residue is directly related to its role in binding metals. This evidence points to apo SOD1 as a strained intermediate with "self-allostery" for high metal-binding affinity. Thus, the prerequisites for the function of SOD1 as an antioxidant compete with apo state thermo-mechanical stability, increasing the susceptibility of the protein to misfold in the apo state.

ID: 25762331
Title: Arresting amyloid with coulomb's law: acetylation of ALS-linked SOD1 by aspirin impedes aggregation.
Abstract: Although the magnitude of a protein's net charge (Z) can control its rate of self-assembly into amyloid, and its interactions with cellular membranes, the net charge of a protein is not viewed as a druggable parameter. This article demonstrates that aspirin (the quintessential acylating pharmacon) can inhibit the amyloidogenesis of superoxide dismutase (SOD1) by increasing the intrinsic net negative charge of the polypeptide, i.e., by acetylation (neutralization) of multiple lysines. The protective effects of acetylation were diminished (but not abolished) in 100 mM NaCl and were statistically significant: a total of 432 thioflavin-T amyloid assays were performed for all studied proteins. The acetylation of as few as three lysines by aspirin in A4V apo-SOD1-a variant that causes familial amyotrophic lateral sclerosis (ALS)-delayed amyloid nucleation by 38% and slowed amyloid propagation by twofold. Lysines in wild-type- and ALS-variant apo-SOD1 could also be peracetylated with aspirin after fibrillization, resulting in supercharged fibrils, with increases in formal net charge of ∼2 million units. Peracetylated SOD1 amyloid defibrillized at temperatures below unacetylated fibrils, and below the melting temperature of native Cu2,Zn2-SOD1 (e.g., fibril Tm = 84.49°C for acetylated D90A apo-SOD1 fibrils). Targeting the net charge of native or misfolded proteins with small molecules-analogous to how an enzyme's Km or Vmax are medicinally targeted-holds promise as a strategy in the design of therapies for diseases linked to protein self-assembly.

ID: 26719414
Title: Nonnative SOD1 trimer is toxic to motor neurons in a model of amyotrophic lateral sclerosis.
Abstract: 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.

ID: 28974578
Title: Lysine acylation in superoxide dismutase-1 electrostatically inhibits formation of fibrils with prion-like seeding.
Abstract: The acylation of lysine residues in superoxide dismutase-1 (SOD1) has been previously shown to decrease its rate of nucleation and elongation into amyloid-like fibrils linked to amyotrophic lateral sclerosis. The chemical mechanism underlying this effect is unclear, i.e. hydrophobic/steric effects versus electrostatic effects. Moreover, the degree to which the acylation might alter the prion-like seeding of SOD1 in vivo has not been addressed. Here, we acylated a fraction of lysine residues in SOD1 with groups of variable hydrophobicity, charge, and conformational entropy. The effect of each acyl group on the rate of SOD1 fibril nucleation and elongation were quantified in vitro with thioflavin-T (ThT) fluorescence, and we performed 594 iterate aggregation assays to obtain statistically significant rates. The effect of the lysine acylation on the prion-like seeding of SOD1 was assayed in spinal cord extracts of transgenic mice expressing a G85R SOD1-yellow fluorescent protein construct. Acyl groups with >2 carboxylic acids diminished self-assembly into ThT-positive fibrils and instead promoted the self-assembly of ThT-negative fibrils and amorphous complexes. The addition of ThT-negative, acylated SOD1 fibrils to organotypic spinal cord failed to produce the SOD1 inclusion pathology that typically results from the addition of ThT-positive SOD1 fibrils. These results suggest that chemically increasing the net negative surface charge of SOD1 via acylation can block the prion-like propagation of oligomeric SOD1 in spinal cord.

ID: 29666246
Title: Large SOD1 aggregates, unlike trimeric SOD1, do not impact cell viability in a model of amyotrophic lateral sclerosis.
Abstract: Aberrant accumulation of misfolded Cu, Zn superoxide dismutase (SOD1) is a hallmark of SOD1-associated amyotrophic lateral sclerosis (ALS), an invariably fatal neurodegenerative disease. While recent discovery of nonnative trimeric SOD1-associated neurotoxicity has suggested a potential pathway for motor neuron impairment, it is yet unknown whether large, insoluble aggregates are cytotoxic. Here we designed SOD1 mutations that specifically stabilize either the fibrillar form or the trimeric state of SOD1. The designed mutants display elevated populations of fibrils or trimers correspondingly, as demonstrated by gel filtration chromatography and electron microscopy. The trimer-stabilizing mutant, G147P, promoted cell death, even more potently in comparison with the aggressive ALS-associated mutants A4V and G93A. In contrast, the fibril-stabilizing mutants, N53I and D101I, positively impacted the survival of motor neuron-like cells. Hence, we conclude the SOD1 oligomer and not the mature form of aggregated fibril is critical for the neurotoxic effects in the model of ALS. The formation of large aggregates is in competition with trimer formation, suggesting that aggregation may be a protective mechanism against formation of toxic oligomeric intermediates.

ID: 31011770
Title: Network mapping of the conformational heterogeneity of SOD1 by deploying statistical cluster analysis of FTIR spectra.
Abstract: A crucial contribution to the heterogeneity of the conformational landscape of a protein comes from the way an intermediate relates to another intermediate state in its journey from the unfolded to folded or misfolded form. Unfortunately, it is extremely hard to decode this relatedness in a quantifiable manner. Here, we developed an application of statistical cluster analyses to explore the conformational heterogeneity of a metalloenzyme, human cytosolic copper-zinc superoxide dismutase (SOD1), using the inputs from infrared spectroscopy. This study provides a quantifiable picture of how conformational information at one particular site (for example, the copper-binding pocket) is related to the information at the second site (for example, the zinc-binding pocket), and how this relatedness is transferred to the global conformational information of the protein. The distance outputs were used to quantitatively generate a network capturing the folding sub-stages of SOD1.

ID: 31324499
Title: Therapeutic vaccines for amyotrophic lateral sclerosis directed against disease specific epitopes of superoxide dismutase 1.
Abstract: Emerging evidence suggests seeding and prion-like propagation of mutant Superoxide Dismutase 1 (SOD1) misfolding to be a potential mechanism for ALS pathogenesis and progression. Immuno-targeting of misfolded SOD1 has shown positive clinical outcomes in mutant SOD1 transgenic mice. However, a major challenge in developing active immunotherapies for proteinopathies such as ALS is the design of immunogens enabling exclusive recognition of pathogenic species of a self-protein. Ideally, one would achieve a robust antibody response against the disease-misfolded protein while sparing the natively folded conformer to avoid inducing deleterious autoimmune complications, or inhibiting its normal function. Using a motor neuron disease mouse model expressing human SOD1-G37R, we herein report the immunogenicity and therapeutic efficacy of two ALS vaccines, tgG-DSE2lim and tgG-DSE5b, based on the notion that native SOD1 would undergo early unfolding in disease to present "disease specific epitopes" (DSE). Both vaccines elicited rapid, robust, and well-sustained epitope-specific antibody responses with a desirable Th2-biased immune response. Both vaccines significantly extended the life expectancy of hSOD1G37R mice, with tgG-DSE2lim displaying greater protection than tgG-DSE5b at earlier pre-symptomatic stage. tgG-DSE5b, but not tgG-DSE2lim, significantly delayed disease onset and appreciably slowed disease progression. This implies that conformationally distinct species of misfolded SOD1 may derive from the same mutation, thereby modifying disease phenotypes in a different fashion. Our results validate the rationale for conformation-based immuno-targeting of misfolded SOD1 as a promising therapeutic strategy to slow or even halt disease progression in familial ALS associated with SOD1 mutations, as well as a prophylactic intervention for carriers of SOD1 mutations. Our study not only provides important proof-of-principle data for the development of a safe and effective human therapeutic/prophylactic ALS vaccine against misfolded SOD1, but also predicts a great potential to extend our DSE-based vaccination approach to other types of ALS, such as those associated with TDP-43 proteinopathies.

ID: 32139772
Title: Ebselen as template for stabilization of A4V mutant dimer for motor neuron disease therapy.
Abstract: Mutations to the gene encoding superoxide dismutase-1 (SOD1) were the first genetic elements discovered that cause motor neuron disease (MND). These mutations result in compromised SOD1 dimer stability, with one of the severest and most common mutations Ala4Val (A4V) displaying a propensity to monomerise and aggregate leading to neuronal death. We show that the clinically used ebselen and related analogues promote thermal stability of A4V SOD1 when binding to Cys111 only. We have developed a A4V SOD1 differential scanning fluorescence-based assay on a C6S mutation background that is effective in assessing suitability of compounds. Crystallographic data show that the selenium atom of these compounds binds covalently to A4V SOD1 at Cys111 at the dimer interface, resulting in stabilisation. This together with chemical amenability for hit expansion of ebselen and its on-target SOD1 pharmacological chaperone activity holds remarkable promise for structure-based therapeutics for MND using ebselen as a template.

ID: 32701214
Title: Examination of SOD1 aggregation modulators and their effect on SOD1 enzymatic activity as a proxy for potential toxicity.
Abstract: Small-molecule inhibitors of abnormal protein self-assembly are promising candidates for developing therapy against proteinopathies. Such compounds have been examined primarily as inhibitors of amyloid β-protein (Aβ), whereas testing of inhibitors of other amyloidogenic proteins has lagged behind. An important issue with screening compound libraries is that although an inhibitor suitable for therapy must be both effective and nontoxic, typical screening focuses on efficacy, whereas safety typically is tested at a later stage using cells and/or animals. In addition, typical thioflavin T (ThT)-fluorescence-based screens use the final fluorescence value as a readout, potentially missing important kinetic information. Here, we examined potential inhibitors of superoxide dismutase 1 (SOD1) using ThT-fluorescence including the different phases of fluorescence change and added a parallel screen of SOD1 activity as a potential proxy for compound toxicity. Some compounds previously reported to inhibit other amyloidogenic proteins also inhibited SOD1 aggregation at low micromolar concentrations, whereas others were ineffective. Analysis of the lag phase and exponential slope added important information that could help exclude false-positive or false-negative results. SOD1 was highly resistant to inhibition of its activity, and therefore, did not have the necessary sensitivity to serve as a proxy for examining potential toxicity.

ID: 32794552
Title: Molecular and pharmacological chaperones for SOD1.
Abstract: The efficacy of superoxide dismutase-1 (SOD1) folding impacts neuronal loss in motor system neurodegenerative diseases. Mutations can prevent SOD1 post-translational processing leading to misfolding and cytoplasmic aggregation in familial amyotrophic lateral sclerosis (ALS). Evidence of immature, wild-type SOD1 misfolding has also been observed in sporadic ALS, non-SOD1 familial ALS and Parkinson's disease. The copper chaperone for SOD1 (hCCS) is a dedicated and specific chaperone that assists SOD1 folding and maturation to produce the active enzyme. Misfolded or misfolding prone SOD1 also interacts with heat shock proteins and macrophage migration inhibitory factor to aid folding, refolding or degradation. Recognition of specific SOD1 structures by the molecular chaperone network and timely dissociation of SOD1-chaperone complexes are, therefore, important steps in SOD1 processing. Harnessing these interactions for therapeutic benefit is actively pursued as is the modulation of SOD1 behaviour with pharmacological and peptide chaperones. This review highlights the structural and mechanistic aspects of a selection of SOD1-chaperone interactions together with their impact on disease models.

ID: 33326235
Title: Exposure of β6/β7-Loop in Zn/Cu Superoxide Dismutase (SOD1) Is Coupled to Metal Loss and Is Transiently Reversible During Misfolding.
Abstract: Upon losing its structural integrity (misfolding), SOD1 acquires neurotoxic properties to become a pathogenic protein in ALS, a neurodegenerative disease targeting motor neurons; understanding the mechanism of misfolding may enable new treatment strategies for ALS. Here, we reported a monoclonal antibody, SE21, targeting the β6/β7-loop region of SOD1. The exposure of this region is coupled to metal loss and is entirely reversible during the early stages of misfolding. By using SE21 mAb, we demonstrated that, in apo-SOD1 incubated under the misfolding-promoting conditions, the reversible phase, during which SOD1 is capable of restoring its nativelike conformation in the presence of metals, is followed by an irreversible structural transition, autocatalytic in nature, which takes place prior to the onset of SOD1 aggregation and results in the formation of atypical apo-SOD1 that is unable to bind metals. The reversible phase defines a window of opportunity for pharmacological intervention using metal mimetics that stabilize SOD1 structure in its nativelike conformation to attenuate the spreading of the misfolding signal and disease progression by preventing the exposure of pathogenic SOD1 epitopes. Phenotypically similar apo-SOD1 species with impaired metal binding properties may also be produced via oxidation of Cys111, underscoring the diversity of SOD1 misfolding pathways.

ID: 33846297
Title: Simvastatin accelerated motoneurons death in SOD1G93A mice through inhibiting Rab7-mediated maturation of late autophagic vacuoles.
Abstract: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease caused by motoneuron loss, for which there is currently no effective treatment. Statins, as inhibitors of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, are used as drugs for treatment for a variety of disease such as ischemic diseases, neurodegenerative diseases, cancer, and inflammation. However, our previous evidence has demonstrated that simvastatin leads to cytotoxicity in NSC34-hSOD1G93A cells by aggravating the impairment of autophagic flux, but the role of simvastatin in ALS model remains elusive. In present study, we reported that after simvastatin treatment, SOD1G93A mice showed early onset of the disease phenotype and shortened life span, with aggravated autophagic flux impairment and increased aggregation of SOD1 protein in spinal cord motoneurons (MNs) of SOD1G93A mice. In addition, simvastatin repressed the ability of Rab7 localization on the membrane by inhibiting isoprenoid synthesis, leading to impaired late stage of autophagic flux rather than initiation. This study suggested that simvastatin significantly worsened impairment of late autophagic flux, resulting in massive MNs death in spinal cord and accelerated disease progression of SOD1G93A mice. Together, these findings might imply a potential risk of clinic application of statins in ALS.

ID: 33923808
Title: A Metal-Free, Disulfide Oxidized Form of Superoxide Dismutase 1 as a Primary Misfolded Species with Prion-Like Properties in the Extracellular Environments Surrounding Motor Neuron-Like Cells.
Abstract: Superoxide dismutase 1 (SOD1) is a metalloenzyme with high structural stability, but a lack of Cu and Zn ions decreases its stability and enhances the likelihood of misfolding, which is a pathological hallmark of amyotrophic lateral sclerosis (ALS). A growing body of evidence has demonstrated that misfolded SOD1 has prion-like properties such as transmissibility between cells and intracellular propagation of misfolding of natively folded SOD1. Recently, we found that SOD1 is misfolded in the cerebrospinal fluid of sporadic ALS patients, providing a route by which misfolded SOD1 spreads via the extracellular environment of the central nervous system. Unlike intracellular misfolded SOD1, it is unknown which extracellular misfolded species is most relevant to prion-like properties. Here, we determined a conformational feature of extracellular misfolded SOD1 that is linked to prion-like properties. Using culture media from motor neuron-like cells, NSC-34, extracellular misfolded wild-type, and four ALS-causing SOD1 mutants were characterized as a metal-free, disulfide oxidized form of SOD1 (apo-SOD1S-S). Extracellular misfolded apo-SOD1S-S exhibited cell-to-cell transmission from the culture medium to recipient cells as well as intracellular propagation of SOD1 misfolding in recipient cells. Furthermore, culture medium containing misfolded apo-SOD1S-S exerted cytotoxicity to motor neuron-like cells, which was blocked by removal of misfolded apo-SOD1S-S from the medium. We conclude that misfolded apo-SOD1S-S is a primary extracellular species that is linked to prion-like properties.

ID: 35478453
Title: P2X7 receptor activation mediates superoxide dismutase 1 (SOD1) release from murine NSC-34 motor neurons.
Abstract: Mutant superoxide dismutase 1 (SOD1) can be constitutively released from motor neurons and transmitted to naïve motor neurons to promote the progression of amyotrophic lateral sclerosis (ALS). However, the biological impacts of this process and the precise mechanisms of SOD1 release remain to be fully resolved. Using biochemical and fluorescent techniques, this study aimed to determine if P2X7 receptor activation could induce mutant SOD1 release from motor neurons and whether this released SOD1 could be transmitted to motor neurons or microglia to mediate effects associated with neurodegeneration in ALS. Aggregated SOD1G93A, released from murine NSC-34 motor neurons transiently transfected with SOD1G93A, could be transmitted to naïve NSC-34 cells and murine EOC13 microglia to induce endoplasmic reticulum (ER) stress and tumour necrosis factor-alpha (TNFα) release, respectively. Immunoblotting revealed NSC-34 cells expressed P2X7. Extracellular ATP induced cation dye uptake into these cells, which was blocked by the P2X7 antagonist AZ10606120, demonstrating these cells express functional P2X7. Moreover, ATP induced the rapid release of aggregated SOD1G93A from NSC-34 cells transiently transfected with SOD1G93A, a process blocked by AZ10606120 and revealing a role for P2X7 in this process. ATP-induced SOD1G93A release coincided with membrane blebbing. Finally, aggregated SOD1G93A released via P2X7 activation could also be transmitted to NSC-34 and EOC13 cells to induce ER stress and TNFα release, respectively. Collectively, these results identify a novel role for P2X7 in the prion-like propagation of SOD1 in ALS and provide a possible explanation for the therapeutic benefits of P2X7 antagonism previously observed in ALS SOD1G93A mice.

ID: 35505609
Title: Toxic SOD1 trimers are off-pathway in the formation of amyloid-like fibrils in ALS.
Abstract: Accumulation of insoluble amyloid fibrils is widely studied as a critical factor in the pathology of multiple neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease. Misfolded Cu, Zn superoxide dismutase (SOD1) was the first protein linked to ALS, and non-native SOD1 trimeric oligomers were recently linked to cytotoxicity, while larger oligomers were protective to cells. The balance between trimers and larger aggregates in the process of SOD1 aggregation is, thus, a critical determinant of potential therapeutic approaches to treat ALS. However, it is unknown whether these trimeric oligomers are a necessary intermediate for larger aggregate formation or a distinct off-pathway species competing with fibril formation. Depending on the on- or off-pathway scenario of trimer formation, we expect drastically different therapeutic approaches. Here, we show that the toxic SOD1 trimer is an off-pathway intermediate competing with protective fibril formation. We design mutant SOD1 constructs that remain in a trimeric state (super-stable trimers) and show that stabilizing the trimeric SOD1 prevents formation of fibrils in vitro and in a motor neuron-like cell model (NSC-34). Using size exclusion chromatography, we track the aggregation kinetics of purified SOD1 and show direct competition of trimeric SOD1 with larger oligomer and fibril formation. Finally, we show the trimer is structurally independent of both larger soluble oligomers and insoluble fibrils using circular dichroism spectroscopy and limited proteolysis.

ID: 35817830
Title: SOD1 gains pro-oxidant activity upon aberrant oligomerization: change in enzymatic activity by intramolecular disulfide bond cleavage.
Abstract: Copper-zinc superoxide dismutase (SOD1) has been proposed as one of the causative proteins of amyotrophic lateral sclerosis (ALS). The accumulation of non-native conformers, oligomers, and aggregates of SOD1 in motor neurons is considered responsible for this disease. However, it remains unclear which specific feature of these species induces the onset of ALS. In this study, we showed that disulfide-linked oligomers of denatured SOD1 exhibit pro-oxidant activity. Substituting all the cysteine residues in the free thiol state with serine resulted in the loss of both the propensity to oligomerize and the increase in pro-oxidant activity after denaturation. In contrast, these cysteine mutants oligomerized and acquired the pro-oxidant activity after denaturation in the presence of a reductant that cleaves the intramolecular disulfide bond. These results indicate that one of the toxicities of SOD1 oligomers is the pro-oxidant activity induced by scrambling of the disulfide bonds. Small oligomers such as dimers and trimers exhibit stronger pro-oxidant activity than large oligomers and aggregates, consistent with the trend of the cytotoxicity of oligomers and aggregates reported in previous studies. We propose that the cleavage of the intramolecular disulfide bond accompanied by the oligomerization reduces the substrate specificity of SOD1, leading to the non-native enzymatic activity.

ID: 36265587
Title: Metal migration and subunit swapping in ALS-linked SOD1: Zn2+ transfer between mutant and wild-type occurs faster than the rate of heterodimerization.
Abstract: The heterodimerization of WT Cu, Zn superoxide dismutase-1 (SOD1), and mutant SOD1 might be a critical step in the pathogenesis of SOD1-linked amyotrophic lateral sclerosis (ALS). Rates and free energies of heterodimerization (ΔGHet) between WT and ALS-mutant SOD1 in mismatched metalation states-where one subunit is metalated and the other is not-have been difficult to obtain. Consequently, the hypothesis that under-metalated SOD1 might trigger misfolding of metalated SOD1 by "stealing" metal ions remains untested. This study used capillary zone electrophoresis and mass spectrometry to track heterodimerization and metal transfer between WT SOD1, ALS-variant SOD1 (E100K, E100G, D90A), and triply deamidated SOD1 (modeled with N26D/N131D/N139D substitutions). We determined that rates of subunit exchange between apo dimers and metalated dimers-expressed as time to reach 30% heterodimer-ranged from t30% = 67.75 ± 9.08 to 338.53 ± 26.95 min; free energies of heterodimerization ranged from ΔGHet = -1.21 ± 0.31 to -3.06 ± 0.12 kJ/mol. Rates and ΔGHet values of partially metalated heterodimers were more similar to those of fully metalated heterodimers than apo heterodimers, and largely independent of which subunit (mutant or WT) was metal-replete or metal-free. Mass spectrometry and capillary electrophoresis demonstrated that mutant or WT 4Zn-SOD1 could transfer up to two equivalents of Zn2+ to mutant or WT apo-SOD1 (at rates faster than the rate of heterodimerization). This result suggests that zinc-replete SOD1 can function as a chaperone to deliver Zn2+ to apo-SOD1, and that WT apo-SOD1 might increase the toxicity of mutant SOD1 by stealing its Zn2+.

ID: 38446760
Title: Structural insights into the modulation Of SOD1 aggregation By a fungal metabolite Phialomustin-B: Therapeutic potential in ALS.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal human motor neuron disease leading to muscle atrophy and paralysis. Mutations in superoxide dismutase 1 (SOD1) are associated with familial ALS (fALS). The SOD1 mutants in ALS have a toxic-gain of function by destabilizing the functional SOD1 homodimer, consequently inducing fibril-like aggregation with a cytotoxic non-native trimer intermediate. Therefore, reducing SOD1 oligomerization via chemical modulators is an optimal therapy in ALS. Here, we report the discovery of Phialomustin-B, an unsaturated secondary metabolite from the endophytic fungus Phialophora mustea, as a modulator of SOD1 aggregation. The crystal structure of the SOD1-Phialomustin complex refined to 1.90 Å resolution demonstrated for the first time that the ligand binds to the dimer interface and the lateral region near the electrostatic loop. The aggregation analyses of SOD1WT and the disease mutant SOD1A4V revealed that Phialomustin-B reduces cytotoxic trimerization. We propose that Phialomustin-B is a potent lead molecule with therapeutic potential in fALS.

ID: 38522514
Title: Tryptophan residues in TDP-43 and SOD1 modulate the cross-seeding and toxicity of SOD1.
Abstract: Amyotrophic 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 WT TAR DNA-binding protein 43 (TDP-43). We show here that co-expression of mutant or WT TDP-43 with SOD1 leads to misfolding of endogenous SOD1 and aggregation of SOD1 reporter protein SOD1G85R-GFP in human cell cultures and promotes synergistic axonopathy in zebrafish. Intriguingly, this pathological interaction is modulated by natively solvent-exposed tryptophans in SOD1 (tryptophan-32) and TDP-43 RNA-recognition motif RRM1 (tryptophan-172), in concert with natively sequestered TDP-43 N-terminal domain tryptophan-68. TDP-43 RRM1 intrabodies reduce WT SOD1 misfolding in human cell cultures, 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 human cell cultures 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.

ID: 40709254
Title: Trimeric superoxide dismutase 1 antibody as a universal biomarker for ALS.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that leads to the loss of motor neurons, resulting in paralysis and death. Currently, there are no specific biomarkers available for diagnosing ALS. As a result, diagnosis currently relies on excluding other conditions, which forces patients to endure months or even years of uncertainty. The absence of a specific, reliable diagnostic tool has hindered both early intervention and therapeutic progress. Here we develop a novel synthetic antibody that can detect a toxic form of a known protein linked to ALS. This trimeric assembly of superoxide dismutase 1 (SOD1) is a soluble, structurally distinct oligomer that is highly toxic in cell models. The antibody selectively binds this trimer and differentiates individuals with the disease from healthy people and from those with other neurodegenerative diseases (Alzheimer's and Parkinson's disease). This breakthrough provides the first disease-specific diagnostic tool for this condition and reveals a shared pathological signature across patients, even in cases without genetic mutations. After decades without a specific diagnostic tool, this antibody signifies a long-awaited breakthrough, finally offering clinicians and researchers a reliable window into ALS pathology.

ID: 41099622
Title: Oxidative denaturation of Cu/Zn-superoxide dismutase associated with neurodegenerative diseases.
Abstract: Misfolding of mutant Cu/Zn-superoxide dismutase (SOD1) is a well-established pathological feature of familial amyotrophic lateral sclerosis (ALS). While amino acid substitutions in mutant SOD1 destabilize its structure and promote misfolding, oxidation has also been implicated in the pathological alterations of wild-type SOD1, particularly in neurodegenerative diseases including sporadic ALS. However, the impact of oxidation on SOD1 folding remains to be fully elucidated. Here, we demonstrate that Cys111 is primarily oxidized to sulfonic acid upon exposure of apo-SOD1 to hydrogen peroxide, as confirmed by the quantitation of thiol groups and mass spectrometry. Molecular dynamics simulations showed that sulfonylation of Cys111 disrupts the dimer interface and promotes monomerization. This monomeric form then facilitates the subsequent oxidation of buried Cys6, leading to structural disruption, as evidenced by circular dichroism spectroscopy and loss of thiol groups. SOD1 denaturation triggered by Cys111 oxidation became evident when zinc binding was impaired due to pathological mutations and/or under zinc-deficient conditions. Given that increased oxidative stress is frequently associated with many neurodegenerative diseases, modulating Cys111 oxidation may offer a potential strategy for maintaining SOD1 structural stability and preventing its pathological misfolding.

ID: 41109388
Title: Allosteric pathway connects Zn(II) loss from SOD1 to known pathogenic mechanisms.
Abstract: Cu,Zn superoxide dismutase (SOD1) is one of the proteins with mutations linked to hereditary forms of the amyotrophic lateral sclerosis neurodegenerative disorder. The protein is known for its enzymatic activity, but it has been shown to also have regulatory functions, which could be related to its pathogenic potential. Seemingly unrelated to its regulatory roles, the most important hypothesis on SOD1 pathogenicity is related to misfolding of the protein, specifically centered on the region corresponding to its residues 28-38. The present work explores the structural and dynamical effect of Zn(II) removal from SOD1, which is known to influence its regulatory roles, with coarse-grained simulations of 450μs per system. In agreement with experiment, we see an increased solvent exposure of the regulatory region (residues 5-18). We also see an increased solvent exposure of the misfolding-critical 28-38 region. We unveil the mechanism and interactions connecting Zn(II) loss, and solvent exposure of both regions. The present work allows for an unified understanding of two different pathogenic mechanisms of SOD1.

ID: 41579929
Title: An ALS-associated mutant SOD1 protein can be eliminated in microglia culture by selective autophagy.
Abstract: The acquired toxicity of the familial amyotrophic lateral sclerosis (ALS)-associated mutant Zn-superoxide dismutase 1 (SOD1) protein has been implicated in motoneuron death, and cytosolic aggregates or inclusions have been observed in the cytoplasm of motoneurons, astrocytes, and neuronal axons but not in that of microglia. This study elucidates the mechanisms by which mutant SOD1 does not aggregate in and is cleared by microglia. We generated pcDNA3-Venus-tagged SOD1 constructs: wild-type SOD1 and mutant SOD1 were used as controls, and the A4V, D90A, and G93A SOD1 mutants were used as disease-related constructs; these plasmids were introduced into the Ra2 microglia line for subsequent evaluation. In spinal cords collected from postsymptomatic G93A mice, very little aggregation of the mutant SOD1 protein was detected in microglia, consistent with previous reports. Our new findings, which were based on immunohistochemical, Western blot, and enzyme immunoassay analyses, revealed that the protein expression of mutant SOD1 in microglia is significantly lower than that of wild-type SOD1. Furthermore, we observed the recovery of mutant SOD1 protein levels in autophagy suppression experiments and its colocalization with WDFY3, a selective autophagy-related protein. These in vitro results demonstrate that only the mutant SOD1 protein (i.e., not wild-type SOD1) is degraded by selective autophagy. Furthermore, we found that both wild-type and mutant SOD1 are secreted directly from microglia. These findings provide an opportunity to elucidate the precise mechanism through which microglia manage mutant SOD1 proteins during the pathological process of ALS and are likely to lead to improvements in ALS treatment strategies.

ID: 41632439
Title: Comparative cytotoxic and molecular effects of deltamethrin and acetamiprid in normal and cancerous human liver cell lines.
Abstract: Deltamethrin (a pyrethroid) and acetamiprid (a neonicotinoid) are widely used insecticides that have raised increasing concerns due to their potential toxicity. This study aimed to investigate their cytotoxic, morphological and molecular effects on normal (Thle-2) and cancerous (HepG2) human liver cell lines, as well as their interactions with key antioxidant-related enzymes. IC50 values were determined using XTT assay following 24- and 48 h exposures to each compound individually and in combination. Cell motility was evaluated using wound healing assays, while oxidative stress-related gene expressions (CAT, SOD1, GSTK1) were analysed by qRT-PCR.In Thle-2 cells, CAT and GSTK1 expression significantly decreased after acetamiprid exposure (p < 0.05). In HepG2 cells, GSTK1 expression decreased with individual treatments but increased significantly under combined exposure compared to deltamethrin alone (p < 0.05). Moelcular docking analysis revealed that deltamethrin exhibited stronger binding affinities with antioxidant ezymes, particularly SOD1 (−8.1 kcal/mol) and CAT (−8.0 kcal/mol), suggesting a higher potential for enzyme inhibition. In contrast, acetamiprid showed moderate affinities, with the lowest energy for CAT (−6.8 kcal/mol). ProTox predictions indicated moderate hepatotoxic, neurotoxic, and respiratory toxic potentials for deltamethrin, whereas acetamiprdi displayed a generally loe toxicity profile. Overall, these results suggest that both compunds modulate antioxidant defense mechanism and induce oxidative stress responses, with differential toxicity between normal and cancerous liver cells.

ID: 41651252
Title: Novel extracellular vesicle release pathway facilitated by toxic superoxide dismutase 1 oligomers.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that results in paralysis and death within three to five years. Mutations in over forty different proteins have been linked to ALS, raising debate over whether ALS is a single disease or multiple disorders with similar symptoms. Mutations in Cu,Zn superoxide dismutase 1 (SOD1) are found in only 2-3% of ALS cases, yet misfolded SOD1 appears in both sporadic (sALS) and familial (fALS) patients. Furthermore, mutations in TDP-43 or FUS increase levels of misfolded SOD1 on extracellular vesicles (EVs). Small EVs isolated from ALS patient samples have been shown to cause death of wild-type motor neurons and myotubes, supporting the theory that EVs play a role in spreading disease. We hypothesize that the previously identified toxic trimeric SOD1 spreads via EVs in ALS and influences the distribution of other ALS-related proteins, suggesting a common mechanism. To test this, we isolate EVs from motor neuron-like cells expressing mutations that stabilize trimers. We then perform a sandwich enzyme-linked immunosorbent assay (ELISA) using a CD9 capture antibody to measure whether misfolded SOD1 and 17 other ALS-related proteins increase or decrease on EVs with trimer stabilization. We identify which EV release pathway is affected by trimeric SOD1 using endocytosis and exocytosis inhibitors and analyze altered protein interaction pathways through co-immunoprecipitation and mass spectrometry proteomics. Our results show that VAPB, VCP, and Stathmin-2 increase on EVs when trimers are stabilized. The common pathway linking these ALS-associated proteins and SOD1 appears to involve multiple mechanisms, including the Caveolae endocytosis pathway, pointing to a novel hybrid EV release pathway in ALS. Overall, our findings show that trimeric SOD1 influences EV cargo and spread in ALS.

ID: 41664997
Title: N-Truncated Superoxide Dismutase-1 in Cerebrospinal Fluid Is Folded and Active.
Abstract: Mutations in the antioxidant enzyme superoxide dismutase-1 (SOD1) are a well-established cause of amyotrophic lateral sclerosis (ALS). The mutations promote SOD1 misfolding, resulting in protein aggregation and motor neuron degeneration. SOD1 is normally a structurally stable enzyme, and the mechanisms underlying SOD1 misfolding remain poorly understood. Approximately one third of SOD1 in cerebrospinal fluid (CSF) exhibits an N-terminal truncation, the biological significance of which remains unclear. This is remarkable given the dramatic effects ALS-linked C-terminal truncations have on the enzyme. In this study, we identified the truncation site and investigated its impact on SOD1 stability and enzymatic activity. Edman degradation revealed the cleavage site between Asn-26 and Gly-27, generating a 26-residue peptide that was confirmed by mass spectrometry. We analyzed postmortem tissues from different parts of the central nervous system (CNS), including the choroid plexus, and found only trace amounts of N-terminally truncated SOD1. Biochemical characterization of the SOD1 in CSF was done by size exclusion chromatography, ion exchange chromatography, and mass spectrometry. Our findings demonstrate that SOD1 in CSF retains full enzymatic activity, that the N-terminally truncated variant is mainly present in heterodimers with native SOD1 subunits, and that the dimer remains folded and active, with both fragments of the truncated SOD1 fixed after proteolysis. Truncated SOD1 was absent in human plasma. In mice, only transgenically expressed human SOD1 underwent truncation in CSF, whereas endogenous murine SOD1 remained intact. Lastly, the N-terminal truncation does not induce misfolding, unlike the destabilizing effects observed with C-terminal truncations. The location where the truncation takes place and the underlying mechanism could not be identified. Whether the N-truncated SOD1 variant contributes to ALS pathogenesis remains to be determined.

ID: 41702846
Title: Efficient induction of motor neuron disease in transgenic G93A SOD1 mice by prion-like seeding.
Abstract: Mutations in superoxide dismutase 1 (SOD1) cause paralysis in familial amyotrophic lateral sclerosis and promote its misfolding into neurotoxic aggregates. Previous studies have shown that mice expressing the ALS-causing G85R variant of SOD1 develop paralysis much faster after intraspinal injection of spinal homogenates from paralysed G85R SOD1 mice. These findings, and other studies in cell models, established the prionoid templating properties of misfolded mutant SOD1. Previously, however, we noted that the widely used Gur1-G93A SOD1 mice, which express at high levels and develop paralysis by 6 months of age, were resistant to seeding by homogenates from paralysed G93A mice. A line of G93A mice that expresses at very low levels (VLE-G93A) was responsive to seeding but at low efficiency. The poor susceptibility of G93A-SOD1 mice to seeding was not what we expected if prion-like propagation is essential to SOD1 ALS pathogenesis. In our prior studies, seeding homogenates from paralysed G93A-SOD1 mice were injected into the spine of newborn mice, leading us to question whether older G93A SOD1 mice might be more susceptible to seeding. Here, we establish that adult VLE G93A SOD1 mice (up to 12 months of age) injected intrathecally with seeding homogenates containing misfolded G93A or G85R SOD1 developed accelerated motor neuron disease efficiently. Thus, we demonstrate that both the route and age of inoculation can influence the efficiency of SOD1 seeding to induce motor neuron disease in VLE G93A-SOD1 mice. These data, together with our earlier reports, suggest that prion-like templating contributes to disease progression in SOD1-ALS.

ID: 41764208
Title: SOD1 lactylation impair its enzymatic activity by conformational change to aggravate intervertebral disc degeneration.
Abstract: Lactate accumulation is a hallmark and contributing factor of intervertebral disc degeneration (IVDD), while the role of protein lactylation caused by lactate accumulation in IVDD remains unclear. Via metabolomics, single-cell RNA-sequencing analysis, and lactylation proteomics, we reveal the lactylome landscape in IVDD and identified superoxide dismutase 1 (SOD1) lactylation at lysine 123 (SOD1K123la) as crucial for IVDD aggravation. Using in vitro site-directed mutagenesis, in vivo generation of SOD1K123R mutant male rats, and in silico molecular dynamics simulations, we find that SOD1K123la alters SOD1 conformation and impairs its enzymatic activity, and induces oxidative damage, and activates p53 pathway in nucleus pulposus cells (NPCs). Notably, we identify a small molecule ZL-01 that inhibits SOD1K123la. NPC-targeted delivery of ZL-01 via collagen type II-targeted peptide-modified extracellular vesicles alleviated IVDD in male rats. Together, these findings clarify the mechanism by which SOD1K123la promotes IVDD aggravation and provide a promising therapeutic strategy for IVDD.

ID: 41838744
Title: Lumbar Intrathecal Injection of SOD1-ASOs for Precise CNS Targeting and Predictive Efficacy in Human SOD1-G93A ALS Mice.
Abstract: Intrathecal (IT) administration of central nervous system (CNS)-targeted therapeutics offers a minimally invasive route for direct drug delivery into the cerebrospinal fluid (CSF), facilitating enhanced specificity and target engagement. While IT catheterization is standard for sustained delivery in rats, its application in mice is limited by anatomical constraints and elevated risk of procedure-related complications, including spinal injury and infection. To overcome these limitations, we employed an acute needle puncture technique for IT drug delivery in adult mice, providing a reproducible and less invasive alternative compatible with single or repeated dosing regimens. In a transgenic mouse model of amyotrophic lateral sclerosis (ALS) harboring the SOD1-G93A mutation, we achieved efficient IT delivery of antisense oligonucleotides (ASOs) targeting the SOD1 gene. This approach effectively downregulated mutant SOD1 expression and significantly ameliorated the disease phenotype, as demonstrated by electrophysiological and biomarker assessments. These results validate both the IT delivery method and the therapeutic efficacy, with outcomes comparable to intracerebroventricular (ICV) administration. Most importantly, the technique mirrors procedures used in human clinical studies, offering strong translational relevance and utility in preclinical evaluation of CNS-directed interventions. Although technical expertise is required to ensure consistency and avoid off-target effects, this IT delivery strategy represents a robust, reproducible, and clinically relevant methodology for advancing therapeutic development in small animal models.

ID: 41852184
Title: High Prevalence of SOD1 Pathogenic Variants in the UK Biobank: Implications for Early Intervention in Amyotrophic Lateral Sclerosis.
Abstract: SOD1 is the second most frequently mutated gene in European patients with amyotrophic lateral sclerosis (ALS). Given the recent authorization of SOD1-targeted antisense oligonucleotides for SOD1-ALS, prompt screening for SOD1 mutations in patients with ALS patients is highly recommended. Large-scale genomic analysis could inform on the population-based prevalence of SOD1 mutation carriers, who would potentially benefit from treatment. We aim to determine the number of people with pathogenic SOD1 variants in the UK Biobank (UKB), to address a critical gap between clinical and genetic prevalence of SOD1-ALS. We analyzed SOD1 variants within exome sequencing data from 470,000 individuals aged over 40 years. Pathogenicity was evaluated using referenced databases and American College of Medical Genetics and Genomics (ACMG) guidelines. Leveraging the UKB carrier frequency and age at onset data, we estimated the genetic prevalence of SOD1-ALS. We examined factors that may influence penetrance. We identified 122 individuals with monoallelic SOD1 coding variants, 93.4% of whom were asymptomatic. Additionally, the low-penetrance p.Asp91Ala variant was observed in heterozygosis in 535 subjects, whereas it was never found in homozygosis. Excluding this variant, the expected number of people developing SOD1-ALS is 1.04:100,000 in the UK population, 4 times higher than clinically reported figures. Symptomatic carriers had significantly increased levels of serum neurofilament at baseline. Age-related penetrance was higher in non-p.Asp91Ala carriers versus p.Asp91Ala carriers. Long-term survivor status was associated with p.Asp91Ala genotype, older age, and lower neurofilament levels. Incomplete and age-related penetrance, along with underascertainment due to disease heterogeneity and limitations in data collection, likely account for the reduced number of symptomatic patients identified. Our findings highlight the need to identify genetic and environmental factors, as well as biological indicators, able to influence disease penetrance and phenoconversion risk in presymptomatic carriers and to predict treatment response in patients. ANN NEUROL 2026;99:1502-1515.

ID: 41870290
Title: Scalable assay to identify inhibitors of prion-like propagation of protein misfolding as potential therapeutics for neurodegeneration.
Abstract: Protein misfolding is linked to many neurodegenerative diseases. In some cases, misfolding can propagate through a prion-like mechanism whereby natively folded molecules are converted into more copies of the misfolded isoform. Prion-like propagation of misfolding is an attractive therapeutic target, but difficulties with assaying conversion directly and simply have severely limited efforts to find drugs targeting conversion of disease-related proteins. Here, we demonstrate a scalable enzymatic assay for testing potential inhibitors of prion-like conversion in superoxide dismutase-1 (SOD1), whose misfolding is linked to amyotrophic lateral sclerosis (ALS). We tested several small-molecule inhibitors of SOD1 aggregation to determine if they also inhibited prion-like conversion. We found that some compounds, like telbivudine and cisplatin, did indeed significantly delay conversion, but others, like baicalein and quercetin, had little effect. Surprisingly, some compounds, like two statins tested, actually accelerated conversion, suggesting that they might act to promote ALS progression. These results underline the fact that conversion and aggregation are distinct biophysical processes. The ability of the assay to identify compounds effective at delaying prion-like conversion holds out promise for applications in future drug discovery efforts that target propagated misfolding specifically.

ID: 41967177
Title: Nose-to-brain delivery of a SOD1-stabilizing small molecule ameliorates pathology in an ALS mouse model.
Abstract: Exposure of a pathogenic β6/β7 loop neo-epitope has been proposed to contribute to the pathogenesis of misfolded Cu/Zn superoxide dismutase (SOD1) in amyotrophic lateral sclerosis (ALS) by mediating early events in its noxious structural transformation and prion-like activity. Antibody-mediated blockade of this epitope was shown to ameliorate disease phenotype in an ALS animal model. Here, as an alternative strategy, we sought to block this epitope using a small molecule designed to occupy the inter-subunit cavity framed by the two β6/β7 loops. Using a structure-based virtual screen targeting this cavity, we identified a small molecule, N-[3-(3-methylimidazo[2,1-b][1,3]thiazol-6-yl)phenyl]-4-sulfamoylbenzamide (C7), that preferentially bound the native-like conformation of SOD1, reduced β6/β7 loop epitope accessibility, and inhibited irreversible apo-SOD1 misfolding in vitro. Delivered to presymptomatic hSOD1G93A mice via a nanoparticle-based nose-to-brain delivery system, C7 significantly delayed the onset of motor abnormalities and modestly extended survival. At disease onset, spinal cord analysis revealed reduced misfolded SOD1 inclusions and attenuated astro- and microgliosis. Analysis of C7 concentrations in combined brain and spinal cord tissue indicated rapid but saturable nose-to-CNS uptake and slow clearance. Our findings demonstrate that targeting the surface cavity shaped by the β6/β7 loops of SOD1 with a reversibly-binding small molecule can ameliorate ALS-like disease in vivo, potentially by counteracting early misfolding events and/or limiting prion-like propagation of molecular pathology. However, saturable nose-to-CNS uptake of C7 restricts CNS exposure and likely constrains therapeutic efficacy, underscoring the need to define the rate-limiting pharmacokinetic step and to optimize the nanoparticle formulation and/or physicochemical properties of the C7 scaffold.

ID: 42118400
Title: Mechanism of the N87D mutation in SOD1-atypical amyotrophic lateral sclerosis case report and literature review molecular mechanism of N87D mutation in SOD1.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with unclear pathogenesis. This study aimed to investigate the possible molecular mechanisms of ALS by analyzing protein structure and dynamics in a rapidly progressing ALS patient carrying the N87D mutation. A patient with the N87D mutation experienced rapid disease progression and died within one year. We reviewed all known mutations at the 87th position of the superoxide dismutase (SOD1) gene and the clinical characteristics. To investigate the molecular basis of the severe phenotype, we performed protein structure modeling and molecular dynamics (MD) simulations, and compared wild type homodimers, mutant homodimers, and heterodimers in terms of energy, residue fluctuation, number of hydrogen bonds, radius of gyration (Rg), principal component analysis (PCA), free energy landscape (FEL), the contribution of dimer interface residues, solvent-accessible surface area, and metal ion coordination. Our analysis revealed that patients with mutations at the 87th position of the SOD1 gene typically exhibited rapid disease progression. Protein structure modeling and MD simulations demonstrated that the N87D mutation significantly increased the energy and RMSF of SOD1 heterodimers compared to homodimers. Furthermore, Rg, FEL and PCA analyses showed that the heterodimers had a broader and more unstable conformational energy distribution, along with a stronger tendency for aggregation. Additionally, the N87D mutation disrupted metal ion coordination, further destabilizing the heterodimer and promoting protein misfolding. These findings suggest a potential molecular mechanism underlying ALS and support a protein structure based approach for investigating the pathogenic mechanisms of disease causing mutations.

ID: 42125835
Title: Tracking Protein Misfolding and Oligomerization: A Temperature-Controlled Ion Mobility-Mass Spectrometry Approach.
Abstract: Aberrant protein oligomerization is a hallmark of neurodegenerative disorders, yet the conformational and kinetic underpinnings of early aggregation remain poorly understood due to the inability of structural techniques to capture transient, low-abundance oligomeric intermediates. This necessitates the development of a methodology that can characterize the conformational states related to protein unfolding and thus allow for the investigation of the molecular mechanism responsible for disease progression. Here, we demonstrate how temperature-controlled nanoelectrospray ionization (TC-nESI) combined with high-resolution ion mobility-mass spectrometry (IM-MS), surface-induced dissociation (SID), and limited proteolysis can be used to define the misfolding and oligomerization landscape of bovine Cu/Zn superoxide dismutase (SOD1). This integrative approach enables real-time detection of coexisting intermediates, and captures molecular events including metal-induced stability, monomer unfolding and assembly into heterogeneous soluble oligomers. Our results reveal that both holo- and apo-SOD1 undergo dimer dissociation followed by monomer misfolding and assembly into heterogeneous non-native oligomers, and that slow thermal ramping promotes the accumulation of misfolded monomers and higher-order complexes. Apo-SOD1 that lacks stabilizing metal cofactors, forms more compact and kinetically distinct oligomers via monomeric, dimeric and trimeric intermediates. Proteolysis and heat-induced fragmentation identify loops V, VI, VII, and the C-terminus as key labile regions contributing to oligomer interface formation, predominantly through hydrophobic interactions. Our findings establish a mechanistically rich model for early aggregation and demonstrate the capability of TC-nESI-IM-MS to temporally and structurally resolve misfolding transitions and oligomeric populations in a single experiment. This platform provides a framework to dissect oligomerization pathways relevant to neurodegenerative diseases.