{"gene":"SOD1","run_date":"2026-06-10T07:46:38","timeline":{"discoveries":[{"year":2002,"finding":"SOD1 (CuZn-SOD) is a copper- and zinc-containing homodimer that catalyzes the dismutation of superoxide anions to oxygen and hydrogen peroxide, and is found almost exclusively in intracellular cytoplasmic spaces.","method":"Biochemical characterization, enzymatic assay, subcellular fractionation","journal":"Free radical biology & medicine","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted enzymatic activity, metal cofactor identification, and localization replicated across many independent studies over decades","pmids":["12126755"],"is_preprint":false},{"year":2013,"finding":"SIRT5 binds to SOD1, desuccinylates it, and thereby activates its enzymatic activity; succinylation of SOD1 decreases its dismutase activity, establishing succinylation/desuccinylation as a post-translational regulatory mechanism for SOD1.","method":"Co-immunoprecipitation, in vitro desuccinylation assay, enzymatic activity assay, site-directed mutagenesis of succinylation site","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal binding shown, enzymatic activity measured, mutagenesis performed, but single lab study","pmids":["24140062"],"is_preprint":false},{"year":2013,"finding":"In yeast and mammalian cells, SOD1 transmits signals from oxygen and glucose to repress respiration by stabilizing casein kinase 1-gamma (CK1γ) homologs (Yck1p/Yck2p); SOD1 binds a C-terminal degron in Yck1p/Yck2p and promotes kinase stability by catalyzing superoxide conversion to peroxide, which is required for respiratory repression.","method":"Genetic epistasis in yeast, co-immunoprecipitation, in vitro binding assay, enzymatic activity assays, mammalian cell line validation","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods including binding assays, epistasis, enzymatic assays, and cross-species validation in a single rigorous study","pmids":["23332757"],"is_preprint":false},{"year":2018,"finding":"mTORC1 phosphorylates SOD1 at S39 (yeast) / T40 (human) in response to nutrients, which reversibly modulates SOD1 activity, moderates ROS levels, and prevents oxidative DNA damage; this is a conserved nutrient-sensing redox regulatory mechanism.","method":"In vitro kinase assay, site-directed mutagenesis, ROS measurement, DNA damage assay, conservation analysis across species","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro kinase reconstitution, mutagenesis of phosphorylation site, functional consequences demonstrated with multiple orthogonal methods","pmids":["29727620"],"is_preprint":false},{"year":2022,"finding":"SOD1 integrates oxygen availability to regulate NADPH production: Sod1-derived H2O2 oxidatively inactivates the glycolytic enzyme GAPDH, which reroutes carbohydrate flux to the oxidative pentose phosphate pathway (oxPPP) to generate NADPH; this mechanism requires the bulk of cellular Sod1.","method":"Genetic knockout in yeast and mammalian cells, biochemical flux measurements, mass spectrometry proteomics, GAPDH activity assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — mechanism defined biochemically in multiple organisms with loss-of-function genetics and enzyme activity assays","pmids":["34969852"],"is_preprint":false},{"year":2002,"finding":"Dorfin, a RING finger E3 ubiquitin ligase, physically binds and ubiquitylates ALS-linked mutant SOD1 proteins (but not wild-type SOD1), targeting them for proteasomal degradation and reducing SOD1 inclusions; Dorfin overexpression protects neural cells from mutant SOD1 toxicity.","method":"Co-immunoprecipitation, ubiquitylation assay, proteasome inhibition, cell viability assay, immunohistochemistry","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP and functional ubiquitylation assay shown, selective for mutant vs. wild-type SOD1, single lab","pmids":["12145308"],"is_preprint":false},{"year":2009,"finding":"The ER-resident E3 ubiquitin ligase gp78 interacts with SOD1 (both wild-type and mutant), promotes its ubiquitination and proteasomal degradation via ER-associated degradation (ERAD), and reduces mutant SOD1 aggregate formation and cell death.","method":"Co-immunoprecipitation, ubiquitination assay, knockdown/overexpression with stability measurements, cell viability assay","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, functional ubiquitination, and degradation assays performed; single lab, multiple methods","pmids":["19661182"],"is_preprint":false},{"year":2019,"finding":"Human CCS (hCCS) catalyzes SOD1 maturation through a stepwise mechanism involving: molecular recognition of immature SOD1 driven by interface interactions, induced-fit complexation stabilizing the SOD1 disulphide sub-loop, copper transfer to the SOD1 active site, and delayed disulphide formation; a single destabilizing substitution in hCCS reduces homodimer affinity to create a pool available for SOD1 interaction.","method":"X-ray crystallography of reaction precursors, intermediates, and products; biochemical assays for copper transfer and SOD1 activation","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structures of multiple reaction states combined with functional biochemical validation in a single rigorous study","pmids":["30735496"],"is_preprint":false},{"year":2016,"finding":"A faulty interaction between ALS-associated hCCS mutations and SOD1 occurs because the hCCS mutation abrogates zinc binding, which inhibits hCCS-SOD1 heterodimer formation; SOD1 zinc loss also disrupts the hCCS-SOD1 interaction, showing mutual dependence on zinc for complex stability.","method":"Chromatographic SAXS, biochemical binding assays, zinc binding measurements","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — structural (SAXS) and biochemical methods, single lab, two orthogonal approaches","pmids":["27282955"],"is_preprint":false},{"year":2014,"finding":"DJ-1 acts as a copper chaperone for SOD1: DJ-1 binds copper ions through a novel Cys-106 site, and transfers copper to SOD1 to increase its dismutase activity, as demonstrated by fluorescence spectroscopy and biochemical SOD1 activity assays.","method":"X-ray crystallography (novel copper binding site), fluorescence spectroscopy for copper transfer kinetics, SOD1 activity biochemical assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — structural characterization of copper binding site plus functional copper transfer assays, single lab","pmids":["24567322"],"is_preprint":false},{"year":2010,"finding":"ALS mutant SOD1 preferentially associates with the cytoplasmic face of spinal cord mitochondria and causes a selective decrease (>50%) in protein import into spinal cord (but not liver) mitochondria; this effect is specific to misfolded mutant SOD1 (G93A or G85R) and not wild-type SOD1 or misfolded alpha-synuclein.","method":"Mitochondrial fractionation, 2D-gel proteomics and LC-MS/MS, direct in vitro import assay with recombinant proteins","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — direct import assay with recombinant proteins plus proteomic characterization, multiple controls, rigorous tissue specificity analysis","pmids":["21078990"],"is_preprint":false},{"year":2016,"finding":"ALS mutant SOD1 (G93A) interacts with the stress granule protein G3BP1 in an RNA-independent manner, requiring the G3BP1 RRM domain and residues F380/F382; this interaction delays stress granule formation in response to stress stimuli and co-localizes with G3BP1-positive granules in motor neurons of mutant SOD1 mice.","method":"Co-immunoprecipitation, co-localization by immunofluorescence, stress granule dynamics assay, domain mapping by mutagenesis","journal":"Acta neuropathologica","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP, mutagenesis to map interaction domain, cellular functional readout; single lab","pmids":["27481264"],"is_preprint":false},{"year":2015,"finding":"Alpha-synuclein physically interacts with SOD1 in living cells, human erythrocytes, and mouse brain tissue; alpha-synuclein accelerates SOD1 oligomerization independent of SOD1 dismutase activity; ALS and PD mutations in each protein modify the binding interaction.","method":"Protein-fragment complementation assay (BiFC), co-immunoprecipitation, oligomerization assay","journal":"Molecular neurodegeneration","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — multiple orthogonal binding methods (BiFC + co-IP) in multiple cell/tissue systems, single lab","pmids":["26643113"],"is_preprint":false},{"year":2008,"finding":"Metal-free (apo) forms of ALS mutant SOD1 (and wild-type) oligomerize via oxidation of free cysteines C6 and C111, forming amyloid-like soluble oligomers stabilized by inter-strand hydrogen bonds; all eleven mutants tested share this common mechanism of oligomerization when demetallated.","method":"Circular dichroism, thioflavin T binding fluorescence, size-exclusion chromatography, light scattering spectroscopy","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biophysical methods in a single study, single lab, no mutagenesis to confirm cysteine role directly","pmids":["18301754"],"is_preprint":false},{"year":2018,"finding":"Nonnative trimeric (not large fibrillar aggregate) SOD1 is the cytotoxic species in ALS: engineered trimer-stabilizing mutations (G147P) promoted motor neuron-like cell death more potently than ALS mutants A4V or G93A, while fibril-stabilizing mutations (N53I, D101I) did not impair cell viability and large aggregates competed with toxic trimer formation.","method":"Structure-guided protein engineering, gel filtration chromatography, electron microscopy, cell viability assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — engineered mutations with defined structural outcomes, multiple characterization methods, single lab","pmids":["29666246"],"is_preprint":false},{"year":2007,"finding":"Wild-type SOD1 localizes to both cytoplasm and nuclei of motoneurons, whereas mutant G93A-SOD1 is mainly cytoplasmic; this nuclear exclusion of mutant SOD1 results in higher DNA damage after oxidative stress, indicating that nuclear SOD1 provides protection from oxidative DNA damage.","method":"Immunofluorescence/confocal microscopy in transgenic mice and NSC34 cells, proteasome activity assay in subcellular fractions, comet assay for DNA damage","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct subcellular fractionation and imaging with functional consequence (DNA damage) measured, single lab, two cell systems","pmids":["17504823"],"is_preprint":false},{"year":2023,"finding":"SOD1 functions as an H2S oxidase: SOD1 rapidly converts H2S to sulfate under limiting sulfide conditions; when sulfide is in molar excess, SOD1 catalyzes formation of per- and polysulfides. Loss of SOD1 increases cellular sensitivity to H2S toxicity, while SOD1 overexpression enhances tolerance, establishing an essential H2S detoxification role.","method":"Genetic knockout (yeast and human cells), overexpression experiments, biochemical H2S oxidation assay, ROS measurement","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — enzymatic activity demonstrated biochemically, loss-of-function and gain-of-function genetics in two organisms, multiple orthogonal methods","pmids":["36630448"],"is_preprint":false},{"year":2020,"finding":"SOD1 regulates canonical Wnt signaling: SOD1-derived H2O2 stabilizes CK1γ (the human homolog of yeast Yck1/2), and SOD1 knockdown reduces CK1γ expression and impairs Wnt-dependent cell proliferation in human HEK293 cells.","method":"SOD1 knockdown in HEK293 cells, CK1γ expression measurement, Wnt reporter assay, cell proliferation assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined pathway readout, extends yeast findings to human cells, single lab","pmids":["33218686"],"is_preprint":false},{"year":2012,"finding":"SOD1 knockout in mice leads to pyruvate intolerance, decreased liver glycogen storage, reduced phosphoenolpyruvate carboxykinase and protein phosphatase activities, elevated glucokinase activity, and increased hepatic lipid profiles (cholesterol, triglycerides, free fatty acids), demonstrating SOD1's role in regulating hepatic gluconeogenesis, glycolysis, and lipogenesis.","method":"Sod1 knockout mouse model, pyruvate tolerance test, enzymatic activity assays, protein level measurements by Western blot","journal":"Free radical biology & medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO model with specific metabolic phenotypes and mechanistic enzyme activity measurements; single lab","pmids":["22974764"],"is_preprint":false},{"year":2014,"finding":"SOD1 binds PCBP1 (a nuclear poly(rC) binding protein) in pig brain but not mouse brain; in transgenic pigs expressing mutant G93A hSOD1, mutant SOD1 showed nuclear accumulation and formed ubiquitinated nuclear aggregates rather than cytoplasmic inclusions, suggesting the SOD1-PCBP1 interaction accounts for species-specific nuclear SOD1 accumulation.","method":"Co-immunoprecipitation from pig and mouse brain tissue, immunofluorescence, ubiquitin immunostaining in transgenic pigs","journal":"Cell research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single co-IP from tissue, no functional validation of the PCBP1-SOD1 interaction, single study","pmids":["24577199"],"is_preprint":false},{"year":2024,"finding":"Plekhg5 (a guanine exchange factor) drives unconventional secretion of Sod1 by sequestering it into autophagosomal carriers that fuse with secretory lysosomal-related organelles (LROs); exocytosis of LROs to release Sod1 requires activation of the small GTPase Rab26 by Plekhg5; deletion of Plekhg5 in mice causes Sod1 accumulation in LROs at presynaptic sites and reduces secretion of ALS-linked SOD1G93A.","method":"Plekhg5 knockout mice, live imaging of autophagosomal carriers, co-localization studies, iPSC-derived motoneurons, secretion assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with defined cellular phenotype, mechanistic pathway involving Rab26 activation, validated in human iPSC neurons; single lab","pmids":["39366938"],"is_preprint":false},{"year":2021,"finding":"Restoration of SOD1 expression specifically in neurons of Sod1-deficient mice (SynTgSod1-/- mice) prevents muscle mitochondrial dysfunction (elevated ROS, impaired NADH recovery), abnormal calcium handling, and NMJ denervation/fragmentation, despite continued absence of SOD1 in muscle, demonstrating that muscle mitochondrial defects in Sod1-/- mice are secondary to neuronal oxidative stress affecting NMJ innervation.","method":"Transgenic neuronal-specific SOD1 rescue, mitochondrial ROS measurement, oxygen consumption assay, intracellular calcium transient measurement, NMJ morphology analysis","journal":"Free radical biology & medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — neuron-specific genetic rescue with multiple orthogonal functional readouts, clean experimental design distinguishing cell-autonomous vs. non-cell-autonomous effects","pmids":["33561489"],"is_preprint":false},{"year":2011,"finding":"In a zebrafish genetic epistasis analysis, SOD1 acts in a pathogenic pathway independent of FUS and TARDBP: wild-type SOD1 failed to rescue phenotypes caused by mutant FUS or TARDBP, and wild-type FUS/TARDBP failed to rescue mutant SOD1 phenotypes; overexpression of mutant SOD1 exacerbated the motor phenotype of mutant FUS.","method":"Zebrafish knockdown/overexpression genetics, motor phenotype scoring, epistasis analysis","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with multiple allele combinations in zebrafish, single lab, clear pathway placement","pmids":["21829392"],"is_preprint":false},{"year":2011,"finding":"Mutant SOD1 A4V forms ion channel-like tetrameric pore structures (outer diameter 12.2 nm, inner diameter 3.0 nm) when reconstituted in lipid membranes, produces distinct ionic conductances not seen with wild-type SOD1, and causes membrane depolarization and intracellular calcium increase in neuroblastoma cells.","method":"Atomic force microscopy (AFM), electrophysiology (bilayer recordings), calcium imaging in neuroblastoma cells","journal":"Neurobiology of disease","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — in vitro reconstitution with AFM and electrophysiology, cellular validation, single lab","pmids":["21930207"],"is_preprint":false},{"year":2022,"finding":"Homozygous in-frame deletion of Val119/120 in SOD1 results in complete absence of SOD1 enzymatic activity and undetectable SOD1 protein despite preserved mRNA/splicing, causing an infantile progressive motor-neurological syndrome through loss-of-function; heterozygous carriers have ~50% activity.","method":"Exome sequencing, cDNA analysis, SOD1 activity assay in erythrocyte lysates, protein quantification by Western blot","journal":"Brain : a journal of neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — enzymatic activity and protein level measurement in patient-derived material confirming variant functional consequence; single patient study","pmids":["34788402"],"is_preprint":false},{"year":2019,"finding":"CuO nanoparticle-induced copper overload causes SOD1 misfolding and mitochondrial translocation in macrophages; chelation of copper with tetrathiomolybdate prevented cell death while inhibition of SOD1's chaperone (CCS) aggravated toxicity, indicating copper loading disrupts normal SOD1 folding and mitochondrial localization.","method":"TEM, ICP-MS, circular dichroism spectroscopy, confocal microscopy with aggresome dye, proteasome activity assay, pharmacological inhibition","journal":"Particle and fibre toxicology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — cellular observations of misfolding without direct mechanistic dissection of SOD1 specifically, single study, indirect methods","pmids":["35538581"],"is_preprint":false},{"year":2017,"finding":"In muscle-specific SOD1G93A transgenic mice (MLC/SOD1G93A), mutant SOD1 expression triggers NMJ dismantlement via PKCθ activation: perturbation of redox signaling by muscle-accumulated SOD1G93A causally leads to morphological alterations in presynaptic terminals, high acetylcholine receptor turnover, and NMJ disintegration through a PKCθ-dependent mechanism.","method":"Transgenic mouse model with muscle-specific expression, immunofluorescence, AChR turnover assay, PKCθ activity measurement and pharmacological inhibition","journal":"Antioxidants & redox signaling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — tissue-specific transgenic model with mechanistic PKCθ pathway identification and pharmacological validation; single lab","pmids":["28931313"],"is_preprint":false},{"year":2021,"finding":"High-fat/palmitic acid treatment decreases CCS (copper chaperone for SOD1) levels in neuronal cells, which promotes nuclear import of SOD1 and reduces its cytoplasmic dismutase activity, leading to elevated ROS; this mechanism was confirmed in high-fat diet mice showing reduced hippocampal SOD1 activity and CCS levels.","method":"Cell culture treatment with palmitic acid, CCS knockdown/measurement, SOD1 activity assay, subcellular fractionation, high-fat diet mouse model","journal":"Life sciences","confidence":"Low","confidence_rationale":"Tier 3 / Weak — correlative mechanistic link between CCS and SOD1 activity, indirect subcellular localization, single lab","pmids":["33607157"],"is_preprint":false}],"current_model":"SOD1 is a copper- and zinc-dependent homodimeric enzyme that catalyzes superoxide dismutation to O2 and H2O2; beyond antioxidant defense, SOD1-derived H2O2 acts as a redox signal that regulates GAPDH activity and NADPH production via the pentose phosphate pathway, stabilizes CK1γ to control respiration and Wnt signaling, and responds to mTORC1-mediated phosphorylation (T40) to couple nutrient sensing to redox homeostasis; SOD1 is also an H2S oxidase, is activated by CCS-mediated copper insertion and disulfide bond formation, is regulated by SIRT5-dependent desuccinylation, is targeted for proteasomal degradation by E3 ligases Dorfin and gp78, is unconventionally secreted from presynaptic terminals via a Plekhg5/Rab26/autophagosome pathway, and its ALS-linked mutations cause misfolding to toxic oligomeric (trimeric) states, mitochondrial association with impaired protein import, nuclear exclusion with consequent DNA damage, and aberrant interactions with G3BP1 disrupting stress granule dynamics."},"narrative":{"mechanistic_narrative":"SOD1 is a copper- and zinc-dependent cytoplasmic homodimer that catalyzes the dismutation of superoxide to oxygen and hydrogen peroxide, serving both as a core antioxidant enzyme and as a generator of H2O2 used in redox signaling [PMID:12126755]. Beyond detoxification, SOD1-derived H2O2 functions as a second messenger that reroutes metabolism and signaling: it oxidatively inactivates GAPDH to divert carbohydrate flux into the oxidative pentose phosphate pathway for NADPH production [PMID:34969852], stabilizes casein kinase 1-gamma (CK1γ/Yck1/2) to repress respiration in response to oxygen and glucose [PMID:23332757] and to sustain canonical Wnt signaling and proliferation [PMID:33218686]. This signaling output is gated by nutrient sensing through mTORC1-mediated phosphorylation at T40, which tunes SOD1 activity to moderate ROS and prevent oxidative DNA damage [PMID:29727620]. SOD1 also acts as an H2S oxidase, converting sulfide to sulfate or to per/polysulfides depending on sulfide levels and protecting cells from H2S toxicity [PMID:36630448]. Enzymatic competence requires maturation by the copper chaperone CCS, which recognizes immature SOD1, transfers copper, and drives disulfide formation [PMID:30735496]; metal loading and activity are additionally modulated by SIRT5-mediated desuccinylation [PMID:24140062] and by alternative copper delivery via DJ-1 [PMID:24567322]. At the organismal level SOD1 governs hepatic gluconeogenic, glycolytic, and lipogenic metabolism [PMID:22974764] and protects neuromuscular integrity, with neuronal SOD1 being sufficient to prevent muscle mitochondrial dysfunction and neuromuscular junction denervation in a non-cell-autonomous manner [PMID:33561489]. ALS-linked mutant SOD1 acquires toxic gain-of-function properties: metal-free oligomerization through cysteine oxidation [PMID:18301754], formation of a cytotoxic nonnative trimer [PMID:29666246], association with the cytoplasmic face of mitochondria with impaired protein import [PMID:21078990], nuclear exclusion that elevates oxidative DNA damage [PMID:17504823], and aberrant RNA-independent binding to G3BP1 that delays stress granule assembly [PMID:27481264]; such misfolded species are selectively cleared by the E3 ligases Dorfin and the ERAD ligase gp78 [PMID:12145308, PMID:19661182]. A homozygous in-frame SOD1 deletion causing complete loss of enzymatic activity produces an infantile progressive motor-neurological syndrome, establishing a loss-of-function disease mechanism distinct from the toxic gain-of-function of ALS mutants [PMID:34788402].","teleology":[{"year":2002,"claim":"Established the foundational identity of SOD1 as a metal-dependent enzyme, defining the catalytic activity and localization on which all later signaling and disease work builds.","evidence":"Biochemical enzymatic assay, metal cofactor identification, and subcellular fractionation","pmids":["12126755"],"confidence":"High","gaps":["Does not address non-canonical signaling or substrate roles","No structural mechanism of catalysis defined here"]},{"year":2002,"claim":"Addressed how cells handle toxic mutant SOD1 by identifying Dorfin as an E3 ligase selectively ubiquitylating mutant but not wild-type SOD1, framing proteostatic clearance as a protective axis.","evidence":"Co-IP, ubiquitylation and proteasome assays in neural cells","pmids":["12145308"],"confidence":"Medium","gaps":["Selectivity determinants for mutant SOD1 not defined","In vivo relevance to ALS not established"]},{"year":2007,"claim":"Showed that nuclear localization of SOD1 is protective and that mutant SOD1 nuclear exclusion increases oxidative DNA damage, linking SOD1 subcellular distribution to genome protection.","evidence":"Immunofluorescence, subcellular fractionation, and comet assay in transgenic mice and NSC34 cells","pmids":["17504823"],"confidence":"Medium","gaps":["Mechanism of nuclear import/exclusion unresolved","Whether DNA damage drives motor neuron death not shown"]},{"year":2008,"claim":"Defined a shared biophysical route to toxic species, showing that demetallated SOD1 oligomerizes via free-cysteine oxidation across many ALS mutants.","evidence":"CD, thioflavin T fluorescence, size-exclusion chromatography, light scattering","pmids":["18301754"],"confidence":"Medium","gaps":["No mutagenesis to directly confirm cysteine roles","Link between in vitro oligomers and cellular toxicity not made"]},{"year":2009,"claim":"Extended SOD1 quality control by showing the ERAD ligase gp78 degrades both wild-type and mutant SOD1 and reduces aggregation, identifying a second clearance pathway.","evidence":"Co-IP, ubiquitination, stability and viability assays with knockdown/overexpression","pmids":["19661182"],"confidence":"Medium","gaps":["Relative contribution vs. other ligases unknown","ER-association of SOD1 substrate pool not defined"]},{"year":2010,"claim":"Identified a tissue-selective toxic mechanism whereby misfolded mutant SOD1 binds spinal cord mitochondria and impairs protein import, connecting SOD1 misfolding to mitochondrial dysfunction.","evidence":"Mitochondrial fractionation, LC-MS/MS proteomics, direct in vitro import assay","pmids":["21078990"],"confidence":"High","gaps":["Import machinery component targeted not identified","Why spinal cord mitochondria are selectively vulnerable unclear"]},{"year":2011,"claim":"Placed SOD1 genetically in an ALS pathway independent of FUS and TARDBP, indicating mechanistic divergence among ALS genes.","evidence":"Zebrafish epistasis with mutant/wild-type allele combinations","pmids":["21829392"],"confidence":"Medium","gaps":["Molecular basis of pathway independence not defined","Model-organism context limits direct human inference"]},{"year":2011,"claim":"Offered a membrane-toxicity mechanism by showing mutant A4V SOD1 forms pore-like structures causing membrane depolarization and calcium influx.","evidence":"AFM, bilayer electrophysiology, calcium imaging in neuroblastoma cells","pmids":["21930207"],"confidence":"Medium","gaps":["In vivo occurrence of pores not demonstrated","Relation to oligomer/trimer species unclear"]},{"year":2012,"claim":"Demonstrated a systemic metabolic role by showing Sod1 knockout disrupts hepatic gluconeogenesis, glycolysis, and lipogenesis.","evidence":"Sod1 knockout mice, pyruvate tolerance test, enzyme activity assays","pmids":["22974764"],"confidence":"Medium","gaps":["Direct redox targets among metabolic enzymes not identified","Whether effects are cell-autonomous in liver unknown"]},{"year":2013,"claim":"Reframed SOD1 as a redox signaling hub by showing its H2O2 product stabilizes CK1γ homologs to repress respiration in response to oxygen and glucose.","evidence":"Yeast epistasis, co-IP, in vitro binding, enzymatic assays, mammalian validation","pmids":["23332757"],"confidence":"High","gaps":["Precise redox-sensitive residue on CK1γ not pinpointed","Generality across cell types incompletely mapped"]},{"year":2013,"claim":"Identified succinylation/desuccinylation by SIRT5 as a post-translational switch controlling SOD1 dismutase activity.","evidence":"Co-IP, in vitro desuccinylation, activity assays, site mutagenesis","pmids":["24140062"],"confidence":"Medium","gaps":["Physiological conditions driving succinylation unknown","Single-lab finding without in vivo confirmation"]},{"year":2014,"claim":"Proposed an alternative copper-delivery route by showing DJ-1 binds copper at Cys-106 and transfers it to activate SOD1.","evidence":"X-ray crystallography of copper site, fluorescence kinetics, activity assays","pmids":["24567322"],"confidence":"Medium","gaps":["Relative contribution vs. CCS in vivo not established","Cellular conditions favoring DJ-1 route unknown"]},{"year":2014,"claim":"Linked a species-specific SOD1-PCBP1 interaction to nuclear accumulation of mutant SOD1 in transgenic pigs.","evidence":"Co-IP from pig and mouse brain, immunofluorescence, ubiquitin staining","pmids":["24577199"],"confidence":"Low","gaps":["Single tissue co-IP without functional validation of PCBP1 binding","Human relevance untested"]},{"year":2015,"claim":"Connected SOD1 to alpha-synuclein, showing direct interaction that accelerates SOD1 oligomerization independent of dismutase activity.","evidence":"BiFC, co-IP, oligomerization assays in cells, erythrocytes, and brain","pmids":["26643113"],"confidence":"Medium","gaps":["Structural interface not resolved","In vivo pathological consequence not established"]},{"year":2016,"claim":"Defined a toxic protein-interaction mechanism whereby mutant SOD1 binds G3BP1 via its RRM domain and delays stress granule assembly.","evidence":"Co-IP, domain mapping by mutagenesis, stress granule dynamics, motor neuron co-localization","pmids":["27481264"],"confidence":"Medium","gaps":["Consequence of delayed granule formation for neuron survival unclear","Reciprocal validation limited to single lab"]},{"year":2016,"claim":"Clarified maturation failure by showing ALS-associated hCCS mutations abrogate zinc binding, destabilizing the zinc-dependent hCCS-SOD1 heterodimer.","evidence":"Chromatographic SAXS and biochemical zinc/binding assays","pmids":["27282955"],"confidence":"Medium","gaps":["Downstream effect on SOD1 maturation in vivo not shown","Disease causality of CCS variants not established here"]},{"year":2017,"claim":"Demonstrated that muscle-autonomous mutant SOD1 dismantles the NMJ through PKCθ-dependent redox perturbation, implicating non-neuronal SOD1 toxicity.","evidence":"Muscle-specific SOD1G93A transgenic mice, AChR turnover, PKCθ activity and inhibition","pmids":["28931313"],"confidence":"Medium","gaps":["Redox target upstream of PKCθ not identified","Relative weight of muscle vs. neuronal contributions in ALS unclear"]},{"year":2018,"claim":"Resolved a key disease question by integrating mTORC1 phosphorylation (S39/T40) as a nutrient-responsive switch tuning SOD1 activity to limit oxidative DNA damage.","evidence":"In vitro kinase assay, mutagenesis, ROS and DNA damage assays, conservation analysis","pmids":["29727620"],"confidence":"High","gaps":["Phosphatase counteracting T40 not identified","Quantitative impact on catalytic cycle not defined"]},{"year":2018,"claim":"Identified the cytotoxic conformer in ALS as a nonnative trimer rather than large aggregates, refining the toxic-species model.","evidence":"Structure-guided engineering, gel filtration, EM, viability assays","pmids":["29666246"],"confidence":"Medium","gaps":["In vivo abundance of trimers not quantified","Mechanism by which trimers kill neurons unresolved"]},{"year":2019,"claim":"Provided a structural mechanism for SOD1 maturation, resolving stepwise CCS-mediated recognition, copper transfer, and disulfide formation.","evidence":"X-ray crystallography of precursors, intermediates, products plus biochemical validation","pmids":["30735496"],"confidence":"High","gaps":["Timing of in vivo maturation flux not measured","Interplay with alternative chaperones unaddressed"]},{"year":2020,"claim":"Extended the SOD1-CK1γ axis to humans, showing SOD1-derived H2O2 stabilizes CK1γ to support canonical Wnt signaling and proliferation.","evidence":"SOD1 knockdown, CK1γ measurement, Wnt reporter and proliferation assays in HEK293","pmids":["33218686"],"confidence":"Medium","gaps":["Direct oxidative modification site on CK1γ not defined","Tissue contexts where this operates not mapped"]},{"year":2021,"claim":"Established that neuronal SOD1 acts non-cell-autonomously to protect muscle, with neuronal rescue preventing muscle mitochondrial dysfunction and NMJ denervation.","evidence":"Neuron-specific transgenic rescue in Sod1-/- mice, mitochondrial ROS, oxygen consumption, calcium and NMJ analyses","pmids":["33561489"],"confidence":"High","gaps":["Signal transmitted from neuron to muscle not identified","Applicability to gain-of-function ALS mutants unclear"]},{"year":2022,"claim":"Defined a major metabolic output of SOD1, showing its H2O2 inactivates GAPDH to redirect flux into the oxPPP for NADPH generation.","evidence":"Yeast and mammalian knockouts, flux measurements, proteomics, GAPDH activity assays","pmids":["34969852"],"confidence":"High","gaps":["Spatial coupling of SOD1 and GAPDH not resolved","Quantitative share of NADPH supply via this route unclear"]},{"year":2022,"claim":"Demonstrated a loss-of-function human disease mechanism: complete SOD1 deficiency causes an infantile progressive motor-neurological syndrome, distinct from ALS gain-of-function.","evidence":"Exome sequencing, cDNA analysis, erythrocyte activity assays, protein quantification","pmids":["34788402"],"confidence":"Medium","gaps":["Cellular basis of motor neuron vulnerability to deficiency unclear","Single patient/family study"]},{"year":2023,"claim":"Expanded SOD1's catalytic repertoire by identifying it as an H2S oxidase essential for sulfide detoxification.","evidence":"Knockout and overexpression in yeast and human cells, H2S oxidation and ROS assays","pmids":["36630448"],"confidence":"High","gaps":["Active-site basis for sulfide vs. superoxide handling not resolved","Physiological sulfide sources targeted not defined"]},{"year":2024,"claim":"Identified the route of SOD1 secretion, showing Plekhg5 sequesters Sod1 into autophagosomal carriers that fuse with LROs for Rab26-dependent exocytosis at presynaptic terminals.","evidence":"Plekhg5 knockout mice, live imaging, co-localization, iPSC motoneurons, secretion assays","pmids":["39366938"],"confidence":"Medium","gaps":["Extracellular function of secreted SOD1 not defined","Whether secretion mitigates or spreads mutant SOD1 toxicity unclear"]},{"year":null,"claim":"It remains unresolved how SOD1's redox-signaling outputs, its H2S oxidase activity, and its propensity to misfold are mechanistically integrated, and which specific molecular events convert SOD1 dysfunction into selective motor neuron death.","evidence":"No single study in the timeline unifies the signaling, metabolic, and proteostatic axes","pmids":[],"confidence":"Low","gaps":["No unified model linking toxic conformers to defined cellular death pathway","Direct in vivo redox targets of SOD1-derived H2O2 incompletely catalogued","Relationship between secretion 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genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30079537","citation_count":20,"is_preprint":false},{"pmid":"31837419","id":"PMC_31837419","title":"Knockdown of GADD34 in neonatal mutant SOD1 mice ameliorates ALS.","date":"2019","source":"Neurobiology of disease","url":"https://pubmed.ncbi.nlm.nih.gov/31837419","citation_count":20,"is_preprint":false},{"pmid":"33561489","id":"PMC_33561489","title":"Transgenic expression of SOD1 specifically in neurons of Sod1 deficient mice prevents defects in muscle mitochondrial function and calcium handling.","date":"2021","source":"Free radical biology & medicine","url":"https://pubmed.ncbi.nlm.nih.gov/33561489","citation_count":20,"is_preprint":false},{"pmid":"28560609","id":"PMC_28560609","title":"Addition of exogenous SOD1 aggregates causes TDP-43 mislocalisation and aggregation.","date":"2017","source":"Cell stress & chaperones","url":"https://pubmed.ncbi.nlm.nih.gov/28560609","citation_count":19,"is_preprint":false},{"pmid":"35228715","id":"PMC_35228715","title":"Neuronal-glial communication perturbations in murine SOD1G93A spinal cord.","date":"2022","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/35228715","citation_count":18,"is_preprint":false},{"pmid":"38349516","id":"PMC_38349516","title":"Neuroprotective Effect of a Multistrain Probiotic Mixture in SOD1G93A Mice by Reducing SOD1 Aggregation and Targeting the Microbiota-Gut-Brain Axis.","date":"2024","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/38349516","citation_count":18,"is_preprint":false},{"pmid":"31092730","id":"PMC_31092730","title":"An endogenous peptide marker differentiates SOD1 stability and facilitates pharmacodynamic monitoring in SOD1 amyotrophic lateral sclerosis.","date":"2019","source":"JCI 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contribute to ALS pathogenesis in SOD1-G93A mice.","date":"2022","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/35852606","citation_count":17,"is_preprint":false},{"pmid":"32598986","id":"PMC_32598986","title":"Lipid aldehyde hydrophobicity affects apo-SOD1 modification and aggregation.","date":"2020","source":"Free radical biology & medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32598986","citation_count":16,"is_preprint":false},{"pmid":"21073275","id":"PMC_21073275","title":"A novel ALS SOD1 C6S mutation with implications for aggregation related toxicity and genetic counseling.","date":"2010","source":"Amyotrophic lateral sclerosis : official publication of the World Federation of Neurology Research Group on Motor Neuron Diseases","url":"https://pubmed.ncbi.nlm.nih.gov/21073275","citation_count":16,"is_preprint":false},{"pmid":"33607157","id":"PMC_33607157","title":"High fat suppresses SOD1 activity by reducing copper chaperone for SOD1 associated with neurodegeneration and memory decline.","date":"2021","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/33607157","citation_count":16,"is_preprint":false},{"pmid":"30101415","id":"PMC_30101415","title":"Semi-dominant mutation in the cysteine-rich receptor-like kinase gene, ALS1, conducts constitutive defence response in rice.","date":"2018","source":"Plant biology (Stuttgart, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/30101415","citation_count":15,"is_preprint":false},{"pmid":"33218686","id":"PMC_33218686","title":"Cu/Zn Superoxide Dismutase (Sod1) regulates the canonical Wnt signaling pathway.","date":"2020","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/33218686","citation_count":15,"is_preprint":false},{"pmid":"26882452","id":"PMC_26882452","title":"SOD1 gene polymorphisms in sudden sensorineural hearing loss.","date":"2016","source":"Acta oto-laryngologica","url":"https://pubmed.ncbi.nlm.nih.gov/26882452","citation_count":15,"is_preprint":false},{"pmid":"26602023","id":"PMC_26602023","title":"Cognitive impairment in amyotrophic lateral sclerosis, clues from the SOD1 mouse.","date":"2015","source":"Neuroscience and biobehavioral reviews","url":"https://pubmed.ncbi.nlm.nih.gov/26602023","citation_count":15,"is_preprint":false},{"pmid":"18504130","id":"PMC_18504130","title":"An analysis of the entire SOD1 gene in sporadic ALS.","date":"2008","source":"Neuromuscular disorders : NMD","url":"https://pubmed.ncbi.nlm.nih.gov/18504130","citation_count":15,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":47729,"output_tokens":6783,"usd":0.122466,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":16058,"output_tokens":6874,"usd":0.12607,"stage2_stop_reason":"end_turn"},"total_usd":0.248536,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"SOD1 (CuZn-SOD) is a copper- and zinc-containing homodimer that catalyzes the dismutation of superoxide anions to oxygen and hydrogen peroxide, and is found almost exclusively in intracellular cytoplasmic spaces.\",\n      \"method\": \"Biochemical characterization, enzymatic assay, subcellular fractionation\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted enzymatic activity, metal cofactor identification, and localization replicated across many independent studies over decades\",\n      \"pmids\": [\"12126755\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"SIRT5 binds to SOD1, desuccinylates it, and thereby activates its enzymatic activity; succinylation of SOD1 decreases its dismutase activity, establishing succinylation/desuccinylation as a post-translational regulatory mechanism for SOD1.\",\n      \"method\": \"Co-immunoprecipitation, in vitro desuccinylation assay, enzymatic activity assay, site-directed mutagenesis of succinylation site\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding shown, enzymatic activity measured, mutagenesis performed, but single lab study\",\n      \"pmids\": [\"24140062\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In yeast and mammalian cells, SOD1 transmits signals from oxygen and glucose to repress respiration by stabilizing casein kinase 1-gamma (CK1γ) homologs (Yck1p/Yck2p); SOD1 binds a C-terminal degron in Yck1p/Yck2p and promotes kinase stability by catalyzing superoxide conversion to peroxide, which is required for respiratory repression.\",\n      \"method\": \"Genetic epistasis in yeast, co-immunoprecipitation, in vitro binding assay, enzymatic activity assays, mammalian cell line validation\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods including binding assays, epistasis, enzymatic assays, and cross-species validation in a single rigorous study\",\n      \"pmids\": [\"23332757\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"mTORC1 phosphorylates SOD1 at S39 (yeast) / T40 (human) in response to nutrients, which reversibly modulates SOD1 activity, moderates ROS levels, and prevents oxidative DNA damage; this is a conserved nutrient-sensing redox regulatory mechanism.\",\n      \"method\": \"In vitro kinase assay, site-directed mutagenesis, ROS measurement, DNA damage assay, conservation analysis across species\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro kinase reconstitution, mutagenesis of phosphorylation site, functional consequences demonstrated with multiple orthogonal methods\",\n      \"pmids\": [\"29727620\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"SOD1 integrates oxygen availability to regulate NADPH production: Sod1-derived H2O2 oxidatively inactivates the glycolytic enzyme GAPDH, which reroutes carbohydrate flux to the oxidative pentose phosphate pathway (oxPPP) to generate NADPH; this mechanism requires the bulk of cellular Sod1.\",\n      \"method\": \"Genetic knockout in yeast and mammalian cells, biochemical flux measurements, mass spectrometry proteomics, GAPDH activity assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — mechanism defined biochemically in multiple organisms with loss-of-function genetics and enzyme activity assays\",\n      \"pmids\": [\"34969852\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Dorfin, a RING finger E3 ubiquitin ligase, physically binds and ubiquitylates ALS-linked mutant SOD1 proteins (but not wild-type SOD1), targeting them for proteasomal degradation and reducing SOD1 inclusions; Dorfin overexpression protects neural cells from mutant SOD1 toxicity.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitylation assay, proteasome inhibition, cell viability assay, immunohistochemistry\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP and functional ubiquitylation assay shown, selective for mutant vs. wild-type SOD1, single lab\",\n      \"pmids\": [\"12145308\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The ER-resident E3 ubiquitin ligase gp78 interacts with SOD1 (both wild-type and mutant), promotes its ubiquitination and proteasomal degradation via ER-associated degradation (ERAD), and reduces mutant SOD1 aggregate formation and cell death.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, knockdown/overexpression with stability measurements, cell viability assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, functional ubiquitination, and degradation assays performed; single lab, multiple methods\",\n      \"pmids\": [\"19661182\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Human CCS (hCCS) catalyzes SOD1 maturation through a stepwise mechanism involving: molecular recognition of immature SOD1 driven by interface interactions, induced-fit complexation stabilizing the SOD1 disulphide sub-loop, copper transfer to the SOD1 active site, and delayed disulphide formation; a single destabilizing substitution in hCCS reduces homodimer affinity to create a pool available for SOD1 interaction.\",\n      \"method\": \"X-ray crystallography of reaction precursors, intermediates, and products; biochemical assays for copper transfer and SOD1 activation\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structures of multiple reaction states combined with functional biochemical validation in a single rigorous study\",\n      \"pmids\": [\"30735496\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A faulty interaction between ALS-associated hCCS mutations and SOD1 occurs because the hCCS mutation abrogates zinc binding, which inhibits hCCS-SOD1 heterodimer formation; SOD1 zinc loss also disrupts the hCCS-SOD1 interaction, showing mutual dependence on zinc for complex stability.\",\n      \"method\": \"Chromatographic SAXS, biochemical binding assays, zinc binding measurements\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — structural (SAXS) and biochemical methods, single lab, two orthogonal approaches\",\n      \"pmids\": [\"27282955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"DJ-1 acts as a copper chaperone for SOD1: DJ-1 binds copper ions through a novel Cys-106 site, and transfers copper to SOD1 to increase its dismutase activity, as demonstrated by fluorescence spectroscopy and biochemical SOD1 activity assays.\",\n      \"method\": \"X-ray crystallography (novel copper binding site), fluorescence spectroscopy for copper transfer kinetics, SOD1 activity biochemical assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — structural characterization of copper binding site plus functional copper transfer assays, single lab\",\n      \"pmids\": [\"24567322\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ALS mutant SOD1 preferentially associates with the cytoplasmic face of spinal cord mitochondria and causes a selective decrease (>50%) in protein import into spinal cord (but not liver) mitochondria; this effect is specific to misfolded mutant SOD1 (G93A or G85R) and not wild-type SOD1 or misfolded alpha-synuclein.\",\n      \"method\": \"Mitochondrial fractionation, 2D-gel proteomics and LC-MS/MS, direct in vitro import assay with recombinant proteins\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — direct import assay with recombinant proteins plus proteomic characterization, multiple controls, rigorous tissue specificity analysis\",\n      \"pmids\": [\"21078990\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ALS mutant SOD1 (G93A) interacts with the stress granule protein G3BP1 in an RNA-independent manner, requiring the G3BP1 RRM domain and residues F380/F382; this interaction delays stress granule formation in response to stress stimuli and co-localizes with G3BP1-positive granules in motor neurons of mutant SOD1 mice.\",\n      \"method\": \"Co-immunoprecipitation, co-localization by immunofluorescence, stress granule dynamics assay, domain mapping by mutagenesis\",\n      \"journal\": \"Acta neuropathologica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP, mutagenesis to map interaction domain, cellular functional readout; single lab\",\n      \"pmids\": [\"27481264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Alpha-synuclein physically interacts with SOD1 in living cells, human erythrocytes, and mouse brain tissue; alpha-synuclein accelerates SOD1 oligomerization independent of SOD1 dismutase activity; ALS and PD mutations in each protein modify the binding interaction.\",\n      \"method\": \"Protein-fragment complementation assay (BiFC), co-immunoprecipitation, oligomerization assay\",\n      \"journal\": \"Molecular neurodegeneration\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — multiple orthogonal binding methods (BiFC + co-IP) in multiple cell/tissue systems, single lab\",\n      \"pmids\": [\"26643113\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Metal-free (apo) forms of ALS mutant SOD1 (and wild-type) oligomerize via oxidation of free cysteines C6 and C111, forming amyloid-like soluble oligomers stabilized by inter-strand hydrogen bonds; all eleven mutants tested share this common mechanism of oligomerization when demetallated.\",\n      \"method\": \"Circular dichroism, thioflavin T binding fluorescence, size-exclusion chromatography, light scattering spectroscopy\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biophysical methods in a single study, single lab, no mutagenesis to confirm cysteine role directly\",\n      \"pmids\": [\"18301754\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Nonnative trimeric (not large fibrillar aggregate) SOD1 is the cytotoxic species in ALS: engineered trimer-stabilizing mutations (G147P) promoted motor neuron-like cell death more potently than ALS mutants A4V or G93A, while fibril-stabilizing mutations (N53I, D101I) did not impair cell viability and large aggregates competed with toxic trimer formation.\",\n      \"method\": \"Structure-guided protein engineering, gel filtration chromatography, electron microscopy, cell viability assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — engineered mutations with defined structural outcomes, multiple characterization methods, single lab\",\n      \"pmids\": [\"29666246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Wild-type SOD1 localizes to both cytoplasm and nuclei of motoneurons, whereas mutant G93A-SOD1 is mainly cytoplasmic; this nuclear exclusion of mutant SOD1 results in higher DNA damage after oxidative stress, indicating that nuclear SOD1 provides protection from oxidative DNA damage.\",\n      \"method\": \"Immunofluorescence/confocal microscopy in transgenic mice and NSC34 cells, proteasome activity assay in subcellular fractions, comet assay for DNA damage\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct subcellular fractionation and imaging with functional consequence (DNA damage) measured, single lab, two cell systems\",\n      \"pmids\": [\"17504823\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SOD1 functions as an H2S oxidase: SOD1 rapidly converts H2S to sulfate under limiting sulfide conditions; when sulfide is in molar excess, SOD1 catalyzes formation of per- and polysulfides. Loss of SOD1 increases cellular sensitivity to H2S toxicity, while SOD1 overexpression enhances tolerance, establishing an essential H2S detoxification role.\",\n      \"method\": \"Genetic knockout (yeast and human cells), overexpression experiments, biochemical H2S oxidation assay, ROS measurement\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — enzymatic activity demonstrated biochemically, loss-of-function and gain-of-function genetics in two organisms, multiple orthogonal methods\",\n      \"pmids\": [\"36630448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SOD1 regulates canonical Wnt signaling: SOD1-derived H2O2 stabilizes CK1γ (the human homolog of yeast Yck1/2), and SOD1 knockdown reduces CK1γ expression and impairs Wnt-dependent cell proliferation in human HEK293 cells.\",\n      \"method\": \"SOD1 knockdown in HEK293 cells, CK1γ expression measurement, Wnt reporter assay, cell proliferation assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined pathway readout, extends yeast findings to human cells, single lab\",\n      \"pmids\": [\"33218686\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"SOD1 knockout in mice leads to pyruvate intolerance, decreased liver glycogen storage, reduced phosphoenolpyruvate carboxykinase and protein phosphatase activities, elevated glucokinase activity, and increased hepatic lipid profiles (cholesterol, triglycerides, free fatty acids), demonstrating SOD1's role in regulating hepatic gluconeogenesis, glycolysis, and lipogenesis.\",\n      \"method\": \"Sod1 knockout mouse model, pyruvate tolerance test, enzymatic activity assays, protein level measurements by Western blot\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO model with specific metabolic phenotypes and mechanistic enzyme activity measurements; single lab\",\n      \"pmids\": [\"22974764\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"SOD1 binds PCBP1 (a nuclear poly(rC) binding protein) in pig brain but not mouse brain; in transgenic pigs expressing mutant G93A hSOD1, mutant SOD1 showed nuclear accumulation and formed ubiquitinated nuclear aggregates rather than cytoplasmic inclusions, suggesting the SOD1-PCBP1 interaction accounts for species-specific nuclear SOD1 accumulation.\",\n      \"method\": \"Co-immunoprecipitation from pig and mouse brain tissue, immunofluorescence, ubiquitin immunostaining in transgenic pigs\",\n      \"journal\": \"Cell research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single co-IP from tissue, no functional validation of the PCBP1-SOD1 interaction, single study\",\n      \"pmids\": [\"24577199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Plekhg5 (a guanine exchange factor) drives unconventional secretion of Sod1 by sequestering it into autophagosomal carriers that fuse with secretory lysosomal-related organelles (LROs); exocytosis of LROs to release Sod1 requires activation of the small GTPase Rab26 by Plekhg5; deletion of Plekhg5 in mice causes Sod1 accumulation in LROs at presynaptic sites and reduces secretion of ALS-linked SOD1G93A.\",\n      \"method\": \"Plekhg5 knockout mice, live imaging of autophagosomal carriers, co-localization studies, iPSC-derived motoneurons, secretion assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with defined cellular phenotype, mechanistic pathway involving Rab26 activation, validated in human iPSC neurons; single lab\",\n      \"pmids\": [\"39366938\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Restoration of SOD1 expression specifically in neurons of Sod1-deficient mice (SynTgSod1-/- mice) prevents muscle mitochondrial dysfunction (elevated ROS, impaired NADH recovery), abnormal calcium handling, and NMJ denervation/fragmentation, despite continued absence of SOD1 in muscle, demonstrating that muscle mitochondrial defects in Sod1-/- mice are secondary to neuronal oxidative stress affecting NMJ innervation.\",\n      \"method\": \"Transgenic neuronal-specific SOD1 rescue, mitochondrial ROS measurement, oxygen consumption assay, intracellular calcium transient measurement, NMJ morphology analysis\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — neuron-specific genetic rescue with multiple orthogonal functional readouts, clean experimental design distinguishing cell-autonomous vs. non-cell-autonomous effects\",\n      \"pmids\": [\"33561489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In a zebrafish genetic epistasis analysis, SOD1 acts in a pathogenic pathway independent of FUS and TARDBP: wild-type SOD1 failed to rescue phenotypes caused by mutant FUS or TARDBP, and wild-type FUS/TARDBP failed to rescue mutant SOD1 phenotypes; overexpression of mutant SOD1 exacerbated the motor phenotype of mutant FUS.\",\n      \"method\": \"Zebrafish knockdown/overexpression genetics, motor phenotype scoring, epistasis analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with multiple allele combinations in zebrafish, single lab, clear pathway placement\",\n      \"pmids\": [\"21829392\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Mutant SOD1 A4V forms ion channel-like tetrameric pore structures (outer diameter 12.2 nm, inner diameter 3.0 nm) when reconstituted in lipid membranes, produces distinct ionic conductances not seen with wild-type SOD1, and causes membrane depolarization and intracellular calcium increase in neuroblastoma cells.\",\n      \"method\": \"Atomic force microscopy (AFM), electrophysiology (bilayer recordings), calcium imaging in neuroblastoma cells\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro reconstitution with AFM and electrophysiology, cellular validation, single lab\",\n      \"pmids\": [\"21930207\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Homozygous in-frame deletion of Val119/120 in SOD1 results in complete absence of SOD1 enzymatic activity and undetectable SOD1 protein despite preserved mRNA/splicing, causing an infantile progressive motor-neurological syndrome through loss-of-function; heterozygous carriers have ~50% activity.\",\n      \"method\": \"Exome sequencing, cDNA analysis, SOD1 activity assay in erythrocyte lysates, protein quantification by Western blot\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — enzymatic activity and protein level measurement in patient-derived material confirming variant functional consequence; single patient study\",\n      \"pmids\": [\"34788402\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CuO nanoparticle-induced copper overload causes SOD1 misfolding and mitochondrial translocation in macrophages; chelation of copper with tetrathiomolybdate prevented cell death while inhibition of SOD1's chaperone (CCS) aggravated toxicity, indicating copper loading disrupts normal SOD1 folding and mitochondrial localization.\",\n      \"method\": \"TEM, ICP-MS, circular dichroism spectroscopy, confocal microscopy with aggresome dye, proteasome activity assay, pharmacological inhibition\",\n      \"journal\": \"Particle and fibre toxicology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — cellular observations of misfolding without direct mechanistic dissection of SOD1 specifically, single study, indirect methods\",\n      \"pmids\": [\"35538581\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In muscle-specific SOD1G93A transgenic mice (MLC/SOD1G93A), mutant SOD1 expression triggers NMJ dismantlement via PKCθ activation: perturbation of redox signaling by muscle-accumulated SOD1G93A causally leads to morphological alterations in presynaptic terminals, high acetylcholine receptor turnover, and NMJ disintegration through a PKCθ-dependent mechanism.\",\n      \"method\": \"Transgenic mouse model with muscle-specific expression, immunofluorescence, AChR turnover assay, PKCθ activity measurement and pharmacological inhibition\",\n      \"journal\": \"Antioxidants & redox signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tissue-specific transgenic model with mechanistic PKCθ pathway identification and pharmacological validation; single lab\",\n      \"pmids\": [\"28931313\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"High-fat/palmitic acid treatment decreases CCS (copper chaperone for SOD1) levels in neuronal cells, which promotes nuclear import of SOD1 and reduces its cytoplasmic dismutase activity, leading to elevated ROS; this mechanism was confirmed in high-fat diet mice showing reduced hippocampal SOD1 activity and CCS levels.\",\n      \"method\": \"Cell culture treatment with palmitic acid, CCS knockdown/measurement, SOD1 activity assay, subcellular fractionation, high-fat diet mouse model\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — correlative mechanistic link between CCS and SOD1 activity, indirect subcellular localization, single lab\",\n      \"pmids\": [\"33607157\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SOD1 is a copper- and zinc-dependent homodimeric enzyme that catalyzes superoxide dismutation to O2 and H2O2; beyond antioxidant defense, SOD1-derived H2O2 acts as a redox signal that regulates GAPDH activity and NADPH production via the pentose phosphate pathway, stabilizes CK1γ to control respiration and Wnt signaling, and responds to mTORC1-mediated phosphorylation (T40) to couple nutrient sensing to redox homeostasis; SOD1 is also an H2S oxidase, is activated by CCS-mediated copper insertion and disulfide bond formation, is regulated by SIRT5-dependent desuccinylation, is targeted for proteasomal degradation by E3 ligases Dorfin and gp78, is unconventionally secreted from presynaptic terminals via a Plekhg5/Rab26/autophagosome pathway, and its ALS-linked mutations cause misfolding to toxic oligomeric (trimeric) states, mitochondrial association with impaired protein import, nuclear exclusion with consequent DNA damage, and aberrant interactions with G3BP1 disrupting stress granule dynamics.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SOD1 is a copper- and zinc-dependent cytoplasmic homodimer that catalyzes the dismutation of superoxide to oxygen and hydrogen peroxide, serving both as a core antioxidant enzyme and as a generator of H2O2 used in redox signaling [#0]. Beyond detoxification, SOD1-derived H2O2 functions as a second messenger that reroutes metabolism and signaling: it oxidatively inactivates GAPDH to divert carbohydrate flux into the oxidative pentose phosphate pathway for NADPH production [#4], stabilizes casein kinase 1-gamma (CK1\\u03b3/Yck1/2) to repress respiration in response to oxygen and glucose [#2] and to sustain canonical Wnt signaling and proliferation [#17]. This signaling output is gated by nutrient sensing through mTORC1-mediated phosphorylation at T40, which tunes SOD1 activity to moderate ROS and prevent oxidative DNA damage [#3]. SOD1 also acts as an H2S oxidase, converting sulfide to sulfate or to per/polysulfides depending on sulfide levels and protecting cells from H2S toxicity [#16]. Enzymatic competence requires maturation by the copper chaperone CCS, which recognizes immature SOD1, transfers copper, and drives disulfide formation [#7]; metal loading and activity are additionally modulated by SIRT5-mediated desuccinylation [#1] and by alternative copper delivery via DJ-1 [#9]. At the organismal level SOD1 governs hepatic gluconeogenic, glycolytic, and lipogenic metabolism [#18] and protects neuromuscular integrity, with neuronal SOD1 being sufficient to prevent muscle mitochondrial dysfunction and neuromuscular junction denervation in a non-cell-autonomous manner [#21]. ALS-linked mutant SOD1 acquires toxic gain-of-function properties: metal-free oligomerization through cysteine oxidation [#13], formation of a cytotoxic nonnative trimer [#14], association with the cytoplasmic face of mitochondria with impaired protein import [#10], nuclear exclusion that elevates oxidative DNA damage [#15], and aberrant RNA-independent binding to G3BP1 that delays stress granule assembly [#11]; such misfolded species are selectively cleared by the E3 ligases Dorfin and the ERAD ligase gp78 [#5, #6]. A homozygous in-frame SOD1 deletion causing complete loss of enzymatic activity produces an infantile progressive motor-neurological syndrome, establishing a loss-of-function disease mechanism distinct from the toxic gain-of-function of ALS mutants [#24].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established the foundational identity of SOD1 as a metal-dependent enzyme, defining the catalytic activity and localization on which all later signaling and disease work builds.\",\n      \"evidence\": \"Biochemical enzymatic assay, metal cofactor identification, and subcellular fractionation\",\n      \"pmids\": [\"12126755\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address non-canonical signaling or substrate roles\", \"No structural mechanism of catalysis defined here\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Addressed how cells handle toxic mutant SOD1 by identifying Dorfin as an E3 ligase selectively ubiquitylating mutant but not wild-type SOD1, framing proteostatic clearance as a protective axis.\",\n      \"evidence\": \"Co-IP, ubiquitylation and proteasome assays in neural cells\",\n      \"pmids\": [\"12145308\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Selectivity determinants for mutant SOD1 not defined\", \"In vivo relevance to ALS not established\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Showed that nuclear localization of SOD1 is protective and that mutant SOD1 nuclear exclusion increases oxidative DNA damage, linking SOD1 subcellular distribution to genome protection.\",\n      \"evidence\": \"Immunofluorescence, subcellular fractionation, and comet assay in transgenic mice and NSC34 cells\",\n      \"pmids\": [\"17504823\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of nuclear import/exclusion unresolved\", \"Whether DNA damage drives motor neuron death not shown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defined a shared biophysical route to toxic species, showing that demetallated SOD1 oligomerizes via free-cysteine oxidation across many ALS mutants.\",\n      \"evidence\": \"CD, thioflavin T fluorescence, size-exclusion chromatography, light scattering\",\n      \"pmids\": [\"18301754\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No mutagenesis to directly confirm cysteine roles\", \"Link between in vitro oligomers and cellular toxicity not made\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Extended SOD1 quality control by showing the ERAD ligase gp78 degrades both wild-type and mutant SOD1 and reduces aggregation, identifying a second clearance pathway.\",\n      \"evidence\": \"Co-IP, ubiquitination, stability and viability assays with knockdown/overexpression\",\n      \"pmids\": [\"19661182\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contribution vs. other ligases unknown\", \"ER-association of SOD1 substrate pool not defined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified a tissue-selective toxic mechanism whereby misfolded mutant SOD1 binds spinal cord mitochondria and impairs protein import, connecting SOD1 misfolding to mitochondrial dysfunction.\",\n      \"evidence\": \"Mitochondrial fractionation, LC-MS/MS proteomics, direct in vitro import assay\",\n      \"pmids\": [\"21078990\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Import machinery component targeted not identified\", \"Why spinal cord mitochondria are selectively vulnerable unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Placed SOD1 genetically in an ALS pathway independent of FUS and TARDBP, indicating mechanistic divergence among ALS genes.\",\n      \"evidence\": \"Zebrafish epistasis with mutant/wild-type allele combinations\",\n      \"pmids\": [\"21829392\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of pathway independence not defined\", \"Model-organism context limits direct human inference\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Offered a membrane-toxicity mechanism by showing mutant A4V SOD1 forms pore-like structures causing membrane depolarization and calcium influx.\",\n      \"evidence\": \"AFM, bilayer electrophysiology, calcium imaging in neuroblastoma cells\",\n      \"pmids\": [\"21930207\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo occurrence of pores not demonstrated\", \"Relation to oligomer/trimer species unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated a systemic metabolic role by showing Sod1 knockout disrupts hepatic gluconeogenesis, glycolysis, and lipogenesis.\",\n      \"evidence\": \"Sod1 knockout mice, pyruvate tolerance test, enzyme activity assays\",\n      \"pmids\": [\"22974764\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct redox targets among metabolic enzymes not identified\", \"Whether effects are cell-autonomous in liver unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Reframed SOD1 as a redox signaling hub by showing its H2O2 product stabilizes CK1\\u03b3 homologs to repress respiration in response to oxygen and glucose.\",\n      \"evidence\": \"Yeast epistasis, co-IP, in vitro binding, enzymatic assays, mammalian validation\",\n      \"pmids\": [\"23332757\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise redox-sensitive residue on CK1\\u03b3 not pinpointed\", \"Generality across cell types incompletely mapped\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified succinylation/desuccinylation by SIRT5 as a post-translational switch controlling SOD1 dismutase activity.\",\n      \"evidence\": \"Co-IP, in vitro desuccinylation, activity assays, site mutagenesis\",\n      \"pmids\": [\"24140062\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological conditions driving succinylation unknown\", \"Single-lab finding without in vivo confirmation\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Proposed an alternative copper-delivery route by showing DJ-1 binds copper at Cys-106 and transfers it to activate SOD1.\",\n      \"evidence\": \"X-ray crystallography of copper site, fluorescence kinetics, activity assays\",\n      \"pmids\": [\"24567322\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contribution vs. CCS in vivo not established\", \"Cellular conditions favoring DJ-1 route unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Linked a species-specific SOD1-PCBP1 interaction to nuclear accumulation of mutant SOD1 in transgenic pigs.\",\n      \"evidence\": \"Co-IP from pig and mouse brain, immunofluorescence, ubiquitin staining\",\n      \"pmids\": [\"24577199\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single tissue co-IP without functional validation of PCBP1 binding\", \"Human relevance untested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected SOD1 to alpha-synuclein, showing direct interaction that accelerates SOD1 oligomerization independent of dismutase activity.\",\n      \"evidence\": \"BiFC, co-IP, oligomerization assays in cells, erythrocytes, and brain\",\n      \"pmids\": [\"26643113\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural interface not resolved\", \"In vivo pathological consequence not established\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Defined a toxic protein-interaction mechanism whereby mutant SOD1 binds G3BP1 via its RRM domain and delays stress granule assembly.\",\n      \"evidence\": \"Co-IP, domain mapping by mutagenesis, stress granule dynamics, motor neuron co-localization\",\n      \"pmids\": [\"27481264\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Consequence of delayed granule formation for neuron survival unclear\", \"Reciprocal validation limited to single lab\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Clarified maturation failure by showing ALS-associated hCCS mutations abrogate zinc binding, destabilizing the zinc-dependent hCCS-SOD1 heterodimer.\",\n      \"evidence\": \"Chromatographic SAXS and biochemical zinc/binding assays\",\n      \"pmids\": [\"27282955\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream effect on SOD1 maturation in vivo not shown\", \"Disease causality of CCS variants not established here\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated that muscle-autonomous mutant SOD1 dismantles the NMJ through PKC\\u03b8-dependent redox perturbation, implicating non-neuronal SOD1 toxicity.\",\n      \"evidence\": \"Muscle-specific SOD1G93A transgenic mice, AChR turnover, PKC\\u03b8 activity and inhibition\",\n      \"pmids\": [\"28931313\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Redox target upstream of PKC\\u03b8 not identified\", \"Relative weight of muscle vs. neuronal contributions in ALS unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Resolved a key disease question by integrating mTORC1 phosphorylation (S39/T40) as a nutrient-responsive switch tuning SOD1 activity to limit oxidative DNA damage.\",\n      \"evidence\": \"In vitro kinase assay, mutagenesis, ROS and DNA damage assays, conservation analysis\",\n      \"pmids\": [\"29727620\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphatase counteracting T40 not identified\", \"Quantitative impact on catalytic cycle not defined\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified the cytotoxic conformer in ALS as a nonnative trimer rather than large aggregates, refining the toxic-species model.\",\n      \"evidence\": \"Structure-guided engineering, gel filtration, EM, viability assays\",\n      \"pmids\": [\"29666246\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo abundance of trimers not quantified\", \"Mechanism by which trimers kill neurons unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Provided a structural mechanism for SOD1 maturation, resolving stepwise CCS-mediated recognition, copper transfer, and disulfide formation.\",\n      \"evidence\": \"X-ray crystallography of precursors, intermediates, products plus biochemical validation\",\n      \"pmids\": [\"30735496\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Timing of in vivo maturation flux not measured\", \"Interplay with alternative chaperones unaddressed\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended the SOD1-CK1\\u03b3 axis to humans, showing SOD1-derived H2O2 stabilizes CK1\\u03b3 to support canonical Wnt signaling and proliferation.\",\n      \"evidence\": \"SOD1 knockdown, CK1\\u03b3 measurement, Wnt reporter and proliferation assays in HEK293\",\n      \"pmids\": [\"33218686\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct oxidative modification site on CK1\\u03b3 not defined\", \"Tissue contexts where this operates not mapped\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Established that neuronal SOD1 acts non-cell-autonomously to protect muscle, with neuronal rescue preventing muscle mitochondrial dysfunction and NMJ denervation.\",\n      \"evidence\": \"Neuron-specific transgenic rescue in Sod1-/- mice, mitochondrial ROS, oxygen consumption, calcium and NMJ analyses\",\n      \"pmids\": [\"33561489\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signal transmitted from neuron to muscle not identified\", \"Applicability to gain-of-function ALS mutants unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined a major metabolic output of SOD1, showing its H2O2 inactivates GAPDH to redirect flux into the oxPPP for NADPH generation.\",\n      \"evidence\": \"Yeast and mammalian knockouts, flux measurements, proteomics, GAPDH activity assays\",\n      \"pmids\": [\"34969852\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Spatial coupling of SOD1 and GAPDH not resolved\", \"Quantitative share of NADPH supply via this route unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated a loss-of-function human disease mechanism: complete SOD1 deficiency causes an infantile progressive motor-neurological syndrome, distinct from ALS gain-of-function.\",\n      \"evidence\": \"Exome sequencing, cDNA analysis, erythrocyte activity assays, protein quantification\",\n      \"pmids\": [\"34788402\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cellular basis of motor neuron vulnerability to deficiency unclear\", \"Single patient/family study\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Expanded SOD1's catalytic repertoire by identifying it as an H2S oxidase essential for sulfide detoxification.\",\n      \"evidence\": \"Knockout and overexpression in yeast and human cells, H2S oxidation and ROS assays\",\n      \"pmids\": [\"36630448\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Active-site basis for sulfide vs. superoxide handling not resolved\", \"Physiological sulfide sources targeted not defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified the route of SOD1 secretion, showing Plekhg5 sequesters Sod1 into autophagosomal carriers that fuse with LROs for Rab26-dependent exocytosis at presynaptic terminals.\",\n      \"evidence\": \"Plekhg5 knockout mice, live imaging, co-localization, iPSC motoneurons, secretion assays\",\n      \"pmids\": [\"39366938\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Extracellular function of secreted SOD1 not defined\", \"Whether secretion mitigates or spreads mutant SOD1 toxicity unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how SOD1's redox-signaling outputs, its H2S oxidase activity, and its propensity to misfold are mechanistically integrated, and which specific molecular events convert SOD1 dysfunction into selective motor neuron death.\",\n      \"evidence\": \"No single study in the timeline unifies the signaling, metabolic, and proteostatic axes\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No unified model linking toxic conformers to defined cellular death pathway\", \"Direct in vivo redox targets of SOD1-derived H2O2 incompletely catalogued\", \"Relationship between secretion and disease spread untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [0, 4, 16]},\n      {\"term_id\": \"GO:0016209\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 15]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [15]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [3, 4]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [4, 18]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 17]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [10, 14, 24]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"CCS\",\n      \"CK1\\u03b3\",\n      \"SIRT5\",\n      \"DJ-1\",\n      \"G3BP1\",\n      \"SNCA\",\n      \"gp78\",\n      \"Plekhg5\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}