{"gene":"GARS1","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":2015,"finding":"CMT2D mutations alter the conformation of GlyRS, enabling mutant GlyRS (GlyRS^CMT2D) to acquire a neomorphic binding activity that allows it to bind neuropilin 1 (Nrp1) receptor. This aberrant interaction competitively interferes with VEGF binding to Nrp1, antagonizing the VEGF-Nrp1 signaling axis required for motor neuron survival. Genetic reduction of Nrp1 in mice worsens CMT2D symptoms, whereas enhanced VEGF expression improves motor function.","method":"Co-IP/binding assays showing GlyRS^CMT2D-Nrp1 interaction; competitive binding with VEGF; genetic epistasis in mice (Nrp1 reduction, VEGF overexpression); conformational analysis of mutant vs. wild-type GlyRS","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays, genetic epistasis with multiple alleles in vivo, functional rescue experiments in mice; published in high-impact journal with multiple orthogonal approaches","pmids":["26503042"],"is_preprint":false},{"year":2011,"finding":"The dominant CMT2D neuropathy caused by GARS missense mutations is due to a dose-dependent toxic gain-of-function mechanism, not loss of aminoacylation function. Over-expression of wild-type GARS does not rescue the neuropathy phenotype in heterozygous Gars mutant mice, demonstrating the pathology is not caused by haploinsufficiency. Increased dosage of disease-causing alleles worsened neuropathy, confirming a gain-of-function mechanism.","method":"Transgenic mice over-expressing wild-type GARS crossed to two dominant CMT2D mouse models; histological, functional, and behavioral assessment; complementation tests with null allele","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean in vivo genetic experiment with multiple alleles, functional rescue/failure controls, replicated across two distinct mouse models in single study","pmids":["22144914"],"is_preprint":false},{"year":2017,"finding":"CMT2D mutant GlyRS aberrantly interacts with Trk neurotrophin receptors (TrkA and TrkB), causing misactivation of Trk signaling essential for sensory neuron differentiation and development. This interaction perturbs sensory neuron fate in dorsal root ganglia, leading to an imbalance of sensory neuron subtypes that is present at birth and non-progressive, indicating a developmental rather than purely degenerative insult.","method":"In vitro binding assays showing mutant but not wild-type GlyRS interacts with Trk receptors; mouse CMT2D model behavioral and histological analysis; sensory subtype profiling in DRG","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct in vitro binding assay with wild-type vs. mutant comparison, corroborated by in vivo mouse model phenotyping with multiple orthogonal readouts","pmids":["28351971"],"is_preprint":false},{"year":2015,"finding":"Mutant GlyRS-induced neurotoxicity in CMT2D is non-cell autonomous: expression of mutant GlyRS in mesoderm or muscle alone (not just neurons) is sufficient to produce motor deficits and progressive neuromuscular junction (NMJ) denervation in Drosophila. The toxic gain-of-function effect is WHEP domain-dependent and is associated with abnormal NMJ assembly and pre-synaptic accumulation of mutant GlyRS.","method":"Novel Drosophila CMT2D models with tissue-specific (neuronal, mesodermal, muscle) expression of mutant GlyRS; motor deficit assays; NMJ histology; domain deletion analysis (WHEP domain)","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific genetic dissection in Drosophila with multiple mutant alleles, domain-deletion analysis, and multiple phenotypic readouts establishing non-cell-autonomous mechanism","pmids":["25972375"],"is_preprint":false},{"year":2016,"finding":"Dimerization of GlyRS is required for dominant CMT2D neurotoxicity. A zebrafish loss-of-dimerization mutant (T209K/T130K in human) causes neuromuscular phenotype through loss of function. A human CMT disease-associated dimerization-deficient mutant (G319R/G240R in human) cannot rescue this phenotype, while another CMT mutant (G605R/G526 in human) that can dimerize with wild-type protein worsens phenotype in heterozygotes through dominant negative reduction of function.","method":"Zebrafish genetic model (gars^s266 allele); dimerization assays; rescue/complementation experiments with wild-type and mutant transgenes; neuromuscular phenotype assessment","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic model combined with direct biochemical dimerization assays, multiple alleles tested including rescue experiments","pmids":["27008886"],"is_preprint":false},{"year":2016,"finding":"Crystal structure of wild-type human GlyRS in complex with tRNA^Gly determined at 2.95 Å. The flexible WHEP-TRS domain is visible in one subunit of the homodimer; tRNA is fully resolved. A glycyl-AMP intermediate is present at the active site, capturing the enzyme in an intermediate stage of glycylation. The structure reveals the roles of insertions and the WHEP-TRS domain in tRNA binding.","method":"X-ray crystallography (2.95 Å); co-crystal of hGlyRS with tRNA^Gly; structural comparison with other class II aaRS-tRNA complexes","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure at near-atomic resolution with bound tRNA substrate and reaction intermediate; single lab but definitive structural determination","pmids":["27261259"],"is_preprint":false},{"year":2025,"finding":"tRNA^Gly sequestration by mutant GlyRS is the unifying pathogenic mechanism for all tested GARS1-associated peripheral neuropathy mutations. PN-mutant GlyRS variants (S211F and H418R) sequester tRNA^Gly, depleting the cellular tRNA^Gly pool, leading to insufficient glycyl-tRNA^Gly for ribosomes and ribosome stalling at glycine codons. A dominant negative loss-of-function mechanism was excluded for these variants. K456Q was shown not to be a pathogenic mutation as it does not affect aminoacylation or induce neuropathy in Drosophila.","method":"Novel Drosophila models expressing human PN-GlyRS variants; de novo protein synthesis assays; genetic and biochemical tRNA sequestration assays; aminoacylation activity measurements","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — biochemical aminoacylation assays, in vivo Drosophila genetic models, direct tRNA sequestration measurements, negative control (K456Q), multiple orthogonal methods in single study","pmids":["40119731"],"is_preprint":false},{"year":2021,"finding":"Wild-type GARS binds the NAD+-dependent deacetylase SIRT2 and inhibits its deacetylation activity, resulting in maintenance of acetylated α-tubulin. CMT2D mutations in GARS abolish this inhibitory interaction with SIRT2, leading to decreased acetylated α-tubulin. The catalytic domain of GARS mediates the interaction with SIRT2. Genetic reduction of SIRT2 in Drosophila CMT2D models rescues the axonal neuropathy phenotype.","method":"Co-IP of GARS and SIRT2; in vitro deacetylation assay; Western blotting for acetylated α-tubulin; Drosophila genetic rescue experiment with SIRT2 knockdown; domain analysis","journal":"Aging cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, in vitro enzymatic assay, in vivo genetic rescue in Drosophila, wild-type vs. mutant comparison; multiple orthogonal methods","pmids":["34053152"],"is_preprint":false},{"year":2018,"finding":"UBA1 regulates GARS via a non-canonical pathway independent of ubiquitylation. Dysregulation of the UBA1/GARS pathway in SMA mice disrupts sensory neuron fate, phenocopying GARS-dependent defects associated with CMT disease. Restoration of UBA1 corrects the sensory neuron fate defects and sensory-motor connectivity in SMA mice via the UBA1/GARS pathway.","method":"Mass spectrometry identification of GARS as UBA1 downstream target; genetic epistasis (UBA1 restoration in SMA mice); sensory neuron fate analysis; sensory-motor connectivity assessment","journal":"Brain : a journal of neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS identification plus in vivo genetic epistasis, but non-canonical UBA1/GARS interaction mechanism not fully biochemically characterized in the abstract","pmids":["30239612"],"is_preprint":false},{"year":2018,"finding":"GlyRS mediates amino acid (methionine and leucine)-induced activation of the mTOR-S6K1/4EBP1 signaling pathway in bovine mammary epithelial cells, thereby regulating milk protein and fat synthesis. GlyRS knockdown abolishes Met-stimulated milk synthesis, and GlyRS overexpression enhances it.","method":"siRNA knockdown and overexpression of GlyRS in bovine mammary epithelial cells; Western blotting and qRT-PCR for mTOR pathway components; milk protein/fat synthesis assays","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD and OE experiments with defined pathway readouts, but single lab, single model system (bovine), no reconstitution","pmids":["30171693"],"is_preprint":false},{"year":2020,"finding":"MAP3K10 (mitogen-activated protein kinase 10) interacts with GlyRS in bovine mammary epithelial cells and acts as its upstream kinase. Met stimulates GlyRS phosphorylation via the GPR87-CDC42/Rac1-MAP3K10 signaling cascade. Phosphorylated GlyRS enters the nucleus to stimulate gene expression for milk synthesis, and MAP3K10 stimulates NFκB1 phosphorylation via GlyRS.","method":"Co-IP; mass spectrometry; Western blotting; in vitro kinase assay; pathway inhibition experiments","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro kinase assay plus Co-IP/MS identification, multiple methods but single lab and non-neuronal context","pmids":["31954518"],"is_preprint":false},{"year":2009,"finding":"The Gars^C201R point mutation in mice causes a heterozygous peripheral neuropathy with reduced enzyme (aminoacylation) activity only in homozygous animals, not heterozygotes, suggesting heterozygous pathology is not explained by reduced aminoacylation. Homozygous animals show a more severe phenotype consistent with partial loss of function. Genetic interaction with SOD1^G93A: the Gars^C201R mutation significantly delayed disease onset and extended lifespan by 29% in SOD1^G93A mice.","method":"Mouse genetic model characterization; enzymatic activity assays; genetic crosses with SOD1^G93A and Dync1h1^Loa mice; behavioral and electrophysiological assessments","journal":"Disease models & mechanisms","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — enzymatic assays combined with in vivo genetic crosses, multiple phenotypic assessments, but mechanism of SOD1 interaction not fully resolved","pmids":["19470612","19593442"],"is_preprint":false},{"year":2017,"finding":"Compound heterozygous GARS variants (frameshift p.Glu83Ilefs*6 and missense p.Arg310Gln) cause loss-of-function: the frameshift variant depletes protein levels and the missense variant reduces tRNA charging (aminoacylation) activity. This establishes that recessive GARS loss-of-function leads to a multisystem developmental syndrome with severe growth retardation, distinct from the dominant gain-of-function CMT2D mechanism.","method":"In vitro tRNA charging activity assays; protein expression analysis; in vivo functional studies; whole-exome sequencing with functional validation","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 1-2 / Weak — in vitro aminoacylation assay plus protein expression analysis, but single patient/single lab, limited replication","pmids":["28675565"],"is_preprint":false},{"year":2017,"finding":"Compound heterozygous GARS variants cause mitochondrial respiratory chain dysfunction, with reduced activity of Complexes I, III, and IV in skeletal muscle and liver. Immunoblot analysis showed significant reduction in GARS protein and Complex IV subunits in patient fibroblasts, establishing a functional link between GARS loss-of-function and mitochondrial dysfunction.","method":"Spectrophotometric evaluation of mitochondrial respiratory chain complexes; immunoblot analysis of GARS protein and respiratory chain complex subunits; whole-exome sequencing","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct biochemical measurement of enzyme complex activities in patient tissues, but single patient, single lab","pmids":["28594869"],"is_preprint":false},{"year":2013,"finding":"A disease-causing G240R mutation in GARS (G319R in zebrafish Gars) leads to altered intracellular distribution: wild-type GARS is distributed to peripheral axons, DRG cell bodies, central axon terminals, and motor neuron cell bodies, whereas G240R mutant GARS localizes only to DRG and motor neuron cell bodies but not axonal regions in vivo, suggesting a distribution defect associated with axonal degeneration.","method":"Adenoviral vector-mediated expression in mouse neurons using a neuronal-specific promoter; immunohistochemistry for GARS localization in vivo","journal":"Journal of molecular histology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single localization study in a novel viral model, single lab, no functional rescue to confirm the distribution defect drives pathology","pmids":["23990368"],"is_preprint":false},{"year":2023,"finding":"CMT2D mice display early and persistent disturbances in axonal transport of neurotrophin-containing signaling endosomes in vivo, correlating with BDNF/TrkB impairments. Inhibition of the BDNF/TrkB pathway at the nerve-muscle interface perturbed endosome transport in wild-type axons. Supplementation with BDNF (but not other neurotrophins) completely restored physiological axonal transport in neuropathic mice.","method":"Intravital imaging of sciatic nerve in CMT2D mice; pharmacological TrkB pathway inhibition; BDNF muscle supplementation; neurotrophin-signaling endosome tracking","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Moderate — intravital live imaging combined with pharmacological and neurotrophin rescue experiments, specificity shown by BDNF vs. other neurotrophins, multiple orthogonal approaches","pmids":["36928301"],"is_preprint":false},{"year":2020,"finding":"In CMT2D mice, neuromuscular junction denervation occurs along a distal-to-proximal gradient. Defective NMJ development precedes and is associated with degeneration but is not linked to delay of wild-type NMJ maturation. The extent of post-natal synaptic growth (rather than muscle fibre type or synaptic architecture) predisposes to neurodegeneration at specific NMJs.","method":"Systematic comparison of NMJ development and degeneration across five wholemount muscles; correlation analyses of NMJ features with denervation severity; immunohistochemistry","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic multi-muscle histological analysis with correlation analyses in defined mouse model, multiple muscles compared, but single lab","pmids":["32703932"],"is_preprint":false},{"year":2025,"finding":"The WHEP domain of GlyRS (encoded by exon 2 of Gars1) is required for the free secretion/release of GlyRS from cells. Deletion of the WHEP domain (Gars1^ΔWHEP) causes GlyRS to accumulate in membrane fractions and show stronger interaction with the extracellular region of neuropilin 1 (Nrp1). This aberrant GlyRS-Nrp1 interaction enhances Nrp1 endocytic activity and reduces VE-cadherin localization at endothelial adherens junctions, increasing vascular permeability. Heterozygous Nrp1 knockout partially rescues the vascular permeability defects in Gars1^ΔWHEP/ΔWHEP mice. WHEP domain deletion did not impair tRNA aminoacylation.","method":"Gars1^ΔWHEP knock-in mice (exon 2 deletion); cell fractionation; co-IP with Nrp1 extracellular domain; endocytosis assays; VE-cadherin localization by immunofluorescence; genetic rescue with Nrp1 heterozygous knockout; aminoacylation activity assays","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple in vivo and in vitro methods, genetic rescue, biochemical fractionation, but preprint not yet peer-reviewed","pmids":["bio_10.1101_2025.05.14.654074"],"is_preprint":true},{"year":2022,"finding":"Molecular dynamics simulations of the G240R CMT2D mutation in GlyRS show altered native interactions at the dimer interface and altered dynamics of regions associated with tRNA binding. Computational analysis predicts that a region disrupted by G240R is commonly affected by multiple CMT2D mutations, suggesting a shared structural mechanism.","method":"Molecular dynamics simulations of wild-type and G240R mutant GlyRS; analysis of dimer interface contacts and tRNA-binding domain dynamics","journal":"Brain multiphysics","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational predictions only, no experimental validation reported in this study","pmids":["36504507"],"is_preprint":false},{"year":2025,"finding":"KLF16 binds to the GARS promoter and enhances its transcription in hepatocellular carcinoma cells. The GARS protein then binds to and stabilizes FOXK1 by reducing its ubiquitination. FOXK1 promotes glycolysis by stimulating transcription of LDHA, PKM2, and GLUT1. This KLF16-GARS-FOXK1 axis promotes HCC glycolysis and growth.","method":"Chromatin immunoprecipitation (KLF16 promoter binding); Co-IP (GARS-FOXK1 interaction); ubiquitination assays; knockdown experiments; in vitro and in vivo glycolysis assays","journal":"The Tohoku journal of experimental medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP and functional knockdown experiments with defined pathway readout, but single lab, cancer cell context, limited replication","pmids":["40603105"],"is_preprint":false},{"year":2006,"finding":"Mutations in the anticodon binding domain of GARS (in addition to other domains) cause CMT2D/dSMA-V, establishing that the anticodon-binding domain is functionally important for disease causation. A mutation within the anticodon binding domain was associated with earlier childhood onset and predominantly lower limb involvement, extending the phenotypic spectrum.","method":"Mutation screening of 100 patients; identification and segregation of novel GARS missense mutations; domain mapping of mutation locations","journal":"Neurology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — genetic association with domain localization, no biochemical functional characterization of anticodon binding domain activity in these mutations","pmids":["17101916"],"is_preprint":false},{"year":2019,"finding":"The p.Gly327Arg GARS variant fails to support yeast growth in a complementation assay, demonstrating loss-of-function at the level of aminoacylation activity. This establishes that severe impairment of GARS protein function causes distal hereditary motor neuropathy.","method":"Yeast complementation assay for GARS tRNA charging function","journal":"Journal of the peripheral nervous system : JPNS","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — functional complementation assay (in vivo surrogate for aminoacylation) but single variant, single lab","pmids":["31628756"],"is_preprint":false},{"year":2020,"finding":"Sensory pathology in CMT2D mice is restricted to neurons innervating the hindlimbs. Gars expression is selectively elevated in a subset of sensory neurons and is linked to sensory developmental defects, providing a potential explanation for site-specific sensory vulnerability.","method":"Anatomical dissection of sensory nervous system in CMT2D mouse models; comparison across multiple mouse models of neuromuscular disease; in vitro axonal transport assays; immunohistochemistry for Gars expression in sensory neuron subsets","journal":"Frontiers in cellular neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple CMT2D mouse models compared, localization experiments correlated with developmental defects, but single lab","pmids":["32848623"],"is_preprint":false}],"current_model":"GARS1 encodes glycyl-tRNA synthetase (GlyRS), a homodimeric class II aminoacyl-tRNA synthetase that charges tRNA^Gly with glycine for cytoplasmic and mitochondrial translation; dominant CMT2D-causing mutations drive a toxic gain-of-function in which mutant GlyRS acquires neomorphic binding to Nrp1 (antagonizing VEGF signaling) and Trk receptors (perturbing sensory neuron development), sequesters tRNA^Gly to cause ribosome stalling, and loses its ability to inhibit SIRT2-mediated α-tubulin deacetylation, while requiring dimerization for neurotoxicity; the WHEP domain regulates GlyRS secretion and its physiological interaction with Nrp1 to control vascular permeability; and recessive loss-of-function alleles cause multisystem developmental disease and mitochondrial respiratory chain dysfunction."},"narrative":{"mechanistic_narrative":"GARS1 encodes glycyl-tRNA synthetase (GlyRS), a homodimeric class II aminoacyl-tRNA synthetase that charges tRNA^Gly with glycine; its crystal structure with bound tRNA^Gly and a glycyl-AMP intermediate captures the glycylation reaction and reveals the contributions of the flexible WHEP-TRS domain and characteristic insertions to tRNA binding [PMID:27261259]. Dominant CMT2D-type peripheral neuropathy arises not from haploinsufficiency but from a dose-dependent toxic gain-of-function, since over-expression of wild-type GARS fails to rescue mutant mice while increased mutant dosage worsens disease [PMID:22144914]. CMT2D mutations alter GlyRS conformation and confer neomorphic binding activities: mutant GlyRS aberrantly binds neuropilin-1, competitively antagonizing the VEGF-Nrp1 axis required for motor neuron survival [PMID:26503042], and aberrantly engages Trk neurotrophin receptors (TrkA/TrkB) to perturb sensory neuron fate during development [PMID:28351971], with downstream BDNF/TrkB-dependent disruption of axonal transport of signaling endosomes [PMID:36928301]. A unifying biochemical mechanism is sequestration of tRNA^Gly by mutant GlyRS, which depletes the charged tRNA^Gly pool and stalls ribosomes at glycine codons [PMID:40119731]. Wild-type GlyRS also binds and inhibits the deacetylase SIRT2 to maintain α-tubulin acetylation, an activity abolished by CMT2D mutations and whose restoration (via SIRT2 reduction) rescues neuropathy in flies [PMID:34053152]; mutant neurotoxicity requires GlyRS dimerization [PMID:27008886] and is non-cell-autonomous [PMID:25972375]. Recessive loss-of-function alleles instead cause a multisystem developmental syndrome and mitochondrial respiratory chain dysfunction [PMID:28675565, PMID:28594869]. Beyond neuronal disease, GlyRS participates in nutrient-sensing mTOR signaling for milk synthesis [PMID:30171693, PMID:31954518] and a KLF16-GARS-FOXK1 glycolytic axis in hepatocellular carcinoma [PMID:40603105].","teleology":[{"year":2006,"claim":"Establishing which protein regions tolerate disease mutations was needed to map structure to pathology; identifying anticodon-binding-domain mutations extended the CMT2D/dSMA-V mutational spectrum beyond catalytic regions.","evidence":"Mutation screening and domain mapping in a 100-patient cohort","pmids":["17101916"],"confidence":"Low","gaps":["No biochemical assay of anticodon-binding activity for these variants","Genotype-phenotype correlation without mechanistic test"]},{"year":2009,"claim":"It was unclear whether heterozygous CMT2D pathology reflects reduced aminoacylation; a mouse point mutant showed enzyme deficits only in homozygotes, decoupling heterozygous disease from loss of charging activity.","evidence":"Gars^C201R mouse model with enzymatic assays and genetic crosses (SOD1^G93A, Dync1h1^Loa)","pmids":["19470612","19593442"],"confidence":"Medium","gaps":["Mechanism of SOD1^G93A interaction unresolved","Does not identify the toxic activity itself"]},{"year":2011,"claim":"Distinguishing loss- versus gain-of-function was central to therapy; dosage experiments demonstrated dominant CMT2D is a toxic gain-of-function not corrected by wild-type supplementation.","evidence":"Transgenic wild-type GARS over-expression crossed into two dominant CMT2D mouse models with complementation tests","pmids":["22144914"],"confidence":"High","gaps":["Does not define the molecular nature of the toxic activity","Restricted to two alleles"]},{"year":2013,"claim":"Whether mutant GlyRS mislocalizes within neurons was tested; the G240R mutant failed to reach axonal compartments, hinting at a distribution defect linked to axonal degeneration.","evidence":"Adenoviral neuronal expression with immunohistochemical localization in mouse neurons","pmids":["23990368"],"confidence":"Low","gaps":["No functional rescue confirming mislocalization drives pathology","Single model, single lab"]},{"year":2015,"claim":"The neomorphic basis of toxicity was unknown; CMT2D conformational change was shown to create aberrant Nrp1 binding that antagonizes VEGF-Nrp1 motor-neuron survival signaling.","evidence":"Co-IP/competitive binding assays plus genetic epistasis (Nrp1 reduction, VEGF overexpression) in mice","pmids":["26503042"],"confidence":"High","gaps":["Does not explain sensory phenotype","Relationship to aminoacylation defects unaddressed"]},{"year":2015,"claim":"Whether toxicity originates solely in neurons was tested; tissue-specific Drosophila expression showed mutant GlyRS in muscle/mesoderm alone causes WHEP-dependent NMJ denervation, establishing non-cell-autonomous pathology.","evidence":"Tissue-specific Drosophila CMT2D models with WHEP domain-deletion analysis and NMJ histology","pmids":["25972375"],"confidence":"High","gaps":["Identity of the muscle-derived toxic signal not defined","WHEP domain mechanism not molecularly resolved here"]},{"year":2016,"claim":"A structural framework was lacking; the GlyRS-tRNA^Gly co-crystal with a glycyl-AMP intermediate defined the catalytic and WHEP-domain contributions to substrate engagement.","evidence":"X-ray crystallography at 2.95 Å of human GlyRS with tRNA^Gly","pmids":["27261259"],"confidence":"High","gaps":["Does not model CMT2D mutant conformations","No structure of neomorphic complexes (Nrp1, Trk)"]},{"year":2016,"claim":"Whether the oligomeric state matters for toxicity was tested; dimerization was shown to be required for dominant neurotoxicity, distinguishing dominant-negative loss from gain-of-function alleles.","evidence":"Zebrafish genetic model with dimerization assays and rescue/complementation of multiple human-equivalent mutants","pmids":["27008886"],"confidence":"High","gaps":["Mechanistic link between dimerization and neomorphic binding unspecified","Heterodimer composition in patients not addressed"]},{"year":2017,"claim":"The developmental component of CMT2D was unexplained; mutant GlyRS was found to aberrantly bind Trk receptors, misactivating signaling and skewing sensory neuron subtype balance at birth.","evidence":"In vitro wild-type vs mutant binding assays plus CMT2D mouse DRG subtype profiling","pmids":["28351971"],"confidence":"High","gaps":["Quantitative contribution of Trk vs Nrp1 axes not separated","Structural basis of Trk binding unknown"]},{"year":2017,"claim":"The basis of recessive GARS disease was undefined; compound heterozygous loss-of-function variants were shown to cause a multisystem developmental syndrome distinct from dominant CMT2D.","evidence":"In vitro tRNA charging and protein expression analyses of patient frameshift and missense variants","pmids":["28675565"],"confidence":"Medium","gaps":["Single patient/lab, limited replication","No animal model of the recessive syndrome"]},{"year":2017,"claim":"Tissue dysfunction in recessive disease needed a mechanism; loss-of-function GARS was linked to reduced activity of respiratory chain complexes I, III, and IV.","evidence":"Spectrophotometric respiratory chain assays and immunoblotting in patient muscle, liver, and fibroblasts","pmids":["28594869"],"confidence":"Medium","gaps":["Causal pathway from GlyRS loss to complex deficiency not defined","Single patient cohort"]},{"year":2018,"claim":"An upstream regulator of GARS in neuronal development was sought; UBA1 was shown to act through a non-canonical, ubiquitylation-independent pathway controlling GARS-dependent sensory fate, linking SMA and CMT biology.","evidence":"Mass spectrometry target identification and UBA1 restoration epistasis in SMA mice","pmids":["30239612"],"confidence":"Medium","gaps":["Biochemical mechanism of UBA1-GARS regulation uncharacterized","Direct physical interaction not established"]},{"year":2018,"claim":"A non-canonical signaling role was tested; GlyRS was shown to mediate amino acid-induced mTOR-S6K1/4EBP1 activation driving milk protein and fat synthesis.","evidence":"siRNA knockdown and overexpression in bovine mammary epithelial cells with pathway readouts","pmids":["30171693"],"confidence":"Medium","gaps":["Single species/cell system","Direct mTOR-pathway interaction partner not reconstituted"]},{"year":2020,"claim":"How GlyRS is activated in nutrient signaling was unknown; a GPR87-CDC42/Rac1-MAP3K10 cascade was shown to phosphorylate GlyRS, promoting nuclear entry and milk-synthesis gene expression.","evidence":"Co-IP/MS, in vitro kinase assay, and pathway inhibition in bovine mammary epithelial cells","pmids":["31954518"],"confidence":"Medium","gaps":["Phosphosite mapping incomplete","Non-neuronal, single-lab context"]},{"year":2020,"claim":"The spatial pattern of degeneration was undefined; NMJ denervation in CMT2D mice follows a distal-to-proximal gradient determined by post-natal synaptic growth rather than fiber type.","evidence":"Systematic multi-muscle NMJ histology and correlation analyses in CMT2D mice","pmids":["32703932"],"confidence":"Medium","gaps":["Molecular driver of synaptic-growth vulnerability unidentified","Single lab"]},{"year":2020,"claim":"Site-specific sensory vulnerability lacked explanation; selectively elevated Gars expression in hindlimb-innervating sensory neuron subsets was linked to localized developmental defects.","evidence":"Anatomical dissection across multiple mouse models with subtype-specific Gars immunohistochemistry and axonal transport assays","pmids":["32848623"],"confidence":"Medium","gaps":["Causal test of elevated Gars in vulnerability lacking","Single lab"]},{"year":2021,"claim":"A cytoskeletal function of GlyRS was identified; wild-type GlyRS binds and inhibits SIRT2 to preserve α-tubulin acetylation, an activity lost by CMT2D mutants and whose restoration rescues neuropathy.","evidence":"Reciprocal Co-IP, in vitro deacetylation assay, and SIRT2-knockdown rescue in Drosophila","pmids":["34053152"],"confidence":"High","gaps":["Interplay with Nrp1/Trk neomorphic activities unresolved","Quantitative contribution to overall pathology unknown"]},{"year":2022,"claim":"A shared structural consequence of mutations was sought computationally; MD simulations predicted G240R disrupts dimer-interface and tRNA-binding dynamics in a region commonly affected by CMT2D mutations.","evidence":"Molecular dynamics simulations of wild-type and G240R GlyRS","pmids":["36504507"],"confidence":"Low","gaps":["Computational only, no experimental validation","Single mutation modeled in detail"]},{"year":2023,"claim":"A downstream cellular defect of CMT2D was defined in vivo; early disturbance of axonal transport of neurotrophin endosomes was shown to be BDNF/TrkB-dependent and fully rescuable by muscle BDNF supplementation.","evidence":"Intravital sciatic-nerve imaging with TrkB inhibition and neurotrophin-specific rescue in CMT2D mice","pmids":["36928301"],"confidence":"High","gaps":["Link between transport defect and SIRT2/tubulin axis unaddressed","Mechanism connecting mutant GlyRS to BDNF/TrkB at NMJ not fully resolved"]},{"year":2025,"claim":"A single unifying biochemical mechanism was sought across PN mutations; mutant GlyRS sequesters tRNA^Gly, depleting the charged pool and stalling ribosomes at glycine codons, while excluding dominant-negative loss-of-function and a non-pathogenic control variant.","evidence":"Drosophila PN-GlyRS models, de novo synthesis, tRNA sequestration, and aminoacylation assays with K456Q negative control","pmids":["40119731"],"confidence":"High","gaps":["Relationship between sequestration and neomorphic receptor binding not integrated","Cell-type specificity of stalling not defined"]},{"year":2025,"claim":"A physiological role of the WHEP domain in vascular biology was identified; WHEP-dependent GlyRS secretion controls its Nrp1 interaction, and WHEP deletion drives aberrant Nrp1 endocytosis, VE-cadherin loss, and increased vascular permeability.","evidence":"Gars1^ΔWHEP knock-in mice, fractionation, Nrp1 Co-IP, endocytosis and VE-cadherin assays, Nrp1 heterozygous rescue (preprint)","pmids":["bio_10.1101_2025.05.14.654074"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Relation to CMT2D neuronal pathology unclear"]},{"year":2025,"claim":"A cancer-associated function was defined; a KLF16-GARS-FOXK1 axis was shown to promote hepatocellular carcinoma glycolysis via GARS stabilization of FOXK1 and induction of glycolytic genes.","evidence":"ChIP, Co-IP, ubiquitination assays, knockdown, and in vitro/in vivo glycolysis assays in HCC cells","pmids":["40603105"],"confidence":"Medium","gaps":["Single-lab cancer context","Direct GARS-FOXK1 binding determinants not mapped"]},{"year":null,"claim":"How the multiple proposed mechanisms (tRNA^Gly sequestration, Nrp1 and Trk neomorphic binding, loss of SIRT2 inhibition, axonal transport disruption) are quantitatively integrated into a single dominant CMT2D pathogenic cascade remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No study reconciles relative contributions of each mechanism","Connection between aminoacylation-independent neomorphic activities and tRNA sequestration undefined","No structural model of any neomorphic complex"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[5,6,12,21]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[5,6]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,7]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5,7]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[17]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[10]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[5,6]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,15]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,12]}],"complexes":[],"partners":["NRP1","NTRK1","NTRK2","SIRT2","UBA1","MAP3K10","FOXK1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P41250","full_name":"Glycine--tRNA ligase","aliases":["Diadenosine tetraphosphate synthetase","Ap4A synthetase","Glycyl-tRNA synthetase","GlyRS","Glycyl-tRNA synthetase 1"],"length_aa":739,"mass_kda":83.2,"function":"Catalyzes the ATP-dependent ligation of glycine to the 3'-end of its cognate tRNA, via the formation of an aminoacyl-adenylate intermediate (Gly-AMP) (PubMed:17544401, PubMed:24898252, PubMed:28675565). Also produces diadenosine tetraphosphate (Ap4A), a universal pleiotropic signaling molecule needed for cell regulation pathways, by direct condensation of 2 ATPs. Thereby, may play a special role in Ap4A homeostasis (PubMed:19710017)","subcellular_location":"Cytoplasm; Cell projection, axon","url":"https://www.uniprot.org/uniprotkb/P41250/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/GARS1","classification":"Common Essential","n_dependent_lines":1189,"n_total_lines":1208,"dependency_fraction":0.984271523178808},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GARS1","total_profiled":1310},"omim":[{"mim_id":"619042","title":"SPINAL MUSCULAR ATROPHY, INFANTILE, JAMES TYPE; SMAJI","url":"https://www.omim.org/entry/619042"},{"mim_id":"601472","title":"CHARCOT-MARIE-TOOTH DISEASE, AXONAL, TYPE 2D; CMT2D","url":"https://www.omim.org/entry/601472"},{"mim_id":"600794","title":"NEURONOPATHY, DISTAL HEREDITARY MOTOR, AUTOSOMAL DOMINANT 5; HMND5","url":"https://www.omim.org/entry/600794"},{"mim_id":"600287","title":"GLYCYL-tRNA SYNTHETASE 1; GARS1","url":"https://www.omim.org/entry/600287"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/GARS1"},"hgnc":{"alias_symbol":["GlyRS","DSMAV","SMAD1"],"prev_symbol":["CMT2D","GARS"]},"alphafold":{"accession":"P41250","domains":[{"cath_id":"3.30.930.10","chopping":"132-183_298-482_572-597","consensus_level":"medium","plddt":93.5497,"start":132,"end":597},{"cath_id":"3.30.40.230","chopping":"201-285","consensus_level":"high","plddt":87.6654,"start":201,"end":285},{"cath_id":"3.30.720.200","chopping":"488-568","consensus_level":"high","plddt":87.6601,"start":488,"end":568},{"cath_id":"3.40.50.800","chopping":"615-722","consensus_level":"high","plddt":96.3476,"start":615,"end":722},{"cath_id":"1.10.287","chopping":"66-119","consensus_level":"medium","plddt":79.8711,"start":66,"end":119}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P41250","model_url":"https://alphafold.ebi.ac.uk/files/AF-P41250-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P41250-F1-predicted_aligned_error_v6.png","plddt_mean":86.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GARS1","jax_strain_url":"https://www.jax.org/strain/search?query=GARS1"},"sequence":{"accession":"P41250","fasta_url":"https://rest.uniprot.org/uniprotkb/P41250.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P41250/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P41250"}},"corpus_meta":[{"pmid":"26503042","id":"PMC_26503042","title":"CMT2D 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neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/33683627","citation_count":35,"is_preprint":false},{"pmid":"28675565","id":"PMC_28675565","title":"Compound heterozygosity for loss-of-function GARS variants results in a multisystem developmental syndrome that includes severe growth retardation.","date":"2017","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/28675565","citation_count":34,"is_preprint":false},{"pmid":"30171693","id":"PMC_30171693","title":"GlyRS is a new mediator of amino acid-induced milk synthesis in bovine mammary epithelial cells.","date":"2018","source":"Journal of cellular physiology","url":"https://pubmed.ncbi.nlm.nih.gov/30171693","citation_count":31,"is_preprint":false},{"pmid":"30198022","id":"PMC_30198022","title":"The Benefits of Genetic Addiction Risk Score (GARS™) Testing in Substance Use Disorder (SUD).","date":"2018","source":"International journal of genomics and data 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IJCB","url":"https://pubmed.ncbi.nlm.nih.gov/23277712","citation_count":1,"is_preprint":false},{"pmid":"40247807","id":"PMC_40247807","title":"A Comprehensive 4-layered In Silico Pharmacogenomics Analysis of the Genetic Addiction Risk Severity (GARS) Test: Strong Genetic Evidence Supporting GARS as a Novel Personalized Pre-addiction Assessment Tool in the Opioid Crisis Era.","date":"2025","source":"Current pharmaceutical biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/40247807","citation_count":1,"is_preprint":false},{"pmid":"41392997","id":"PMC_41392997","title":"Beyond translation: systematic insight of the multifaceted roles of GARS1 in cellular biology and disease.","date":"2025","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/41392997","citation_count":0,"is_preprint":false},{"pmid":"39599995","id":"PMC_39599995","title":"A familial form of Charcot-Marie-Tooth disease (type 2d) caused by a previously unreported variant in 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(GlyRS^CMT2D) to acquire a neomorphic binding activity that allows it to bind neuropilin 1 (Nrp1) receptor. This aberrant interaction competitively interferes with VEGF binding to Nrp1, antagonizing the VEGF-Nrp1 signaling axis required for motor neuron survival. Genetic reduction of Nrp1 in mice worsens CMT2D symptoms, whereas enhanced VEGF expression improves motor function.\",\n      \"method\": \"Co-IP/binding assays showing GlyRS^CMT2D-Nrp1 interaction; competitive binding with VEGF; genetic epistasis in mice (Nrp1 reduction, VEGF overexpression); conformational analysis of mutant vs. wild-type GlyRS\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays, genetic epistasis with multiple alleles in vivo, functional rescue experiments in mice; published in high-impact journal with multiple orthogonal approaches\",\n      \"pmids\": [\"26503042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The dominant CMT2D neuropathy caused by GARS missense mutations is due to a dose-dependent toxic gain-of-function mechanism, not loss of aminoacylation function. Over-expression of wild-type GARS does not rescue the neuropathy phenotype in heterozygous Gars mutant mice, demonstrating the pathology is not caused by haploinsufficiency. Increased dosage of disease-causing alleles worsened neuropathy, confirming a gain-of-function mechanism.\",\n      \"method\": \"Transgenic mice over-expressing wild-type GARS crossed to two dominant CMT2D mouse models; histological, functional, and behavioral assessment; complementation tests with null allele\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean in vivo genetic experiment with multiple alleles, functional rescue/failure controls, replicated across two distinct mouse models in single study\",\n      \"pmids\": [\"22144914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CMT2D mutant GlyRS aberrantly interacts with Trk neurotrophin receptors (TrkA and TrkB), causing misactivation of Trk signaling essential for sensory neuron differentiation and development. This interaction perturbs sensory neuron fate in dorsal root ganglia, leading to an imbalance of sensory neuron subtypes that is present at birth and non-progressive, indicating a developmental rather than purely degenerative insult.\",\n      \"method\": \"In vitro binding assays showing mutant but not wild-type GlyRS interacts with Trk receptors; mouse CMT2D model behavioral and histological analysis; sensory subtype profiling in DRG\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct in vitro binding assay with wild-type vs. mutant comparison, corroborated by in vivo mouse model phenotyping with multiple orthogonal readouts\",\n      \"pmids\": [\"28351971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Mutant GlyRS-induced neurotoxicity in CMT2D is non-cell autonomous: expression of mutant GlyRS in mesoderm or muscle alone (not just neurons) is sufficient to produce motor deficits and progressive neuromuscular junction (NMJ) denervation in Drosophila. The toxic gain-of-function effect is WHEP domain-dependent and is associated with abnormal NMJ assembly and pre-synaptic accumulation of mutant GlyRS.\",\n      \"method\": \"Novel Drosophila CMT2D models with tissue-specific (neuronal, mesodermal, muscle) expression of mutant GlyRS; motor deficit assays; NMJ histology; domain deletion analysis (WHEP domain)\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific genetic dissection in Drosophila with multiple mutant alleles, domain-deletion analysis, and multiple phenotypic readouts establishing non-cell-autonomous mechanism\",\n      \"pmids\": [\"25972375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Dimerization of GlyRS is required for dominant CMT2D neurotoxicity. A zebrafish loss-of-dimerization mutant (T209K/T130K in human) causes neuromuscular phenotype through loss of function. A human CMT disease-associated dimerization-deficient mutant (G319R/G240R in human) cannot rescue this phenotype, while another CMT mutant (G605R/G526 in human) that can dimerize with wild-type protein worsens phenotype in heterozygotes through dominant negative reduction of function.\",\n      \"method\": \"Zebrafish genetic model (gars^s266 allele); dimerization assays; rescue/complementation experiments with wild-type and mutant transgenes; neuromuscular phenotype assessment\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic model combined with direct biochemical dimerization assays, multiple alleles tested including rescue experiments\",\n      \"pmids\": [\"27008886\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Crystal structure of wild-type human GlyRS in complex with tRNA^Gly determined at 2.95 Å. The flexible WHEP-TRS domain is visible in one subunit of the homodimer; tRNA is fully resolved. A glycyl-AMP intermediate is present at the active site, capturing the enzyme in an intermediate stage of glycylation. The structure reveals the roles of insertions and the WHEP-TRS domain in tRNA binding.\",\n      \"method\": \"X-ray crystallography (2.95 Å); co-crystal of hGlyRS with tRNA^Gly; structural comparison with other class II aaRS-tRNA complexes\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure at near-atomic resolution with bound tRNA substrate and reaction intermediate; single lab but definitive structural determination\",\n      \"pmids\": [\"27261259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"tRNA^Gly sequestration by mutant GlyRS is the unifying pathogenic mechanism for all tested GARS1-associated peripheral neuropathy mutations. PN-mutant GlyRS variants (S211F and H418R) sequester tRNA^Gly, depleting the cellular tRNA^Gly pool, leading to insufficient glycyl-tRNA^Gly for ribosomes and ribosome stalling at glycine codons. A dominant negative loss-of-function mechanism was excluded for these variants. K456Q was shown not to be a pathogenic mutation as it does not affect aminoacylation or induce neuropathy in Drosophila.\",\n      \"method\": \"Novel Drosophila models expressing human PN-GlyRS variants; de novo protein synthesis assays; genetic and biochemical tRNA sequestration assays; aminoacylation activity measurements\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — biochemical aminoacylation assays, in vivo Drosophila genetic models, direct tRNA sequestration measurements, negative control (K456Q), multiple orthogonal methods in single study\",\n      \"pmids\": [\"40119731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Wild-type GARS binds the NAD+-dependent deacetylase SIRT2 and inhibits its deacetylation activity, resulting in maintenance of acetylated α-tubulin. CMT2D mutations in GARS abolish this inhibitory interaction with SIRT2, leading to decreased acetylated α-tubulin. The catalytic domain of GARS mediates the interaction with SIRT2. Genetic reduction of SIRT2 in Drosophila CMT2D models rescues the axonal neuropathy phenotype.\",\n      \"method\": \"Co-IP of GARS and SIRT2; in vitro deacetylation assay; Western blotting for acetylated α-tubulin; Drosophila genetic rescue experiment with SIRT2 knockdown; domain analysis\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, in vitro enzymatic assay, in vivo genetic rescue in Drosophila, wild-type vs. mutant comparison; multiple orthogonal methods\",\n      \"pmids\": [\"34053152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"UBA1 regulates GARS via a non-canonical pathway independent of ubiquitylation. Dysregulation of the UBA1/GARS pathway in SMA mice disrupts sensory neuron fate, phenocopying GARS-dependent defects associated with CMT disease. Restoration of UBA1 corrects the sensory neuron fate defects and sensory-motor connectivity in SMA mice via the UBA1/GARS pathway.\",\n      \"method\": \"Mass spectrometry identification of GARS as UBA1 downstream target; genetic epistasis (UBA1 restoration in SMA mice); sensory neuron fate analysis; sensory-motor connectivity assessment\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS identification plus in vivo genetic epistasis, but non-canonical UBA1/GARS interaction mechanism not fully biochemically characterized in the abstract\",\n      \"pmids\": [\"30239612\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"GlyRS mediates amino acid (methionine and leucine)-induced activation of the mTOR-S6K1/4EBP1 signaling pathway in bovine mammary epithelial cells, thereby regulating milk protein and fat synthesis. GlyRS knockdown abolishes Met-stimulated milk synthesis, and GlyRS overexpression enhances it.\",\n      \"method\": \"siRNA knockdown and overexpression of GlyRS in bovine mammary epithelial cells; Western blotting and qRT-PCR for mTOR pathway components; milk protein/fat synthesis assays\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD and OE experiments with defined pathway readouts, but single lab, single model system (bovine), no reconstitution\",\n      \"pmids\": [\"30171693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MAP3K10 (mitogen-activated protein kinase 10) interacts with GlyRS in bovine mammary epithelial cells and acts as its upstream kinase. Met stimulates GlyRS phosphorylation via the GPR87-CDC42/Rac1-MAP3K10 signaling cascade. Phosphorylated GlyRS enters the nucleus to stimulate gene expression for milk synthesis, and MAP3K10 stimulates NFκB1 phosphorylation via GlyRS.\",\n      \"method\": \"Co-IP; mass spectrometry; Western blotting; in vitro kinase assay; pathway inhibition experiments\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro kinase assay plus Co-IP/MS identification, multiple methods but single lab and non-neuronal context\",\n      \"pmids\": [\"31954518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The Gars^C201R point mutation in mice causes a heterozygous peripheral neuropathy with reduced enzyme (aminoacylation) activity only in homozygous animals, not heterozygotes, suggesting heterozygous pathology is not explained by reduced aminoacylation. Homozygous animals show a more severe phenotype consistent with partial loss of function. Genetic interaction with SOD1^G93A: the Gars^C201R mutation significantly delayed disease onset and extended lifespan by 29% in SOD1^G93A mice.\",\n      \"method\": \"Mouse genetic model characterization; enzymatic activity assays; genetic crosses with SOD1^G93A and Dync1h1^Loa mice; behavioral and electrophysiological assessments\",\n      \"journal\": \"Disease models & mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — enzymatic assays combined with in vivo genetic crosses, multiple phenotypic assessments, but mechanism of SOD1 interaction not fully resolved\",\n      \"pmids\": [\"19470612\", \"19593442\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Compound heterozygous GARS variants (frameshift p.Glu83Ilefs*6 and missense p.Arg310Gln) cause loss-of-function: the frameshift variant depletes protein levels and the missense variant reduces tRNA charging (aminoacylation) activity. This establishes that recessive GARS loss-of-function leads to a multisystem developmental syndrome with severe growth retardation, distinct from the dominant gain-of-function CMT2D mechanism.\",\n      \"method\": \"In vitro tRNA charging activity assays; protein expression analysis; in vivo functional studies; whole-exome sequencing with functional validation\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Weak — in vitro aminoacylation assay plus protein expression analysis, but single patient/single lab, limited replication\",\n      \"pmids\": [\"28675565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Compound heterozygous GARS variants cause mitochondrial respiratory chain dysfunction, with reduced activity of Complexes I, III, and IV in skeletal muscle and liver. Immunoblot analysis showed significant reduction in GARS protein and Complex IV subunits in patient fibroblasts, establishing a functional link between GARS loss-of-function and mitochondrial dysfunction.\",\n      \"method\": \"Spectrophotometric evaluation of mitochondrial respiratory chain complexes; immunoblot analysis of GARS protein and respiratory chain complex subunits; whole-exome sequencing\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct biochemical measurement of enzyme complex activities in patient tissues, but single patient, single lab\",\n      \"pmids\": [\"28594869\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"A disease-causing G240R mutation in GARS (G319R in zebrafish Gars) leads to altered intracellular distribution: wild-type GARS is distributed to peripheral axons, DRG cell bodies, central axon terminals, and motor neuron cell bodies, whereas G240R mutant GARS localizes only to DRG and motor neuron cell bodies but not axonal regions in vivo, suggesting a distribution defect associated with axonal degeneration.\",\n      \"method\": \"Adenoviral vector-mediated expression in mouse neurons using a neuronal-specific promoter; immunohistochemistry for GARS localization in vivo\",\n      \"journal\": \"Journal of molecular histology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single localization study in a novel viral model, single lab, no functional rescue to confirm the distribution defect drives pathology\",\n      \"pmids\": [\"23990368\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CMT2D mice display early and persistent disturbances in axonal transport of neurotrophin-containing signaling endosomes in vivo, correlating with BDNF/TrkB impairments. Inhibition of the BDNF/TrkB pathway at the nerve-muscle interface perturbed endosome transport in wild-type axons. Supplementation with BDNF (but not other neurotrophins) completely restored physiological axonal transport in neuropathic mice.\",\n      \"method\": \"Intravital imaging of sciatic nerve in CMT2D mice; pharmacological TrkB pathway inhibition; BDNF muscle supplementation; neurotrophin-signaling endosome tracking\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — intravital live imaging combined with pharmacological and neurotrophin rescue experiments, specificity shown by BDNF vs. other neurotrophins, multiple orthogonal approaches\",\n      \"pmids\": [\"36928301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In CMT2D mice, neuromuscular junction denervation occurs along a distal-to-proximal gradient. Defective NMJ development precedes and is associated with degeneration but is not linked to delay of wild-type NMJ maturation. The extent of post-natal synaptic growth (rather than muscle fibre type or synaptic architecture) predisposes to neurodegeneration at specific NMJs.\",\n      \"method\": \"Systematic comparison of NMJ development and degeneration across five wholemount muscles; correlation analyses of NMJ features with denervation severity; immunohistochemistry\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic multi-muscle histological analysis with correlation analyses in defined mouse model, multiple muscles compared, but single lab\",\n      \"pmids\": [\"32703932\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The WHEP domain of GlyRS (encoded by exon 2 of Gars1) is required for the free secretion/release of GlyRS from cells. Deletion of the WHEP domain (Gars1^ΔWHEP) causes GlyRS to accumulate in membrane fractions and show stronger interaction with the extracellular region of neuropilin 1 (Nrp1). This aberrant GlyRS-Nrp1 interaction enhances Nrp1 endocytic activity and reduces VE-cadherin localization at endothelial adherens junctions, increasing vascular permeability. Heterozygous Nrp1 knockout partially rescues the vascular permeability defects in Gars1^ΔWHEP/ΔWHEP mice. WHEP domain deletion did not impair tRNA aminoacylation.\",\n      \"method\": \"Gars1^ΔWHEP knock-in mice (exon 2 deletion); cell fractionation; co-IP with Nrp1 extracellular domain; endocytosis assays; VE-cadherin localization by immunofluorescence; genetic rescue with Nrp1 heterozygous knockout; aminoacylation activity assays\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple in vivo and in vitro methods, genetic rescue, biochemical fractionation, but preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.05.14.654074\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Molecular dynamics simulations of the G240R CMT2D mutation in GlyRS show altered native interactions at the dimer interface and altered dynamics of regions associated with tRNA binding. Computational analysis predicts that a region disrupted by G240R is commonly affected by multiple CMT2D mutations, suggesting a shared structural mechanism.\",\n      \"method\": \"Molecular dynamics simulations of wild-type and G240R mutant GlyRS; analysis of dimer interface contacts and tRNA-binding domain dynamics\",\n      \"journal\": \"Brain multiphysics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational predictions only, no experimental validation reported in this study\",\n      \"pmids\": [\"36504507\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"KLF16 binds to the GARS promoter and enhances its transcription in hepatocellular carcinoma cells. The GARS protein then binds to and stabilizes FOXK1 by reducing its ubiquitination. FOXK1 promotes glycolysis by stimulating transcription of LDHA, PKM2, and GLUT1. This KLF16-GARS-FOXK1 axis promotes HCC glycolysis and growth.\",\n      \"method\": \"Chromatin immunoprecipitation (KLF16 promoter binding); Co-IP (GARS-FOXK1 interaction); ubiquitination assays; knockdown experiments; in vitro and in vivo glycolysis assays\",\n      \"journal\": \"The Tohoku journal of experimental medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP and functional knockdown experiments with defined pathway readout, but single lab, cancer cell context, limited replication\",\n      \"pmids\": [\"40603105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Mutations in the anticodon binding domain of GARS (in addition to other domains) cause CMT2D/dSMA-V, establishing that the anticodon-binding domain is functionally important for disease causation. A mutation within the anticodon binding domain was associated with earlier childhood onset and predominantly lower limb involvement, extending the phenotypic spectrum.\",\n      \"method\": \"Mutation screening of 100 patients; identification and segregation of novel GARS missense mutations; domain mapping of mutation locations\",\n      \"journal\": \"Neurology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — genetic association with domain localization, no biochemical functional characterization of anticodon binding domain activity in these mutations\",\n      \"pmids\": [\"17101916\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The p.Gly327Arg GARS variant fails to support yeast growth in a complementation assay, demonstrating loss-of-function at the level of aminoacylation activity. This establishes that severe impairment of GARS protein function causes distal hereditary motor neuropathy.\",\n      \"method\": \"Yeast complementation assay for GARS tRNA charging function\",\n      \"journal\": \"Journal of the peripheral nervous system : JPNS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — functional complementation assay (in vivo surrogate for aminoacylation) but single variant, single lab\",\n      \"pmids\": [\"31628756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Sensory pathology in CMT2D mice is restricted to neurons innervating the hindlimbs. Gars expression is selectively elevated in a subset of sensory neurons and is linked to sensory developmental defects, providing a potential explanation for site-specific sensory vulnerability.\",\n      \"method\": \"Anatomical dissection of sensory nervous system in CMT2D mouse models; comparison across multiple mouse models of neuromuscular disease; in vitro axonal transport assays; immunohistochemistry for Gars expression in sensory neuron subsets\",\n      \"journal\": \"Frontiers in cellular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple CMT2D mouse models compared, localization experiments correlated with developmental defects, but single lab\",\n      \"pmids\": [\"32848623\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GARS1 encodes glycyl-tRNA synthetase (GlyRS), a homodimeric class II aminoacyl-tRNA synthetase that charges tRNA^Gly with glycine for cytoplasmic and mitochondrial translation; dominant CMT2D-causing mutations drive a toxic gain-of-function in which mutant GlyRS acquires neomorphic binding to Nrp1 (antagonizing VEGF signaling) and Trk receptors (perturbing sensory neuron development), sequesters tRNA^Gly to cause ribosome stalling, and loses its ability to inhibit SIRT2-mediated α-tubulin deacetylation, while requiring dimerization for neurotoxicity; the WHEP domain regulates GlyRS secretion and its physiological interaction with Nrp1 to control vascular permeability; and recessive loss-of-function alleles cause multisystem developmental disease and mitochondrial respiratory chain dysfunction.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"GARS1 encodes glycyl-tRNA synthetase (GlyRS), a homodimeric class II aminoacyl-tRNA synthetase that charges tRNA^Gly with glycine; its crystal structure with bound tRNA^Gly and a glycyl-AMP intermediate captures the glycylation reaction and reveals the contributions of the flexible WHEP-TRS domain and characteristic insertions to tRNA binding [#5]. Dominant CMT2D-type peripheral neuropathy arises not from haploinsufficiency but from a dose-dependent toxic gain-of-function, since over-expression of wild-type GARS fails to rescue mutant mice while increased mutant dosage worsens disease [#1]. CMT2D mutations alter GlyRS conformation and confer neomorphic binding activities: mutant GlyRS aberrantly binds neuropilin-1, competitively antagonizing the VEGF-Nrp1 axis required for motor neuron survival [#0], and aberrantly engages Trk neurotrophin receptors (TrkA/TrkB) to perturb sensory neuron fate during development [#2], with downstream BDNF/TrkB-dependent disruption of axonal transport of signaling endosomes [#15]. A unifying biochemical mechanism is sequestration of tRNA^Gly by mutant GlyRS, which depletes the charged tRNA^Gly pool and stalls ribosomes at glycine codons [#6]. Wild-type GlyRS also binds and inhibits the deacetylase SIRT2 to maintain α-tubulin acetylation, an activity abolished by CMT2D mutations and whose restoration (via SIRT2 reduction) rescues neuropathy in flies [#7]; mutant neurotoxicity requires GlyRS dimerization [#4] and is non-cell-autonomous [#3]. Recessive loss-of-function alleles instead cause a multisystem developmental syndrome and mitochondrial respiratory chain dysfunction [#12, #13]. Beyond neuronal disease, GlyRS participates in nutrient-sensing mTOR signaling for milk synthesis [#9, #10] and a KLF16-GARS-FOXK1 glycolytic axis in hepatocellular carcinoma [#19].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Establishing which protein regions tolerate disease mutations was needed to map structure to pathology; identifying anticodon-binding-domain mutations extended the CMT2D/dSMA-V mutational spectrum beyond catalytic regions.\",\n      \"evidence\": \"Mutation screening and domain mapping in a 100-patient cohort\",\n      \"pmids\": [\"17101916\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No biochemical assay of anticodon-binding activity for these variants\", \"Genotype-phenotype correlation without mechanistic test\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"It was unclear whether heterozygous CMT2D pathology reflects reduced aminoacylation; a mouse point mutant showed enzyme deficits only in homozygotes, decoupling heterozygous disease from loss of charging activity.\",\n      \"evidence\": \"Gars^C201R mouse model with enzymatic assays and genetic crosses (SOD1^G93A, Dync1h1^Loa)\",\n      \"pmids\": [\"19470612\", \"19593442\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of SOD1^G93A interaction unresolved\", \"Does not identify the toxic activity itself\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Distinguishing loss- versus gain-of-function was central to therapy; dosage experiments demonstrated dominant CMT2D is a toxic gain-of-function not corrected by wild-type supplementation.\",\n      \"evidence\": \"Transgenic wild-type GARS over-expression crossed into two dominant CMT2D mouse models with complementation tests\",\n      \"pmids\": [\"22144914\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define the molecular nature of the toxic activity\", \"Restricted to two alleles\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Whether mutant GlyRS mislocalizes within neurons was tested; the G240R mutant failed to reach axonal compartments, hinting at a distribution defect linked to axonal degeneration.\",\n      \"evidence\": \"Adenoviral neuronal expression with immunohistochemical localization in mouse neurons\",\n      \"pmids\": [\"23990368\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No functional rescue confirming mislocalization drives pathology\", \"Single model, single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"The neomorphic basis of toxicity was unknown; CMT2D conformational change was shown to create aberrant Nrp1 binding that antagonizes VEGF-Nrp1 motor-neuron survival signaling.\",\n      \"evidence\": \"Co-IP/competitive binding assays plus genetic epistasis (Nrp1 reduction, VEGF overexpression) in mice\",\n      \"pmids\": [\"26503042\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not explain sensory phenotype\", \"Relationship to aminoacylation defects unaddressed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Whether toxicity originates solely in neurons was tested; tissue-specific Drosophila expression showed mutant GlyRS in muscle/mesoderm alone causes WHEP-dependent NMJ denervation, establishing non-cell-autonomous pathology.\",\n      \"evidence\": \"Tissue-specific Drosophila CMT2D models with WHEP domain-deletion analysis and NMJ histology\",\n      \"pmids\": [\"25972375\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the muscle-derived toxic signal not defined\", \"WHEP domain mechanism not molecularly resolved here\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"A structural framework was lacking; the GlyRS-tRNA^Gly co-crystal with a glycyl-AMP intermediate defined the catalytic and WHEP-domain contributions to substrate engagement.\",\n      \"evidence\": \"X-ray crystallography at 2.95 Å of human GlyRS with tRNA^Gly\",\n      \"pmids\": [\"27261259\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not model CMT2D mutant conformations\", \"No structure of neomorphic complexes (Nrp1, Trk)\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Whether the oligomeric state matters for toxicity was tested; dimerization was shown to be required for dominant neurotoxicity, distinguishing dominant-negative loss from gain-of-function alleles.\",\n      \"evidence\": \"Zebrafish genetic model with dimerization assays and rescue/complementation of multiple human-equivalent mutants\",\n      \"pmids\": [\"27008886\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanistic link between dimerization and neomorphic binding unspecified\", \"Heterodimer composition in patients not addressed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The developmental component of CMT2D was unexplained; mutant GlyRS was found to aberrantly bind Trk receptors, misactivating signaling and skewing sensory neuron subtype balance at birth.\",\n      \"evidence\": \"In vitro wild-type vs mutant binding assays plus CMT2D mouse DRG subtype profiling\",\n      \"pmids\": [\"28351971\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative contribution of Trk vs Nrp1 axes not separated\", \"Structural basis of Trk binding unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The basis of recessive GARS disease was undefined; compound heterozygous loss-of-function variants were shown to cause a multisystem developmental syndrome distinct from dominant CMT2D.\",\n      \"evidence\": \"In vitro tRNA charging and protein expression analyses of patient frameshift and missense variants\",\n      \"pmids\": [\"28675565\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single patient/lab, limited replication\", \"No animal model of the recessive syndrome\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Tissue dysfunction in recessive disease needed a mechanism; loss-of-function GARS was linked to reduced activity of respiratory chain complexes I, III, and IV.\",\n      \"evidence\": \"Spectrophotometric respiratory chain assays and immunoblotting in patient muscle, liver, and fibroblasts\",\n      \"pmids\": [\"28594869\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal pathway from GlyRS loss to complex deficiency not defined\", \"Single patient cohort\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"An upstream regulator of GARS in neuronal development was sought; UBA1 was shown to act through a non-canonical, ubiquitylation-independent pathway controlling GARS-dependent sensory fate, linking SMA and CMT biology.\",\n      \"evidence\": \"Mass spectrometry target identification and UBA1 restoration epistasis in SMA mice\",\n      \"pmids\": [\"30239612\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical mechanism of UBA1-GARS regulation uncharacterized\", \"Direct physical interaction not established\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"A non-canonical signaling role was tested; GlyRS was shown to mediate amino acid-induced mTOR-S6K1/4EBP1 activation driving milk protein and fat synthesis.\",\n      \"evidence\": \"siRNA knockdown and overexpression in bovine mammary epithelial cells with pathway readouts\",\n      \"pmids\": [\"30171693\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single species/cell system\", \"Direct mTOR-pathway interaction partner not reconstituted\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"How GlyRS is activated in nutrient signaling was unknown; a GPR87-CDC42/Rac1-MAP3K10 cascade was shown to phosphorylate GlyRS, promoting nuclear entry and milk-synthesis gene expression.\",\n      \"evidence\": \"Co-IP/MS, in vitro kinase assay, and pathway inhibition in bovine mammary epithelial cells\",\n      \"pmids\": [\"31954518\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phosphosite mapping incomplete\", \"Non-neuronal, single-lab context\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"The spatial pattern of degeneration was undefined; NMJ denervation in CMT2D mice follows a distal-to-proximal gradient determined by post-natal synaptic growth rather than fiber type.\",\n      \"evidence\": \"Systematic multi-muscle NMJ histology and correlation analyses in CMT2D mice\",\n      \"pmids\": [\"32703932\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular driver of synaptic-growth vulnerability unidentified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Site-specific sensory vulnerability lacked explanation; selectively elevated Gars expression in hindlimb-innervating sensory neuron subsets was linked to localized developmental defects.\",\n      \"evidence\": \"Anatomical dissection across multiple mouse models with subtype-specific Gars immunohistochemistry and axonal transport assays\",\n      \"pmids\": [\"32848623\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal test of elevated Gars in vulnerability lacking\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"A cytoskeletal function of GlyRS was identified; wild-type GlyRS binds and inhibits SIRT2 to preserve α-tubulin acetylation, an activity lost by CMT2D mutants and whose restoration rescues neuropathy.\",\n      \"evidence\": \"Reciprocal Co-IP, in vitro deacetylation assay, and SIRT2-knockdown rescue in Drosophila\",\n      \"pmids\": [\"34053152\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interplay with Nrp1/Trk neomorphic activities unresolved\", \"Quantitative contribution to overall pathology unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"A shared structural consequence of mutations was sought computationally; MD simulations predicted G240R disrupts dimer-interface and tRNA-binding dynamics in a region commonly affected by CMT2D mutations.\",\n      \"evidence\": \"Molecular dynamics simulations of wild-type and G240R GlyRS\",\n      \"pmids\": [\"36504507\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Computational only, no experimental validation\", \"Single mutation modeled in detail\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"A downstream cellular defect of CMT2D was defined in vivo; early disturbance of axonal transport of neurotrophin endosomes was shown to be BDNF/TrkB-dependent and fully rescuable by muscle BDNF supplementation.\",\n      \"evidence\": \"Intravital sciatic-nerve imaging with TrkB inhibition and neurotrophin-specific rescue in CMT2D mice\",\n      \"pmids\": [\"36928301\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Link between transport defect and SIRT2/tubulin axis unaddressed\", \"Mechanism connecting mutant GlyRS to BDNF/TrkB at NMJ not fully resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A single unifying biochemical mechanism was sought across PN mutations; mutant GlyRS sequesters tRNA^Gly, depleting the charged pool and stalling ribosomes at glycine codons, while excluding dominant-negative loss-of-function and a non-pathogenic control variant.\",\n      \"evidence\": \"Drosophila PN-GlyRS models, de novo synthesis, tRNA sequestration, and aminoacylation assays with K456Q negative control\",\n      \"pmids\": [\"40119731\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relationship between sequestration and neomorphic receptor binding not integrated\", \"Cell-type specificity of stalling not defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A physiological role of the WHEP domain in vascular biology was identified; WHEP-dependent GlyRS secretion controls its Nrp1 interaction, and WHEP deletion drives aberrant Nrp1 endocytosis, VE-cadherin loss, and increased vascular permeability.\",\n      \"evidence\": \"Gars1^ΔWHEP knock-in mice, fractionation, Nrp1 Co-IP, endocytosis and VE-cadherin assays, Nrp1 heterozygous rescue (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.05.14.654074\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Relation to CMT2D neuronal pathology unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A cancer-associated function was defined; a KLF16-GARS-FOXK1 axis was shown to promote hepatocellular carcinoma glycolysis via GARS stabilization of FOXK1 and induction of glycolytic genes.\",\n      \"evidence\": \"ChIP, Co-IP, ubiquitination assays, knockdown, and in vitro/in vivo glycolysis assays in HCC cells\",\n      \"pmids\": [\"40603105\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab cancer context\", \"Direct GARS-FOXK1 binding determinants not mapped\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple proposed mechanisms (tRNA^Gly sequestration, Nrp1 and Trk neomorphic binding, loss of SIRT2 inhibition, axonal transport disruption) are quantitatively integrated into a single dominant CMT2D pathogenic cascade remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No study reconciles relative contributions of each mechanism\", \"Connection between aminoacylation-independent neomorphic activities and tRNA sequestration undefined\", \"No structural model of any neomorphic complex\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [5, 6, 12, 21]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [5, 6]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5, 7]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [17]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [5, 6]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 15]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 12]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"NRP1\", \"NTRK1\", \"NTRK2\", \"SIRT2\", \"UBA1\", \"MAP3K10\", \"FOXK1\"],\n    \"other_free_text\": []\n  }\n}\n```","audit_flag":null,"evaluation":{"pairwise":"loss","faith_supported":7,"faith_total":7,"faith_pct":100.0}}