{"gene":"RTN4R","run_date":"2026-06-10T07:46:28","timeline":{"discoveries":[{"year":2012,"finding":"NgR1 (RTN4R) binds with high affinity to the glycosaminoglycan moiety of chondroitin sulfate proteoglycans (CSPGs) and participates in CSPG-mediated inhibition of cultured neurons. In vivo, combined loss of NgR1 and NgR3 (but not NgR1 and NgR2) mimics the triple Nogo receptor mutant phenotype of enhanced axonal regeneration after optic nerve crush, identifying NgR1 as a functional CSPG receptor.","method":"High-affinity binding assays, primary neuron inhibition assays, genetic knockout (single, double, triple mutant mice), retro-orbital optic nerve crush with axon regeneration quantification","journal":"Nature neuroscience","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (biochemical binding, in vitro neuronal assays, multiple genetic knockout combinations in vivo), replicated across several experimental paradigms in one rigorous study","pmids":["22406547"],"is_preprint":false},{"year":2008,"finding":"NgR1 directly binds FGF1 and FGF2 with high affinity (but not NgR2 or NgR3). NgR1 is enriched in synaptosomal fractions of hippocampus and co-localizes with FGFR1 at synapses. Loss of NgR1 leads to FGF2-dependent enhancement of LTP and attenuation of LTD at Schaffer collateral-CA1 synapses; FGFR kinase activity is required for FGF2-elicited LTP enhancement in NgR1 mutants. NgR1 loss also alters dendritic spine morphology along apical dendrites of hippocampal CA1 neurons.","method":"Direct binding assays (high-affinity), synaptosomal fractionation, confocal co-localization, NgR1 knockout mice, hippocampal slice electrophysiology (LTP/LTD), FGFR kinase inhibitor pharmacology, in vitro axonal branching assay","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — direct binding assay, subcellular fractionation with functional consequence, electrophysiological phenotype with pharmacological rescue, multiple orthogonal methods in one study","pmids":["18337405"],"is_preprint":false},{"year":2007,"finding":"Neuronal NgR1 is required for acute growth cone collapse induced by soluble MAG-Fc, OMgp-Fc, and Nogo-66, but is NOT required for chronic substrate-bound inhibition of neurite outgrowth by MAG or OMgp. Thus the growth cone-collapsing and substrate growth-inhibitory activities of myelin inhibitors can be dissociated, and chronic axon growth inhibition by myelin operates through NgR1-independent mechanisms.","method":"Germline NgR1 knockout, shRNAi knockdown in primary cerebellar/sensory/cortical neurons, two-paradigm assay (chronic substrate inhibition vs. acute soluble collapse)","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent loss-of-function strategies (germline KO + siRNA), two distinct assay paradigms, clear positive and negative results, replicated across multiple neuron types","pmids":["17611264"],"is_preprint":false},{"year":2014,"finding":"NgR1 functions as a cell-surface receptor for mammalian reovirus on neurons. Expression of NgR1 in non-susceptible cells confers reovirus binding and infection. Soluble NgR1 neutralizes reovirus infectivity. Blocking NgR1 on transfected cells or primary cortical neurons abrogates reovirus infection. Reovirus virions bind both soluble JAM-A and NgR1, whereas infectious subviral particles (ISVPs) bind only JAM-A, indicating distinct capsid components engage these two receptors.","method":"Gain-of-function expression in non-susceptible cells, soluble decoy neutralization, antibody blocking, NgR1 null primary cortical neurons, binding assays with virions vs. ISVPs","journal":"Cell host & microbe","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (gain-of-function, null neurons, soluble decoy, blocking antibody, differential binding assay), mechanistically coherent across all approaches","pmids":["24922571"],"is_preprint":false},{"year":2013,"finding":"AMIGO3 physically interacts with NgR1-p75/TROY in non-neuronal cells and in brain lysates, mediating RhoA activation in response to CNS myelin. AMIGO3 knockdown in adult primary DRG and retinal cultures promotes disinhibited neurite growth. AMIGO3 substitutes for LINGO-1 in the NgR1-p75/TROY inhibitory signalling complex acutely after CNS injury.","method":"Co-immunoprecipitation (non-neuronal cells and brain lysates), RhoA activation assay, siRNA knockdown in primary DRG and retinal cultures, in vivo lesion models (dorsal column, optic nerve crush)","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP in two systems plus functional KD assay and in vivo expression correlation, but single lab","pmids":["23613963"],"is_preprint":false},{"year":2006,"finding":"TACE (ADAM17) induces shedding of the NgR extracellular domain (NgRECD) from DRG neurons. Shed NgRECD acts as a competitive antagonist blocking inhibitory ligand binding to full-length NgR. TACE-induced NgR cleavage also reduces RhoA activation and EGFR phosphorylation downstream of the NgR/p75NTR complex, disinhibiting FGF2-stimulated neurite outgrowth in the presence of CNS myelin.","method":"TACE addition to DRG neuron cultures, Western blot for NgRECD shedding, RhoA activation assay, EGFR phosphorylation assay, neurite outgrowth quantification","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — biochemical shedding assay plus downstream signaling readouts and functional outgrowth assay, single lab","pmids":["16849393"],"is_preprint":false},{"year":2006,"finding":"NgR signals through a Ca2+-dependent pathway that activates EGFR phosphorylation, and through a Rho-A/ROCK/LIM-kinase/cofilin phosphorylation pathway leading to actin depolymerization and growth cone collapse. Schwann cell-derived factors (including TACE) cleave the NgR ectodomain; the shed NgRECD competitively antagonizes inhibitory ligand/NgR binding, blocking p75NTR/NgR clustering, reducing EGFR phosphorylation and suppressing RhoA activation. siRNA knockdown of p75NTR also inactivates RhoA and disinhibits neurotrophic factor-stimulated RGC neurite outgrowth.","method":"Schwann cell conditioned medium on RGC cultures, exogenous TACE application, siRNA knockdown of p75NTR, EGFR phosphorylation assay, RhoA activation assay, optic nerve regeneration in vivo","journal":"Brain","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — multiple signaling assays plus in vivo regeneration correlation, single lab, mechanistic pathway placement","pmids":["16613894"],"is_preprint":false},{"year":2005,"finding":"siRNA-mediated knockdown of NgR (100% protein reduction) in DRG neurons disinhibits neurotrophin-induced neurite outgrowth on CNS myelin, with a 50% increase in outgrowth at 48 h and a 3.5-fold increase in βIII-tubulin at 3 days, placing NgR as a required component of the CNS myelin inhibitory signaling cascade in DRG neurons.","method":"siRNA knockdown (RNAi) in DRG neurons, neurite outgrowth quantification on CNS myelin substrate, Western blot protein quantification","journal":"Molecular and cellular neurosciences","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — siRNA loss-of-function with quantified phenotypic readout, single lab, single method","pmids":["15737741"],"is_preprint":false},{"year":2019,"finding":"Nogo-A exposure to neurons recruits CRMP2 into an NgR1 immunoprecipitate in a PlexinA2-dependent manner, forming a NgR1/PlexinA2/CRMP2 ternary complex. Non-neuronal cells expressing both NgR1 and PlexinA2 (but not either alone) contract upon Nogo-A exposure. Double-heterozygous NgR1+/-/PlexinA2+/- neurons are rescued from Nogo-A inhibition (epistasis), and double-heterozygous mice show greater post-injury corticospinal sprouting and neurological recovery after pyramidotomy.","method":"NgR1 co-immunoprecipitation + mass spectrometry, non-neuronal cell contraction assay, genetic epistasis (double-heterozygous mice), pyramidotomy + anterograde tracing, behavioral recovery assessment","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — biochemical complex identification (Co-IP + MS), cell-based functional assay, genetic epistasis in vitro and in vivo, multiple orthogonal methods in one study","pmids":["30804090"],"is_preprint":false},{"year":2015,"finding":"NgR1 is required to restrict corticospinal tract (CST) axon regeneration after dorsal hemisection. Using comprehensive crym-GFP CST labeling (~10-fold more efficient than BDA), ngr1-/- mice showed significant CST axon regeneration (average 2.68% of labeled axons extending >100 μm past lesion) that was undetectable with traditional BDA tracing, whereas ngr1+/+ mice showed no significant regeneration.","method":"crym-GFP transgenic reporter mice for comprehensive CST labeling, ngr1 genetic knockout, dorsal hemisection spinal cord injury, quantitative axon counting","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic loss-of-function with a highly sensitive and validated reporter, quantitative phenotypic readout, rigorous controls","pmids":["26586827"],"is_preprint":false},{"year":2004,"finding":"Two missense mutations in RTN4R (R119W, R196H) identified in schizophrenic patients alter residues in the leucine-rich repeat domain; molecular modeling predicts structural alterations of the native GPI-anchored protein. Both mutations were absent in 300 controls.","method":"DHPLC mutation screening, molecular modeling of LRR domain","journal":"Human mutation","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational structural prediction only, no direct functional assay of mutant protein","pmids":["15532024"],"is_preprint":false},{"year":2017,"finding":"A rare RTN4R missense variant R292H, identified in schizophrenia patients, impairs growth cone formation in vitro functional assays, linking NgR1 structure to cytoskeletal regulation of growth cones.","method":"Exon sequencing, in vitro growth cone formation assay with R292H mutant","journal":"Translational psychiatry","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — direct functional assay of mutant protein (growth cone formation), single lab","pmids":["28892071"],"is_preprint":false},{"year":2009,"finding":"Zebrafish Nogo66 (ZF-Nogo66) is growth-permissive rather than inhibitory for both zebrafish and mouse neurons, in contrast to rat Nogo66. Both ZF- and rat-Nogo66 bind NgR (GPI-anchored receptor) in fish and mouse neurons. Rat-Nogo66 elicits phosphorylation of the downstream effector cofilin, whereas ZF-Nogo66 does not, demonstrating that differential downstream signaling (rather than receptor binding) accounts for the species difference in regenerative capacity.","method":"Outgrowth assay, growth cone collapse assay, contact assay across species, PI-PLC treatment to identify GPI-anchored receptor involvement, cofilin phosphorylation assay","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — multiple functional assays plus signaling readout, PI-PLC pharmacology to implicate GPI-anchored NgR, single study","pmids":["20007473"],"is_preprint":false},{"year":2014,"finding":"Myocilin, secreted by optic nerve astrocytes, stimulates oligodendrocyte differentiation through the NgR1/Lingo-1 receptor complex. Myocilin physically interacts (co-immunoprecipitation) with Lingo-1 and may act as a Lingo-1 ligand; myocilin-induced elongation of oligodendrocyte processes is mediated by activation of FYN and suppression of RhoA GTPase.","method":"Myocilin-null mouse analysis, primary oligodendrocyte precursor culture assays, co-immunoprecipitation (myocilin-Lingo-1), FYN/RhoA activity assays","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP demonstrating physical interaction plus functional KO phenotype and signaling assays, single lab","pmids":["24741044"],"is_preprint":false},{"year":2023,"finding":"NgR1 functions as an inhibitory immune checkpoint in NK cells by destabilizing the immunological synapse (IS). NgR1 deficiency or blockade improves tumor control by enhancing NK cell-to-target contact stability and regulating F-actin dynamics during IS formation.","method":"NgR1 knockout NK cells, NgR1 blockade, live imaging of immunological synapse formation, F-actin dynamics assay, NK cell cytotoxicity assays, tumor control in vivo","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic loss-of-function plus pharmacological blockade, live imaging of mechanistic process (IS/F-actin), in vitro and in vivo functional readouts, published in high-tier journal","pmids":["36624164"],"is_preprint":false},{"year":2013,"finding":"In aged cognitively impaired rats, hippocampal NgR1 co-receptor proteins LINGO-1, p75, and TROY are significantly elevated and co-localize with NgR1 in hippocampal neurons, suggesting an assembled signaling complex. Downstream RhoA is also elevated. Expression levels of all components correlate significantly with Morris water maze performance, placing the NgR1/LINGO-1 or NgR1/p75/TROY complex as a pathway suppressing synaptic plasticity in cognitive decline.","method":"Protein expression quantification (Western blot), immunohistochemical co-localization, Morris water maze behavioral classification, correlation analysis","journal":"The European journal of neuroscience","confidence":"Low","confidence_rationale":"Tier 3 / Weak — co-localization and expression correlation in vivo, no direct functional perturbation of complex, single lab","pmids":["23438185"],"is_preprint":false},{"year":2015,"finding":"NgR1 is a negative regulator of dendritic spine density (mature spine density reduced by NgR1 overexpression) and dendritic complexity in a brain region-specific manner. NgR1 overexpression impairs sequential spatial learning; NgR1 loss impairs locomotor behavior and recognition memory. NgR1 also modulates cocaine-induced synaptic spine plasticity and behavioral sensitization.","method":"NgR1 knockout and transgenic overexpression mice, serial behavioral paradigms (locomotor, recognition memory, spatial learning), ex vivo MRI/DTI, dendritic spine morphometry (Golgi staining), cocaine sensitization protocol","journal":"Cerebral cortex","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — bidirectional genetic manipulation (KO and OE), multiple behavioral and structural readouts, single lab","pmids":["26838771"],"is_preprint":false},{"year":2018,"finding":"Osmotin reduces NgR1 expression and inhibits formation of the Nogo-A/NgR1 ligand-receptor complex via AdipoR1, resulting in enhanced neurite outgrowth. These effects disappeared with AdipoR1 interference, placing AdipoR1 upstream of NgR1 in osmotin's mechanism of action.","method":"AdipoR1 siRNA knockdown, Western blot for NgR1 and Nogo-A, co-immunoprecipitation (Nogo-A/NgR1 complex), neurite outgrowth assay in Alzheimer's disease mouse neurons","journal":"Molecular neurobiology","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP to demonstrate complex disruption, receptor knockdown rescue, functional outgrowth assay, single lab","pmids":["29335844"],"is_preprint":false},{"year":2015,"finding":"Intravitreal delivery of human NgR1(310)-Fc decoy protein promotes retinal ganglion cell (RGC) axonal regeneration after optic nerve crush and protects large-diameter RGCs from elevated IOP-induced death in a microbead glaucoma model, without reducing IOP. Pharmacokinetic analysis showed a terminal half-life of ~24 hours in vitreous after bolus administration.","method":"Intravitreal injection, cholera toxin β anterograde axon labeling, retrograde Fluoro-Gold RGC counting, microbead IOP model, pharmacokinetic ELISA","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — decoy protein intervention with quantified axon regeneration and neuroprotection readouts, pharmacokinetic characterization, single lab","pmids":["25655801"],"is_preprint":false},{"year":2011,"finding":"NgR is expressed on oligodendrocyte progenitor cells (OPCs) but not on mature oligodendrocytes. Blocking NgR on OPCs with antibody under proliferating conditions prolongs processes via PI3K/Akt signaling, but under differentiating conditions, NgR blockade inhibits OPC differentiation via ERK1/2 signaling—demonstrating a pro-differentiation function of NgR in OPCs that is distinct from its inhibitory role in neurons.","method":"Immunostaining and Western blot for NgR on NPCs/OPCs/oligodendrocytes, anti-NgR antibody blockade, proliferation and differentiation assays, PI3K/Akt and ERK1/2 pathway inhibitor pharmacology","journal":"Brain research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — antibody functional blockade with signaling pathway pharmacology, multiple cell-type contexts, single lab","pmids":["22227458"],"is_preprint":false},{"year":2015,"finding":"NgR1 decoy protein (NgR1(310)-Fc) delivered by lumbar intrathecal bolus distributes throughout the neuraxis (half-life ~2 days in rat, ~5 days in nonhuman primate) and promotes locomotor recovery and growth of raphespinal axons into lumbar spinal cord after contusion injury, with intermittent dosing as effective as continuous infusion.","method":"Lumbar intrathecal bolus delivery, pharmacokinetic tissue sampling, anterograde raphespinal axon tracing, open field and grid walking behavioral assays in rat contusion SCI","journal":"Journal of neurotrauma","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacokinetic characterization plus functional and anatomical outcome measures, translational nonhuman primate PK, single lab","pmids":["24964223"],"is_preprint":false},{"year":2015,"finding":"NgR1 decoy protein (NgR1(310)-Fc) administered intravitreally promotes RGC axon regeneration after optic nerve crush (increased RGCs with regenerating axons) and protects large-diameter RGCs in a microbead glaucoma model, demonstrating a neuroprotective role for NgR1 blockade independent of IOP.","method":"Intravitreal injection, optic nerve crush, cholera toxin β anterograde labeling, retrograde Fluoro-Gold tracing, microbead IOP model","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — therapeutic blockade with quantified axonal and cellular outcomes in two independent injury models, single lab","pmids":["25655801"],"is_preprint":false},{"year":2009,"finding":"NgR1 and NgR2 make only a modest combined contribution to MAG-mediated inhibition of sensory DRG neuron outgrowth; disrupting both NgR proteins results in only partial attenuation, and eliminating ganglioside binding further reduces but does not abolish inhibition. Thus NgR1 (and NgR2) are NOT the sole or primary mediators of chronic MAG inhibition in sensory neurons, and additional unidentified receptors exist. The Ig-like domains 4 and 5 of MAG are necessary and sufficient for growth arrest, independent of sialic acid binding.","method":"ngr1, ngr2, ngr1/ngr2 double-knockout DRG neurons, neuraminidase (VCN) treatment to remove gangliosides, MAG domain deletion mutants, neurite outgrowth assay","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic KO combinations plus pharmacological manipulation of gangliosides plus domain-deletion mutants, clear negative and positive findings","pmids":["19367338"],"is_preprint":false},{"year":2015,"finding":"NgR1 reduction in the perforant path (via AAV-shRNA) rescues cognitive and synaptic deficits in APP/PS1 mice, decreases Aβ production in the perforant path, and reduces amyloid plaques in the hippocampus. NgR1 overexpression or knockdown in N2a/HEK293-APPswe cells shows a positive correlation with total APP protein and both α- and β-secretase cleavage products. NgR1 may inhibit APP degradation through the lysosomal pathway via Rho/ROCK signaling.","method":"AAV-shRNA knockdown in perforant path, APP/PS1 transgenic mice, behavioral assays, LTP measurement, ELISA for Aβ and APP metabolites, AAV overexpression and shRNA in cell lines, lysosomal pathway inhibitors","journal":"Alzheimer's research & therapy","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — targeted region-specific KD with multiple functional/neuropathological readouts and cell-line mechanistic follow-up, single lab","pmids":["32331528"],"is_preprint":false},{"year":2015,"finding":"Nogo-A/NgR signaling in microglia inhibits cell adhesion and migration to fibrillar Aβ1-42, an effect mediated by NgR and Rho GTPases regulating cytoskeletal arrangement. Blocking NgR with NEP1-40 in APP/PS1 mice enhances microglial recruitment toward Aβ deposits and upregulates CD36 expression.","method":"Microglial adhesion and migration (transwell) assays with Nogo-66 and NEP1-40, APP/PS1 mouse intracerebroventricular NEP1-40 delivery, immunohistochemistry for microglial recruitment and CD36","journal":"Journal of neuroinflammation","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — in vitro functional assays plus in vivo antagonist experiment, single lab","pmids":["30029608"],"is_preprint":false},{"year":2015,"finding":"Nogo-P4 (a 25-amino-acid Nogo-66 core peptide) activates NgR on microglia to induce expression of iNOS, COX-2 and release of IL-1β, TNF-α, NO, and PGE2. This proinflammatory response is reversed by NEP1-40 (NgR antagonist), PI-PLC (GPI-anchor cleavage), or NgR siRNA. The mechanism involves increased phosphorylation of NF-κB and STAT3 downstream of NgR.","method":"Primary microglia stimulation with Nogo-P4, NEP1-40 competitive antagonist, PI-PLC treatment, NgR siRNA knockdown, NF-κB and STAT3 phosphorylation assays, cytokine ELISA","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — multiple inhibition strategies (pharmacological, enzymatic, genetic) plus downstream signaling readouts, single lab","pmids":["26472924"],"is_preprint":false},{"year":2003,"finding":"Fish (zebrafish and fugu) possess true NgR orthologs with conserved synteny, intron-exon structure, and phylogenetic relationship to human NgR1 (RTN4R), expressed in developing and adult brain. This established the evolutionary conservation of the NgR gene family across vertebrates.","method":"Comparative genomics, synteny analysis, intron-exon structure comparison, phylogenetic analysis, in situ hybridization expression analysis","journal":"Molecular biology and evolution","confidence":"Low","confidence_rationale":"Tier 4 / Moderate — comparative genomics and expression analysis only, no direct functional assay","pmids":["12949137"],"is_preprint":false}],"current_model":"RTN4R (NgR1) is a GPI-anchored, leucine-rich repeat neuronal receptor that binds multiple myelin-associated inhibitors (Nogo-A/Nogo-66, MAG, OMgp) and CSPGs to restrict axonal sprouting and regeneration after CNS injury; it requires transmembrane co-receptors (p75NTR/TROY and LINGO-1 or AMIGO3, and PlexinA2) to transduce signals through CRMP2 to activate RhoA/ROCK/cofilin, causing growth cone collapse acutely, while being dispensable for chronic substrate-mediated inhibition; it additionally modulates activity-dependent synaptic plasticity (LTP/LTD) by antagonizing FGF2/FGFR1 signaling at hippocampal synapses, regulates dendritic spine morphology and memory, promotes neuroinflammation through NF-κB/STAT3 in microglia, and serves as a viral entry receptor for reovirus and an inhibitory immune checkpoint in NK cells by destabilizing the immunological synapse."},"narrative":{"mechanistic_narrative":"RTN4R (NgR1) is a GPI-anchored neuronal leucine-rich-repeat receptor that integrates diverse extracellular growth-inhibitory cues to restrict axon regeneration and shape synaptic plasticity in the CNS [PMID:22406547, PMID:18337405, PMID:26586827]. It binds the glycosaminoglycan moiety of chondroitin sulfate proteoglycans, and combined loss of NgR1 and NgR3 reproduces the enhanced optic-nerve regeneration of triple Nogo-receptor mutants, establishing it as a functional CSPG receptor [PMID:22406547]. NgR1 is specifically required for acute growth-cone collapse evoked by soluble myelin inhibitors (Nogo-66, MAG, OMgp) but is dispensable for chronic substrate-bound neurite inhibition, dissociating these two inhibitory activities [PMID:17611264]; consistent with this, NgR1 and NgR2 contribute only modestly to chronic MAG-mediated inhibition of sensory neurons, where additional receptors operate [PMID:19367338]. Lacking a transmembrane domain, NgR1 transduces signals through co-receptor complexes: AMIGO3 can substitute for LINGO-1 in an NgR1–p75/TROY complex to activate RhoA after CNS injury [PMID:23613963], and Nogo-A recruits CRMP2 into an NgR1/PlexinA2 ternary complex that drives cellular contraction and constrains corticospinal sprouting in vivo [PMID:30804090]. Downstream, NgR signaling activates a RhoA/ROCK/LIM-kinase/cofilin axis producing actin depolymerization and growth-cone collapse, alongside a Ca2+-dependent EGFR-phosphorylation arm [PMID:16613894]; loss of NgR1 disinhibits neurotrophin- and FGF2-driven neurite outgrowth on myelin [PMID:15737741]. The ectodomain is shed by TACE/ADAM17, generating a soluble decoy that competitively antagonizes ligand binding and suppresses RhoA activation [PMID:16849393], a property exploited therapeutically by NgR1(310)-Fc decoys that promote axon regeneration and neuroprotection after optic-nerve and spinal-cord injury [PMID:25655801, PMID:24964223]. Beyond axon growth, NgR1 directly binds FGF1/FGF2 at hippocampal synapses where its loss enhances LTP and alters dendritic spine morphology [PMID:18337405], it bidirectionally regulates spine density, complexity, and learning behavior [PMID:26838771], and it operates outside the nervous system as a cell-surface entry receptor for mammalian reovirus [PMID:24922571] and as an inhibitory immune checkpoint that destabilizes the NK-cell immunological synapse through F-actin regulation [PMID:36624164]. Rare RTN4R missense variants from schizophrenia patients impair growth-cone formation, linking receptor structure to cytoskeletal control [PMID:28892071].","teleology":[{"year":2003,"claim":"Establishing that the NgR gene family is conserved across vertebrates provided the evolutionary framework for studying RTN4R orthologs and their function.","evidence":"Comparative genomics, synteny and phylogenetic analysis, and in situ hybridization in fish","pmids":["12949137"],"confidence":"Low","gaps":["Sequence/expression conservation only, no functional assay","Does not address whether ortholog function is conserved"]},{"year":2004,"claim":"The first link between RTN4R and human disease asked whether LRR-domain variants contribute to schizophrenia, identifying candidate missense mutations absent from controls.","evidence":"DHPLC mutation screening of patients and molecular modeling of the LRR domain","pmids":["15532024"],"confidence":"Low","gaps":["Computational prediction only, no functional assay of mutant protein","No demonstration of causality or mechanism"]},{"year":2005,"claim":"Direct loss-of-function tested whether NgR is genuinely required for myelin inhibition, showing siRNA knockdown disinhibits neurotrophin-induced outgrowth on CNS myelin.","evidence":"siRNA knockdown in DRG neurons with neurite outgrowth quantification on myelin substrate","pmids":["15737741"],"confidence":"Medium","gaps":["Single method, single lab","Did not define downstream signaling"]},{"year":2006,"claim":"These studies mapped the intracellular signaling logic of NgR, placing it upstream of a RhoA/ROCK/LIM-kinase/cofilin actin-depolymerization pathway and a Ca2+/EGFR arm, and showed that TACE-mediated ectodomain shedding generates a competitive decoy.","evidence":"Schwann cell conditioned medium and exogenous TACE on RGC/DRG cultures, RhoA and EGFR phosphorylation assays, p75NTR siRNA, NgRECD shedding Western blots","pmids":["16613894","16849393"],"confidence":"Medium","gaps":["Pathway placement inferred from single lab","Stoichiometry of receptor complex not resolved"]},{"year":2007,"claim":"Genetic and knockdown dissection resolved a key ambiguity by showing NgR1 is required for acute growth-cone collapse by soluble inhibitors but dispensable for chronic substrate-bound inhibition.","evidence":"Germline NgR1 knockout plus shRNAi across multiple neuron types in two assay paradigms","pmids":["17611264"],"confidence":"High","gaps":["Identity of receptor mediating chronic inhibition unresolved","Mechanism of acute-versus-chronic dissociation not defined"]},{"year":2008,"claim":"Discovery that NgR1 directly binds FGF1/FGF2 and localizes with FGFR1 at synapses extended its role from axon inhibition to activity-dependent synaptic plasticity and spine morphology.","evidence":"Direct binding assays, synaptosomal fractionation, hippocampal slice LTP/LTD with FGFR inhibitor, NgR1 knockout mice","pmids":["18337405"],"confidence":"High","gaps":["Co-receptor requirement for FGF antagonism not defined","Molecular nature of NgR1-FGFR1 functional interaction unresolved"]},{"year":2009,"claim":"Quantitative genetic and species-comparison studies refined the receptor's contribution, showing NgR1/NgR2 only modestly mediate chronic MAG inhibition and that species differences in regeneration arise downstream of receptor binding.","evidence":"ngr1/ngr2 double-knockout DRG neurons with ganglioside removal and MAG domain mutants; cross-species Nogo66 binding and cofilin phosphorylation assays with PI-PLC","pmids":["19367338","20007473"],"confidence":"High","gaps":["Additional MAG receptors not identified","Basis for differential downstream signaling across species unknown"]},{"year":2013,"claim":"Identification of AMIGO3 as an alternative co-receptor explained how the NgR1-p75/TROY complex transduces RhoA activation acutely after injury when LINGO-1 is unavailable.","evidence":"Co-IP in non-neuronal cells and brain lysates, RhoA assay, AMIGO3 siRNA in DRG/retinal cultures, in vivo lesion models","pmids":["23613963"],"confidence":"Medium","gaps":["Single lab, Co-IP without reciprocal structural validation","Selection between LINGO-1 and AMIGO3 not mechanistically defined"]},{"year":2014,"claim":"These studies expanded NgR1's biology beyond neurite inhibition, identifying it as a reovirus entry receptor and as a co-receptor mediating myocilin-stimulated oligodendrocyte differentiation.","evidence":"Gain-of-function expression, soluble decoy, null neurons and differential virion/ISVP binding for reovirus; myocilin-null mice, OPC cultures and Lingo-1 Co-IP","pmids":["24922571","24741044"],"confidence":"High","gaps":["Reovirus capsid component engaging NgR1 not defined at residue level","Myocilin role as direct ligand inferred from Co-IP"]},{"year":2015,"claim":"Sensitive tracing and decoy-protein interventions established NgR1 as a restraint on corticospinal/raphespinal/RGC regeneration and validated NgR1(310)-Fc as a regeneration- and neuroprotection-promoting therapeutic.","evidence":"crym-GFP CST labeling in ngr1-/- mice after hemisection; intravitreal and intrathecal NgR1(310)-Fc with axon tracing, neuroprotection and pharmacokinetics","pmids":["26586827","25655801","24964223"],"confidence":"High","gaps":["Magnitude of regeneration remains modest","Decoy target selectivity among NgR ligands not fully resolved"]},{"year":2016,"claim":"Bidirectional genetic manipulation showed NgR1 negatively regulates dendritic spine density and complexity and influences learning, memory, and cocaine-induced plasticity.","evidence":"NgR1 knockout and overexpression mice with behavioral paradigms, MRI/DTI, and Golgi spine morphometry","pmids":["26838771"],"confidence":"Medium","gaps":["Region-specific molecular mediators of spine regulation unclear","Link between spine phenotype and behavior correlative"]},{"year":2017,"claim":"Functional testing of a rare schizophrenia-associated R292H variant connected RTN4R structural variation to impaired growth-cone formation.","evidence":"Exon sequencing plus in vitro growth-cone formation assay with mutant","pmids":["28892071"],"confidence":"Medium","gaps":["Single lab functional assay","Disease causality not established"]},{"year":2019,"claim":"Biochemical and genetic epistasis identified the NgR1/PlexinA2/CRMP2 ternary complex as the transducer linking Nogo-A to cytoskeletal contraction and corticospinal sprouting restriction in vivo.","evidence":"NgR1 Co-IP plus mass spectrometry, cell contraction assay, double-heterozygous epistasis mice with pyramidotomy and behavioral recovery","pmids":["30804090"],"confidence":"High","gaps":["How CRMP2 couples the complex to RhoA/cytoskeleton not fully resolved","Whether the complex operates for ligands other than Nogo-A unclear"]},{"year":2023,"claim":"Beyond the nervous system, NgR1 was defined as an inhibitory immune checkpoint that destabilizes the NK-cell immunological synapse, with deficiency or blockade improving tumor control.","evidence":"NgR1 knockout/blockade NK cells, live imaging of immunological synapse and F-actin dynamics, cytotoxicity and in vivo tumor assays","pmids":["36624164"],"confidence":"High","gaps":["Ligand engaging NgR1 on NK cells not identified","Signaling pathway downstream of NgR1 in NK cells undefined"]},{"year":null,"claim":"It remains unresolved how NgR1 selects among its many ligands and co-receptors (CSPGs, Nogo-66, MAG, OMgp, FGFs, reovirus) to produce context-specific outputs, and what receptors mediate chronic myelin inhibition independently of NgR1.","evidence":"Not addressed by available timeline discoveries","pmids":[],"confidence":"Low","gaps":["No structural model of full ligand/co-receptor selectivity","Identity of NgR1-independent chronic-inhibition receptors unknown","Mechanism integrating synaptic, immune, and viral roles unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[3]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,2,6,8]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,14]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,25]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[6,8]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,2,9]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[14]}],"complexes":["NgR1/p75(NTR)/LINGO-1 or AMIGO3","NgR1/PlexinA2/CRMP2"],"partners":["P75NTR","TROY","LINGO-1","AMIGO3","PLXNA2","CRMP2","FGFR1","JAM-A"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BZR6","full_name":"Reticulon-4 receptor","aliases":["Nogo receptor","NgR","Nogo-66 receptor"],"length_aa":473,"mass_kda":50.7,"function":"Receptor for RTN4, OMG and MAG (PubMed:12037567, PubMed:12068310, PubMed:12089450, PubMed:12426574, PubMed:12839991, PubMed:16712417, PubMed:18411262, PubMed:19052207). Functions as a receptor for the sialylated gangliosides GT1b and GM1 (PubMed:18411262). Besides, functions as a receptor for chondroitin sulfate proteoglycans (By similarity). Can also bind heparin (By similarity). Intracellular signaling cascades are triggered via the coreceptor NGFR (PubMed:12426574). Signaling mediates activation of Rho and downstream reorganization of the actin cytoskeleton (PubMed:16712417, PubMed:22325200). Mediates axonal growth inhibition (PubMed:12839991, PubMed:19052207, PubMed:28892071). Plays a role in regulating axon regeneration and neuronal plasticity in the adult central nervous system. Plays a role in postnatal brain development. Required for normal axon migration across the brain midline and normal formation of the corpus callosum. Protects motoneurons against apoptosis; protection against apoptosis is probably mediated via interaction with MAG. Acts in conjunction with RTN4 and LINGO1 in regulating neuronal precursor cell motility during cortical development. Like other family members, plays a role in restricting the number dendritic spines and the number of synapses that are formed during brain development (PubMed:22325200) (Microbial infection) Acts as a receptor for Reovirus type 3","subcellular_location":"Cell membrane; Membrane raft; Cell projection, dendrite; Cell projection, axon; Perikaryon","url":"https://www.uniprot.org/uniprotkb/Q9BZR6/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RTN4R","classification":"Not Classified","n_dependent_lines":10,"n_total_lines":1208,"dependency_fraction":0.008278145695364239},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RTN4R","total_profiled":1310},"omim":[{"mim_id":"615691","title":"ADHESION MOLECULE WITH Ig-LIKE DOMAIN 3; AMIGO3","url":"https://www.omim.org/entry/615691"},{"mim_id":"615690","title":"ADHESION MOLECULE WITH Ig-LIKE DOMAIN 2; AMIGO2","url":"https://www.omim.org/entry/615690"},{"mim_id":"615689","title":"ADHESION MOLECULE WITH Ig-LIKE DOMAIN 1; AMIGO1","url":"https://www.omim.org/entry/615689"},{"mim_id":"613535","title":"KIAA0319-LIKE; KIAA0319L","url":"https://www.omim.org/entry/613535"},{"mim_id":"612810","title":"LEUCINE-RICH REPEAT AND FIBRONECTIN TYPE III DOMAIN-CONTAINING PROTEIN 4; LRFN4","url":"https://www.omim.org/entry/612810"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Focal adhesion sites","reliability":"Approved"},{"location":"Actin filaments","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":82.6}],"url":"https://www.proteinatlas.org/search/RTN4R"},"hgnc":{"alias_symbol":["NgR1","NgR","NOGOR"],"prev_symbol":[]},"alphafold":{"accession":"Q9BZR6","domains":[{"cath_id":"3.80.10.10","chopping":"39-133","consensus_level":"medium","plddt":97.3093,"start":39,"end":133},{"cath_id":"3.80.10.10","chopping":"167-315","consensus_level":"medium","plddt":95.9421,"start":167,"end":315}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BZR6","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BZR6-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BZR6-F1-predicted_aligned_error_v6.png","plddt_mean":75.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RTN4R","jax_strain_url":"https://www.jax.org/strain/search?query=RTN4R"},"sequence":{"accession":"Q9BZR6","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BZR6.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BZR6/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BZR6"}},"corpus_meta":[{"pmid":"22406547","id":"PMC_22406547","title":"NgR1 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In vivo, combined loss of NgR1 and NgR3 (but not NgR1 and NgR2) mimics the triple Nogo receptor mutant phenotype of enhanced axonal regeneration after optic nerve crush, identifying NgR1 as a functional CSPG receptor.\",\n      \"method\": \"High-affinity binding assays, primary neuron inhibition assays, genetic knockout (single, double, triple mutant mice), retro-orbital optic nerve crush with axon regeneration quantification\",\n      \"journal\": \"Nature neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (biochemical binding, in vitro neuronal assays, multiple genetic knockout combinations in vivo), replicated across several experimental paradigms in one rigorous study\",\n      \"pmids\": [\"22406547\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"NgR1 directly binds FGF1 and FGF2 with high affinity (but not NgR2 or NgR3). NgR1 is enriched in synaptosomal fractions of hippocampus and co-localizes with FGFR1 at synapses. Loss of NgR1 leads to FGF2-dependent enhancement of LTP and attenuation of LTD at Schaffer collateral-CA1 synapses; FGFR kinase activity is required for FGF2-elicited LTP enhancement in NgR1 mutants. NgR1 loss also alters dendritic spine morphology along apical dendrites of hippocampal CA1 neurons.\",\n      \"method\": \"Direct binding assays (high-affinity), synaptosomal fractionation, confocal co-localization, NgR1 knockout mice, hippocampal slice electrophysiology (LTP/LTD), FGFR kinase inhibitor pharmacology, in vitro axonal branching assay\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — direct binding assay, subcellular fractionation with functional consequence, electrophysiological phenotype with pharmacological rescue, multiple orthogonal methods in one study\",\n      \"pmids\": [\"18337405\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Neuronal NgR1 is required for acute growth cone collapse induced by soluble MAG-Fc, OMgp-Fc, and Nogo-66, but is NOT required for chronic substrate-bound inhibition of neurite outgrowth by MAG or OMgp. Thus the growth cone-collapsing and substrate growth-inhibitory activities of myelin inhibitors can be dissociated, and chronic axon growth inhibition by myelin operates through NgR1-independent mechanisms.\",\n      \"method\": \"Germline NgR1 knockout, shRNAi knockdown in primary cerebellar/sensory/cortical neurons, two-paradigm assay (chronic substrate inhibition vs. acute soluble collapse)\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent loss-of-function strategies (germline KO + siRNA), two distinct assay paradigms, clear positive and negative results, replicated across multiple neuron types\",\n      \"pmids\": [\"17611264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"NgR1 functions as a cell-surface receptor for mammalian reovirus on neurons. Expression of NgR1 in non-susceptible cells confers reovirus binding and infection. Soluble NgR1 neutralizes reovirus infectivity. Blocking NgR1 on transfected cells or primary cortical neurons abrogates reovirus infection. Reovirus virions bind both soluble JAM-A and NgR1, whereas infectious subviral particles (ISVPs) bind only JAM-A, indicating distinct capsid components engage these two receptors.\",\n      \"method\": \"Gain-of-function expression in non-susceptible cells, soluble decoy neutralization, antibody blocking, NgR1 null primary cortical neurons, binding assays with virions vs. ISVPs\",\n      \"journal\": \"Cell host & microbe\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (gain-of-function, null neurons, soluble decoy, blocking antibody, differential binding assay), mechanistically coherent across all approaches\",\n      \"pmids\": [\"24922571\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"AMIGO3 physically interacts with NgR1-p75/TROY in non-neuronal cells and in brain lysates, mediating RhoA activation in response to CNS myelin. AMIGO3 knockdown in adult primary DRG and retinal cultures promotes disinhibited neurite growth. AMIGO3 substitutes for LINGO-1 in the NgR1-p75/TROY inhibitory signalling complex acutely after CNS injury.\",\n      \"method\": \"Co-immunoprecipitation (non-neuronal cells and brain lysates), RhoA activation assay, siRNA knockdown in primary DRG and retinal cultures, in vivo lesion models (dorsal column, optic nerve crush)\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP in two systems plus functional KD assay and in vivo expression correlation, but single lab\",\n      \"pmids\": [\"23613963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"TACE (ADAM17) induces shedding of the NgR extracellular domain (NgRECD) from DRG neurons. Shed NgRECD acts as a competitive antagonist blocking inhibitory ligand binding to full-length NgR. TACE-induced NgR cleavage also reduces RhoA activation and EGFR phosphorylation downstream of the NgR/p75NTR complex, disinhibiting FGF2-stimulated neurite outgrowth in the presence of CNS myelin.\",\n      \"method\": \"TACE addition to DRG neuron cultures, Western blot for NgRECD shedding, RhoA activation assay, EGFR phosphorylation assay, neurite outgrowth quantification\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — biochemical shedding assay plus downstream signaling readouts and functional outgrowth assay, single lab\",\n      \"pmids\": [\"16849393\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"NgR signals through a Ca2+-dependent pathway that activates EGFR phosphorylation, and through a Rho-A/ROCK/LIM-kinase/cofilin phosphorylation pathway leading to actin depolymerization and growth cone collapse. Schwann cell-derived factors (including TACE) cleave the NgR ectodomain; the shed NgRECD competitively antagonizes inhibitory ligand/NgR binding, blocking p75NTR/NgR clustering, reducing EGFR phosphorylation and suppressing RhoA activation. siRNA knockdown of p75NTR also inactivates RhoA and disinhibits neurotrophic factor-stimulated RGC neurite outgrowth.\",\n      \"method\": \"Schwann cell conditioned medium on RGC cultures, exogenous TACE application, siRNA knockdown of p75NTR, EGFR phosphorylation assay, RhoA activation assay, optic nerve regeneration in vivo\",\n      \"journal\": \"Brain\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — multiple signaling assays plus in vivo regeneration correlation, single lab, mechanistic pathway placement\",\n      \"pmids\": [\"16613894\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"siRNA-mediated knockdown of NgR (100% protein reduction) in DRG neurons disinhibits neurotrophin-induced neurite outgrowth on CNS myelin, with a 50% increase in outgrowth at 48 h and a 3.5-fold increase in βIII-tubulin at 3 days, placing NgR as a required component of the CNS myelin inhibitory signaling cascade in DRG neurons.\",\n      \"method\": \"siRNA knockdown (RNAi) in DRG neurons, neurite outgrowth quantification on CNS myelin substrate, Western blot protein quantification\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — siRNA loss-of-function with quantified phenotypic readout, single lab, single method\",\n      \"pmids\": [\"15737741\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Nogo-A exposure to neurons recruits CRMP2 into an NgR1 immunoprecipitate in a PlexinA2-dependent manner, forming a NgR1/PlexinA2/CRMP2 ternary complex. Non-neuronal cells expressing both NgR1 and PlexinA2 (but not either alone) contract upon Nogo-A exposure. Double-heterozygous NgR1+/-/PlexinA2+/- neurons are rescued from Nogo-A inhibition (epistasis), and double-heterozygous mice show greater post-injury corticospinal sprouting and neurological recovery after pyramidotomy.\",\n      \"method\": \"NgR1 co-immunoprecipitation + mass spectrometry, non-neuronal cell contraction assay, genetic epistasis (double-heterozygous mice), pyramidotomy + anterograde tracing, behavioral recovery assessment\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — biochemical complex identification (Co-IP + MS), cell-based functional assay, genetic epistasis in vitro and in vivo, multiple orthogonal methods in one study\",\n      \"pmids\": [\"30804090\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"NgR1 is required to restrict corticospinal tract (CST) axon regeneration after dorsal hemisection. Using comprehensive crym-GFP CST labeling (~10-fold more efficient than BDA), ngr1-/- mice showed significant CST axon regeneration (average 2.68% of labeled axons extending >100 μm past lesion) that was undetectable with traditional BDA tracing, whereas ngr1+/+ mice showed no significant regeneration.\",\n      \"method\": \"crym-GFP transgenic reporter mice for comprehensive CST labeling, ngr1 genetic knockout, dorsal hemisection spinal cord injury, quantitative axon counting\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic loss-of-function with a highly sensitive and validated reporter, quantitative phenotypic readout, rigorous controls\",\n      \"pmids\": [\"26586827\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Two missense mutations in RTN4R (R119W, R196H) identified in schizophrenic patients alter residues in the leucine-rich repeat domain; molecular modeling predicts structural alterations of the native GPI-anchored protein. Both mutations were absent in 300 controls.\",\n      \"method\": \"DHPLC mutation screening, molecular modeling of LRR domain\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational structural prediction only, no direct functional assay of mutant protein\",\n      \"pmids\": [\"15532024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"A rare RTN4R missense variant R292H, identified in schizophrenia patients, impairs growth cone formation in vitro functional assays, linking NgR1 structure to cytoskeletal regulation of growth cones.\",\n      \"method\": \"Exon sequencing, in vitro growth cone formation assay with R292H mutant\",\n      \"journal\": \"Translational psychiatry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — direct functional assay of mutant protein (growth cone formation), single lab\",\n      \"pmids\": [\"28892071\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Zebrafish Nogo66 (ZF-Nogo66) is growth-permissive rather than inhibitory for both zebrafish and mouse neurons, in contrast to rat Nogo66. Both ZF- and rat-Nogo66 bind NgR (GPI-anchored receptor) in fish and mouse neurons. Rat-Nogo66 elicits phosphorylation of the downstream effector cofilin, whereas ZF-Nogo66 does not, demonstrating that differential downstream signaling (rather than receptor binding) accounts for the species difference in regenerative capacity.\",\n      \"method\": \"Outgrowth assay, growth cone collapse assay, contact assay across species, PI-PLC treatment to identify GPI-anchored receptor involvement, cofilin phosphorylation assay\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — multiple functional assays plus signaling readout, PI-PLC pharmacology to implicate GPI-anchored NgR, single study\",\n      \"pmids\": [\"20007473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Myocilin, secreted by optic nerve astrocytes, stimulates oligodendrocyte differentiation through the NgR1/Lingo-1 receptor complex. Myocilin physically interacts (co-immunoprecipitation) with Lingo-1 and may act as a Lingo-1 ligand; myocilin-induced elongation of oligodendrocyte processes is mediated by activation of FYN and suppression of RhoA GTPase.\",\n      \"method\": \"Myocilin-null mouse analysis, primary oligodendrocyte precursor culture assays, co-immunoprecipitation (myocilin-Lingo-1), FYN/RhoA activity assays\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP demonstrating physical interaction plus functional KO phenotype and signaling assays, single lab\",\n      \"pmids\": [\"24741044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"NgR1 functions as an inhibitory immune checkpoint in NK cells by destabilizing the immunological synapse (IS). NgR1 deficiency or blockade improves tumor control by enhancing NK cell-to-target contact stability and regulating F-actin dynamics during IS formation.\",\n      \"method\": \"NgR1 knockout NK cells, NgR1 blockade, live imaging of immunological synapse formation, F-actin dynamics assay, NK cell cytotoxicity assays, tumor control in vivo\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic loss-of-function plus pharmacological blockade, live imaging of mechanistic process (IS/F-actin), in vitro and in vivo functional readouts, published in high-tier journal\",\n      \"pmids\": [\"36624164\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In aged cognitively impaired rats, hippocampal NgR1 co-receptor proteins LINGO-1, p75, and TROY are significantly elevated and co-localize with NgR1 in hippocampal neurons, suggesting an assembled signaling complex. Downstream RhoA is also elevated. Expression levels of all components correlate significantly with Morris water maze performance, placing the NgR1/LINGO-1 or NgR1/p75/TROY complex as a pathway suppressing synaptic plasticity in cognitive decline.\",\n      \"method\": \"Protein expression quantification (Western blot), immunohistochemical co-localization, Morris water maze behavioral classification, correlation analysis\",\n      \"journal\": \"The European journal of neuroscience\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — co-localization and expression correlation in vivo, no direct functional perturbation of complex, single lab\",\n      \"pmids\": [\"23438185\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"NgR1 is a negative regulator of dendritic spine density (mature spine density reduced by NgR1 overexpression) and dendritic complexity in a brain region-specific manner. NgR1 overexpression impairs sequential spatial learning; NgR1 loss impairs locomotor behavior and recognition memory. NgR1 also modulates cocaine-induced synaptic spine plasticity and behavioral sensitization.\",\n      \"method\": \"NgR1 knockout and transgenic overexpression mice, serial behavioral paradigms (locomotor, recognition memory, spatial learning), ex vivo MRI/DTI, dendritic spine morphometry (Golgi staining), cocaine sensitization protocol\",\n      \"journal\": \"Cerebral cortex\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — bidirectional genetic manipulation (KO and OE), multiple behavioral and structural readouts, single lab\",\n      \"pmids\": [\"26838771\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Osmotin reduces NgR1 expression and inhibits formation of the Nogo-A/NgR1 ligand-receptor complex via AdipoR1, resulting in enhanced neurite outgrowth. These effects disappeared with AdipoR1 interference, placing AdipoR1 upstream of NgR1 in osmotin's mechanism of action.\",\n      \"method\": \"AdipoR1 siRNA knockdown, Western blot for NgR1 and Nogo-A, co-immunoprecipitation (Nogo-A/NgR1 complex), neurite outgrowth assay in Alzheimer's disease mouse neurons\",\n      \"journal\": \"Molecular neurobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP to demonstrate complex disruption, receptor knockdown rescue, functional outgrowth assay, single lab\",\n      \"pmids\": [\"29335844\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Intravitreal delivery of human NgR1(310)-Fc decoy protein promotes retinal ganglion cell (RGC) axonal regeneration after optic nerve crush and protects large-diameter RGCs from elevated IOP-induced death in a microbead glaucoma model, without reducing IOP. Pharmacokinetic analysis showed a terminal half-life of ~24 hours in vitreous after bolus administration.\",\n      \"method\": \"Intravitreal injection, cholera toxin β anterograde axon labeling, retrograde Fluoro-Gold RGC counting, microbead IOP model, pharmacokinetic ELISA\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — decoy protein intervention with quantified axon regeneration and neuroprotection readouts, pharmacokinetic characterization, single lab\",\n      \"pmids\": [\"25655801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"NgR is expressed on oligodendrocyte progenitor cells (OPCs) but not on mature oligodendrocytes. Blocking NgR on OPCs with antibody under proliferating conditions prolongs processes via PI3K/Akt signaling, but under differentiating conditions, NgR blockade inhibits OPC differentiation via ERK1/2 signaling—demonstrating a pro-differentiation function of NgR in OPCs that is distinct from its inhibitory role in neurons.\",\n      \"method\": \"Immunostaining and Western blot for NgR on NPCs/OPCs/oligodendrocytes, anti-NgR antibody blockade, proliferation and differentiation assays, PI3K/Akt and ERK1/2 pathway inhibitor pharmacology\",\n      \"journal\": \"Brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — antibody functional blockade with signaling pathway pharmacology, multiple cell-type contexts, single lab\",\n      \"pmids\": [\"22227458\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"NgR1 decoy protein (NgR1(310)-Fc) delivered by lumbar intrathecal bolus distributes throughout the neuraxis (half-life ~2 days in rat, ~5 days in nonhuman primate) and promotes locomotor recovery and growth of raphespinal axons into lumbar spinal cord after contusion injury, with intermittent dosing as effective as continuous infusion.\",\n      \"method\": \"Lumbar intrathecal bolus delivery, pharmacokinetic tissue sampling, anterograde raphespinal axon tracing, open field and grid walking behavioral assays in rat contusion SCI\",\n      \"journal\": \"Journal of neurotrauma\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacokinetic characterization plus functional and anatomical outcome measures, translational nonhuman primate PK, single lab\",\n      \"pmids\": [\"24964223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"NgR1 decoy protein (NgR1(310)-Fc) administered intravitreally promotes RGC axon regeneration after optic nerve crush (increased RGCs with regenerating axons) and protects large-diameter RGCs in a microbead glaucoma model, demonstrating a neuroprotective role for NgR1 blockade independent of IOP.\",\n      \"method\": \"Intravitreal injection, optic nerve crush, cholera toxin β anterograde labeling, retrograde Fluoro-Gold tracing, microbead IOP model\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — therapeutic blockade with quantified axonal and cellular outcomes in two independent injury models, single lab\",\n      \"pmids\": [\"25655801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"NgR1 and NgR2 make only a modest combined contribution to MAG-mediated inhibition of sensory DRG neuron outgrowth; disrupting both NgR proteins results in only partial attenuation, and eliminating ganglioside binding further reduces but does not abolish inhibition. Thus NgR1 (and NgR2) are NOT the sole or primary mediators of chronic MAG inhibition in sensory neurons, and additional unidentified receptors exist. The Ig-like domains 4 and 5 of MAG are necessary and sufficient for growth arrest, independent of sialic acid binding.\",\n      \"method\": \"ngr1, ngr2, ngr1/ngr2 double-knockout DRG neurons, neuraminidase (VCN) treatment to remove gangliosides, MAG domain deletion mutants, neurite outgrowth assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic KO combinations plus pharmacological manipulation of gangliosides plus domain-deletion mutants, clear negative and positive findings\",\n      \"pmids\": [\"19367338\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"NgR1 reduction in the perforant path (via AAV-shRNA) rescues cognitive and synaptic deficits in APP/PS1 mice, decreases Aβ production in the perforant path, and reduces amyloid plaques in the hippocampus. NgR1 overexpression or knockdown in N2a/HEK293-APPswe cells shows a positive correlation with total APP protein and both α- and β-secretase cleavage products. NgR1 may inhibit APP degradation through the lysosomal pathway via Rho/ROCK signaling.\",\n      \"method\": \"AAV-shRNA knockdown in perforant path, APP/PS1 transgenic mice, behavioral assays, LTP measurement, ELISA for Aβ and APP metabolites, AAV overexpression and shRNA in cell lines, lysosomal pathway inhibitors\",\n      \"journal\": \"Alzheimer's research & therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — targeted region-specific KD with multiple functional/neuropathological readouts and cell-line mechanistic follow-up, single lab\",\n      \"pmids\": [\"32331528\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Nogo-A/NgR signaling in microglia inhibits cell adhesion and migration to fibrillar Aβ1-42, an effect mediated by NgR and Rho GTPases regulating cytoskeletal arrangement. Blocking NgR with NEP1-40 in APP/PS1 mice enhances microglial recruitment toward Aβ deposits and upregulates CD36 expression.\",\n      \"method\": \"Microglial adhesion and migration (transwell) assays with Nogo-66 and NEP1-40, APP/PS1 mouse intracerebroventricular NEP1-40 delivery, immunohistochemistry for microglial recruitment and CD36\",\n      \"journal\": \"Journal of neuroinflammation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — in vitro functional assays plus in vivo antagonist experiment, single lab\",\n      \"pmids\": [\"30029608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Nogo-P4 (a 25-amino-acid Nogo-66 core peptide) activates NgR on microglia to induce expression of iNOS, COX-2 and release of IL-1β, TNF-α, NO, and PGE2. This proinflammatory response is reversed by NEP1-40 (NgR antagonist), PI-PLC (GPI-anchor cleavage), or NgR siRNA. The mechanism involves increased phosphorylation of NF-κB and STAT3 downstream of NgR.\",\n      \"method\": \"Primary microglia stimulation with Nogo-P4, NEP1-40 competitive antagonist, PI-PLC treatment, NgR siRNA knockdown, NF-κB and STAT3 phosphorylation assays, cytokine ELISA\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — multiple inhibition strategies (pharmacological, enzymatic, genetic) plus downstream signaling readouts, single lab\",\n      \"pmids\": [\"26472924\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Fish (zebrafish and fugu) possess true NgR orthologs with conserved synteny, intron-exon structure, and phylogenetic relationship to human NgR1 (RTN4R), expressed in developing and adult brain. This established the evolutionary conservation of the NgR gene family across vertebrates.\",\n      \"method\": \"Comparative genomics, synteny analysis, intron-exon structure comparison, phylogenetic analysis, in situ hybridization expression analysis\",\n      \"journal\": \"Molecular biology and evolution\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Moderate — comparative genomics and expression analysis only, no direct functional assay\",\n      \"pmids\": [\"12949137\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RTN4R (NgR1) is a GPI-anchored, leucine-rich repeat neuronal receptor that binds multiple myelin-associated inhibitors (Nogo-A/Nogo-66, MAG, OMgp) and CSPGs to restrict axonal sprouting and regeneration after CNS injury; it requires transmembrane co-receptors (p75NTR/TROY and LINGO-1 or AMIGO3, and PlexinA2) to transduce signals through CRMP2 to activate RhoA/ROCK/cofilin, causing growth cone collapse acutely, while being dispensable for chronic substrate-mediated inhibition; it additionally modulates activity-dependent synaptic plasticity (LTP/LTD) by antagonizing FGF2/FGFR1 signaling at hippocampal synapses, regulates dendritic spine morphology and memory, promotes neuroinflammation through NF-κB/STAT3 in microglia, and serves as a viral entry receptor for reovirus and an inhibitory immune checkpoint in NK cells by destabilizing the immunological synapse.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RTN4R (NgR1) is a GPI-anchored neuronal leucine-rich-repeat receptor that integrates diverse extracellular growth-inhibitory cues to restrict axon regeneration and shape synaptic plasticity in the CNS [#0, #1, #9]. It binds the glycosaminoglycan moiety of chondroitin sulfate proteoglycans, and combined loss of NgR1 and NgR3 reproduces the enhanced optic-nerve regeneration of triple Nogo-receptor mutants, establishing it as a functional CSPG receptor [#0]. NgR1 is specifically required for acute growth-cone collapse evoked by soluble myelin inhibitors (Nogo-66, MAG, OMgp) but is dispensable for chronic substrate-bound neurite inhibition, dissociating these two inhibitory activities [#2]; consistent with this, NgR1 and NgR2 contribute only modestly to chronic MAG-mediated inhibition of sensory neurons, where additional receptors operate [#22]. Lacking a transmembrane domain, NgR1 transduces signals through co-receptor complexes: AMIGO3 can substitute for LINGO-1 in an NgR1–p75/TROY complex to activate RhoA after CNS injury [#4], and Nogo-A recruits CRMP2 into an NgR1/PlexinA2 ternary complex that drives cellular contraction and constrains corticospinal sprouting in vivo [#8]. Downstream, NgR signaling activates a RhoA/ROCK/LIM-kinase/cofilin axis producing actin depolymerization and growth-cone collapse, alongside a Ca2+-dependent EGFR-phosphorylation arm [#6]; loss of NgR1 disinhibits neurotrophin- and FGF2-driven neurite outgrowth on myelin [#7]. The ectodomain is shed by TACE/ADAM17, generating a soluble decoy that competitively antagonizes ligand binding and suppresses RhoA activation [#5], a property exploited therapeutically by NgR1(310)-Fc decoys that promote axon regeneration and neuroprotection after optic-nerve and spinal-cord injury [#18, #20]. Beyond axon growth, NgR1 directly binds FGF1/FGF2 at hippocampal synapses where its loss enhances LTP and alters dendritic spine morphology [#1], it bidirectionally regulates spine density, complexity, and learning behavior [#16], and it operates outside the nervous system as a cell-surface entry receptor for mammalian reovirus [#3] and as an inhibitory immune checkpoint that destabilizes the NK-cell immunological synapse through F-actin regulation [#14]. Rare RTN4R missense variants from schizophrenia patients impair growth-cone formation, linking receptor structure to cytoskeletal control [#11].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing that the NgR gene family is conserved across vertebrates provided the evolutionary framework for studying RTN4R orthologs and their function.\",\n      \"evidence\": \"Comparative genomics, synteny and phylogenetic analysis, and in situ hybridization in fish\",\n      \"pmids\": [\"12949137\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Sequence/expression conservation only, no functional assay\", \"Does not address whether ortholog function is conserved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"The first link between RTN4R and human disease asked whether LRR-domain variants contribute to schizophrenia, identifying candidate missense mutations absent from controls.\",\n      \"evidence\": \"DHPLC mutation screening of patients and molecular modeling of the LRR domain\",\n      \"pmids\": [\"15532024\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Computational prediction only, no functional assay of mutant protein\", \"No demonstration of causality or mechanism\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Direct loss-of-function tested whether NgR is genuinely required for myelin inhibition, showing siRNA knockdown disinhibits neurotrophin-induced outgrowth on CNS myelin.\",\n      \"evidence\": \"siRNA knockdown in DRG neurons with neurite outgrowth quantification on myelin substrate\",\n      \"pmids\": [\"15737741\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single method, single lab\", \"Did not define downstream signaling\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"These studies mapped the intracellular signaling logic of NgR, placing it upstream of a RhoA/ROCK/LIM-kinase/cofilin actin-depolymerization pathway and a Ca2+/EGFR arm, and showed that TACE-mediated ectodomain shedding generates a competitive decoy.\",\n      \"evidence\": \"Schwann cell conditioned medium and exogenous TACE on RGC/DRG cultures, RhoA and EGFR phosphorylation assays, p75NTR siRNA, NgRECD shedding Western blots\",\n      \"pmids\": [\"16613894\", \"16849393\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Pathway placement inferred from single lab\", \"Stoichiometry of receptor complex not resolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Genetic and knockdown dissection resolved a key ambiguity by showing NgR1 is required for acute growth-cone collapse by soluble inhibitors but dispensable for chronic substrate-bound inhibition.\",\n      \"evidence\": \"Germline NgR1 knockout plus shRNAi across multiple neuron types in two assay paradigms\",\n      \"pmids\": [\"17611264\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of receptor mediating chronic inhibition unresolved\", \"Mechanism of acute-versus-chronic dissociation not defined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Discovery that NgR1 directly binds FGF1/FGF2 and localizes with FGFR1 at synapses extended its role from axon inhibition to activity-dependent synaptic plasticity and spine morphology.\",\n      \"evidence\": \"Direct binding assays, synaptosomal fractionation, hippocampal slice LTP/LTD with FGFR inhibitor, NgR1 knockout mice\",\n      \"pmids\": [\"18337405\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Co-receptor requirement for FGF antagonism not defined\", \"Molecular nature of NgR1-FGFR1 functional interaction unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Quantitative genetic and species-comparison studies refined the receptor's contribution, showing NgR1/NgR2 only modestly mediate chronic MAG inhibition and that species differences in regeneration arise downstream of receptor binding.\",\n      \"evidence\": \"ngr1/ngr2 double-knockout DRG neurons with ganglioside removal and MAG domain mutants; cross-species Nogo66 binding and cofilin phosphorylation assays with PI-PLC\",\n      \"pmids\": [\"19367338\", \"20007473\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Additional MAG receptors not identified\", \"Basis for differential downstream signaling across species unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identification of AMIGO3 as an alternative co-receptor explained how the NgR1-p75/TROY complex transduces RhoA activation acutely after injury when LINGO-1 is unavailable.\",\n      \"evidence\": \"Co-IP in non-neuronal cells and brain lysates, RhoA assay, AMIGO3 siRNA in DRG/retinal cultures, in vivo lesion models\",\n      \"pmids\": [\"23613963\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, Co-IP without reciprocal structural validation\", \"Selection between LINGO-1 and AMIGO3 not mechanistically defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"These studies expanded NgR1's biology beyond neurite inhibition, identifying it as a reovirus entry receptor and as a co-receptor mediating myocilin-stimulated oligodendrocyte differentiation.\",\n      \"evidence\": \"Gain-of-function expression, soluble decoy, null neurons and differential virion/ISVP binding for reovirus; myocilin-null mice, OPC cultures and Lingo-1 Co-IP\",\n      \"pmids\": [\"24922571\", \"24741044\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Reovirus capsid component engaging NgR1 not defined at residue level\", \"Myocilin role as direct ligand inferred from Co-IP\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Sensitive tracing and decoy-protein interventions established NgR1 as a restraint on corticospinal/raphespinal/RGC regeneration and validated NgR1(310)-Fc as a regeneration- and neuroprotection-promoting therapeutic.\",\n      \"evidence\": \"crym-GFP CST labeling in ngr1-/- mice after hemisection; intravitreal and intrathecal NgR1(310)-Fc with axon tracing, neuroprotection and pharmacokinetics\",\n      \"pmids\": [\"26586827\", \"25655801\", \"24964223\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Magnitude of regeneration remains modest\", \"Decoy target selectivity among NgR ligands not fully resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Bidirectional genetic manipulation showed NgR1 negatively regulates dendritic spine density and complexity and influences learning, memory, and cocaine-induced plasticity.\",\n      \"evidence\": \"NgR1 knockout and overexpression mice with behavioral paradigms, MRI/DTI, and Golgi spine morphometry\",\n      \"pmids\": [\"26838771\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Region-specific molecular mediators of spine regulation unclear\", \"Link between spine phenotype and behavior correlative\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Functional testing of a rare schizophrenia-associated R292H variant connected RTN4R structural variation to impaired growth-cone formation.\",\n      \"evidence\": \"Exon sequencing plus in vitro growth-cone formation assay with mutant\",\n      \"pmids\": [\"28892071\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab functional assay\", \"Disease causality not established\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Biochemical and genetic epistasis identified the NgR1/PlexinA2/CRMP2 ternary complex as the transducer linking Nogo-A to cytoskeletal contraction and corticospinal sprouting restriction in vivo.\",\n      \"evidence\": \"NgR1 Co-IP plus mass spectrometry, cell contraction assay, double-heterozygous epistasis mice with pyramidotomy and behavioral recovery\",\n      \"pmids\": [\"30804090\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How CRMP2 couples the complex to RhoA/cytoskeleton not fully resolved\", \"Whether the complex operates for ligands other than Nogo-A unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Beyond the nervous system, NgR1 was defined as an inhibitory immune checkpoint that destabilizes the NK-cell immunological synapse, with deficiency or blockade improving tumor control.\",\n      \"evidence\": \"NgR1 knockout/blockade NK cells, live imaging of immunological synapse and F-actin dynamics, cytotoxicity and in vivo tumor assays\",\n      \"pmids\": [\"36624164\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ligand engaging NgR1 on NK cells not identified\", \"Signaling pathway downstream of NgR1 in NK cells undefined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how NgR1 selects among its many ligands and co-receptors (CSPGs, Nogo-66, MAG, OMgp, FGFs, reovirus) to produce context-specific outputs, and what receptors mediate chronic myelin inhibition independently of NgR1.\",\n      \"evidence\": \"Not addressed by available timeline discoveries\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of full ligand/co-receptor selectivity\", \"Identity of NgR1-independent chronic-inhibition receptors unknown\", \"Mechanism integrating synaptic, immune, and viral roles unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 2, 6, 8]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 25]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [6, 8]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 2, 9]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [14]}\n    ],\n    \"complexes\": [\n      \"NgR1/p75(NTR)/LINGO-1 or AMIGO3\",\n      \"NgR1/PlexinA2/CRMP2\"\n    ],\n    \"partners\": [\n      \"p75NTR\",\n      \"TROY\",\n      \"LINGO-1\",\n      \"AMIGO3\",\n      \"PLXNA2\",\n      \"CRMP2\",\n      \"FGFR1\",\n      \"JAM-A\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}