{"gene":"NRXN2","run_date":"2026-04-29T11:37:57","timeline":{"discoveries":[{"year":2011,"finding":"Truncating mutations in NRXN2 fail to promote synaptic differentiation in neuron coculture and fail to bind the postsynaptic partners LRRTM2 or NLGN2 in cell binding assays, establishing that NRXN2 functions as a synaptic organizer through interactions with these ligands.","method":"Neuron coculture differentiation assay; cell binding assay with LRRTM2 and NLGN2","journal":"Human genetics","confidence":"High","confidence_rationale":"Tier 2 — two orthogonal functional assays (coculture + binding) on truncating variants, moderate evidence","pmids":["21424692"],"is_preprint":false},{"year":2015,"finding":"Nrxn2α knockout mice show reduced spontaneous transmitter release specifically at excitatory (not inhibitory) synapses in the neocortex, and exhibit altered NMDAR-dependent decay time and reduced NMDAR-mediated responses, indicating Nrxn2α is required for excitatory synaptic transmission and NMDAR function, likely via a trans-synaptic complex involving neuroligin and PSD-95.","method":"Patch-clamp electrophysiology in Nrxn2α KO and Nrxn2α/β double-KO mouse neocortex; synapse density and ultrastructure analysis","journal":"Frontiers in synaptic neuroscience","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined electrophysiological phenotype, multiple models tested, replicated across two KO lines","pmids":["25745399"],"is_preprint":false},{"year":2015,"finding":"The β-isoform of Nrxn2 does not contribute strongly to basic excitatory synaptic transmission in the neocortex, as Nrxn2α/β double-KO mice show similar defects to Nrxn2α single-KO mice.","method":"Patch-clamp electrophysiology comparing Nrxn2α KO vs. Nrxn2α/β double-KO mice","journal":"Frontiers in synaptic neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — direct comparison of two KO genotypes, single lab","pmids":["25745399"],"is_preprint":false},{"year":2013,"finding":"SMN deficiency causes altered splicing and reduced expression of Nrxn2 in zebrafish motor neurons; knockdown of two distinct nrxn2a isoforms phenocopies SMN-deficient fish with significant reduction of motor axon excitability, placing Nrxn2 downstream of SMN in the regulation of neuromuscular synapse function.","method":"Transcriptome analysis; live Ca2+ imaging; isoform-specific knockdown in zebrafish SMA model; Smn−/−;SMN2+/+ mouse motor neuron RT-PCR","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 — functional knockdown phenocopies disease model, supported by mouse validation, single lab","pmids":["24218366"],"is_preprint":false},{"year":2019,"finding":"Deletion of Nrxn2α in mice induces atypical structural connectivity in socially relevant brain regions (amygdala, anterior cingulate cortex, orbitofrontal cortex, hippocampus), including increased fractional anisotropy and altered axonal orientation, linking presynaptic Nrxn2α loss to macroscale circuit-level structural changes.","method":"Diffusion tensor MRI (9.4 T) combined with CLARITY immunolabeling in Nrxn2α KO mice","journal":"Molecular autism","confidence":"Medium","confidence_rationale":"Tier 2 — two orthogonal structural imaging methods in the same animals, single lab","pmids":["30858964"],"is_preprint":false},{"year":2020,"finding":"miR-873-5p directly represses NRXN2 expression; a dual-luciferase reporter assay confirmed 20–30% inhibition of NRXN2 by wild-type miR-873, and the ASD-associated seed-region mutation (rs777143952) alters this regulatory effect, identifying miR-873 as an upstream post-transcriptional regulator of NRXN2.","method":"Dual-luciferase reporter assay; qPCR in transfected SH-SY5Y cells; pull-down transcriptome analysis","journal":"Translational psychiatry","confidence":"Medium","confidence_rationale":"Tier 2 — luciferase reporter plus qPCR validation, single lab","pmids":["33262327"],"is_preprint":false},{"year":2025,"finding":"IGF2BP3 stabilizes NRXN2 mRNA in an m6A-dependent manner in AML cells; a specific m6A site on NRXN2 mRNA was identified, mutation of this site (c.1770A>T) reduced m6A modification, decreased IGF2BP3 enrichment on the mRNA, and destabilized NRXN2 mRNA, thereby suppressing AML cell proliferation.","method":"MeRIP-qPCR (m6A immunoprecipitation); RNA immunoprecipitation; site-directed mutagenesis of m6A site; siRNA knockdown and overexpression in HL-60 cells; proliferation and apoptosis assays","journal":"Turkish journal of haematology","confidence":"Medium","confidence_rationale":"Tier 1–2 — m6A site mutagenesis combined with RIP and functional rescue, single lab","pmids":["41263466"],"is_preprint":false}],"current_model":"NRXN2 is a presynaptic cell-adhesion molecule that organizes excitatory synapses by binding postsynaptic ligands LRRTM2 and NLGN2, promotes synaptic differentiation, and is required for normal spontaneous glutamate release and NMDAR function in the neocortex; its expression is regulated post-transcriptionally by miR-873 and by IGF2BP3-dependent m6A modification of its mRNA, and upstream by SMN-dependent splicing in motor neurons."},"narrative":{"teleology":[{"year":2011,"claim":"Establishing NRXN2 as a synapse organizer: truncating mutations were shown to abolish both LRRTM2/NLGN2 binding and synaptogenic activity, demonstrating that NRXN2 functions through trans-synaptic ligand interactions to promote synaptic differentiation.","evidence":"Neuron coculture differentiation assay and cell binding assay with recombinant LRRTM2/NLGN2 using truncating NRXN2 variants","pmids":["21424692"],"confidence":"High","gaps":["Which specific extracellular domains are necessary and sufficient for each ligand interaction","Whether NRXN2 splice variants differentially engage LRRTM2 vs. NLGN2","Structural basis of the NRXN2–ligand interface not resolved"]},{"year":2013,"claim":"Linking NRXN2 to motor neuron disease pathways: SMN deficiency was shown to alter Nrxn2 splicing and expression, and isoform-specific knockdown phenocopied SMA motor axon defects, placing NRXN2 as a functional effector downstream of SMN.","evidence":"Transcriptome analysis, live Ca²⁺ imaging, and isoform-specific morpholino knockdown in zebrafish SMA model; validated in Smn−/−;SMN2+/+ mouse motor neurons by RT-PCR","pmids":["24218366"],"confidence":"Medium","gaps":["Mechanism by which SMN regulates Nrxn2 splicing (direct vs. indirect) not determined","Whether restoring Nrxn2 expression rescues SMA phenotypes in mammalian models","Single-lab finding in zebrafish with limited mammalian functional validation"]},{"year":2015,"claim":"Defining the α-isoform as the critical form for excitatory transmission: Nrxn2α knockout reduced spontaneous excitatory release and NMDAR function in neocortex, while additional β-isoform deletion did not worsen the phenotype, establishing Nrxn2α as the functionally dominant isoform at excitatory synapses.","evidence":"Patch-clamp electrophysiology in Nrxn2α KO and Nrxn2α/β double-KO mouse neocortical slices; synapse density and ultrastructure analysis","pmids":["25745399"],"confidence":"High","gaps":["Whether the NMDAR deficit is due to altered surface expression, trafficking, or signaling through neuroligin–PSD-95","Whether inhibitory synaptic functions of Nrxn2 become apparent in other brain regions","Molecular identity of the trans-synaptic complex mediating NMDAR regulation not directly shown"]},{"year":2019,"claim":"Extending the functional impact to circuit-level wiring: Nrxn2α deletion was shown to alter structural connectivity in socially relevant brain regions, linking synaptic-level adhesion loss to macroscale white-matter changes relevant to social behavior circuits.","evidence":"Diffusion tensor MRI at 9.4 T combined with CLARITY immunolabeling in Nrxn2α KO mouse brains","pmids":["30858964"],"confidence":"Medium","gaps":["Whether structural changes are developmental or reflect ongoing synaptic dysfunction","Causal relationship between connectivity changes and behavioral phenotypes not established","Single-lab imaging study without electrophysiological correlation in the same regions"]},{"year":2020,"claim":"Identifying a post-transcriptional regulator: miR-873-5p was shown to directly repress NRXN2 mRNA, and an ASD-associated seed-region variant altered this regulation, revealing a layer of miRNA-mediated control over NRXN2 expression.","evidence":"Dual-luciferase reporter assay and qPCR in transfected SH-SY5Y neuroblastoma cells","pmids":["33262327"],"confidence":"Medium","gaps":["Effect size of miR-873 on endogenous NRXN2 protein levels in neurons not measured","Whether the ASD-associated miR-873 variant affects NRXN2-dependent synaptic function in vivo","Other miRNA regulators of NRXN2 not systematically surveyed"]},{"year":2025,"claim":"Revealing epitranscriptomic regulation: IGF2BP3 was shown to stabilize NRXN2 mRNA through recognition of a specific m6A site, and mutation of this site destabilized the transcript and suppressed AML cell proliferation, uncovering an m6A-dependent regulatory axis for NRXN2 outside the nervous system.","evidence":"MeRIP-qPCR, RNA immunoprecipitation, m6A site-directed mutagenesis (c.1770A>T), siRNA knockdown and overexpression in HL-60 AML cells","pmids":["41263466"],"confidence":"Medium","gaps":["Relevance of IGF2BP3–m6A regulation of NRXN2 in neuronal contexts not tested","Whether NRXN2 protein is functionally important in AML or is a bystander transcript","Single-lab study in one AML cell line without in vivo validation"]},{"year":null,"claim":"The structural basis of NRXN2's selective engagement with different postsynaptic ligands, the molecular mechanism by which Nrxn2α controls NMDAR function trans-synaptically, and whether NRXN2 plays functional roles outside the nervous system remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal structure of NRXN2 in complex with LRRTM2 or NLGN2","Trans-synaptic signaling cascade from Nrxn2α to NMDAR subunit composition or trafficking undefined","Functional significance of NRXN2 expression in non-neuronal tissues (e.g., AML) unclear"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[1,2,3]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[0,1]}],"complexes":[],"partners":["LRRTM2","NLGN2","IGF2BP3","SMN"],"other_free_text":[]},"mechanistic_narrative":"NRXN2 is a presynaptic cell-adhesion molecule that organizes excitatory synapses by binding the postsynaptic ligands LRRTM2 and NLGN2, and truncating mutations abolish both ligand binding and synaptogenic activity in coculture assays [PMID:21424692]. The α-isoform (Nrxn2α) is the functionally dominant form at neocortical excitatory synapses, where its deletion reduces spontaneous glutamate release and impairs NMDAR-mediated transmission, likely through a trans-synaptic complex involving neuroligin and PSD-95 [PMID:25745399]. NRXN2 expression is regulated post-transcriptionally by miR-873-5p, which directly represses NRXN2 mRNA [PMID:33262327], and by IGF2BP3-mediated stabilization of NRXN2 mRNA through m6A modification [PMID:41263466]. Upstream, SMN deficiency alters Nrxn2 splicing and expression in motor neurons, placing NRXN2 downstream of SMN in neuromuscular synapse regulation [PMID:24218366]."},"prefetch_data":{"uniprot":{"accession":"P58401","full_name":"Neurexin-2-beta","aliases":["Neurexin II-beta"],"length_aa":666,"mass_kda":70.9,"function":"Neuronal cell surface protein that may be involved in cell recognition and cell adhesion","subcellular_location":"Presynaptic cell membrane","url":"https://www.uniprot.org/uniprotkb/P58401/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/NRXN2","classification":"Not Classified","n_dependent_lines":7,"n_total_lines":1208,"dependency_fraction":0.005794701986754967},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/NRXN2","total_profiled":1310},"omim":[{"mim_id":"621407","title":"SCHIZOPHRENIA 17; SCZD17","url":"https://www.omim.org/entry/621407"},{"mim_id":"615029","title":"PRECEREBELLIN 4; CBLN4","url":"https://www.omim.org/entry/615029"},{"mim_id":"612840","title":"LEUKOCYTE ADHESION DEFICIENCY, TYPE III; LAD3","url":"https://www.omim.org/entry/612840"},{"mim_id":"610421","title":"KH DOMAIN-CONTAINING, RNA-BINDING, SIGNAL TRANSDUCTION-ASSOCIATED PROTEIN 3; KHDRBS3","url":"https://www.omim.org/entry/610421"},{"mim_id":"609374","title":"CELL DIVISION CYCLE-ASSOCIATED PROTEIN 5; CDCA5","url":"https://www.omim.org/entry/609374"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":184.5}],"url":"https://www.proteinatlas.org/search/NRXN2"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"P58401","domains":[{"cath_id":"2.60.120.200","chopping":"91-204_242-291","consensus_level":"high","plddt":96.5646,"start":91,"end":291}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P58401","model_url":"https://alphafold.ebi.ac.uk/files/AF-P58401-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P58401-F1-predicted_aligned_error_v6.png","plddt_mean":61.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NRXN2","jax_strain_url":"https://www.jax.org/strain/search?query=NRXN2"},"sequence":{"accession":"P58401","fasta_url":"https://rest.uniprot.org/uniprotkb/P58401.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P58401/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P58401"}},"corpus_meta":[{"pmid":"21424692","id":"PMC_21424692","title":"Truncating mutations in NRXN2 and NRXN1 in autism spectrum disorders and schizophrenia.","date":"2011","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21424692","citation_count":224,"is_preprint":false},{"pmid":"25745399","id":"PMC_25745399","title":"Genetic targeting of NRXN2 in mice unveils role in excitatory cortical synapse function and social behaviors.","date":"2015","source":"Frontiers in synaptic neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/25745399","citation_count":67,"is_preprint":false},{"pmid":"24218366","id":"PMC_24218366","title":"SMN deficiency alters Nrxn2 expression and splicing in zebrafish and mouse models of spinal muscular atrophy.","date":"2013","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24218366","citation_count":66,"is_preprint":false},{"pmid":"24405718","id":"PMC_24405718","title":"CpG sites associated with NRP1, NRXN2 and miR-29b-2 are hypomethylated in monocytes during ageing.","date":"2014","source":"Immunity & ageing : I & A","url":"https://pubmed.ncbi.nlm.nih.gov/24405718","citation_count":24,"is_preprint":false},{"pmid":"33262327","id":"PMC_33262327","title":"Autism-associated miR-873 regulates ARID1B, SHANK3 and NRXN2 involved in neurodevelopment.","date":"2020","source":"Translational psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/33262327","citation_count":22,"is_preprint":false},{"pmid":"30858964","id":"PMC_30858964","title":"The within-subject application of diffusion tensor MRI and CLARITY reveals brain structural changes in Nrxn2 deletion mice.","date":"2019","source":"Molecular autism","url":"https://pubmed.ncbi.nlm.nih.gov/30858964","citation_count":13,"is_preprint":false},{"pmid":"34126933","id":"PMC_34126933","title":"A genetic interaction of NRXN2 with GABRE, SYT1 and CASK in migraine patients: a case-control study.","date":"2021","source":"The journal of headache and pain","url":"https://pubmed.ncbi.nlm.nih.gov/34126933","citation_count":6,"is_preprint":false},{"pmid":"34777568","id":"PMC_34777568","title":"NRXN2 Possesses a Tumor Suppressor Potential via Inhibiting the Growth of Thyroid Cancer Cells.","date":"2021","source":"Computational and mathematical methods in medicine","url":"https://pubmed.ncbi.nlm.nih.gov/34777568","citation_count":4,"is_preprint":false},{"pmid":"39748282","id":"PMC_39748282","title":"NRXN2 Homozygous Variant Identified in a Family with Global Developmental Delay, Severe Intellectual Disability, EEG Abnormalities and Speech Delay: A new Syndrome?","date":"2025","source":"Clinical EEG and neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/39748282","citation_count":0,"is_preprint":false},{"pmid":"41263466","id":"PMC_41263466","title":"IGF2BP3 Promoted the Overproliferation of AML Cells via Stability of NRXN2 mRNA.","date":"2025","source":"Turkish journal of haematology : official journal of Turkish Society of Haematology","url":"https://pubmed.ncbi.nlm.nih.gov/41263466","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.19.688847","title":"A novel method to sort and enrich sensory neurons","date":"2025-11-19","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.19.688847","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.11.24.690344","title":"Modelling mental disorders in zebrafish. Neurexins severely modulate anxiety, social behaviours and aggression","date":"2025-11-25","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.24.690344","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8009,"output_tokens":1780,"usd":0.025364},"stage2":{"model":"claude-opus-4-6","input_tokens":5116,"output_tokens":2237,"usd":0.122258},"total_usd":0.147622,"stage1_batch_id":"msgbatch_012ZiiCUBfB62NCTQd4Bk1Jo","stage2_batch_id":"msgbatch_01Xuqq9aUHoQouS7UVGZNStZ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"Truncating mutations in NRXN2 fail to promote synaptic differentiation in neuron coculture and fail to bind the postsynaptic partners LRRTM2 or NLGN2 in cell binding assays, establishing that NRXN2 functions as a synaptic organizer through interactions with these ligands.\",\n      \"method\": \"Neuron coculture differentiation assay; cell binding assay with LRRTM2 and NLGN2\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — two orthogonal functional assays (coculture + binding) on truncating variants, moderate evidence\",\n      \"pmids\": [\"21424692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Nrxn2α knockout mice show reduced spontaneous transmitter release specifically at excitatory (not inhibitory) synapses in the neocortex, and exhibit altered NMDAR-dependent decay time and reduced NMDAR-mediated responses, indicating Nrxn2α is required for excitatory synaptic transmission and NMDAR function, likely via a trans-synaptic complex involving neuroligin and PSD-95.\",\n      \"method\": \"Patch-clamp electrophysiology in Nrxn2α KO and Nrxn2α/β double-KO mouse neocortex; synapse density and ultrastructure analysis\",\n      \"journal\": \"Frontiers in synaptic neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined electrophysiological phenotype, multiple models tested, replicated across two KO lines\",\n      \"pmids\": [\"25745399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The β-isoform of Nrxn2 does not contribute strongly to basic excitatory synaptic transmission in the neocortex, as Nrxn2α/β double-KO mice show similar defects to Nrxn2α single-KO mice.\",\n      \"method\": \"Patch-clamp electrophysiology comparing Nrxn2α KO vs. Nrxn2α/β double-KO mice\",\n      \"journal\": \"Frontiers in synaptic neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct comparison of two KO genotypes, single lab\",\n      \"pmids\": [\"25745399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"SMN deficiency causes altered splicing and reduced expression of Nrxn2 in zebrafish motor neurons; knockdown of two distinct nrxn2a isoforms phenocopies SMN-deficient fish with significant reduction of motor axon excitability, placing Nrxn2 downstream of SMN in the regulation of neuromuscular synapse function.\",\n      \"method\": \"Transcriptome analysis; live Ca2+ imaging; isoform-specific knockdown in zebrafish SMA model; Smn−/−;SMN2+/+ mouse motor neuron RT-PCR\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional knockdown phenocopies disease model, supported by mouse validation, single lab\",\n      \"pmids\": [\"24218366\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Deletion of Nrxn2α in mice induces atypical structural connectivity in socially relevant brain regions (amygdala, anterior cingulate cortex, orbitofrontal cortex, hippocampus), including increased fractional anisotropy and altered axonal orientation, linking presynaptic Nrxn2α loss to macroscale circuit-level structural changes.\",\n      \"method\": \"Diffusion tensor MRI (9.4 T) combined with CLARITY immunolabeling in Nrxn2α KO mice\",\n      \"journal\": \"Molecular autism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — two orthogonal structural imaging methods in the same animals, single lab\",\n      \"pmids\": [\"30858964\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"miR-873-5p directly represses NRXN2 expression; a dual-luciferase reporter assay confirmed 20–30% inhibition of NRXN2 by wild-type miR-873, and the ASD-associated seed-region mutation (rs777143952) alters this regulatory effect, identifying miR-873 as an upstream post-transcriptional regulator of NRXN2.\",\n      \"method\": \"Dual-luciferase reporter assay; qPCR in transfected SH-SY5Y cells; pull-down transcriptome analysis\",\n      \"journal\": \"Translational psychiatry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — luciferase reporter plus qPCR validation, single lab\",\n      \"pmids\": [\"33262327\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"IGF2BP3 stabilizes NRXN2 mRNA in an m6A-dependent manner in AML cells; a specific m6A site on NRXN2 mRNA was identified, mutation of this site (c.1770A>T) reduced m6A modification, decreased IGF2BP3 enrichment on the mRNA, and destabilized NRXN2 mRNA, thereby suppressing AML cell proliferation.\",\n      \"method\": \"MeRIP-qPCR (m6A immunoprecipitation); RNA immunoprecipitation; site-directed mutagenesis of m6A site; siRNA knockdown and overexpression in HL-60 cells; proliferation and apoptosis assays\",\n      \"journal\": \"Turkish journal of haematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — m6A site mutagenesis combined with RIP and functional rescue, single lab\",\n      \"pmids\": [\"41263466\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"NRXN2 is a presynaptic cell-adhesion molecule that organizes excitatory synapses by binding postsynaptic ligands LRRTM2 and NLGN2, promotes synaptic differentiation, and is required for normal spontaneous glutamate release and NMDAR function in the neocortex; its expression is regulated post-transcriptionally by miR-873 and by IGF2BP3-dependent m6A modification of its mRNA, and upstream by SMN-dependent splicing in motor neurons.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"NRXN2 is a presynaptic cell-adhesion molecule that organizes excitatory synapses by binding the postsynaptic ligands LRRTM2 and NLGN2, and truncating mutations abolish both ligand binding and synaptogenic activity in coculture assays [PMID:21424692]. The α-isoform (Nrxn2α) is the functionally dominant form at neocortical excitatory synapses, where its deletion reduces spontaneous glutamate release and impairs NMDAR-mediated transmission, likely through a trans-synaptic complex involving neuroligin and PSD-95 [PMID:25745399]. NRXN2 expression is regulated post-transcriptionally by miR-873-5p, which directly represses NRXN2 mRNA [PMID:33262327], and by IGF2BP3-mediated stabilization of NRXN2 mRNA through m6A modification [PMID:41263466]. Upstream, SMN deficiency alters Nrxn2 splicing and expression in motor neurons, placing NRXN2 downstream of SMN in neuromuscular synapse regulation [PMID:24218366].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Establishing NRXN2 as a synapse organizer: truncating mutations were shown to abolish both LRRTM2/NLGN2 binding and synaptogenic activity, demonstrating that NRXN2 functions through trans-synaptic ligand interactions to promote synaptic differentiation.\",\n      \"evidence\": \"Neuron coculture differentiation assay and cell binding assay with recombinant LRRTM2/NLGN2 using truncating NRXN2 variants\",\n      \"pmids\": [\"21424692\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Which specific extracellular domains are necessary and sufficient for each ligand interaction\",\n        \"Whether NRXN2 splice variants differentially engage LRRTM2 vs. NLGN2\",\n        \"Structural basis of the NRXN2–ligand interface not resolved\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Linking NRXN2 to motor neuron disease pathways: SMN deficiency was shown to alter Nrxn2 splicing and expression, and isoform-specific knockdown phenocopied SMA motor axon defects, placing NRXN2 as a functional effector downstream of SMN.\",\n      \"evidence\": \"Transcriptome analysis, live Ca²⁺ imaging, and isoform-specific morpholino knockdown in zebrafish SMA model; validated in Smn−/−;SMN2+/+ mouse motor neurons by RT-PCR\",\n      \"pmids\": [\"24218366\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which SMN regulates Nrxn2 splicing (direct vs. indirect) not determined\",\n        \"Whether restoring Nrxn2 expression rescues SMA phenotypes in mammalian models\",\n        \"Single-lab finding in zebrafish with limited mammalian functional validation\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defining the α-isoform as the critical form for excitatory transmission: Nrxn2α knockout reduced spontaneous excitatory release and NMDAR function in neocortex, while additional β-isoform deletion did not worsen the phenotype, establishing Nrxn2α as the functionally dominant isoform at excitatory synapses.\",\n      \"evidence\": \"Patch-clamp electrophysiology in Nrxn2α KO and Nrxn2α/β double-KO mouse neocortical slices; synapse density and ultrastructure analysis\",\n      \"pmids\": [\"25745399\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the NMDAR deficit is due to altered surface expression, trafficking, or signaling through neuroligin–PSD-95\",\n        \"Whether inhibitory synaptic functions of Nrxn2 become apparent in other brain regions\",\n        \"Molecular identity of the trans-synaptic complex mediating NMDAR regulation not directly shown\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Extending the functional impact to circuit-level wiring: Nrxn2α deletion was shown to alter structural connectivity in socially relevant brain regions, linking synaptic-level adhesion loss to macroscale white-matter changes relevant to social behavior circuits.\",\n      \"evidence\": \"Diffusion tensor MRI at 9.4 T combined with CLARITY immunolabeling in Nrxn2α KO mouse brains\",\n      \"pmids\": [\"30858964\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether structural changes are developmental or reflect ongoing synaptic dysfunction\",\n        \"Causal relationship between connectivity changes and behavioral phenotypes not established\",\n        \"Single-lab imaging study without electrophysiological correlation in the same regions\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identifying a post-transcriptional regulator: miR-873-5p was shown to directly repress NRXN2 mRNA, and an ASD-associated seed-region variant altered this regulation, revealing a layer of miRNA-mediated control over NRXN2 expression.\",\n      \"evidence\": \"Dual-luciferase reporter assay and qPCR in transfected SH-SY5Y neuroblastoma cells\",\n      \"pmids\": [\"33262327\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Effect size of miR-873 on endogenous NRXN2 protein levels in neurons not measured\",\n        \"Whether the ASD-associated miR-873 variant affects NRXN2-dependent synaptic function in vivo\",\n        \"Other miRNA regulators of NRXN2 not systematically surveyed\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Revealing epitranscriptomic regulation: IGF2BP3 was shown to stabilize NRXN2 mRNA through recognition of a specific m6A site, and mutation of this site destabilized the transcript and suppressed AML cell proliferation, uncovering an m6A-dependent regulatory axis for NRXN2 outside the nervous system.\",\n      \"evidence\": \"MeRIP-qPCR, RNA immunoprecipitation, m6A site-directed mutagenesis (c.1770A>T), siRNA knockdown and overexpression in HL-60 AML cells\",\n      \"pmids\": [\"41263466\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Relevance of IGF2BP3–m6A regulation of NRXN2 in neuronal contexts not tested\",\n        \"Whether NRXN2 protein is functionally important in AML or is a bystander transcript\",\n        \"Single-lab study in one AML cell line without in vivo validation\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis of NRXN2's selective engagement with different postsynaptic ligands, the molecular mechanism by which Nrxn2α controls NMDAR function trans-synaptically, and whether NRXN2 plays functional roles outside the nervous system remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No crystal structure of NRXN2 in complex with LRRTM2 or NLGN2\",\n        \"Trans-synaptic signaling cascade from Nrxn2α to NMDAR subunit composition or trafficking undefined\",\n        \"Functional significance of NRXN2 expression in non-neuronal tissues (e.g., AML) unclear\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [1, 2, 3]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"LRRTM2\",\n      \"NLGN2\",\n      \"IGF2BP3\",\n      \"SMN\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}