{"gene":"CNTNAP4","run_date":"2026-04-28T17:28:53","timeline":{"discoveries":[{"year":2002,"finding":"Caspr4 (CNTNAP4) cytoplasmic tail interacts with PDZ domain-containing proteins of the CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex, establishing it as a member of the NCP/neurexin superfamily with PDZ-mediated protein interactions.","method":"PDZ domain interaction assay, protein binding experiments","journal":"Molecular and cellular neurosciences","confidence":"Medium","confidence_rationale":"Tier 3 — direct binding assay but single lab, single method","pmids":["12093160"],"is_preprint":false},{"year":2014,"finding":"Cntnap4 is localized presynaptically in cortical parvalbumin-positive GABAergic basket cells; loss of Cntnap4 reduces GABAergic synaptic output from these interneurons and paradoxically augments dopaminergic release in the nucleus accumbens.","method":"Cntnap4 knockout mice, electrophysiology, immunohistochemistry, pharmacological rescue","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined cellular phenotypes (GABAergic and dopaminergic), multiple orthogonal methods, high citation count indicating broad replication","pmids":["24870235"],"is_preprint":false},{"year":2014,"finding":"Caspr4 interacts with LNX2 (Ligand of Numb protein X2) in a PDZ domain-dependent manner; this interaction is required for Caspr4 to promote neuronal differentiation and restrain proliferation of neural progenitor cells in the subventricular zone.","method":"Co-immunoprecipitation, shRNA knockdown, overexpression of intracellular domain (C4ICD), rescue experiments in cultured mouse NPCs","journal":"Stem cells and development","confidence":"Medium","confidence_rationale":"Tier 2/3 — reciprocal rescue experiments and Co-IP support PDZ-dependent interaction, single lab","pmids":["25279559"],"is_preprint":false},{"year":2018,"finding":"CNTNAP4 regulates GABAergic inhibitory synaptic transmission via interaction with GABAAR β2/3 subunits and GABARAP; knockdown or overexpression of CNTNAP4 alters GABAAR β2/3 membrane protein levels (not total protein), affecting neuronal excitability.","method":"Lentiviral knockdown/overexpression in vivo, co-immunoprecipitation, Western blotting for membrane vs. total GABAAR protein, electrophysiology in Mg2+-free epilepsy cell model","journal":"Cerebral cortex","confidence":"Medium","confidence_rationale":"Tier 2/3 — Co-IP plus functional electrophysiology and in vivo knockdown/overexpression, single lab","pmids":["28968899"],"is_preprint":false},{"year":2018,"finding":"Cntnap4 functions as a cell-surface receptor for the secreted glycoprotein NELL-1 during osteogenesis; Cntnap4 and NELL-1 colocalize on the surface of osteogenic cells, display high-affinity binding, and Cntnap4 knockdown abrogates NELL-1-responsive Wnt and MAPK signaling as well as osteogenic effects.","method":"Colocalization assays, high-affinity binding assay, shRNA knockdown, Wnt1-Cre conditional Cntnap4 KO mice, signaling pathway analysis","journal":"Journal of bone and mineral research","confidence":"High","confidence_rationale":"Tier 1/2 — ligand-receptor interaction validated by binding assay, knockdown, conditional KO, and signaling readouts with multiple orthogonal methods","pmids":["29905970"],"is_preprint":false},{"year":2020,"finding":"CNTNAP4 deficiency in dopaminergic neurons induces mitophagy, increases α-synuclein expression, reduces synaptic vesicles, and increases autophagosomes in the substantia nigra, leading to DA neuronal degeneration and parkinsonian motor deficits.","method":"shRNA knockdown in MN9D cell line, AAV-mediated SN-specific knockdown, CNTNAP4 KO mice, Western blotting, immunohistochemistry, transmission electron microscopy, RNA sequencing","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 — multiple in vitro and in vivo models with defined cellular phenotypes and mechanistic readouts, single lab","pmids":["32194851"],"is_preprint":false},{"year":2022,"finding":"Cntnap4 knockout reduces GABAergic transmission and GABA receptor expression specifically in the basolateral amygdala (but not prefrontal cortex), contributing to impaired fear conditioning; L. reuteri treatment rescues both GABAergic transmission and fear memory in Cntnap4-/- mice.","method":"Electrophysiological recording, RNA-sequencing, Cntnap4-/- mice, L. reuteri supplementation and fecal microbiota transplantation","journal":"EBioMedicine","confidence":"Medium","confidence_rationale":"Tier 2 — electrophysiology plus genetic KO and functional rescue, single lab","pmids":["36395738"],"is_preprint":false},{"year":2023,"finding":"Cntnap4 deficiency exacerbates α-synuclein pathology via an astrocyte-microglia complement crosstalk: α-synuclein from damaged DA neurons stimulates astrocytes to release complement C3, which activates microglial C3aR, triggering microglia to secrete C1q and pro-inflammatory cytokines, further driving DA neuron death.","method":"AAV-mediated α-synuclein overexpression in Cntnap4 heterozygous KO mice, A53T transgenic mice with AAV-Cntnap4 shRNA, microglial depletion, targeted delivery of C3aR antagonist SB290157","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — multiple genetic and pharmacological interventions define pathway, single lab","pmids":["37087484"],"is_preprint":false},{"year":2023,"finding":"CNTNAP4 acts downstream of NELL-1 signaling in osteosarcoma; CRISPR/Cas9 deletion of CNTNAP4 reduces tumor growth, angiogenesis, and metastasis, phenocopying NELL-1 KO, and abolishes NELL-1 responsiveness; CNTNAP4 KO reduces MAPK/ERK signaling, rescued by ERK1/2 agonist isoproterenol.","method":"CRISPR/Cas9 KO in OS cells, in vivo tumor models, phospho-array, transcriptomics, ERK agonist rescue","journal":"NPJ precision oncology","confidence":"Medium","confidence_rationale":"Tier 2 — CRISPR KO with epistasis and signaling rescue, single lab","pmids":["36599925"],"is_preprint":false},{"year":2024,"finding":"EBF3 transcription factor directly binds the CNTNAP4 promoter and activates CNTNAP4 transcription; CNTNAP4 knockdown abolishes the neuroprotective anti-apoptotic effect of EBF3 in dopaminergic neurons, placing CNTNAP4 downstream of EBF3 in a PD-relevant pathway.","method":"Luciferase reporter assay, chromatin immunoprecipitation (ChIP), DNA pull-down assay, shRNA knockdown, MPTP mouse model and MPP+-treated SH-SY5Y cells","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP, luciferase reporter, and DNA pull-down with functional rescue, single lab","pmids":["38479556"],"is_preprint":false}],"current_model":"CNTNAP4 (Caspr4) is a presynaptic neurexin superfamily transmembrane protein that localizes to GABAergic interneuron and dopaminergic synapses, where it regulates GABA release by PV+ basket cells and dopamine release in the nucleus accumbens; it interacts via its cytoplasmic PDZ-binding tail with LNX2 and the CASK/Veli/Mint complex to control neural progenitor differentiation, interacts with GABAAR β2/3 subunits and GABARAP to regulate inhibitory receptor membrane levels, and serves as a cell-surface receptor for the secreted ligand NELL-1 that signals through Wnt and MAPK/ERK pathways in both neural and osteogenic contexts; its deficiency disrupts mitophagy and α-synuclein homeostasis in dopaminergic neurons and triggers complement-mediated astrocyte-microglia neuroinflammation."},"narrative":{"teleology":[{"year":2002,"claim":"Establishing CNTNAP4 as a PDZ-interacting neurexin superfamily member resolved how this orphan transmembrane protein might couple to intracellular scaffolding, showing its cytoplasmic tail engages the CASK/Veli/Mint complex.","evidence":"PDZ domain interaction assays with recombinant proteins","pmids":["12093160"],"confidence":"Medium","gaps":["Binding shown by single method without reciprocal validation in neurons","Functional consequence of CASK/Veli/Mint interaction unknown","In vivo relevance of the PDZ interaction not tested"]},{"year":2014,"claim":"Demonstrating that Cntnap4 is a presynaptic protein in PV+ interneurons whose deletion reduces GABAergic output and increases dopaminergic release established the first in vivo circuit-level function for CNTNAP4.","evidence":"Cntnap4 knockout mice with electrophysiology, immunohistochemistry, and pharmacological rescue","pmids":["24870235"],"confidence":"High","gaps":["Molecular mechanism by which presynaptic CNTNAP4 controls vesicle release unresolved","Relationship between GABAergic deficit and dopaminergic phenotype only inferred"]},{"year":2014,"claim":"Identifying LNX2 as a PDZ-dependent partner that mediates CNTNAP4's pro-differentiation effect on neural progenitors revealed a developmental role beyond synaptic function.","evidence":"Co-immunoprecipitation, shRNA knockdown, C4ICD overexpression and rescue in mouse neural progenitor cells","pmids":["25279559"],"confidence":"Medium","gaps":["Single lab; no independent replication","Downstream targets of LNX2-CNTNAP4 signaling in progenitors not identified","Whether this pathway operates in vivo during neurogenesis not confirmed"]},{"year":2018,"claim":"Showing that CNTNAP4 interacts with GABAAR β2/3 subunits and GABARAP to regulate receptor surface levels provided a postsynaptic mechanism complementing its known presynaptic role in GABAergic transmission.","evidence":"Co-immunoprecipitation, membrane fractionation Western blots, lentiviral knockdown/overexpression in vivo, electrophysiology in epilepsy model","pmids":["28968899"],"confidence":"Medium","gaps":["Presynaptic versus postsynaptic localization of this interaction not resolved","Stoichiometry and directness of CNTNAP4–GABAAR interaction not established by purified components"]},{"year":2018,"claim":"Identification of CNTNAP4 as the high-affinity cell-surface receptor for NELL-1 in osteogenesis expanded CNTNAP4 function beyond the nervous system and linked it to Wnt and MAPK/ERK signaling.","evidence":"High-affinity binding assay, colocalization, shRNA knockdown, Wnt1-Cre conditional Cntnap4 KO mice, signaling pathway analysis","pmids":["29905970"],"confidence":"High","gaps":["Whether NELL-1–CNTNAP4 signaling operates similarly at neural synapses unknown","Structural basis of NELL-1–CNTNAP4 binding not determined"]},{"year":2020,"claim":"Linking CNTNAP4 deficiency to mitophagy, α-synuclein accumulation, and dopaminergic neurodegeneration established a cell-autonomous neuroprotective role in the substantia nigra.","evidence":"shRNA knockdown in MN9D cells, AAV-mediated SN knockdown, Cntnap4 KO mice, TEM, Western blotting, RNA-seq","pmids":["32194851"],"confidence":"Medium","gaps":["Direct molecular target through which CNTNAP4 suppresses mitophagy and α-synuclein not identified","Single lab; awaits independent replication"]},{"year":2022,"claim":"Demonstrating region-specific loss of GABAergic transmission in the basolateral amygdala (but not PFC) of Cntnap4 KO mice, with rescue by L. reuteri, revealed circuit-selective vulnerability and a gut-brain interaction.","evidence":"Electrophysiology, RNA-seq, Cntnap4−/− mice, probiotic and fecal transplant rescue","pmids":["36395738"],"confidence":"Medium","gaps":["Mechanism by which gut bacteria restore amygdala GABAergic signaling not elucidated","Whether probiotic rescue is CNTNAP4-specific or a general GABAergic effect unknown"]},{"year":2023,"claim":"Elucidating a complement-mediated astrocyte-microglia neuroinflammatory cascade downstream of CNTNAP4 deficiency and α-synuclein pathology clarified the non-cell-autonomous neurodegeneration mechanism.","evidence":"AAV α-synuclein overexpression in Cntnap4 heterozygous KO and A53T transgenic mice, microglial depletion, C3aR antagonist SB290157","pmids":["37087484"],"confidence":"Medium","gaps":["How CNTNAP4 loss increases α-synuclein release from neurons remains unclear","Single lab; pathway steps not fully validated with genetic complement KOs"]},{"year":2023,"claim":"CRISPR deletion of CNTNAP4 in osteosarcoma phenocopied NELL-1 KO and abolished NELL-1-driven MAPK/ERK signaling, confirming epistatic receptor function in a tumor context.","evidence":"CRISPR/Cas9 KO in OS cells, in vivo xenograft, phospho-array, ERK agonist rescue","pmids":["36599925"],"confidence":"Medium","gaps":["Whether CNTNAP4 has NELL-1-independent oncogenic roles not addressed","Applicability beyond osteosarcoma not tested"]},{"year":2024,"claim":"Identification of EBF3 as a direct transcriptional activator of CNTNAP4, whose neuroprotective effect requires CNTNAP4, placed CNTNAP4 within a defined transcriptional hierarchy in dopaminergic neuron survival.","evidence":"ChIP, luciferase reporter, DNA pull-down, shRNA knockdown, MPTP and MPP+ models","pmids":["38479556"],"confidence":"Medium","gaps":["Single lab; no independent confirmation of EBF3–CNTNAP4 axis","How CNTNAP4 mediates anti-apoptotic signaling downstream of EBF3 is unknown"]},{"year":null,"claim":"The direct molecular mechanism by which CNTNAP4 controls presynaptic neurotransmitter vesicle release, and whether NELL-1 signaling through CNTNAP4 operates at synapses, remain central unresolved questions.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of CNTNAP4 or its complexes exists","Presynaptic vesicle release mechanism not defined at the molecular level","Whether NELL-1–CNTNAP4 signaling occurs in neurons is untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[4,8]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,2,3]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,4]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[1,3,6]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,8]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[7]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[5,9]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[5]}],"complexes":["CASK/Veli/Mint complex"],"partners":["NELL1","LNX2","CASK","GABRB2","GABRB3","GABARAP","EBF3"],"other_free_text":[]},"mechanistic_narrative":"CNTNAP4 (Caspr4) is a neurexin superfamily transmembrane protein that functions as a presynaptic regulator of neurotransmitter release and as a cell-surface receptor for the secreted ligand NELL-1. In the brain, CNTNAP4 localizes to parvalbumin-positive GABAergic interneuron terminals where it controls GABAergic output, and its loss reduces inhibitory transmission in the cortex and basolateral amygdala while paradoxically augmenting dopaminergic release in the nucleus accumbens [PMID:24870235, PMID:36395738]; it also interacts with GABAAR β2/3 subunits and GABARAP to regulate inhibitory receptor surface levels [PMID:28968899]. CNTNAP4 signals through its cytoplasmic PDZ-binding domain by engaging the CASK/Veli/Mint complex and LNX2 to promote neural progenitor differentiation [PMID:12093160, PMID:25279559], and serves as a high-affinity receptor for NELL-1 to activate Wnt and MAPK/ERK pathways in both osteogenic and tumor contexts [PMID:29905970, PMID:36599925]. In dopaminergic neurons, CNTNAP4 deficiency triggers mitophagy, α-synuclein accumulation, and complement-mediated astrocyte–microglia neuroinflammation leading to neurodegeneration [PMID:32194851, PMID:37087484]."},"prefetch_data":{"uniprot":{"accession":"Q9C0A0","full_name":"Contactin-associated protein-like 4","aliases":["Cell recognition molecule Caspr4"],"length_aa":1308,"mass_kda":145.3,"function":"Presynaptic protein involved in both dopaminergic synaptic transmission and GABAergic system, thereby participating in the structural maturation of inhibitory interneuron synapses. Involved in the dopaminergic synaptic transmission by attenuating dopamine release through a presynaptic mechanism. Also participates in the GABAergic system (By similarity)","subcellular_location":"Presynaptic cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9C0A0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CNTNAP4","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CNTNAP4","total_profiled":1310},"omim":[{"mim_id":"610518","title":"CONTACTIN-ASSOCIATED PROTEIN-LIKE 4; CNTNAP4","url":"https://www.omim.org/entry/610518"},{"mim_id":"610517","title":"CONTACTIN-ASSOCIATED PROTEIN-LIKE 3; CNTNAP3","url":"https://www.omim.org/entry/610517"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":94.7}],"url":"https://www.proteinatlas.org/search/CNTNAP4"},"hgnc":{"alias_symbol":["CASPR4","KIAA1763"],"prev_symbol":[]},"alphafold":{"accession":"Q9C0A0","domains":[{"cath_id":"2.60.120.260","chopping":"34-179","consensus_level":"high","plddt":91.6875,"start":34,"end":179},{"cath_id":"2.60.120.200","chopping":"184-318_325-358","consensus_level":"high","plddt":82.2433,"start":184,"end":358},{"cath_id":"2.60.120.200","chopping":"377-545","consensus_level":"high","plddt":83.4873,"start":377,"end":545},{"cath_id":"2.60.120.1000","chopping":"631-787","consensus_level":"high","plddt":91.7171,"start":631,"end":787},{"cath_id":"2.60.120.200","chopping":"795-959","consensus_level":"high","plddt":91.5963,"start":795,"end":959},{"cath_id":"2.10.25.10","chopping":"963-998","consensus_level":"medium","plddt":87.4578,"start":963,"end":998},{"cath_id":"2.60.120.200","chopping":"1001-1017_1034-1200","consensus_level":"high","plddt":90.328,"start":1001,"end":1200}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9C0A0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9C0A0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9C0A0-F1-predicted_aligned_error_v6.png","plddt_mean":83.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CNTNAP4","jax_strain_url":"https://www.jax.org/strain/search?query=CNTNAP4"},"sequence":{"accession":"Q9C0A0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9C0A0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9C0A0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9C0A0"}},"corpus_meta":[{"pmid":"24870235","id":"PMC_24870235","title":"Cntnap4 differentially contributes to GABAergic and dopaminergic synaptic transmission.","date":"2014","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/24870235","citation_count":147,"is_preprint":false},{"pmid":"12093160","id":"PMC_12093160","title":"Caspr3 and caspr4, two novel members of the caspr family are expressed in the nervous system and interact with PDZ domains.","date":"2002","source":"Molecular and cellular neurosciences","url":"https://pubmed.ncbi.nlm.nih.gov/12093160","citation_count":79,"is_preprint":false},{"pmid":"37087484","id":"PMC_37087484","title":"Cntnap4 partial deficiency exacerbates α-synuclein pathology through astrocyte-microglia C3-C3aR pathway.","date":"2023","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/37087484","citation_count":35,"is_preprint":false},{"pmid":"25279559","id":"PMC_25279559","title":"Caspr4 interaction with LNX2 modulates the proliferation and neuronal differentiation of mouse neural progenitor cells.","date":"2014","source":"Stem cells and development","url":"https://pubmed.ncbi.nlm.nih.gov/25279559","citation_count":29,"is_preprint":false},{"pmid":"32194851","id":"PMC_32194851","title":"CNTNAP4 deficiency in dopaminergic neurons initiates parkinsonian phenotypes.","date":"2020","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/32194851","citation_count":29,"is_preprint":false},{"pmid":"29905970","id":"PMC_29905970","title":"Neurexin Superfamily Cell Membrane Receptor Contactin-Associated Protein Like-4 (Cntnap4) Is Involved in Neural EGFL-Like 1 (Nell-1)-Responsive Osteogenesis.","date":"2018","source":"Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research","url":"https://pubmed.ncbi.nlm.nih.gov/29905970","citation_count":25,"is_preprint":false},{"pmid":"37933376","id":"PMC_37933376","title":"Microglial targeted therapy relieves cognitive impairment caused by Cntnap4 deficiency.","date":"2023","source":"Exploration (Beijing, China)","url":"https://pubmed.ncbi.nlm.nih.gov/37933376","citation_count":24,"is_preprint":false},{"pmid":"36395738","id":"PMC_36395738","title":"Lactobacillus reuteri normalizes altered fear memory in male Cntnap4 knockout mice.","date":"2022","source":"EBioMedicine","url":"https://pubmed.ncbi.nlm.nih.gov/36395738","citation_count":22,"is_preprint":false},{"pmid":"28968899","id":"PMC_28968899","title":"CNTNAP4 Impacts Epilepsy Through GABAA Receptors Regulation: Evidence From Temporal Lobe Epilepsy Patients and Mouse Models.","date":"2018","source":"Cerebral cortex (New York, N.Y. : 1991)","url":"https://pubmed.ncbi.nlm.nih.gov/28968899","citation_count":22,"is_preprint":false},{"pmid":"24223195","id":"PMC_24223195","title":"A common copy number variation (CNV) polymorphism in the CNTNAP4 gene: association with aging in females.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24223195","citation_count":19,"is_preprint":false},{"pmid":"38479556","id":"PMC_38479556","title":"Early B Cell Factor 3 (EBF3) attenuates Parkinson's disease through directly regulating contactin-associated protein-like 4 (CNTNAP4) transcription: An experimental study.","date":"2024","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/38479556","citation_count":5,"is_preprint":false},{"pmid":"36599925","id":"PMC_36599925","title":"CNTNAP4 signaling regulates osteosarcoma disease progression.","date":"2023","source":"NPJ precision oncology","url":"https://pubmed.ncbi.nlm.nih.gov/36599925","citation_count":5,"is_preprint":false},{"pmid":"39647729","id":"PMC_39647729","title":"Novel insights into Cntnap4 in Alzheimer's disease: Intestinal flora interaction.","date":"2024","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/39647729","citation_count":3,"is_preprint":false},{"pmid":"40262286","id":"PMC_40262286","title":"Investigation of the transcriptome and metabolome of the cerebral cortex and testes in Cntnap4-deficient mice.","date":"2025","source":"Journal of psychiatric research","url":"https://pubmed.ncbi.nlm.nih.gov/40262286","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9247,"output_tokens":2527,"usd":0.032823},"stage2":{"model":"claude-opus-4-6","input_tokens":5864,"output_tokens":2894,"usd":0.152505},"total_usd":0.185328,"stage1_batch_id":"msgbatch_011kfMfE81o6CTcyhVUqumuW","stage2_batch_id":"msgbatch_01DTputS6WNkH745x1nVSoBo","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"Caspr4 (CNTNAP4) cytoplasmic tail interacts with PDZ domain-containing proteins of the CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex, establishing it as a member of the NCP/neurexin superfamily with PDZ-mediated protein interactions.\",\n      \"method\": \"PDZ domain interaction assay, protein binding experiments\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — direct binding assay but single lab, single method\",\n      \"pmids\": [\"12093160\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Cntnap4 is localized presynaptically in cortical parvalbumin-positive GABAergic basket cells; loss of Cntnap4 reduces GABAergic synaptic output from these interneurons and paradoxically augments dopaminergic release in the nucleus accumbens.\",\n      \"method\": \"Cntnap4 knockout mice, electrophysiology, immunohistochemistry, pharmacological rescue\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular phenotypes (GABAergic and dopaminergic), multiple orthogonal methods, high citation count indicating broad replication\",\n      \"pmids\": [\"24870235\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Caspr4 interacts with LNX2 (Ligand of Numb protein X2) in a PDZ domain-dependent manner; this interaction is required for Caspr4 to promote neuronal differentiation and restrain proliferation of neural progenitor cells in the subventricular zone.\",\n      \"method\": \"Co-immunoprecipitation, shRNA knockdown, overexpression of intracellular domain (C4ICD), rescue experiments in cultured mouse NPCs\",\n      \"journal\": \"Stem cells and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — reciprocal rescue experiments and Co-IP support PDZ-dependent interaction, single lab\",\n      \"pmids\": [\"25279559\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CNTNAP4 regulates GABAergic inhibitory synaptic transmission via interaction with GABAAR β2/3 subunits and GABARAP; knockdown or overexpression of CNTNAP4 alters GABAAR β2/3 membrane protein levels (not total protein), affecting neuronal excitability.\",\n      \"method\": \"Lentiviral knockdown/overexpression in vivo, co-immunoprecipitation, Western blotting for membrane vs. total GABAAR protein, electrophysiology in Mg2+-free epilepsy cell model\",\n      \"journal\": \"Cerebral cortex\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — Co-IP plus functional electrophysiology and in vivo knockdown/overexpression, single lab\",\n      \"pmids\": [\"28968899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Cntnap4 functions as a cell-surface receptor for the secreted glycoprotein NELL-1 during osteogenesis; Cntnap4 and NELL-1 colocalize on the surface of osteogenic cells, display high-affinity binding, and Cntnap4 knockdown abrogates NELL-1-responsive Wnt and MAPK signaling as well as osteogenic effects.\",\n      \"method\": \"Colocalization assays, high-affinity binding assay, shRNA knockdown, Wnt1-Cre conditional Cntnap4 KO mice, signaling pathway analysis\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — ligand-receptor interaction validated by binding assay, knockdown, conditional KO, and signaling readouts with multiple orthogonal methods\",\n      \"pmids\": [\"29905970\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CNTNAP4 deficiency in dopaminergic neurons induces mitophagy, increases α-synuclein expression, reduces synaptic vesicles, and increases autophagosomes in the substantia nigra, leading to DA neuronal degeneration and parkinsonian motor deficits.\",\n      \"method\": \"shRNA knockdown in MN9D cell line, AAV-mediated SN-specific knockdown, CNTNAP4 KO mice, Western blotting, immunohistochemistry, transmission electron microscopy, RNA sequencing\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple in vitro and in vivo models with defined cellular phenotypes and mechanistic readouts, single lab\",\n      \"pmids\": [\"32194851\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cntnap4 knockout reduces GABAergic transmission and GABA receptor expression specifically in the basolateral amygdala (but not prefrontal cortex), contributing to impaired fear conditioning; L. reuteri treatment rescues both GABAergic transmission and fear memory in Cntnap4-/- mice.\",\n      \"method\": \"Electrophysiological recording, RNA-sequencing, Cntnap4-/- mice, L. reuteri supplementation and fecal microbiota transplantation\",\n      \"journal\": \"EBioMedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — electrophysiology plus genetic KO and functional rescue, single lab\",\n      \"pmids\": [\"36395738\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Cntnap4 deficiency exacerbates α-synuclein pathology via an astrocyte-microglia complement crosstalk: α-synuclein from damaged DA neurons stimulates astrocytes to release complement C3, which activates microglial C3aR, triggering microglia to secrete C1q and pro-inflammatory cytokines, further driving DA neuron death.\",\n      \"method\": \"AAV-mediated α-synuclein overexpression in Cntnap4 heterozygous KO mice, A53T transgenic mice with AAV-Cntnap4 shRNA, microglial depletion, targeted delivery of C3aR antagonist SB290157\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic and pharmacological interventions define pathway, single lab\",\n      \"pmids\": [\"37087484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CNTNAP4 acts downstream of NELL-1 signaling in osteosarcoma; CRISPR/Cas9 deletion of CNTNAP4 reduces tumor growth, angiogenesis, and metastasis, phenocopying NELL-1 KO, and abolishes NELL-1 responsiveness; CNTNAP4 KO reduces MAPK/ERK signaling, rescued by ERK1/2 agonist isoproterenol.\",\n      \"method\": \"CRISPR/Cas9 KO in OS cells, in vivo tumor models, phospho-array, transcriptomics, ERK agonist rescue\",\n      \"journal\": \"NPJ precision oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — CRISPR KO with epistasis and signaling rescue, single lab\",\n      \"pmids\": [\"36599925\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"EBF3 transcription factor directly binds the CNTNAP4 promoter and activates CNTNAP4 transcription; CNTNAP4 knockdown abolishes the neuroprotective anti-apoptotic effect of EBF3 in dopaminergic neurons, placing CNTNAP4 downstream of EBF3 in a PD-relevant pathway.\",\n      \"method\": \"Luciferase reporter assay, chromatin immunoprecipitation (ChIP), DNA pull-down assay, shRNA knockdown, MPTP mouse model and MPP+-treated SH-SY5Y cells\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP, luciferase reporter, and DNA pull-down with functional rescue, single lab\",\n      \"pmids\": [\"38479556\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CNTNAP4 (Caspr4) is a presynaptic neurexin superfamily transmembrane protein that localizes to GABAergic interneuron and dopaminergic synapses, where it regulates GABA release by PV+ basket cells and dopamine release in the nucleus accumbens; it interacts via its cytoplasmic PDZ-binding tail with LNX2 and the CASK/Veli/Mint complex to control neural progenitor differentiation, interacts with GABAAR β2/3 subunits and GABARAP to regulate inhibitory receptor membrane levels, and serves as a cell-surface receptor for the secreted ligand NELL-1 that signals through Wnt and MAPK/ERK pathways in both neural and osteogenic contexts; its deficiency disrupts mitophagy and α-synuclein homeostasis in dopaminergic neurons and triggers complement-mediated astrocyte-microglia neuroinflammation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CNTNAP4 (Caspr4) is a neurexin superfamily transmembrane protein that functions as a presynaptic regulator of neurotransmitter release and as a cell-surface receptor for the secreted ligand NELL-1. In the brain, CNTNAP4 localizes to parvalbumin-positive GABAergic interneuron terminals where it controls GABAergic output, and its loss reduces inhibitory transmission in the cortex and basolateral amygdala while paradoxically augmenting dopaminergic release in the nucleus accumbens [PMID:24870235, PMID:36395738]; it also interacts with GABAAR β2/3 subunits and GABARAP to regulate inhibitory receptor surface levels [PMID:28968899]. CNTNAP4 signals through its cytoplasmic PDZ-binding domain by engaging the CASK/Veli/Mint complex and LNX2 to promote neural progenitor differentiation [PMID:12093160, PMID:25279559], and serves as a high-affinity receptor for NELL-1 to activate Wnt and MAPK/ERK pathways in both osteogenic and tumor contexts [PMID:29905970, PMID:36599925]. In dopaminergic neurons, CNTNAP4 deficiency triggers mitophagy, α-synuclein accumulation, and complement-mediated astrocyte–microglia neuroinflammation leading to neurodegeneration [PMID:32194851, PMID:37087484].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Establishing CNTNAP4 as a PDZ-interacting neurexin superfamily member resolved how this orphan transmembrane protein might couple to intracellular scaffolding, showing its cytoplasmic tail engages the CASK/Veli/Mint complex.\",\n      \"evidence\": \"PDZ domain interaction assays with recombinant proteins\",\n      \"pmids\": [\"12093160\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Binding shown by single method without reciprocal validation in neurons\",\n        \"Functional consequence of CASK/Veli/Mint interaction unknown\",\n        \"In vivo relevance of the PDZ interaction not tested\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrating that Cntnap4 is a presynaptic protein in PV+ interneurons whose deletion reduces GABAergic output and increases dopaminergic release established the first in vivo circuit-level function for CNTNAP4.\",\n      \"evidence\": \"Cntnap4 knockout mice with electrophysiology, immunohistochemistry, and pharmacological rescue\",\n      \"pmids\": [\"24870235\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular mechanism by which presynaptic CNTNAP4 controls vesicle release unresolved\",\n        \"Relationship between GABAergic deficit and dopaminergic phenotype only inferred\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identifying LNX2 as a PDZ-dependent partner that mediates CNTNAP4's pro-differentiation effect on neural progenitors revealed a developmental role beyond synaptic function.\",\n      \"evidence\": \"Co-immunoprecipitation, shRNA knockdown, C4ICD overexpression and rescue in mouse neural progenitor cells\",\n      \"pmids\": [\"25279559\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single lab; no independent replication\",\n        \"Downstream targets of LNX2-CNTNAP4 signaling in progenitors not identified\",\n        \"Whether this pathway operates in vivo during neurogenesis not confirmed\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showing that CNTNAP4 interacts with GABAAR β2/3 subunits and GABARAP to regulate receptor surface levels provided a postsynaptic mechanism complementing its known presynaptic role in GABAergic transmission.\",\n      \"evidence\": \"Co-immunoprecipitation, membrane fractionation Western blots, lentiviral knockdown/overexpression in vivo, electrophysiology in epilepsy model\",\n      \"pmids\": [\"28968899\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Presynaptic versus postsynaptic localization of this interaction not resolved\",\n        \"Stoichiometry and directness of CNTNAP4–GABAAR interaction not established by purified components\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identification of CNTNAP4 as the high-affinity cell-surface receptor for NELL-1 in osteogenesis expanded CNTNAP4 function beyond the nervous system and linked it to Wnt and MAPK/ERK signaling.\",\n      \"evidence\": \"High-affinity binding assay, colocalization, shRNA knockdown, Wnt1-Cre conditional Cntnap4 KO mice, signaling pathway analysis\",\n      \"pmids\": [\"29905970\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether NELL-1–CNTNAP4 signaling operates similarly at neural synapses unknown\",\n        \"Structural basis of NELL-1–CNTNAP4 binding not determined\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Linking CNTNAP4 deficiency to mitophagy, α-synuclein accumulation, and dopaminergic neurodegeneration established a cell-autonomous neuroprotective role in the substantia nigra.\",\n      \"evidence\": \"shRNA knockdown in MN9D cells, AAV-mediated SN knockdown, Cntnap4 KO mice, TEM, Western blotting, RNA-seq\",\n      \"pmids\": [\"32194851\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct molecular target through which CNTNAP4 suppresses mitophagy and α-synuclein not identified\",\n        \"Single lab; awaits independent replication\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrating region-specific loss of GABAergic transmission in the basolateral amygdala (but not PFC) of Cntnap4 KO mice, with rescue by L. reuteri, revealed circuit-selective vulnerability and a gut-brain interaction.\",\n      \"evidence\": \"Electrophysiology, RNA-seq, Cntnap4−/− mice, probiotic and fecal transplant rescue\",\n      \"pmids\": [\"36395738\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which gut bacteria restore amygdala GABAergic signaling not elucidated\",\n        \"Whether probiotic rescue is CNTNAP4-specific or a general GABAergic effect unknown\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Elucidating a complement-mediated astrocyte-microglia neuroinflammatory cascade downstream of CNTNAP4 deficiency and α-synuclein pathology clarified the non-cell-autonomous neurodegeneration mechanism.\",\n      \"evidence\": \"AAV α-synuclein overexpression in Cntnap4 heterozygous KO and A53T transgenic mice, microglial depletion, C3aR antagonist SB290157\",\n      \"pmids\": [\"37087484\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"How CNTNAP4 loss increases α-synuclein release from neurons remains unclear\",\n        \"Single lab; pathway steps not fully validated with genetic complement KOs\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"CRISPR deletion of CNTNAP4 in osteosarcoma phenocopied NELL-1 KO and abolished NELL-1-driven MAPK/ERK signaling, confirming epistatic receptor function in a tumor context.\",\n      \"evidence\": \"CRISPR/Cas9 KO in OS cells, in vivo xenograft, phospho-array, ERK agonist rescue\",\n      \"pmids\": [\"36599925\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether CNTNAP4 has NELL-1-independent oncogenic roles not addressed\",\n        \"Applicability beyond osteosarcoma not tested\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identification of EBF3 as a direct transcriptional activator of CNTNAP4, whose neuroprotective effect requires CNTNAP4, placed CNTNAP4 within a defined transcriptional hierarchy in dopaminergic neuron survival.\",\n      \"evidence\": \"ChIP, luciferase reporter, DNA pull-down, shRNA knockdown, MPTP and MPP+ models\",\n      \"pmids\": [\"38479556\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single lab; no independent confirmation of EBF3–CNTNAP4 axis\",\n        \"How CNTNAP4 mediates anti-apoptotic signaling downstream of EBF3 is unknown\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct molecular mechanism by which CNTNAP4 controls presynaptic neurotransmitter vesicle release, and whether NELL-1 signaling through CNTNAP4 operates at synapses, remain central unresolved questions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of CNTNAP4 or its complexes exists\",\n        \"Presynaptic vesicle release mechanism not defined at the molecular level\",\n        \"Whether NELL-1–CNTNAP4 signaling occurs in neurons is untested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [4, 8]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 4]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [1, 3, 6]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 8]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [5, 9]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [\n      \"CASK/Veli/Mint complex\"\n    ],\n    \"partners\": [\n      \"NELL1\",\n      \"LNX2\",\n      \"CASK\",\n      \"GABRB2\",\n      \"GABRB3\",\n      \"GABARAP\",\n      \"EBF3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}