{"gene":"CNTNAP4","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2002,"finding":"Caspr4 (CNTNAP4) cytoplasmic tail interacts with PDZ domain-containing proteins of the CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex, as demonstrated by direct binding assays.","method":"PDZ domain interaction assay (pull-down/binding experiments with PDZ domain proteins)","journal":"Molecular and cellular neurosciences","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct binding assay replicated for multiple family members; single lab, one primary method","pmids":["12093160"],"is_preprint":false},{"year":2014,"finding":"Cntnap4 is localized presynaptically in cortical parvalbumin-positive GABAergic basket cells; loss of Cntnap4 reduces the output (GABA release) of these interneurons, establishing a presynaptic role in GABAergic transmission.","method":"Immunohistochemistry for presynaptic localization; electrophysiology and Cntnap4 knockout mice for functional output measurement","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal localization and functional electrophysiology in knockout mice, published in Nature with multiple orthogonal methods","pmids":["24870235"],"is_preprint":false},{"year":2014,"finding":"Loss of Cntnap4 augments dopaminergic release in the nucleus accumbens from midbrain dopaminergic neurons, indicating Cntnap4 normally suppresses dopamine release at these synapses.","method":"In vivo dopamine release measurements (fast-scan cyclic voltammetry) in Cntnap4 knockout mice","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct neurotransmitter release measurement in knockout mice, multiple orthogonal methods in a single rigorous study","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-mediated promotion of neuronal differentiation in neural progenitor cells (NPCs), as the intracellular domain of Caspr4 (C4ICD) rescues neuronal differentiation deficits caused by Caspr4 knockdown only when LNX2 is present.","method":"Co-immunoprecipitation, rescue experiments with C4ICD and LNX2 overexpression/knockdown in cultured mouse NPCs","journal":"Stem cells and development","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP plus functional rescue experiments in cell culture, single lab, two complementary methods","pmids":["25279559"],"is_preprint":false},{"year":2014,"finding":"Caspr4 knockdown in neural progenitor cells (NPCs) enhances NPC proliferation and decreases neuronal differentiation; overexpression has the opposite effect, establishing Caspr4 as a regulator of NPC fate.","method":"shRNA knockdown and overexpression in cultured mouse SVZ-derived NPCs, with proliferation and differentiation assays","journal":"Stem cells and development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function and gain-of-function with defined cellular phenotype, single lab","pmids":["25279559"],"is_preprint":false},{"year":2018,"finding":"CNTNAP4 regulates membrane expression of GABA-A receptor β2/3 subunits (GABAARβ2/3): knockdown or overexpression of CNTNAP4 alters surface GABAARβ2/3 levels without affecting total protein, and CNTNAP4 physically interacts with GABAARβ2/3 and GABARAP in hippocampus of epileptic mice.","method":"Co-immunoprecipitation, surface vs. total protein Western blotting, lentivirus-mediated knockdown/overexpression in mice","journal":"Cerebral cortex","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP plus surface protein analysis and in vivo manipulation, single lab, two orthogonal methods","pmids":["28968899"],"is_preprint":false},{"year":2018,"finding":"Cntnap4 functions as a cell-surface receptor for the secreted glycoprotein NELL-1 in osteogenic cells: Nell-1 and Cntnap4 co-localize on the surface of osteogenic-committed cells, show high-affinity binding, and Cntnap4 knockdown abrogates Nell-1-responsive Wnt and MAPK signaling as well as osteogenic effects.","method":"Co-localization (immunofluorescence), binding affinity assay, Cntnap4 knockdown with signaling readouts (Western blot for Wnt/MAPK), Cntnap4 conditional knockout mouse model","journal":"Journal of bone and mineral research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (co-localization, binding assay, knockdown with pathway readout, in vivo KO model) in a single rigorous study","pmids":["29905970"],"is_preprint":false},{"year":2020,"finding":"CNTNAP4 knockdown in dopaminergic MN9D cells and in substantia nigra DA neurons in vivo induces mitophagy, increases α-synuclein expression, reduces synaptic vesicles, and increases autophagosomes, indicating CNTNAP4 normally suppresses these pathological processes in DA neurons.","method":"Western blotting, immunocytochemistry, RNA sequencing, transmission electron microscopy, AAV-shRNA in vivo knockdown, CNTNAP4 knockout mice","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal in vitro and in vivo methods in a single lab","pmids":["32194851"],"is_preprint":false},{"year":2022,"finding":"Cntnap4 deficiency reduces GABAergic transmission specifically in the basolateral amygdala (BLA) but not the prefrontal cortex, as assessed by electrophysiological recording in Cntnap4 knockout mice, with associated impairment of tone-cue fear conditioning.","method":"Electrophysiological recording (mIPSC/eIPSC) in Cntnap4-/- mice, behavioral fear conditioning assays","journal":"EBioMedicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct electrophysiology in knockout mice with region-specific dissection, single lab","pmids":["36395738"],"is_preprint":false},{"year":2023,"finding":"Cntnap4 deficiency exacerbates α-synuclein pathology via an astrocyte-microglia crosstalk mechanism: damaged DA neurons stimulate 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 partial knockout and shRNA knockdown mice; in vivo microglial depletion and C3aR antagonist (SB290157) delivery; immunohistochemistry and behavioral tests","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway dissected with genetic and pharmacological interventions in vivo, single lab","pmids":["37087484"],"is_preprint":false},{"year":2023,"finding":"CNTNAP4 deletion in osteosarcoma cells reduces MAPK/ERK signaling cascade activity, and the ERK1/2 agonist isoproterenol restores cell attachment, migration, and invasion in CNTNAP4 KO tumor cells, placing CNTNAP4 upstream of MAPK/ERK in this context.","method":"CRISPR/Cas9 knockout, phospho-protein array, transcriptomic analysis, pharmacological ERK1/2 rescue","journal":"NPJ precision oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with phospho-array and rescue, single lab, multiple methods","pmids":["36599925"],"is_preprint":false},{"year":2024,"finding":"EBF3 (Early B Cell Factor 3) directly binds the CNTNAP4 promoter and activates CNTNAP4 transcription, as shown by luciferase reporter, ChIP, and DNA pull-down assays; CNTNAP4 knockdown abolishes the neuroprotective effect of EBF3 in a PD cell model.","method":"Luciferase reporter assay, chromatin immunoprecipitation (ChIP), DNA pull-down assay, siRNA knockdown epistasis","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — three orthogonal methods confirming direct promoter binding plus epistasis experiment, single lab","pmids":["38479556"],"is_preprint":false}],"current_model":"CNTNAP4 (Caspr4) is a presynaptic neurexin superfamily transmembrane protein that promotes GABAergic output from cortical parvalbumin interneurons and restrains dopamine release in the nucleus accumbens; its cytoplasmic tail engages PDZ domain proteins (CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex and LNX2) to regulate neural progenitor cell differentiation, while its extracellular domain acts as a high-affinity receptor for the secreted glycoprotein NELL-1 coupling to Wnt and MAPK/ERK signaling in both osteogenic and tumor contexts; additionally, CNTNAP4 regulates surface levels of GABA-A receptor β2/3 subunits through interaction with GABAARβ2/3 and GABARAP, and in dopaminergic neurons it normally suppresses mitophagy and α-synuclein accumulation, with its transcription directly activated by the EBF3 transcription factor."},"narrative":{"mechanistic_narrative":"CNTNAP4 (Caspr4) is a neurexin-superfamily transmembrane protein that tunes synaptic output and acts as a cell-surface signaling receptor in both neural and non-neural contexts [PMID:24870235, PMID:29905970]. In the brain it localizes presynaptically in cortical parvalbumin-positive GABAergic basket cells, where its loss reduces GABA release, while in midbrain dopaminergic projections to the nucleus accumbens it normally suppresses dopamine release [PMID:24870235]; region-specific dissection shows it sustains GABAergic transmission in the basolateral amygdala in support of fear conditioning [PMID:36395738]. CNTNAP4 controls inhibitory tone in part by regulating the surface expression of GABA-A receptor β2/3 subunits through physical interaction with GABAARβ2/3 and GABARAP [PMID:28968899]. Its cytoplasmic tail engages PDZ-domain scaffolds of the CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex and binds LNX2, and this PDZ-dependent LNX2 interaction drives neuronal differentiation of neural progenitor cells at the expense of proliferation [PMID:12093160, PMID:25279559]. Its extracellular domain serves as a high-affinity receptor for the secreted glycoprotein NELL-1, coupling to Wnt and MAPK/ERK signaling to promote osteogenesis, and the same MAPK/ERK axis supports attachment, migration, and invasion in osteosarcoma cells [PMID:29905970, PMID:36599925]. In dopaminergic neurons CNTNAP4 restrains mitophagy and α-synuclein accumulation, and its deficiency exacerbates α-synuclein pathology through an astrocyte-microglia complement (C3–C3aR–C1q) inflammatory cascade; CNTNAP4 transcription is directly activated by EBF3, which acts neuroprotectively in Parkinson's disease cell models through CNTNAP4 [PMID:32194851, PMID:37087484, PMID:38479556].","teleology":[{"year":2002,"claim":"Established the first molecular partners of CNTNAP4 by showing its cytoplasmic tail docks onto a defined PDZ-scaffold complex, implying a role in organizing membrane signaling/adhesion assemblies.","evidence":"PDZ domain binding/pull-down assays with CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex proteins","pmids":["12093160"],"confidence":"Medium","gaps":["Single lab, single binding method without in vivo validation","Functional consequence of the scaffold interaction not addressed","Direct vs. bridged binding within the complex not resolved"]},{"year":2014,"claim":"Defined the in vivo neural role of CNTNAP4, answering what circuit function it serves: it acts presynaptically to support GABA release from parvalbumin interneurons and to restrain dopamine release, linking it to inhibitory and dopaminergic balance.","evidence":"Immunohistochemistry, electrophysiology, and fast-scan cyclic voltammetry in Cntnap4 knockout mice","pmids":["24870235"],"confidence":"High","gaps":["Molecular mechanism by which CNTNAP4 controls release is not defined","Presynaptic binding partners mediating these effects unidentified","Opposite directional effects in GABA vs. dopamine synapses unexplained mechanistically"]},{"year":2014,"claim":"Connected CNTNAP4 to neural progenitor fate, showing its intracellular domain promotes differentiation over proliferation through a PDZ-dependent LNX2 interaction.","evidence":"Co-immunoprecipitation and knockdown/overexpression rescue experiments in cultured mouse SVZ-derived NPCs","pmids":["25279559"],"confidence":"Medium","gaps":["Downstream effectors of the LNX2 interaction unknown","Cell-culture only; in vivo NPC role not tested","Relationship to the synaptic role of CNTNAP4 unclear"]},{"year":2018,"claim":"Provided a molecular handle on how CNTNAP4 controls inhibitory transmission, showing it sets surface GABA-A receptor β2/3 levels via interaction with the receptor and GABARAP.","evidence":"Co-IP, surface vs. total Western blotting, and lentiviral knockdown/overexpression in epileptic mouse hippocampus","pmids":["28968899"],"confidence":"Medium","gaps":["Whether interaction is direct or scaffold-mediated unresolved","Trafficking step regulated (insertion vs. retrieval) not pinpointed","Single lab, two methods"]},{"year":2018,"claim":"Revealed an unexpected non-neural function, identifying CNTNAP4 as a high-affinity cell-surface receptor for NELL-1 that couples to Wnt and MAPK signaling to drive osteogenesis.","evidence":"Co-localization, binding affinity assay, knockdown signaling readouts, and conditional knockout mouse in osteogenic cells","pmids":["29905970"],"confidence":"High","gaps":["Structural basis of NELL-1 binding not defined","How receptor engagement transduces to Wnt/MAPK mechanistically unknown","Whether NELL-1 acts on CNTNAP4 in neurons untested"]},{"year":2020,"claim":"Implicated CNTNAP4 in dopaminergic neuron homeostasis, showing its loss triggers mitophagy and α-synuclein accumulation, framing it as a protective factor in Parkinson-relevant pathology.","evidence":"Western blot, immunocytochemistry, RNA-seq, electron microscopy, AAV-shRNA in vivo and knockout mice in DA neurons","pmids":["32194851"],"confidence":"Medium","gaps":["Direct molecular trigger of mitophagy suppression not identified","Link between membrane receptor activity and autophagy regulation unclear","Single lab"]},{"year":2022,"claim":"Refined CNTNAP4's circuit specificity, showing its GABAergic role is region-selective (basolateral amygdala, not prefrontal cortex) and behaviorally relevant to fear learning.","evidence":"mIPSC/eIPSC electrophysiology in Cntnap4 knockout mice with fear conditioning behavior","pmids":["36395738"],"confidence":"Medium","gaps":["Basis of regional selectivity not explained","Cell-type identity of affected interneurons in BLA not fully defined","Single lab"]},{"year":2023,"claim":"Extended the MAPK/ERK receptor function into cancer, placing CNTNAP4 upstream of ERK1/2 in osteosarcoma cell adhesion, migration, and invasion.","evidence":"CRISPR/Cas9 knockout, phospho-protein array, transcriptomics, and pharmacological ERK1/2 rescue in osteosarcoma cells","pmids":["36599925"],"confidence":"Medium","gaps":["Ligand driving ERK activation in tumor cells not identified","Direct receptor-to-ERK coupling mechanism unresolved","In vivo tumor relevance not established"]},{"year":2023,"claim":"Mapped the non-cell-autonomous consequences of CNTNAP4 loss in PD, defining an astrocyte-microglia complement cascade (C3–C3aR–C1q) that amplifies α-synuclein-driven neurodegeneration.","evidence":"AAV α-synuclein overexpression in Cntnap4 partial-KO/knockdown mice with microglial depletion and C3aR antagonist intervention","pmids":["37087484"],"confidence":"Medium","gaps":["How neuronal CNTNAP4 loss initiates astrocyte C3 release unknown","Direct vs. indirect role of CNTNAP4 in glial activation unresolved","Single lab"]},{"year":2024,"claim":"Identified an upstream transcriptional regulator, showing EBF3 directly activates CNTNAP4 and requires it for neuroprotection, embedding CNTNAP4 in a defined gene-regulatory axis.","evidence":"Luciferase reporter, ChIP, DNA pull-down, and siRNA epistasis in a PD cell model","pmids":["38479556"],"confidence":"Medium","gaps":["In vivo confirmation of the EBF3–CNTNAP4 axis lacking","Whether EBF3 regulates CNTNAP4 in non-PD contexts untested","Single lab"]},{"year":null,"claim":"How CNTNAP4 mechanistically transduces extracellular signals across its membrane and reconciles its receptor function with its presynaptic and progenitor roles remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the CNTNAP4 ectodomain or its NELL-1 complex","Mechanism linking surface receptor engagement to intracellular PDZ-scaffold and ERK/Wnt outputs not defined","Whether neural and skeletal/tumor functions share a common signaling logic is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[6]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[6,10]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,3,5]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,6]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[1,2,8]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[6,10]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[3,4,6]}],"complexes":["CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex"],"partners":["CASK","LIN7","APBA1","LNX2","GABRB2","GABRB3","GABARAP","NELL1"],"other_free_text":[]}},"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":149,"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":80,"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":38,"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":31,"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":"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":27,"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":"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":"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":"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":"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":6,"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":"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":4,"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":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10013,"output_tokens":2915,"usd":0.036882,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10287,"output_tokens":4046,"usd":0.076292,"stage2_stop_reason":"end_turn"},"total_usd":0.113174,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","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, as demonstrated by direct binding assays.\",\n      \"method\": \"PDZ domain interaction assay (pull-down/binding experiments with PDZ domain proteins)\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct binding assay replicated for multiple family members; single lab, one primary 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 the output (GABA release) of these interneurons, establishing a presynaptic role in GABAergic transmission.\",\n      \"method\": \"Immunohistochemistry for presynaptic localization; electrophysiology and Cntnap4 knockout mice for functional output measurement\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal localization and functional electrophysiology in knockout mice, published in Nature with multiple orthogonal methods\",\n      \"pmids\": [\"24870235\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Loss of Cntnap4 augments dopaminergic release in the nucleus accumbens from midbrain dopaminergic neurons, indicating Cntnap4 normally suppresses dopamine release at these synapses.\",\n      \"method\": \"In vivo dopamine release measurements (fast-scan cyclic voltammetry) in Cntnap4 knockout mice\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct neurotransmitter release measurement in knockout mice, multiple orthogonal methods in a single rigorous study\",\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-mediated promotion of neuronal differentiation in neural progenitor cells (NPCs), as the intracellular domain of Caspr4 (C4ICD) rescues neuronal differentiation deficits caused by Caspr4 knockdown only when LNX2 is present.\",\n      \"method\": \"Co-immunoprecipitation, rescue experiments with C4ICD and LNX2 overexpression/knockdown in cultured mouse NPCs\",\n      \"journal\": \"Stem cells and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP plus functional rescue experiments in cell culture, single lab, two complementary methods\",\n      \"pmids\": [\"25279559\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Caspr4 knockdown in neural progenitor cells (NPCs) enhances NPC proliferation and decreases neuronal differentiation; overexpression has the opposite effect, establishing Caspr4 as a regulator of NPC fate.\",\n      \"method\": \"shRNA knockdown and overexpression in cultured mouse SVZ-derived NPCs, with proliferation and differentiation assays\",\n      \"journal\": \"Stem cells and development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function and gain-of-function with defined cellular phenotype, single lab\",\n      \"pmids\": [\"25279559\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CNTNAP4 regulates membrane expression of GABA-A receptor β2/3 subunits (GABAARβ2/3): knockdown or overexpression of CNTNAP4 alters surface GABAARβ2/3 levels without affecting total protein, and CNTNAP4 physically interacts with GABAARβ2/3 and GABARAP in hippocampus of epileptic mice.\",\n      \"method\": \"Co-immunoprecipitation, surface vs. total protein Western blotting, lentivirus-mediated knockdown/overexpression in mice\",\n      \"journal\": \"Cerebral cortex\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP plus surface protein analysis and in vivo manipulation, single lab, two orthogonal methods\",\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 in osteogenic cells: Nell-1 and Cntnap4 co-localize on the surface of osteogenic-committed cells, show high-affinity binding, and Cntnap4 knockdown abrogates Nell-1-responsive Wnt and MAPK signaling as well as osteogenic effects.\",\n      \"method\": \"Co-localization (immunofluorescence), binding affinity assay, Cntnap4 knockdown with signaling readouts (Western blot for Wnt/MAPK), Cntnap4 conditional knockout mouse model\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (co-localization, binding assay, knockdown with pathway readout, in vivo KO model) in a single rigorous study\",\n      \"pmids\": [\"29905970\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CNTNAP4 knockdown in dopaminergic MN9D cells and in substantia nigra DA neurons in vivo induces mitophagy, increases α-synuclein expression, reduces synaptic vesicles, and increases autophagosomes, indicating CNTNAP4 normally suppresses these pathological processes in DA neurons.\",\n      \"method\": \"Western blotting, immunocytochemistry, RNA sequencing, transmission electron microscopy, AAV-shRNA in vivo knockdown, CNTNAP4 knockout mice\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal in vitro and in vivo methods in a single lab\",\n      \"pmids\": [\"32194851\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cntnap4 deficiency reduces GABAergic transmission specifically in the basolateral amygdala (BLA) but not the prefrontal cortex, as assessed by electrophysiological recording in Cntnap4 knockout mice, with associated impairment of tone-cue fear conditioning.\",\n      \"method\": \"Electrophysiological recording (mIPSC/eIPSC) in Cntnap4-/- mice, behavioral fear conditioning assays\",\n      \"journal\": \"EBioMedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct electrophysiology in knockout mice with region-specific dissection, 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 crosstalk mechanism: damaged DA neurons stimulate 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 partial knockout and shRNA knockdown mice; in vivo microglial depletion and C3aR antagonist (SB290157) delivery; immunohistochemistry and behavioral tests\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway dissected with genetic and pharmacological interventions in vivo, single lab\",\n      \"pmids\": [\"37087484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CNTNAP4 deletion in osteosarcoma cells reduces MAPK/ERK signaling cascade activity, and the ERK1/2 agonist isoproterenol restores cell attachment, migration, and invasion in CNTNAP4 KO tumor cells, placing CNTNAP4 upstream of MAPK/ERK in this context.\",\n      \"method\": \"CRISPR/Cas9 knockout, phospho-protein array, transcriptomic analysis, pharmacological ERK1/2 rescue\",\n      \"journal\": \"NPJ precision oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with phospho-array and rescue, single lab, multiple methods\",\n      \"pmids\": [\"36599925\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"EBF3 (Early B Cell Factor 3) directly binds the CNTNAP4 promoter and activates CNTNAP4 transcription, as shown by luciferase reporter, ChIP, and DNA pull-down assays; CNTNAP4 knockdown abolishes the neuroprotective effect of EBF3 in a PD cell model.\",\n      \"method\": \"Luciferase reporter assay, chromatin immunoprecipitation (ChIP), DNA pull-down assay, siRNA knockdown epistasis\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — three orthogonal methods confirming direct promoter binding plus epistasis experiment, single lab\",\n      \"pmids\": [\"38479556\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CNTNAP4 (Caspr4) is a presynaptic neurexin superfamily transmembrane protein that promotes GABAergic output from cortical parvalbumin interneurons and restrains dopamine release in the nucleus accumbens; its cytoplasmic tail engages PDZ domain proteins (CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex and LNX2) to regulate neural progenitor cell differentiation, while its extracellular domain acts as a high-affinity receptor for the secreted glycoprotein NELL-1 coupling to Wnt and MAPK/ERK signaling in both osteogenic and tumor contexts; additionally, CNTNAP4 regulates surface levels of GABA-A receptor β2/3 subunits through interaction with GABAARβ2/3 and GABARAP, and in dopaminergic neurons it normally suppresses mitophagy and α-synuclein accumulation, with its transcription directly activated by the EBF3 transcription factor.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CNTNAP4 (Caspr4) is a neurexin-superfamily transmembrane protein that tunes synaptic output and acts as a cell-surface signaling receptor in both neural and non-neural contexts [#1, #6]. In the brain it localizes presynaptically in cortical parvalbumin-positive GABAergic basket cells, where its loss reduces GABA release, while in midbrain dopaminergic projections to the nucleus accumbens it normally suppresses dopamine release [#1, #2]; region-specific dissection shows it sustains GABAergic transmission in the basolateral amygdala in support of fear conditioning [#8]. CNTNAP4 controls inhibitory tone in part by regulating the surface expression of GABA-A receptor \\u03b22/3 subunits through physical interaction with GABAAR\\u03b22/3 and GABARAP [#5]. Its cytoplasmic tail engages PDZ-domain scaffolds of the CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex and binds LNX2, and this PDZ-dependent LNX2 interaction drives neuronal differentiation of neural progenitor cells at the expense of proliferation [#0, #3, #4]. Its extracellular domain serves as a high-affinity receptor for the secreted glycoprotein NELL-1, coupling to Wnt and MAPK/ERK signaling to promote osteogenesis, and the same MAPK/ERK axis supports attachment, migration, and invasion in osteosarcoma cells [#6, #10]. In dopaminergic neurons CNTNAP4 restrains mitophagy and \\u03b1-synuclein accumulation, and its deficiency exacerbates \\u03b1-synuclein pathology through an astrocyte-microglia complement (C3\\u2013C3aR\\u2013C1q) inflammatory cascade; CNTNAP4 transcription is directly activated by EBF3, which acts neuroprotectively in Parkinson's disease cell models through CNTNAP4 [#7, #9, #11].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established the first molecular partners of CNTNAP4 by showing its cytoplasmic tail docks onto a defined PDZ-scaffold complex, implying a role in organizing membrane signaling/adhesion assemblies.\",\n      \"evidence\": \"PDZ domain binding/pull-down assays with CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex proteins\",\n      \"pmids\": [\"12093160\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab, single binding method without in vivo validation\", \"Functional consequence of the scaffold interaction not addressed\", \"Direct vs. bridged binding within the complex not resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined the in vivo neural role of CNTNAP4, answering what circuit function it serves: it acts presynaptically to support GABA release from parvalbumin interneurons and to restrain dopamine release, linking it to inhibitory and dopaminergic balance.\",\n      \"evidence\": \"Immunohistochemistry, electrophysiology, and fast-scan cyclic voltammetry in Cntnap4 knockout mice\",\n      \"pmids\": [\"24870235\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular mechanism by which CNTNAP4 controls release is not defined\", \"Presynaptic binding partners mediating these effects unidentified\", \"Opposite directional effects in GABA vs. dopamine synapses unexplained mechanistically\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Connected CNTNAP4 to neural progenitor fate, showing its intracellular domain promotes differentiation over proliferation through a PDZ-dependent LNX2 interaction.\",\n      \"evidence\": \"Co-immunoprecipitation and knockdown/overexpression rescue experiments in cultured mouse SVZ-derived NPCs\",\n      \"pmids\": [\"25279559\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Downstream effectors of the LNX2 interaction unknown\", \"Cell-culture only; in vivo NPC role not tested\", \"Relationship to the synaptic role of CNTNAP4 unclear\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Provided a molecular handle on how CNTNAP4 controls inhibitory transmission, showing it sets surface GABA-A receptor \\u03b22/3 levels via interaction with the receptor and GABARAP.\",\n      \"evidence\": \"Co-IP, surface vs. total Western blotting, and lentiviral knockdown/overexpression in epileptic mouse hippocampus\",\n      \"pmids\": [\"28968899\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Whether interaction is direct or scaffold-mediated unresolved\", \"Trafficking step regulated (insertion vs. retrieval) not pinpointed\", \"Single lab, two methods\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Revealed an unexpected non-neural function, identifying CNTNAP4 as a high-affinity cell-surface receptor for NELL-1 that couples to Wnt and MAPK signaling to drive osteogenesis.\",\n      \"evidence\": \"Co-localization, binding affinity assay, knockdown signaling readouts, and conditional knockout mouse in osteogenic cells\",\n      \"pmids\": [\"29905970\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structural basis of NELL-1 binding not defined\", \"How receptor engagement transduces to Wnt/MAPK mechanistically unknown\", \"Whether NELL-1 acts on CNTNAP4 in neurons untested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Implicated CNTNAP4 in dopaminergic neuron homeostasis, showing its loss triggers mitophagy and \\u03b1-synuclein accumulation, framing it as a protective factor in Parkinson-relevant pathology.\",\n      \"evidence\": \"Western blot, immunocytochemistry, RNA-seq, electron microscopy, AAV-shRNA in vivo and knockout mice in DA neurons\",\n      \"pmids\": [\"32194851\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Direct molecular trigger of mitophagy suppression not identified\", \"Link between membrane receptor activity and autophagy regulation unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Refined CNTNAP4's circuit specificity, showing its GABAergic role is region-selective (basolateral amygdala, not prefrontal cortex) and behaviorally relevant to fear learning.\",\n      \"evidence\": \"mIPSC/eIPSC electrophysiology in Cntnap4 knockout mice with fear conditioning behavior\",\n      \"pmids\": [\"36395738\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Basis of regional selectivity not explained\", \"Cell-type identity of affected interneurons in BLA not fully defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended the MAPK/ERK receptor function into cancer, placing CNTNAP4 upstream of ERK1/2 in osteosarcoma cell adhesion, migration, and invasion.\",\n      \"evidence\": \"CRISPR/Cas9 knockout, phospho-protein array, transcriptomics, and pharmacological ERK1/2 rescue in osteosarcoma cells\",\n      \"pmids\": [\"36599925\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Ligand driving ERK activation in tumor cells not identified\", \"Direct receptor-to-ERK coupling mechanism unresolved\", \"In vivo tumor relevance not established\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mapped the non-cell-autonomous consequences of CNTNAP4 loss in PD, defining an astrocyte-microglia complement cascade (C3\\u2013C3aR\\u2013C1q) that amplifies \\u03b1-synuclein-driven neurodegeneration.\",\n      \"evidence\": \"AAV \\u03b1-synuclein overexpression in Cntnap4 partial-KO/knockdown mice with microglial depletion and C3aR antagonist intervention\",\n      \"pmids\": [\"37087484\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How neuronal CNTNAP4 loss initiates astrocyte C3 release unknown\", \"Direct vs. indirect role of CNTNAP4 in glial activation unresolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified an upstream transcriptional regulator, showing EBF3 directly activates CNTNAP4 and requires it for neuroprotection, embedding CNTNAP4 in a defined gene-regulatory axis.\",\n      \"evidence\": \"Luciferase reporter, ChIP, DNA pull-down, and siRNA epistasis in a PD cell model\",\n      \"pmids\": [\"38479556\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"In vivo confirmation of the EBF3\\u2013CNTNAP4 axis lacking\", \"Whether EBF3 regulates CNTNAP4 in non-PD contexts untested\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CNTNAP4 mechanistically transduces extracellular signals across its membrane and reconciles its receptor function with its presynaptic and progenitor roles remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No structural model of the CNTNAP4 ectodomain or its NELL-1 complex\", \"Mechanism linking surface receptor engagement to intracellular PDZ-scaffold and ERK/Wnt outputs not defined\", \"Whether neural and skeletal/tumor functions share a common signaling logic is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [6, 10]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 3, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [1, 2, 8]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [6, 10]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [3, 4, 6]}\n    ],\n    \"complexes\": [\"CASK/Lin2-Veli/Lin7-Mint1/Lin10 complex\"],\n    \"partners\": [\"CASK\", \"LIN7\", \"APBA1\", \"LNX2\", \"GABRB2\", \"GABRB3\", \"GABARAP\", \"NELL1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}