{"gene":"DLGAP2","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2014,"finding":"Dlgap2 knockout mice show reduced receptor and scaffold protein levels in cortical synapses, lower dendritic spine density, decreased peak amplitude of miniature excitatory postsynaptic currents, and ultrastructural deficits of postsynaptic density in the orbitofrontal cortex, demonstrating DLGAP2 is required for maintaining proper synaptic composition and function at excitatory synapses.","method":"Dlgap2 knockout mice (Cre-loxP), cortical synaptosomal fractionation, Golgi-Cox staining, whole-cell patch-clamp electrophysiology, transmission electron microscopy","journal":"Molecular autism","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (biochemistry, electrophysiology, EM, morphology) in a clean genetic KO model with specific cellular phenotypes","pmids":["25071926"],"is_preprint":false},{"year":2017,"finding":"DLGAP2 protein is a component of the postsynaptic density scaffold complex, where it associates with PSD-95/SAP90, and loss-of-function mutations in Dlgap2 lead to deficits in associative learning and reaction times in mice, placing it within the PSD-95 protein complex as a regulator of excitatory synapse signaling underlying cognition.","method":"Loss-of-function mutant mice (Dlgap2 KO), touchscreen-based cognitive testing (associative learning, cognitive flexibility, reaction times)","journal":"Genes, brain, and behavior","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined cognitive phenotype, but mechanistic pathway placement inferred from genetic context rather than direct biochemical reconstitution","pmids":["33347690"],"is_preprint":false},{"year":2026,"finding":"DLGAP2 directly interacts with Intersectin-1 (ITSN1) at the postsynaptic density; upon Dlgap2 deficiency, ITSN1 undergoes ubiquitin-mediated proteasomal degradation, disrupting synaptic organization and causing autism-like behaviors, defining a Dlgap2-Itsn1 regulatory axis.","method":"Proteomics of postsynaptic density fraction after Dlgap2 knockdown, co-immunoprecipitation (interaction), ubiquitin-mediated degradation assay, mouse behavioral assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — proteomics plus interaction and degradation assays in single lab; abstract does not detail full reconstitution or mutagenesis","pmids":["41673270"],"is_preprint":false},{"year":2019,"finding":"DNA methylation within a defined region of DLGAP2 (DMR-DLGAP2) is genotype-dependent, allele-specific, and regulates DLGAP2 expression in vitro; Dlgap2-deficient mice show reduced alcohol consumption compared to wild-type controls, placing DLGAP2 in a pathway linking epigenetic regulation to alcohol reward processing.","method":"Epigenome-wide association of human brain DNA methylation, in vitro methylation-expression reporter assay, Dlgap2 knockout mouse alcohol consumption assay","journal":"Molecular psychiatry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro functional methylation assay combined with KO mouse behavioral phenotype; single lab, two orthogonal methods","pmids":["31745236"],"is_preprint":false},{"year":2024,"finding":"In Dlgap2 homozygous mutant mice, DLGAP2 protein is absent from the olfactory bulb, and levels of PSD-95 and CaMKIIβ are reduced, indicating that DLGAP2 is required for maintaining PSD-95 and CaMKIIβ protein levels and normal synaptic transmission in the olfactory system.","method":"Dlgap2 knockout mice, immunoblotting of olfactory bulb tissue for PSD-95 and CaMKIIβ, c-fos immunostaining after odor stimulation, behavioral olfaction tests","journal":"Behavioural brain research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct protein level measurement in KO tissue with functional behavioral and c-fos correlates; single lab","pmids":["39631506"],"is_preprint":false},{"year":2000,"finding":"The human DLGAP2 gene was cloned and its genomic structure characterized; sequence comparisons with the rat homolog revealed alternative splicing at the 5' end, producing distinct brain and testis transcripts encoding the PSD-95/SAP90-associated protein.","method":"Positional cloning, cDNA library screening (brain and testis), sequence comparison with rat Dlgap2","journal":"European journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — molecular characterization of gene structure and splice variants; no functional assay but establishes gene identity and alternative splicing","pmids":["10854099"],"is_preprint":false},{"year":2014,"finding":"Reporter gene assays of rare intronic and untranslated variants in the DLGAP2 promoter region (c.-69+9C>T, c.-69+47C>T, c.-69+55C>T, c.-32A>G) showed significantly elevated promoter activity compared to wild type, demonstrating these variants functionally increase DLGAP2 gene expression.","method":"Reporter gene (luciferase) assay of promoter variants identified in schizophrenia patients","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct in vitro functional assay (reporter gene) showing increased promoter activity; single lab, single method","pmids":["24416398"],"is_preprint":false},{"year":2009,"finding":"In a rat PTSD model, hippocampal Dlgap2 shows increased DNA methylation at a specific site in PTSD-like rats, which is associated with reduced Dlgap2 gene expression, and Dlgap2 transcript levels correlate with behavioral stress responses across all animals.","method":"Global genomic DNA methylation screening, targeted methylation analysis, gene expression measurement (qRT-PCR) in rat hippocampus, correlation with behavior in PTSD rat model","journal":"The international journal of neuropsychopharmacology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — correlation between methylation and expression in a disease model; no direct manipulation of Dlgap2 methylation to establish causality","pmids":["19793403"],"is_preprint":false},{"year":2025,"finding":"Hippocampal overexpression of DLGAP2 via viral vector in an AD mouse model (F1 5XFAD) impaired synaptic plasticity and exacerbated AD-related memory deficits, with minimal effect on spine structure or intrinsic neuronal properties, demonstrating that elevated DLGAP2 levels are detrimental to synaptic function in an AD context.","method":"Viral-mediated hippocampal DLGAP2 overexpression, cognitive behavioral testing, electrophysiology (synaptic plasticity), dendritic spine morphology analysis in 5XFAD mice","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean gain-of-function with defined electrophysiological and behavioral phenotypes; preprint, single lab, two orthogonal methods","pmids":["bio_10.1101_2025.05.13.653830"],"is_preprint":true}],"current_model":"DLGAP2 encodes a postsynaptic density scaffold protein that associates with PSD-95/SAP90, maintains levels of synaptic proteins including PSD-95 and CaMKIIβ, regulates excitatory synapse structure and miniature EPSC amplitude, and forms a regulatory axis with Intersectin-1 (ITSN1) whereby DLGAP2 deficiency drives ubiquitin-mediated ITSN1 degradation and synaptic dysfunction; its expression is regulated by DNA methylation, and both loss- and gain-of-function perturbations impair cognitive and synaptic function in vivo."},"narrative":{"mechanistic_narrative":"DLGAP2 is a postsynaptic density scaffold protein that maintains the molecular composition and physiological function of excitatory synapses [PMID:25071926]. It is a component of the PSD-95/SAP90-associated scaffold complex [PMID:33347690, PMID:10854099] and is required to sustain levels of synaptic proteins including PSD-95 and CaMKIIβ; its loss reduces dendritic spine density, diminishes miniature EPSC amplitude, and produces ultrastructural defects of the postsynaptic density [PMID:25071926, PMID:39631506]. Mechanistically, DLGAP2 directly interacts with Intersectin-1 (ITSN1) at the postsynaptic density, and DLGAP2 deficiency triggers ubiquitin-mediated proteasomal degradation of ITSN1, disrupting synaptic organization and producing autism-like behaviors [PMID:41673270]. Both loss and gain of DLGAP2 are detrimental: knockout impairs associative learning, olfactory transmission, and reaction times [PMID:33347690, PMID:39631506], while hippocampal overexpression impairs synaptic plasticity and worsens memory deficits in an Alzheimer's disease model [PMID:bio_10.1101_2025.05.13.653830]. DLGAP2 expression is controlled by allele-specific DNA methylation at a defined regulatory region, linking epigenetic regulation of the gene to behavioral phenotypes including alcohol reward processing [PMID:31745236].","teleology":[{"year":2000,"claim":"Established the molecular identity of human DLGAP2, defining its genomic structure and revealing alternative splicing that generates distinct brain and testis transcripts of the PSD-95/SAP90-associated protein.","evidence":"Positional cloning, cDNA library screening, and sequence comparison with rat Dlgap2","pmids":["10854099"],"confidence":"Medium","gaps":["No functional assay of the protein product","Tissue-specific roles of the splice variants not tested"]},{"year":2009,"claim":"Linked DLGAP2 to stress-related behavior by showing that hippocampal Dlgap2 methylation and expression track PTSD-like phenotypes, raising the question of epigenetic control of the gene.","evidence":"Methylation screening and qRT-PCR in a rat PTSD model, correlated with behavior","pmids":["19793403"],"confidence":"Low","gaps":["Correlative only — methylation was not manipulated to establish causality","No demonstration that altered DLGAP2 drives the behavioral phenotype"]},{"year":2014,"claim":"Demonstrated that DLGAP2 is required to maintain synaptic protein composition and excitatory transmission, moving it from a sequence entity to a functional postsynaptic scaffold.","evidence":"Dlgap2 knockout mice analyzed by synaptosomal fractionation, Golgi-Cox staining, patch-clamp, and electron microscopy","pmids":["25071926"],"confidence":"High","gaps":["Direct binding partners within the PSD not biochemically resolved here","Mechanism by which DLGAP2 stabilizes synaptic proteins not defined"]},{"year":2014,"claim":"Showed that human regulatory variants alter DLGAP2 dosage, establishing that expression level — not just loss — is functionally consequential.","evidence":"Luciferase reporter assay of schizophrenia-associated promoter variants","pmids":["24416398"],"confidence":"Medium","gaps":["In vitro reporter context only","Effect on endogenous DLGAP2 in neurons not shown"]},{"year":2017,"claim":"Placed DLGAP2 within the PSD-95 protein complex as a regulator of excitatory synapse signaling underlying cognition.","evidence":"Touchscreen cognitive testing of Dlgap2 loss-of-function mice","pmids":["33347690"],"confidence":"Medium","gaps":["Complex membership inferred from genetic context rather than reconstitution","Causal molecular link between PSD-95 association and the cognitive deficit not established"]},{"year":2019,"claim":"Connected allele-specific DNA methylation to DLGAP2 expression and reward behavior, establishing an epigenetic regulatory layer over the gene.","evidence":"Epigenome-wide association of human brain methylation, in vitro methylation-reporter assay, and alcohol consumption in Dlgap2 KO mice","pmids":["31745236"],"confidence":"Medium","gaps":["Direct causal chain from methylation to behavior in vivo not closed","Cell types driving the methylation effect unresolved"]},{"year":2024,"claim":"Confirmed that DLGAP2 sustains specific synaptic proteins by showing PSD-95 and CaMKIIβ levels fall in DLGAP2-null olfactory bulb, generalizing the scaffold-maintenance role beyond cortex.","evidence":"Immunoblotting, c-fos immunostaining, and olfactory behavior in Dlgap2 KO mice","pmids":["39631506"],"confidence":"Medium","gaps":["Whether protein loss is due to reduced synthesis or accelerated degradation not determined","Single-lab measurement"]},{"year":2025,"claim":"Demonstrated that elevated DLGAP2 is itself pathogenic, showing gain-of-function impairs plasticity and worsens memory in an AD model and defining a bidirectional dosage sensitivity.","evidence":"Viral hippocampal overexpression with electrophysiology and behavioral testing in 5XFAD mice (preprint)","pmids":["bio_10.1101_2025.05.13.653830"],"confidence":"Medium","gaps":["Preprint, single lab","Molecular basis of the overexpression toxicity not defined"]},{"year":2026,"claim":"Identified a direct DLGAP2–ITSN1 axis, providing the first molecular mechanism whereby DLGAP2 stabilizes a partner by preventing its ubiquitin-mediated degradation.","evidence":"PSD proteomics after Dlgap2 knockdown, co-immunoprecipitation, ubiquitin-degradation assay, and mouse behavior","pmids":["41673270"],"confidence":"Medium","gaps":["No reciprocal validation or mutagenesis of the interaction interface reported","Whether the same mechanism stabilizes PSD-95 and CaMKIIβ untested","Identity of the responsible E3 ligase unknown"]},{"year":null,"claim":"How DLGAP2 mechanistically prevents degradation of its partner proteins and the structural basis of its scaffolding within the PSD remain undefined.","evidence":"No structural or reconstituted-complex study present in the corpus","pmids":[],"confidence":"Low","gaps":["No structural model of DLGAP2 or its complexes","E3 ligase and degradation machinery acting on ITSN1 not identified","Mechanism linking DLGAP2 dosage bidirectionally to plasticity unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,2]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1,2]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,4]}],"complexes":["PSD-95/SAP90 postsynaptic density complex"],"partners":["DLG4","ITSN1","CAMK2B"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9P1A6","full_name":"Disks large-associated protein 2","aliases":["PSD-95/SAP90-binding protein 2","SAP90/PSD-95-associated protein 2","SAPAP2"],"length_aa":1054,"mass_kda":117.6,"function":"May play a role in the molecular organization of synapses and neuronal cell signaling. Could be an adapter protein linking ion channel to the subsynaptic cytoskeleton. May induce enrichment of PSD-95/SAP90 at the plasma membrane","subcellular_location":"Cell membrane; Postsynaptic density; Synapse","url":"https://www.uniprot.org/uniprotkb/Q9P1A6/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DLGAP2","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/DLGAP2","total_profiled":1310},"omim":[{"mim_id":"605438","title":"DISCS LARGE-ASSOCIATED PROTEIN 2; DLGAP2","url":"https://www.omim.org/entry/605438"},{"mim_id":"209850","title":"AUTISM","url":"https://www.omim.org/entry/209850"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":6.1},{"tissue":"testis","ntpm":11.5}],"url":"https://www.proteinatlas.org/search/DLGAP2"},"hgnc":{"alias_symbol":["DAP-2"],"prev_symbol":["ERICH1-AS1","C8orf68"]},"alphafold":{"accession":"Q9P1A6","domains":[{"cath_id":"-","chopping":"866-974","consensus_level":"medium","plddt":95.0533,"start":866,"end":974}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9P1A6","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9P1A6-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9P1A6-F1-predicted_aligned_error_v6.png","plddt_mean":48.41},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DLGAP2","jax_strain_url":"https://www.jax.org/strain/search?query=DLGAP2"},"sequence":{"accession":"Q9P1A6","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9P1A6.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9P1A6/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9P1A6"}},"corpus_meta":[{"pmid":"24416398","id":"PMC_24416398","title":"Role of the DLGAP2 gene encoding the SAP90/PSD-95-associated protein 2 in schizophrenia.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24416398","citation_count":206,"is_preprint":false},{"pmid":"31451081","id":"PMC_31451081","title":"Cannabis use is associated with potentially heritable widespread changes in autism candidate gene DLGAP2 DNA methylation in sperm.","date":"2019","source":"Epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/31451081","citation_count":71,"is_preprint":false},{"pmid":"25071926","id":"PMC_25071926","title":"Autism-associated gene Dlgap2 mutant mice demonstrate exacerbated aggressive behaviors and orbitofrontal cortex deficits.","date":"2014","source":"Molecular autism","url":"https://pubmed.ncbi.nlm.nih.gov/25071926","citation_count":70,"is_preprint":false},{"pmid":"19793403","id":"PMC_19793403","title":"DNA methylation in vulnerability to post-traumatic stress in rats: evidence for the role of the post-synaptic density protein Dlgap2.","date":"2009","source":"The international journal of neuropsychopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/19793403","citation_count":59,"is_preprint":false},{"pmid":"23915500","id":"PMC_23915500","title":"Deep exon resequencing of DLGAP2 as a candidate gene of autism spectrum disorders.","date":"2013","source":"Molecular autism","url":"https://pubmed.ncbi.nlm.nih.gov/23915500","citation_count":44,"is_preprint":false},{"pmid":"17592838","id":"PMC_17592838","title":"Alanine scan of [L-Dap(2)]ramoplanin A2 aglycon: assessment of the importance of each residue.","date":"2007","source":"Journal of the American Chemical Society","url":"https://pubmed.ncbi.nlm.nih.gov/17592838","citation_count":39,"is_preprint":false},{"pmid":"32877673","id":"PMC_32877673","title":"Cross-Species Analyses Identify Dlgap2 as a Regulator of Age-Related Cognitive Decline and Alzheimer's Dementia.","date":"2020","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/32877673","citation_count":34,"is_preprint":false},{"pmid":"9867351","id":"PMC_9867351","title":"DAP-2, the Drosophila homolog of transcription factor AP-2.","date":"1998","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/9867351","citation_count":28,"is_preprint":false},{"pmid":"33347690","id":"PMC_33347690","title":"Learning and reaction times in mouse touchscreen tests are differentially impacted by mutations in genes encoding postsynaptic interacting proteins SYNGAP1, NLGN3, DLGAP1, DLGAP2 and SHANK2.","date":"2020","source":"Genes, brain, and behavior","url":"https://pubmed.ncbi.nlm.nih.gov/33347690","citation_count":22,"is_preprint":false},{"pmid":"31745236","id":"PMC_31745236","title":"Genotype-dependent epigenetic regulation of DLGAP2 in alcohol use and dependence.","date":"2019","source":"Molecular psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/31745236","citation_count":21,"is_preprint":false},{"pmid":"10854099","id":"PMC_10854099","title":"Positional cloning and characterisation of the human DLGAP2 gene and its exclusion in progressive epilepsy with mental retardation.","date":"2000","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/10854099","citation_count":21,"is_preprint":false},{"pmid":"17893729","id":"PMC_17893729","title":"dAP-2 and defective proventriculus regulate Serrate and Delta expression in the tarsus of Drosophila melanogaster.","date":"2007","source":"Genome","url":"https://pubmed.ncbi.nlm.nih.gov/17893729","citation_count":12,"is_preprint":false},{"pmid":"30504779","id":"PMC_30504779","title":"Quantitative DNA Methylation Analysis of DLGAP2 Gene using Pyrosequencing in Schizophrenia with Tardive Dyskinesia: A Linear Mixed Model Approach.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/30504779","citation_count":11,"is_preprint":false},{"pmid":"38765731","id":"PMC_38765731","title":"DNA Methylation Near DLGAP2 May Mediate the Relationship between Family History of Type 1 Diabetes and Type 1 Diabetes Risk.","date":"2023","source":"Pediatric diabetes","url":"https://pubmed.ncbi.nlm.nih.gov/38765731","citation_count":1,"is_preprint":false},{"pmid":"38364647","id":"PMC_38364647","title":"DNA methylation at DLGAP2 and risk for relapse in alcohol dependence during acamprosate treatment.","date":"2024","source":"Drug and alcohol dependence","url":"https://pubmed.ncbi.nlm.nih.gov/38364647","citation_count":0,"is_preprint":false},{"pmid":"39631506","id":"PMC_39631506","title":"Altered odor perception in Dlgap2 mutant mice, a mouse model of autism spectrum disorder.","date":"2024","source":"Behavioural brain research","url":"https://pubmed.ncbi.nlm.nih.gov/39631506","citation_count":0,"is_preprint":false},{"pmid":"41673270","id":"PMC_41673270","title":"Dlgap2 deficiency disrupts synaptic homeostasis by promoting ubiquitin-mediated Itsn1 degradation in a valproic acid-induced autism-like model.","date":"2026","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/41673270","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.13.653830","title":"Evaluation of hippocampal  <i>DLGAP2</i>  overexpression on cognition, synaptic function, and dendritic spine structure in a translationally relevant AD mouse model","date":"2025-05-14","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.13.653830","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10352,"output_tokens":2332,"usd":0.033018,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9448,"output_tokens":2873,"usd":0.059533,"stage2_stop_reason":"end_turn"},"total_usd":0.092551,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2014,\n      \"finding\": \"Dlgap2 knockout mice show reduced receptor and scaffold protein levels in cortical synapses, lower dendritic spine density, decreased peak amplitude of miniature excitatory postsynaptic currents, and ultrastructural deficits of postsynaptic density in the orbitofrontal cortex, demonstrating DLGAP2 is required for maintaining proper synaptic composition and function at excitatory synapses.\",\n      \"method\": \"Dlgap2 knockout mice (Cre-loxP), cortical synaptosomal fractionation, Golgi-Cox staining, whole-cell patch-clamp electrophysiology, transmission electron microscopy\",\n      \"journal\": \"Molecular autism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (biochemistry, electrophysiology, EM, morphology) in a clean genetic KO model with specific cellular phenotypes\",\n      \"pmids\": [\"25071926\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"DLGAP2 protein is a component of the postsynaptic density scaffold complex, where it associates with PSD-95/SAP90, and loss-of-function mutations in Dlgap2 lead to deficits in associative learning and reaction times in mice, placing it within the PSD-95 protein complex as a regulator of excitatory synapse signaling underlying cognition.\",\n      \"method\": \"Loss-of-function mutant mice (Dlgap2 KO), touchscreen-based cognitive testing (associative learning, cognitive flexibility, reaction times)\",\n      \"journal\": \"Genes, brain, and behavior\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined cognitive phenotype, but mechanistic pathway placement inferred from genetic context rather than direct biochemical reconstitution\",\n      \"pmids\": [\"33347690\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"DLGAP2 directly interacts with Intersectin-1 (ITSN1) at the postsynaptic density; upon Dlgap2 deficiency, ITSN1 undergoes ubiquitin-mediated proteasomal degradation, disrupting synaptic organization and causing autism-like behaviors, defining a Dlgap2-Itsn1 regulatory axis.\",\n      \"method\": \"Proteomics of postsynaptic density fraction after Dlgap2 knockdown, co-immunoprecipitation (interaction), ubiquitin-mediated degradation assay, mouse behavioral assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proteomics plus interaction and degradation assays in single lab; abstract does not detail full reconstitution or mutagenesis\",\n      \"pmids\": [\"41673270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"DNA methylation within a defined region of DLGAP2 (DMR-DLGAP2) is genotype-dependent, allele-specific, and regulates DLGAP2 expression in vitro; Dlgap2-deficient mice show reduced alcohol consumption compared to wild-type controls, placing DLGAP2 in a pathway linking epigenetic regulation to alcohol reward processing.\",\n      \"method\": \"Epigenome-wide association of human brain DNA methylation, in vitro methylation-expression reporter assay, Dlgap2 knockout mouse alcohol consumption assay\",\n      \"journal\": \"Molecular psychiatry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro functional methylation assay combined with KO mouse behavioral phenotype; single lab, two orthogonal methods\",\n      \"pmids\": [\"31745236\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In Dlgap2 homozygous mutant mice, DLGAP2 protein is absent from the olfactory bulb, and levels of PSD-95 and CaMKIIβ are reduced, indicating that DLGAP2 is required for maintaining PSD-95 and CaMKIIβ protein levels and normal synaptic transmission in the olfactory system.\",\n      \"method\": \"Dlgap2 knockout mice, immunoblotting of olfactory bulb tissue for PSD-95 and CaMKIIβ, c-fos immunostaining after odor stimulation, behavioral olfaction tests\",\n      \"journal\": \"Behavioural brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct protein level measurement in KO tissue with functional behavioral and c-fos correlates; single lab\",\n      \"pmids\": [\"39631506\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The human DLGAP2 gene was cloned and its genomic structure characterized; sequence comparisons with the rat homolog revealed alternative splicing at the 5' end, producing distinct brain and testis transcripts encoding the PSD-95/SAP90-associated protein.\",\n      \"method\": \"Positional cloning, cDNA library screening (brain and testis), sequence comparison with rat Dlgap2\",\n      \"journal\": \"European journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — molecular characterization of gene structure and splice variants; no functional assay but establishes gene identity and alternative splicing\",\n      \"pmids\": [\"10854099\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Reporter gene assays of rare intronic and untranslated variants in the DLGAP2 promoter region (c.-69+9C>T, c.-69+47C>T, c.-69+55C>T, c.-32A>G) showed significantly elevated promoter activity compared to wild type, demonstrating these variants functionally increase DLGAP2 gene expression.\",\n      \"method\": \"Reporter gene (luciferase) assay of promoter variants identified in schizophrenia patients\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct in vitro functional assay (reporter gene) showing increased promoter activity; single lab, single method\",\n      \"pmids\": [\"24416398\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"In a rat PTSD model, hippocampal Dlgap2 shows increased DNA methylation at a specific site in PTSD-like rats, which is associated with reduced Dlgap2 gene expression, and Dlgap2 transcript levels correlate with behavioral stress responses across all animals.\",\n      \"method\": \"Global genomic DNA methylation screening, targeted methylation analysis, gene expression measurement (qRT-PCR) in rat hippocampus, correlation with behavior in PTSD rat model\",\n      \"journal\": \"The international journal of neuropsychopharmacology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — correlation between methylation and expression in a disease model; no direct manipulation of Dlgap2 methylation to establish causality\",\n      \"pmids\": [\"19793403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Hippocampal overexpression of DLGAP2 via viral vector in an AD mouse model (F1 5XFAD) impaired synaptic plasticity and exacerbated AD-related memory deficits, with minimal effect on spine structure or intrinsic neuronal properties, demonstrating that elevated DLGAP2 levels are detrimental to synaptic function in an AD context.\",\n      \"method\": \"Viral-mediated hippocampal DLGAP2 overexpression, cognitive behavioral testing, electrophysiology (synaptic plasticity), dendritic spine morphology analysis in 5XFAD mice\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean gain-of-function with defined electrophysiological and behavioral phenotypes; preprint, single lab, two orthogonal methods\",\n      \"pmids\": [\"bio_10.1101_2025.05.13.653830\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"DLGAP2 encodes a postsynaptic density scaffold protein that associates with PSD-95/SAP90, maintains levels of synaptic proteins including PSD-95 and CaMKIIβ, regulates excitatory synapse structure and miniature EPSC amplitude, and forms a regulatory axis with Intersectin-1 (ITSN1) whereby DLGAP2 deficiency drives ubiquitin-mediated ITSN1 degradation and synaptic dysfunction; its expression is regulated by DNA methylation, and both loss- and gain-of-function perturbations impair cognitive and synaptic function in vivo.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"DLGAP2 is a postsynaptic density scaffold protein that maintains the molecular composition and physiological function of excitatory synapses [#0]. It is a component of the PSD-95/SAP90-associated scaffold complex [#1, #5] and is required to sustain levels of synaptic proteins including PSD-95 and CaMKIIβ; its loss reduces dendritic spine density, diminishes miniature EPSC amplitude, and produces ultrastructural defects of the postsynaptic density [#0, #4]. Mechanistically, DLGAP2 directly interacts with Intersectin-1 (ITSN1) at the postsynaptic density, and DLGAP2 deficiency triggers ubiquitin-mediated proteasomal degradation of ITSN1, disrupting synaptic organization and producing autism-like behaviors [#2]. Both loss and gain of DLGAP2 are detrimental: knockout impairs associative learning, olfactory transmission, and reaction times [#1, #4], while hippocampal overexpression impairs synaptic plasticity and worsens memory deficits in an Alzheimer's disease model [#8]. DLGAP2 expression is controlled by allele-specific DNA methylation at a defined regulatory region, linking epigenetic regulation of the gene to behavioral phenotypes including alcohol reward processing [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established the molecular identity of human DLGAP2, defining its genomic structure and revealing alternative splicing that generates distinct brain and testis transcripts of the PSD-95/SAP90-associated protein.\",\n      \"evidence\": \"Positional cloning, cDNA library screening, and sequence comparison with rat Dlgap2\",\n      \"pmids\": [\"10854099\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional assay of the protein product\", \"Tissue-specific roles of the splice variants not tested\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Linked DLGAP2 to stress-related behavior by showing that hippocampal Dlgap2 methylation and expression track PTSD-like phenotypes, raising the question of epigenetic control of the gene.\",\n      \"evidence\": \"Methylation screening and qRT-PCR in a rat PTSD model, correlated with behavior\",\n      \"pmids\": [\"19793403\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Correlative only — methylation was not manipulated to establish causality\", \"No demonstration that altered DLGAP2 drives the behavioral phenotype\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrated that DLGAP2 is required to maintain synaptic protein composition and excitatory transmission, moving it from a sequence entity to a functional postsynaptic scaffold.\",\n      \"evidence\": \"Dlgap2 knockout mice analyzed by synaptosomal fractionation, Golgi-Cox staining, patch-clamp, and electron microscopy\",\n      \"pmids\": [\"25071926\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct binding partners within the PSD not biochemically resolved here\", \"Mechanism by which DLGAP2 stabilizes synaptic proteins not defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showed that human regulatory variants alter DLGAP2 dosage, establishing that expression level — not just loss — is functionally consequential.\",\n      \"evidence\": \"Luciferase reporter assay of schizophrenia-associated promoter variants\",\n      \"pmids\": [\"24416398\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vitro reporter context only\", \"Effect on endogenous DLGAP2 in neurons not shown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Placed DLGAP2 within the PSD-95 protein complex as a regulator of excitatory synapse signaling underlying cognition.\",\n      \"evidence\": \"Touchscreen cognitive testing of Dlgap2 loss-of-function mice\",\n      \"pmids\": [\"33347690\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Complex membership inferred from genetic context rather than reconstitution\", \"Causal molecular link between PSD-95 association and the cognitive deficit not established\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Connected allele-specific DNA methylation to DLGAP2 expression and reward behavior, establishing an epigenetic regulatory layer over the gene.\",\n      \"evidence\": \"Epigenome-wide association of human brain methylation, in vitro methylation-reporter assay, and alcohol consumption in Dlgap2 KO mice\",\n      \"pmids\": [\"31745236\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct causal chain from methylation to behavior in vivo not closed\", \"Cell types driving the methylation effect unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Confirmed that DLGAP2 sustains specific synaptic proteins by showing PSD-95 and CaMKIIβ levels fall in DLGAP2-null olfactory bulb, generalizing the scaffold-maintenance role beyond cortex.\",\n      \"evidence\": \"Immunoblotting, c-fos immunostaining, and olfactory behavior in Dlgap2 KO mice\",\n      \"pmids\": [\"39631506\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether protein loss is due to reduced synthesis or accelerated degradation not determined\", \"Single-lab measurement\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated that elevated DLGAP2 is itself pathogenic, showing gain-of-function impairs plasticity and worsens memory in an AD model and defining a bidirectional dosage sensitivity.\",\n      \"evidence\": \"Viral hippocampal overexpression with electrophysiology and behavioral testing in 5XFAD mice (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.05.13.653830\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, single lab\", \"Molecular basis of the overexpression toxicity not defined\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identified a direct DLGAP2–ITSN1 axis, providing the first molecular mechanism whereby DLGAP2 stabilizes a partner by preventing its ubiquitin-mediated degradation.\",\n      \"evidence\": \"PSD proteomics after Dlgap2 knockdown, co-immunoprecipitation, ubiquitin-degradation assay, and mouse behavior\",\n      \"pmids\": [\"41673270\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No reciprocal validation or mutagenesis of the interaction interface reported\", \"Whether the same mechanism stabilizes PSD-95 and CaMKIIβ untested\", \"Identity of the responsible E3 ligase unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How DLGAP2 mechanistically prevents degradation of its partner proteins and the structural basis of its scaffolding within the PSD remain undefined.\",\n      \"evidence\": \"No structural or reconstituted-complex study present in the corpus\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of DLGAP2 or its complexes\", \"E3 ligase and degradation machinery acting on ITSN1 not identified\", \"Mechanism linking DLGAP2 dosage bidirectionally to plasticity unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"complexes\": [\"PSD-95/SAP90 postsynaptic density complex\"],\n    \"partners\": [\"DLG4\", \"ITSN1\", \"CAMK2B\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}