{"gene":"PLCXD2","run_date":"2026-04-28T19:45:44","timeline":{"discoveries":[{"year":2025,"finding":"PLCXD2 is a constitutively active phospholipase C (PLC) family member that forms a postsynaptic signaling complex with the GPCR-like receptor GPR158. In mouse cortical neurons in vivo, absence of GPR158 results in unrestrained PLCXD2 activity that impedes spine apparatus (SA) incorporation into dendritic spines and hampers structural and functional dendritic spine maturation, establishing PLCXD2 as a downstream effector whose activity must be restrained by GPR158 for proper postsynaptic development.","method":"Sparse in vivo genetic manipulations (loss-of-function) in mouse cortical neurons, co-immunoprecipitation of GPR158-PLCXD2 complex, structural/functional spine maturation readouts","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — in vivo genetic epistasis with defined phenotypic readout, complex identified by co-IP, replicated between preprint and peer-reviewed publication with multiple orthogonal methods","pmids":["40393451"],"is_preprint":false},{"year":2025,"finding":"Extracellular heparan sulfate proteoglycan (HSPG) binding modulates the GPR158-PLCXD2 interaction, providing spatiotemporal control over GPR158-mediated inhibition of PLCXD2 activity at synapses. This reveals a direct GPCR-like receptor-to-PLC signaling pathway that bypasses canonical PLC regulation via G proteins.","method":"Biochemical binding assays and in vivo functional assays examining HSPG modulation of GPR158-PLCXD2 interaction","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 — mechanistic modulation demonstrated in single study with functional in vivo context, but specific biochemical method details not fully specified in abstract","pmids":["40393451"],"is_preprint":false},{"year":2025,"finding":"The GPR158-PLCXD2 signaling module regulates spine apparatus abundance, which is required for proper postsynaptic structure and function, linking PLCXD2 phospholipase activity to endoplasmic reticulum-related organelle (spine apparatus) dynamics in dendritic spines.","method":"In vivo sparse genetic manipulation, live imaging of spine apparatus, functional spine maturation assays in mouse cortical neurons","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — in vivo loss-of-function with defined organelle localization and functional phenotype readouts across peer-reviewed publication","pmids":["40393451"],"is_preprint":false},{"year":2022,"finding":"PLCXD2 expression in gastric cancer cells is suppressed by miR-378a-3p, which directly targets PLCXD2 mRNA. Knockdown of PLCXD2 rescued the inhibitory effect of lncRNA ACTA2-AS1 overexpression on malignant behaviors (proliferation, migration, invasion, EMT), indicating PLCXD2 acts downstream of the ACTA2-AS1/miR-378a-3p ceRNA axis to suppress malignant phenotypes.","method":"RNA pulldown assays, luciferase reporter assays, RNA immunoprecipitation assays, siRNA knockdown with cellular phenotype readouts (CCK-8, colony formation, wound healing, Transwell, Western blot)","journal":"Open medicine (Warsaw, Poland)","confidence":"Medium","confidence_rationale":"Tier 3 — multiple biochemical methods validating miRNA-mRNA interaction, functional rescue experiment, but single lab and no direct enzymatic characterization of PLCXD2","pmids":["35274046"],"is_preprint":false}],"current_model":"PLCXD2 is a constitutively active PLC family member that, in neurons, is restrained by direct interaction with the GPCR-like receptor GPR158 (modulated by extracellular HSPG binding) to control spine apparatus abundance and dendritic spine maturation; in gastric cancer cells, PLCXD2 protein levels are post-transcriptionally regulated by miR-378a-3p and suppress malignant phenotypes downstream of the lncRNA ACTA2-AS1 ceRNA axis."},"narrative":{"teleology":[{"year":2022,"claim":"Identification of PLCXD2 as a functionally relevant target downstream of a non-coding RNA regulatory axis in cancer cells established that PLCXD2 protein levels are post-transcriptionally controlled by miR-378a-3p and that PLCXD2 expression suppresses proliferative and invasive phenotypes in gastric cancer.","evidence":"Luciferase reporter assays, RNA immunoprecipitation, siRNA knockdown with proliferation/migration/invasion readouts in gastric cancer cell lines","pmids":["35274046"],"confidence":"Medium","gaps":["No direct measurement of PLCXD2 phospholipase activity in cancer cells","Single-lab study without independent replication","Whether the tumor-suppressive role depends on catalytic activity versus scaffolding is unknown"]},{"year":2025,"claim":"Discovery that PLCXD2 is a constitutively active PLC restrained by GPR158 in a postsynaptic complex resolved how neurons control PLCXD2 enzymatic output and linked its unrestrained activity to defective spine apparatus dynamics and impaired dendritic spine maturation.","evidence":"In vivo sparse genetic loss-of-function in mouse cortical neurons, co-immunoprecipitation of GPR158–PLCXD2 complex, spine apparatus imaging and functional spine maturation readouts","pmids":["40393451"],"confidence":"High","gaps":["The lipid substrate specificity and catalytic products of PLCXD2 have not been biochemically defined","No structural model of the GPR158–PLCXD2 complex exists","Whether PLCXD2 functions in non-neuronal postmitotic cells through a similar GPR158-dependent mechanism is unknown"]},{"year":2025,"claim":"The finding that extracellular HSPGs modulate the GPR158–PLCXD2 interaction revealed a non-canonical GPCR-to-PLC signaling pathway that bypasses classical G-protein intermediates, suggesting spatiotemporal regulation of PLCXD2 by the extracellular matrix.","evidence":"Biochemical binding assays and in vivo functional assays examining HSPG modulation of GPR158–PLCXD2 interaction in mouse cortical neurons","pmids":["40393451"],"confidence":"Medium","gaps":["The specific HSPG species and binding domains involved are not defined","Quantitative biochemistry of HSPG-dependent inhibition kinetics is lacking","Whether HSPG modulation is activity-dependent or developmentally programmed is unresolved"]},{"year":null,"claim":"The substrate specificity, catalytic mechanism, and lipid products of PLCXD2 remain undefined, and the structural basis for GPR158-mediated inhibition of its constitutive activity has not been determined.","evidence":"","pmids":[],"confidence":"High","gaps":["No in vitro enzymatic reconstitution with defined substrates has been reported","No crystal or cryo-EM structure of PLCXD2 alone or in complex with GPR158 exists","Downstream signaling consequences of PLCXD2 catalytic products at synapses are unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,2]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,2]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,2]}],"complexes":[],"partners":["GPR158"],"other_free_text":[]},"mechanistic_narrative":"PLCXD2 is a constitutively active phospholipase C family member that functions as a postsynaptic effector controlling spine apparatus abundance and dendritic spine maturation in cortical neurons. PLCXD2 forms a signaling complex with the GPCR-like receptor GPR158, which directly restrains PLCXD2 enzymatic activity; loss of GPR158 leads to unrestrained PLCXD2 activity, impeding spine apparatus incorporation into dendritic spines and disrupting both structural and functional spine maturation [PMID:40393451]. Extracellular heparan sulfate proteoglycans modulate the GPR158–PLCXD2 interaction, providing spatiotemporal control that bypasses canonical G-protein-mediated PLC regulation [PMID:40393451]. In gastric cancer cells, PLCXD2 protein levels are post-transcriptionally suppressed by miR-378a-3p within the ACTA2-AS1 ceRNA axis, and PLCXD2 expression suppresses malignant phenotypes including proliferation, migration, and epithelial-mesenchymal transition [PMID:35274046]."},"prefetch_data":{"uniprot":{"accession":"Q0VAA5","full_name":"PI-PLC X domain-containing protein 2","aliases":["Phospholipase C X-domain containing protein 2","PLCXD-2"],"length_aa":305,"mass_kda":34.8,"function":"Catalyzes the hydrolysis of inositol from phosphatidylinositol (1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol), PI) (PubMed:22732399). Could also hydrolyze various multi-phosphorylated derivatives of PI, such as phosphatidylinositol-4,5 bisphosphate (PIP2), releasing inositol-1,4,5-trisphosphate (IP3) and the protein kinase C activator diacylglycerol (DAG), therefore mediating cell signaling (Probable)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q0VAA5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PLCXD2","classification":"Not Classified","n_dependent_lines":9,"n_total_lines":1208,"dependency_fraction":0.0074503311258278145},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PLCXD2","total_profiled":1310},"omim":[{"mim_id":"617016","title":"PHOSPHOLIPASE C, PHOSPHATIDYLINOSITOL-SPECIFIC, X DOMAIN-CONTAINING PROTEIN 3; PLCXD3","url":"https://www.omim.org/entry/617016"},{"mim_id":"617015","title":"PHOSPHOLIPASE C, PHOSPHATIDYLINOSITOL-SPECIFIC, X DOMAIN-CONTAINING PROTEIN 2; PLCXD2","url":"https://www.omim.org/entry/617015"},{"mim_id":"300974","title":"PHOSPHOLIPASE C, PHOSPHATIDYLINOSITOL-SPECIFIC, X DOMAIN-CONTAINING PROTEIN 1; PLCXD1","url":"https://www.omim.org/entry/300974"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"retina","ntpm":13.7}],"url":"https://www.proteinatlas.org/search/PLCXD2"},"hgnc":{"alias_symbol":["FLJ31579"],"prev_symbol":[]},"alphafold":{"accession":"Q0VAA5","domains":[{"cath_id":"3.20.20.190","chopping":"3-7_31-287","consensus_level":"high","plddt":86.8533,"start":3,"end":287}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VAA5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VAA5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q0VAA5-F1-predicted_aligned_error_v6.png","plddt_mean":79.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PLCXD2","jax_strain_url":"https://www.jax.org/strain/search?query=PLCXD2"},"sequence":{"accession":"Q0VAA5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q0VAA5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q0VAA5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q0VAA5"}},"corpus_meta":[{"pmid":"35274046","id":"PMC_35274046","title":"lncRNA ACTA2-AS1 inhibits malignant phenotypes of gastric cancer cells.","date":"2022","source":"Open medicine (Warsaw, Poland)","url":"https://pubmed.ncbi.nlm.nih.gov/35274046","citation_count":8,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"40393451","id":"PMC_40393451","title":"A postsynaptic GPR158-PLCXD2 complex controls spine apparatus abundance and dendritic spine maturation.","date":"2025","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/40393451","citation_count":3,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":null,"id":"bio_10.1101_2024.05.08.592949","title":"Cell-surface receptor-mediated regulation of synaptic organelle distribution controls dendritic spine maturation","date":"2024-05-08","source":"bioRxiv","url":"https://doi.org/10.1101/2024.05.08.592949","citation_count":0,"is_preprint":true,"source_track":"pubmed_title"},{"pmid":"12477932","id":"PMC_12477932","title":"Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.","date":"2002","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/12477932","citation_count":1479,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"28514442","id":"PMC_28514442","title":"Architecture of the human interactome defines protein communities and disease networks.","date":"2017","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/28514442","citation_count":1085,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"14702039","id":"PMC_14702039","title":"Complete sequencing and characterization of 21,243 full-length human cDNAs.","date":"2003","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/14702039","citation_count":754,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"33961781","id":"PMC_33961781","title":"Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.","date":"2021","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/33961781","citation_count":705,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"21873635","id":"PMC_21873635","title":"Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium.","date":"2011","source":"Briefings in bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/21873635","citation_count":656,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"20379614","id":"PMC_20379614","title":"Personalized smoking cessation: interactions between nicotine dose, dependence and quit-success genotype score.","date":"2010","source":"Molecular medicine (Cambridge, Mass.)","url":"https://pubmed.ncbi.nlm.nih.gov/20379614","citation_count":108,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"23333304","id":"PMC_23333304","title":"CBFβ stabilizes HIV Vif to counteract APOBEC3 at the expense of RUNX1 target gene expression.","date":"2013","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/23333304","citation_count":102,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"20125193","id":"PMC_20125193","title":"Common genetic variation and performance on standardized cognitive tests.","date":"2010","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/20125193","citation_count":78,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"32989256","id":"PMC_32989256","title":"Suppression of DDX39B sensitizes ovarian cancer cells to DNA-damaging chemotherapeutic agents via destabilizing BRCA1 mRNA.","date":"2020","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/32989256","citation_count":38,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"20677014","id":"PMC_20677014","title":"An approach based on a genome-wide association study reveals candidate loci for narcolepsy.","date":"2010","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/20677014","citation_count":32,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"31900314","id":"PMC_31900314","title":"AMPK Interactome Reveals New Function in Non-homologous End Joining DNA Repair.","date":"2020","source":"Molecular & cellular proteomics : MCP","url":"https://pubmed.ncbi.nlm.nih.gov/31900314","citation_count":15,"is_preprint":false,"source_track":"gene2pubmed"}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":2874,"output_tokens":1067,"usd":0.012313},"stage2":{"model":"claude-opus-4-6","input_tokens":4268,"output_tokens":1193,"usd":0.076747},"total_usd":0.20035,"stage1_batch_id":"msgbatch_01SUR8NDzVrNmyszWyJeCct7","stage2_batch_id":"msgbatch_01G7Yfutko3cDWzejrwH5AMx","note":"batch pricing = 50% of standard","round2_stage1":{"model":"claude-sonnet-4-6","input_tokens":7658,"output_tokens":1728,"usd":0.024447},"round2_rules_fired":"R3","round2_stage2":{"model":"claude-opus-4-6","input_tokens":4639,"output_tokens":1388,"usd":0.086843}},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2025,\n      \"finding\": \"PLCXD2 forms a postsynaptic signaling complex with the GPCR-like receptor GPR158; in the absence of GPR158, unrestrained PLCXD2 phospholipase C activity impedes spine apparatus (SA) incorporation into dendritic spines and hampers structural and functional dendritic spine maturation, demonstrating that GPR158 restrains PLCXD2 activity in this complex.\",\n      \"method\": \"Co-immunoprecipitation/complex identification, sparse in vivo genetic manipulations of mouse cortical neurons (loss-of-function), structural and functional spine maturation readouts\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic epistasis with defined cellular phenotype, reciprocal complex identification, multiple orthogonal readouts in a peer-reviewed study\",\n      \"pmids\": [\"40393451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Extracellular heparan sulfate proteoglycan (HSPG) binding modulates the GPR158-PLCXD2 interaction, providing spatiotemporal control over GPR158 signaling and PLCXD2 activity at synapses.\",\n      \"method\": \"In vivo genetic manipulations combined with HSPG binding assays and assessment of GPR158-PLCXD2 complex formation\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — single lab, mechanistic binding modulation demonstrated in vivo but limited orthogonal biochemical detail in the abstract\",\n      \"pmids\": [\"40393451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PLCXD2 is a constitutively active phospholipase C family member that operates in a direct GPCR-like receptor-to-PLC signaling pathway that bypasses canonical PLC regulation via G proteins.\",\n      \"method\": \"Genetic and biochemical characterization within the GPR158-PLCXD2 complex; loss-of-function epistasis in mouse cortical neurons\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — constitutive activity inferred from genetic epistasis (unrestrained activity in GPR158 KO); mechanistic claim supported by in vivo data but direct enzymatic reconstitution not described in abstract\",\n      \"pmids\": [\"40393451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PLCXD2 mRNA is a direct target of miR-378a-3p, which suppresses PLCXD2 expression; the lncRNA ACTA2-AS1 acts as a competing endogenous RNA (ceRNA) by binding miR-378a-3p to relieve this suppression, thereby maintaining PLCXD2 levels and inhibiting malignant behaviors of gastric cancer cells.\",\n      \"method\": \"RNA pulldown assays, luciferase reporter assays, RNA immunoprecipitation assays, PLCXD2 knockdown rescue experiments\",\n      \"journal\": \"Open medicine (Warsaw, Poland)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — multiple RNA-interaction assays with functional rescue, but mechanism is indirect (PLCXD2 as downstream target, no direct enzymatic characterization)\",\n      \"pmids\": [\"35274046\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PLCXD2 is a constitutively active phospholipase C that forms a postsynaptic complex with the GPCR-like receptor GPR158, which restrains PLCXD2 activity to permit spine apparatus incorporation into dendritic spines and proper spine maturation; extracellular HSPG binding modulates this GPR158-PLCXD2 interaction for spatiotemporal control, and at the RNA level PLCXD2 expression is post-transcriptionally regulated by miR-378a-3p.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\nI'll classify each paper first, then extract discoveries.\n\n**Classification:**\n\n**Retrieved papers:**\n1. PMID:35274046 — lncRNA ACTA2-AS1 paper. This describes PLCXD2 as a downstream mRNA target regulated via ceRNA mechanism (miR-378a-3p sponging). PLCXD2 knockdown is used functionally in GC cells. **KEEP** (describes canonical PLCXD2 protein function in a cellular context).\n2. PMID:40393451 — GPR158-PLCXD2 complex in dendritic spines. Directly about PLCXD2 mechanism. **KEEP**\n3. bio_10.1101_2024.05.08.592949 — Preprint version of same study as PMID:40393451. **KEEP** (but peer-reviewed version covers same findings)\n\n**Gene2pubmed curated papers:**\n- PMID:12477932 — MGC cDNA sequencing. No mechanistic findings. **EXCLUDE**\n- PMID:28514442 — BioPlex 2.0 interactome. Large-scale AP-MS; may contain PLCXD2 interactions but no specific mechanistic findings described. **EXCLUDE** (no specific PLCXD2 mechanism)\n- PMID:14702039 — FLJ cDNA collection. **EXCLUDE**\n- PMID:33961781 — BioPlex 3.0. Same reasoning. **EXCLUDE**\n- PMID:21873635 — GO phylogenetic propagation. **EXCLUDE**\n- PMID:20379614 — Smoking cessation GWAS. **EXCLUDE**\n- PMID:23333304 — HIV Vif/CBFβ. **EXCLUDE** (alias collision or off-target)\n- PMID:20125193 — Cognitive GWAS. **EXCLUDE**\n- PMID:32989256 — DDX39B/BRCA1. **EXCLUDE**\n- PMID:20677014 — Narcolepsy GWAS. **EXCLUDE**\n- PMID:31900314 — AMPK interactome. **EXCLUDE**\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2025,\n      \"finding\": \"PLCXD2 is a constitutively active phospholipase C (PLC) family member that forms a postsynaptic signaling complex with the GPCR-like receptor GPR158. In mouse cortical neurons in vivo, absence of GPR158 results in unrestrained PLCXD2 activity that impedes spine apparatus (SA) incorporation into dendritic spines and hampers structural and functional dendritic spine maturation, establishing PLCXD2 as a downstream effector whose activity must be restrained by GPR158 for proper postsynaptic development.\",\n      \"method\": \"Sparse in vivo genetic manipulations (loss-of-function) in mouse cortical neurons, co-immunoprecipitation of GPR158-PLCXD2 complex, structural/functional spine maturation readouts\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo genetic epistasis with defined phenotypic readout, complex identified by co-IP, replicated between preprint and peer-reviewed publication with multiple orthogonal methods\",\n      \"pmids\": [\"40393451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Extracellular heparan sulfate proteoglycan (HSPG) binding modulates the GPR158-PLCXD2 interaction, providing spatiotemporal control over GPR158-mediated inhibition of PLCXD2 activity at synapses. This reveals a direct GPCR-like receptor-to-PLC signaling pathway that bypasses canonical PLC regulation via G proteins.\",\n      \"method\": \"Biochemical binding assays and in vivo functional assays examining HSPG modulation of GPR158-PLCXD2 interaction\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — mechanistic modulation demonstrated in single study with functional in vivo context, but specific biochemical method details not fully specified in abstract\",\n      \"pmids\": [\"40393451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The GPR158-PLCXD2 signaling module regulates spine apparatus abundance, which is required for proper postsynaptic structure and function, linking PLCXD2 phospholipase activity to endoplasmic reticulum-related organelle (spine apparatus) dynamics in dendritic spines.\",\n      \"method\": \"In vivo sparse genetic manipulation, live imaging of spine apparatus, functional spine maturation assays in mouse cortical neurons\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo loss-of-function with defined organelle localization and functional phenotype readouts across peer-reviewed publication\",\n      \"pmids\": [\"40393451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PLCXD2 expression in gastric cancer cells is suppressed by miR-378a-3p, which directly targets PLCXD2 mRNA. Knockdown of PLCXD2 rescued the inhibitory effect of lncRNA ACTA2-AS1 overexpression on malignant behaviors (proliferation, migration, invasion, EMT), indicating PLCXD2 acts downstream of the ACTA2-AS1/miR-378a-3p ceRNA axis to suppress malignant phenotypes.\",\n      \"method\": \"RNA pulldown assays, luciferase reporter assays, RNA immunoprecipitation assays, siRNA knockdown with cellular phenotype readouts (CCK-8, colony formation, wound healing, Transwell, Western blot)\",\n      \"journal\": \"Open medicine (Warsaw, Poland)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — multiple biochemical methods validating miRNA-mRNA interaction, functional rescue experiment, but single lab and no direct enzymatic characterization of PLCXD2\",\n      \"pmids\": [\"35274046\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PLCXD2 is a constitutively active PLC family member that, in neurons, is restrained by direct interaction with the GPCR-like receptor GPR158 (modulated by extracellular HSPG binding) to control spine apparatus abundance and dendritic spine maturation; in gastric cancer cells, PLCXD2 protein levels are post-transcriptionally regulated by miR-378a-3p and suppress malignant phenotypes downstream of the lncRNA ACTA2-AS1 ceRNA axis.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"PLCXD2 is a constitutively active phospholipase C that functions in a non-canonical, G-protein-independent signaling pathway at postsynaptic sites, where it forms a complex with the GPCR-like receptor GPR158 [PMID:40393451]. GPR158 restrains PLCXD2 enzymatic activity to permit spine apparatus incorporation into dendritic spines and proper structural and functional spine maturation; loss of GPR158 leads to unrestrained PLCXD2 activity that impedes these processes [PMID:40393451]. Extracellular heparan sulfate proteoglycans modulate the GPR158–PLCXD2 interaction, providing spatiotemporal control of this signaling axis at synapses [PMID:40393451]. PLCXD2 expression is post-transcriptionally regulated by miR-378a-3p, and relief of this suppression via the competing endogenous RNA ACTA2-AS1 maintains PLCXD2 levels in gastric cancer cells [PMID:35274046].\",\n  \"teleology\": [\n    {\n      \"year\": 2022,\n      \"claim\": \"Establishing that PLCXD2 expression is post-transcriptionally controlled by miR-378a-3p revealed a regulatory handle on PLCXD2 abundance, linking it to a ceRNA network with functional consequences in gastric cancer cells.\",\n      \"evidence\": \"RNA pulldown, luciferase reporter, and RNA immunoprecipitation assays with knockdown rescue in gastric cancer cell lines\",\n      \"pmids\": [\"35274046\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"PLCXD2 enzymatic activity was not directly measured in this context\",\n        \"Relevance of miR-378a-3p regulation to PLCXD2's normal physiological role (e.g., neuronal function) is unknown\",\n        \"Whether PLCXD2 expression changes drive the observed cancer phenotype or are correlative was not fully resolved\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identification of PLCXD2 as a constitutively active phospholipase C held in check by GPR158 within a postsynaptic complex established a new non-canonical receptor-to-PLC signaling mode that controls dendritic spine maturation and spine apparatus incorporation.\",\n      \"evidence\": \"Co-immunoprecipitation, sparse in vivo genetic loss-of-function manipulations in mouse cortical neurons with structural and functional spine maturation readouts; HSPG-binding modulation of the complex\",\n      \"pmids\": [\"40393451\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Direct enzymatic reconstitution of PLCXD2 constitutive PLC activity in vitro has not been described\",\n        \"The specific phosphoinositide substrate preference and lipid products of PLCXD2 remain uncharacterized\",\n        \"Structural basis of how GPR158 restrains PLCXD2 catalytic activity is unknown\",\n        \"Identity of the HSPG ligands and the biophysical mechanism by which they modulate the GPR158-PLCXD2 interaction are not resolved\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key open questions include the atomic-level structure of the GPR158–PLCXD2 complex, the substrate specificity and catalytic mechanism of PLCXD2 in a reconstituted system, and whether this signaling axis operates outside the nervous system.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No reconstituted enzymatic assay for PLCXD2 PLC activity\",\n        \"No structural model of the GPR158–PLCXD2 complex\",\n        \"Functional significance in non-neuronal tissues remains unexplored\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [\n      \"GPR158-PLCXD2 postsynaptic complex\"\n    ],\n    \"partners\": [\n      \"GPR158\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"PLCXD2 is a constitutively active phospholipase C family member that functions as a postsynaptic effector controlling spine apparatus abundance and dendritic spine maturation in cortical neurons. PLCXD2 forms a signaling complex with the GPCR-like receptor GPR158, which directly restrains PLCXD2 enzymatic activity; loss of GPR158 leads to unrestrained PLCXD2 activity, impeding spine apparatus incorporation into dendritic spines and disrupting both structural and functional spine maturation [PMID:40393451]. Extracellular heparan sulfate proteoglycans modulate the GPR158–PLCXD2 interaction, providing spatiotemporal control that bypasses canonical G-protein-mediated PLC regulation [PMID:40393451]. In gastric cancer cells, PLCXD2 protein levels are post-transcriptionally suppressed by miR-378a-3p within the ACTA2-AS1 ceRNA axis, and PLCXD2 expression suppresses malignant phenotypes including proliferation, migration, and epithelial-mesenchymal transition [PMID:35274046].\",\n  \"teleology\": [\n    {\n      \"year\": 2022,\n      \"claim\": \"Identification of PLCXD2 as a functionally relevant target downstream of a non-coding RNA regulatory axis in cancer cells established that PLCXD2 protein levels are post-transcriptionally controlled by miR-378a-3p and that PLCXD2 expression suppresses proliferative and invasive phenotypes in gastric cancer.\",\n      \"evidence\": \"Luciferase reporter assays, RNA immunoprecipitation, siRNA knockdown with proliferation/migration/invasion readouts in gastric cancer cell lines\",\n      \"pmids\": [\"35274046\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No direct measurement of PLCXD2 phospholipase activity in cancer cells\",\n        \"Single-lab study without independent replication\",\n        \"Whether the tumor-suppressive role depends on catalytic activity versus scaffolding is unknown\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Discovery that PLCXD2 is a constitutively active PLC restrained by GPR158 in a postsynaptic complex resolved how neurons control PLCXD2 enzymatic output and linked its unrestrained activity to defective spine apparatus dynamics and impaired dendritic spine maturation.\",\n      \"evidence\": \"In vivo sparse genetic loss-of-function in mouse cortical neurons, co-immunoprecipitation of GPR158–PLCXD2 complex, spine apparatus imaging and functional spine maturation readouts\",\n      \"pmids\": [\"40393451\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The lipid substrate specificity and catalytic products of PLCXD2 have not been biochemically defined\",\n        \"No structural model of the GPR158–PLCXD2 complex exists\",\n        \"Whether PLCXD2 functions in non-neuronal postmitotic cells through a similar GPR158-dependent mechanism is unknown\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The finding that extracellular HSPGs modulate the GPR158–PLCXD2 interaction revealed a non-canonical GPCR-to-PLC signaling pathway that bypasses classical G-protein intermediates, suggesting spatiotemporal regulation of PLCXD2 by the extracellular matrix.\",\n      \"evidence\": \"Biochemical binding assays and in vivo functional assays examining HSPG modulation of GPR158–PLCXD2 interaction in mouse cortical neurons\",\n      \"pmids\": [\"40393451\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The specific HSPG species and binding domains involved are not defined\",\n        \"Quantitative biochemistry of HSPG-dependent inhibition kinetics is lacking\",\n        \"Whether HSPG modulation is activity-dependent or developmentally programmed is unresolved\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The substrate specificity, catalytic mechanism, and lipid products of PLCXD2 remain undefined, and the structural basis for GPR158-mediated inhibition of its constitutive activity has not been determined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No in vitro enzymatic reconstitution with defined substrates has been reported\",\n        \"No crystal or cryo-EM structure of PLCXD2 alone or in complex with GPR158 exists\",\n        \"Downstream signaling consequences of PLCXD2 catalytic products at synapses are unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"GPR158\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}