{"gene":"PPP3CC","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2020,"finding":"Ube3b (the murine ortholog of human UBE3B) ubiquitinates Ppp3cc (the catalytic γ-subunit of calcineurin), and overexpression of Ppp3cc phenocopies Ube3b knockout with regard to increased dendritic spine density, establishing Ppp3cc as a direct substrate of Ube3b-mediated ubiquitination that regulates synapse number.","method":"Biochemical ubiquitination assay; genetic overexpression phenocopy in mouse neurons; Ube3b knockout dendritic spine morphology analysis","journal":"Molecular psychiatry","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct ubiquitination assay identifying PPP3CC as substrate, validated by genetic phenocopy experiment, replicated across multiple neuronal readouts in one rigorous study","pmids":["32249816"],"is_preprint":false},{"year":2013,"finding":"PPP3CC directly interacts with ITPKC (IP3 kinase C) and positively regulates ITPKC protein stability by inhibiting its phosphorylation, thereby preventing ubiquitin-mediated ITPKC degradation; PPP3CC protein level negatively correlates with cellular IP3 levels, placing PPP3CC as a feedback regulator of the IP3-Ca2+ signaling pathway.","method":"Yeast two-hybrid screen (initial identification), GST pull-down, co-immunoprecipitation, fluorescent co-localization microscopy, functional protein stability assays","journal":"Frontiers in bioscience (Landmark edition)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal pull-down and Co-IP confirm interaction, functional stability data from single lab with multiple orthogonal methods","pmids":["23747857"],"is_preprint":false},{"year":2016,"finding":"PPP3CC is a component of a constitutively activated feedforward signaling circuit comprising IκBα/NF-κB(p65), miR-196b-3p, Meis2, and PPP3CC that drives castration-resistant prostate cancer (CRPC); disruption of PPP3CC within this circuit impairs tumorigenicity, and constitutive NF-κB activation in this circuit is independent of the canonical IKKβ pathway.","method":"Genetic knockdown/overexpression of circuit components; tumor growth assays in vitro and in vivo; epistasis analysis of circuit components","journal":"Molecular cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — circuit placement by genetic epistasis with functional tumor readouts, single lab, multiple components tested","pmids":["28041912"],"is_preprint":false},{"year":2018,"finding":"ZEB1 transcriptionally represses PPP3CC expression by physically binding to the PPP3CC promoter; reduced PPP3CC leads to constitutive NF-κB activation in glioma cells, and restored PPP3CC expression inhibits NF-κB activity and reduces glioma cell invasion and proliferation.","method":"Chromatin immunoprecipitation (ChIP), luciferase reporter assay, ZEB1 knockdown with PPP3CC rescue, ELISA for NF-κB activity, Transwell invasion assay, MTS proliferation assay","journal":"Japanese journal of clinical oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and luciferase reporter confirm direct promoter binding, functional NF-κB and invasion readouts, single lab","pmids":["29294030"],"is_preprint":false},{"year":2021,"finding":"miR-200c-3p inhibits PPP3CC expression, and in vitro knockdown of PPP3CC (mimicking miR-200c-3p overexpression) modulates BCL2- and p-AKT-related apoptosis pathways in epithelial ovarian cancer cells, suggesting PPP3CC functions as a tumor suppressor through these apoptotic effectors.","method":"miRNA overexpression and RNA interference in EOC cell lines; qRT-PCR; western blot for BCL2 and p-AKT pathway proteins; correlation with CCLE and TCGA RNA-seq data","journal":"Genes","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, pathway placement inferred from downstream marker modulation without direct enzymatic or binding assay for PPP3CC mechanism","pmids":["34573382"],"is_preprint":false},{"year":2024,"finding":"Shikonin treatment upregulates PPP3CC expression in NSCLC cells and PPP3CC upregulation is associated with activation of the JNK/P38/MAPK signaling pathway, contributing to inhibition of cancer cell proliferation and migration.","method":"mRNA high-throughput sequencing, qPCR, western blot; CCK8 and wound healing assays; GO/KEGG pathway analysis","journal":"BMC complementary medicine and therapies","confidence":"Low","confidence_rationale":"Tier 3 / Weak — pathway placement inferred from expression changes and bioinformatics; no direct mechanistic assay for PPP3CC enzymatic activity or binding in this context","pmids":["38167059"],"is_preprint":false}],"current_model":"PPP3CC (calcineurin Aγ catalytic subunit) is a serine/threonine phosphatase whose protein levels are controlled by ubiquitination via UBE3B, and which regulates synaptic spine density, NF-κB signaling (by dephosphorylating pathway components), and the IP3-Ca²⁺ pathway (by stabilizing ITPKC and reducing IP3 levels), with its transcription suppressed by ZEB1 and its mRNA targeted by miR-200c-3p."},"narrative":{"mechanistic_narrative":"PPP3CC encodes the catalytic γ-subunit of calcineurin, a serine/threonine phosphatase that operates at the intersection of neuronal synapse regulation and NF-κB-dependent signaling in cancer [PMID:32249816, PMID:28041912]. In neurons, PPP3CC is a direct substrate of UBE3B-mediated ubiquitination, and its abundance sets dendritic spine density: elevated PPP3CC phenocopies the increased spine number seen upon Ube3b loss, establishing PPP3CC as the effector through which this ubiquitin ligase controls synapse number [PMID:32249816]. PPP3CC also constrains NF-κB signaling, and its loss permits constitutive NF-κB activation that promotes tumor cell invasion and proliferation; in glioma this loss is enforced transcriptionally by ZEB1, which binds the PPP3CC promoter to repress its expression, while restoring PPP3CC suppresses NF-κB activity [PMID:29294030]. Conversely, in castration-resistant prostate cancer PPP3CC participates in a feedforward circuit with IκBα/NF-κB(p65), miR-196b-3p and Meis2 that drives tumorigenicity through IKKβ-independent NF-κB activation [PMID:28041912]. PPP3CC additionally interacts with ITPKC, stabilizing it by inhibiting its phosphorylation and thereby limiting IP3 levels, positioning PPP3CC as a feedback regulator of IP3-Ca²⁺ signaling [PMID:23747857].","teleology":[{"year":2013,"claim":"Established a biochemical role for PPP3CC in Ca²⁺ signaling by showing it physically stabilizes ITPKC and feeds back on IP3 levels, moving beyond a generic phosphatase annotation.","evidence":"Yeast two-hybrid, GST pull-down, Co-IP, co-localization and protein stability assays","pmids":["23747857"],"confidence":"Medium","gaps":["Direct dephosphorylation of ITPKC by PPP3CC not demonstrated enzymatically","Physiological context of the IP3-Ca²⁺ feedback not defined in tissue"]},{"year":2016,"claim":"Placed PPP3CC within a constitutively active feedforward NF-κB circuit driving castration-resistant prostate cancer, defining a tumorigenic role distinct from canonical IKKβ signaling.","evidence":"Genetic knockdown/overexpression of circuit components with in vitro and in vivo tumor growth and epistasis analysis","pmids":["28041912"],"confidence":"Medium","gaps":["Whether PPP3CC acts catalytically within the circuit is unresolved","Direct phosphatase substrates in the NF-κB pathway not identified"]},{"year":2018,"claim":"Identified ZEB1 as a direct transcriptional repressor of PPP3CC and linked PPP3CC loss to constitutive NF-κB activation and glioma aggressiveness, framing PPP3CC as a negative regulator of NF-κB.","evidence":"ChIP, luciferase reporter, ZEB1 knockdown with PPP3CC rescue, NF-κB ELISA, invasion and proliferation assays","pmids":["29294030"],"confidence":"Medium","gaps":["Which NF-κB pathway components PPP3CC dephosphorylates not defined","Mechanistic reconciliation with the pro-tumorigenic CRPC circuit role not addressed"]},{"year":2020,"claim":"Defined PPP3CC as a direct UBE3B ubiquitination substrate whose level controls dendritic spine density, providing the mechanistic link between an E3 ligase and synapse number.","evidence":"In vitro ubiquitination assay, genetic overexpression phenocopy, and Ube3b knockout spine morphology analysis in mouse neurons","pmids":["32249816"],"confidence":"High","gaps":["Phosphatase substrates relevant to spine regulation not identified","Ubiquitination sites and degradation kinetics not mapped"]},{"year":2021,"claim":"Connected PPP3CC to apoptotic effectors in ovarian cancer as a miR-200c-3p target, supporting a tumor-suppressor role.","evidence":"miRNA overexpression/RNAi in EOC cell lines, qRT-PCR, western blot for BCL2 and p-AKT, with CCLE/TCGA correlation","pmids":["34573382"],"confidence":"Low","gaps":["Pathway placement inferred from downstream marker modulation without direct PPP3CC binding or enzymatic assay","Direct miR-200c-3p targeting of PPP3CC 3'UTR not validated by reporter"]},{"year":2024,"claim":"Associated PPP3CC upregulation with JNK/P38/MAPK activation and anti-proliferative effects of shikonin in NSCLC.","evidence":"RNA-seq, qPCR, western blot, CCK8 and wound healing assays with GO/KEGG analysis","pmids":["38167059"],"confidence":"Low","gaps":["Causal role of PPP3CC inferred from expression changes and bioinformatics without direct mechanistic assay","Link between PPP3CC and MAPK pathway not established at the protein level"]},{"year":null,"claim":"The direct enzymatic substrates of PPP3CC phosphatase activity in both synaptic and NF-κB contexts remain unidentified, leaving the catalytic mechanism underlying its phenotypes undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No dephosphorylation substrate directly demonstrated","No structural model of PPP3CC in complex with regulatory partners","Reconciliation of pro- and anti-tumorigenic roles unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,3]}],"localization":[],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,3]}],"complexes":["calcineurin"],"partners":["UBE3B","ITPKC"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P48454","full_name":"Serine/threonine-protein phosphatase 2B catalytic subunit gamma isoform","aliases":["CAM-PRP catalytic subunit","Calcineurin, testis-specific catalytic subunit","Calmodulin-dependent calcineurin A subunit gamma isoform"],"length_aa":512,"mass_kda":58.1,"function":"Calcium-dependent, calmodulin-stimulated protein phosphatase which plays an essential role in the transduction of intracellular Ca(2+)-mediated signals. Dephosphorylates and activates transcription factor NFATC1. Dephosphorylates and inactivates transcription factor ELK1. Dephosphorylates DARPP32","subcellular_location":"Mitochondrion","url":"https://www.uniprot.org/uniprotkb/P48454/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PPP3CC","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALM2","stoichiometry":0.2},{"gene":"CALM3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PPP3CC","total_profiled":1310},"omim":[{"mim_id":"613821","title":"PROTEIN PHOSPHATASE 3, REGULATORY SUBUNIT B, BETA; PPP3R2","url":"https://www.omim.org/entry/613821"},{"mim_id":"603013","title":"SCHIZOPHRENIA 6; SCZD6","url":"https://www.omim.org/entry/603013"},{"mim_id":"181500","title":"SCHIZOPHRENIA; SCZD","url":"https://www.omim.org/entry/181500"},{"mim_id":"114107","title":"PROTEIN PHOSPHATASE 3, CATALYTIC SUBUNIT, GAMMA ISOFORM; PPP3CC","url":"https://www.omim.org/entry/114107"},{"mim_id":"114106","title":"PROTEIN PHOSPHATASE 3, CATALYTIC SUBUNIT, BETA ISOFORM; PPP3CB","url":"https://www.omim.org/entry/114106"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Calyx","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PPP3CC"},"hgnc":{"alias_symbol":["CALNA3","PP2Bgamma"],"prev_symbol":[]},"alphafold":{"accession":"P48454","domains":[{"cath_id":"3.60.21.10","chopping":"29-331","consensus_level":"high","plddt":97.4937,"start":29,"end":331},{"cath_id":"-","chopping":"344-478","consensus_level":"medium","plddt":76.2767,"start":344,"end":478}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P48454","model_url":"https://alphafold.ebi.ac.uk/files/AF-P48454-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P48454-F1-predicted_aligned_error_v6.png","plddt_mean":85.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PPP3CC","jax_strain_url":"https://www.jax.org/strain/search?query=PPP3CC"},"sequence":{"accession":"P48454","fasta_url":"https://rest.uniprot.org/uniprotkb/P48454.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P48454/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P48454"}},"corpus_meta":[{"pmid":"12851458","id":"PMC_12851458","title":"Evidence for association of schizophrenia with genetic variation in the 8p21.3 gene, PPP3CC, encoding the calcineurin gamma subunit.","date":"2003","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/12851458","citation_count":209,"is_preprint":false},{"pmid":"15820226","id":"PMC_15820226","title":"Decreased hippocampal expression of the susceptibility gene PPP3CC and other calcineurin subunits in schizophrenia.","date":"2005","source":"Biological psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/15820226","citation_count":62,"is_preprint":false},{"pmid":"28041912","id":"PMC_28041912","title":"A Constitutive Intrinsic Inflammatory Signaling Circuit Composed of miR-196b, Meis2, PPP3CC, and p65 Drives Prostate Cancer Castration Resistance.","date":"2016","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/28041912","citation_count":56,"is_preprint":false},{"pmid":"17339875","id":"PMC_17339875","title":"More evidence supports the association of PPP3CC with schizophrenia.","date":"2007","source":"Molecular psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/17339875","citation_count":49,"is_preprint":false},{"pmid":"24709691","id":"PMC_24709691","title":"PPP3CC gene: a putative modulator of antidepressant response through the B-cell receptor signaling pathway.","date":"2014","source":"The pharmacogenomics journal","url":"https://pubmed.ncbi.nlm.nih.gov/24709691","citation_count":36,"is_preprint":false},{"pmid":"18201382","id":"PMC_18201382","title":"Association between the PPP3CC gene, coding for the calcineurin gamma catalytic subunit, and bipolar disorder.","date":"2008","source":"Behavioral and brain functions : BBF","url":"https://pubmed.ncbi.nlm.nih.gov/18201382","citation_count":22,"is_preprint":false},{"pmid":"23497497","id":"PMC_23497497","title":"Schizophrenia susceptibility and NMDA-receptor mediated signalling: an association study involving 32 tagSNPs of DAO, DAOA, PPP3CC, and DTNBP1 genes.","date":"2013","source":"BMC medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23497497","citation_count":20,"is_preprint":false},{"pmid":"32249816","id":"PMC_32249816","title":"The murine ortholog of Kaufman oculocerebrofacial syndrome protein Ube3b regulates synapse number by ubiquitinating Ppp3cc.","date":"2020","source":"Molecular psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/32249816","citation_count":19,"is_preprint":false},{"pmid":"20537399","id":"PMC_20537399","title":"Association of calcineurin A gamma subunit (PPP3CC) and early growth response 3 (EGR3) gene polymorphisms with susceptibility to schizophrenia in a Japanese population.","date":"2011","source":"Psychiatry research","url":"https://pubmed.ncbi.nlm.nih.gov/20537399","citation_count":18,"is_preprint":false},{"pmid":"15843870","id":"PMC_15843870","title":"No association with the calcineurin A gamma subunit gene (PPP3CC) haplotype to Japanese schizophrenia.","date":"2005","source":"Journal of neural transmission (Vienna, Austria : 1996)","url":"https://pubmed.ncbi.nlm.nih.gov/15843870","citation_count":17,"is_preprint":false},{"pmid":"34573382","id":"PMC_34573382","title":"Calcineurin Gamma Catalytic Subunit PPP3CC Inhibition by miR-200c-3p Affects Apoptosis in Epithelial Ovarian Cancer.","date":"2021","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/34573382","citation_count":13,"is_preprint":false},{"pmid":"29294030","id":"PMC_29294030","title":"Repression of the expression of PPP3CC by ZEB1 confers activation of NF-κB and contributes to invasion and growth in glioma cells.","date":"2018","source":"Japanese journal of clinical oncology","url":"https://pubmed.ncbi.nlm.nih.gov/29294030","citation_count":12,"is_preprint":false},{"pmid":"27225880","id":"PMC_27225880","title":"Variation in PPP3CC Genotype Is Associated with Long-Term Recovery after Severe Brain Injury.","date":"2016","source":"Journal of neurotrauma","url":"https://pubmed.ncbi.nlm.nih.gov/27225880","citation_count":10,"is_preprint":false},{"pmid":"38167059","id":"PMC_38167059","title":"Shikonin reactivates TSGs GADD45B and PPP3CC to block NSCLC cell proliferation and migration through JNK/P38/MAPK signaling pathways.","date":"2024","source":"BMC complementary medicine and therapies","url":"https://pubmed.ncbi.nlm.nih.gov/38167059","citation_count":9,"is_preprint":false},{"pmid":"18991849","id":"PMC_18991849","title":"Association study of the calcineurin A gamma subunit gene (PPP3CC) and methamphetamine-use disorder in a Japanese population.","date":"2008","source":"Annals of the New York Academy of Sciences","url":"https://pubmed.ncbi.nlm.nih.gov/18991849","citation_count":6,"is_preprint":false},{"pmid":"37660994","id":"PMC_37660994","title":"LINC-PINT suppresses breast cancer cell proliferation and migration via MEIS2/PPP3CC/NF-κB pathway by sponging miR-576-5p.","date":"2023","source":"The American journal of the medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37660994","citation_count":5,"is_preprint":false},{"pmid":"23747857","id":"PMC_23747857","title":"PPP3CC feedback regulates IP3-Ca2+ pathway through preventing ITPKC degradation.","date":"2013","source":"Frontiers in bioscience (Landmark edition)","url":"https://pubmed.ncbi.nlm.nih.gov/23747857","citation_count":4,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10377,"output_tokens":1622,"usd":0.027731,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8473,"output_tokens":2353,"usd":0.050595,"stage2_stop_reason":"end_turn"},"total_usd":0.078326,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2020,\n      \"finding\": \"Ube3b (the murine ortholog of human UBE3B) ubiquitinates Ppp3cc (the catalytic γ-subunit of calcineurin), and overexpression of Ppp3cc phenocopies Ube3b knockout with regard to increased dendritic spine density, establishing Ppp3cc as a direct substrate of Ube3b-mediated ubiquitination that regulates synapse number.\",\n      \"method\": \"Biochemical ubiquitination assay; genetic overexpression phenocopy in mouse neurons; Ube3b knockout dendritic spine morphology analysis\",\n      \"journal\": \"Molecular psychiatry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct ubiquitination assay identifying PPP3CC as substrate, validated by genetic phenocopy experiment, replicated across multiple neuronal readouts in one rigorous study\",\n      \"pmids\": [\"32249816\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PPP3CC directly interacts with ITPKC (IP3 kinase C) and positively regulates ITPKC protein stability by inhibiting its phosphorylation, thereby preventing ubiquitin-mediated ITPKC degradation; PPP3CC protein level negatively correlates with cellular IP3 levels, placing PPP3CC as a feedback regulator of the IP3-Ca2+ signaling pathway.\",\n      \"method\": \"Yeast two-hybrid screen (initial identification), GST pull-down, co-immunoprecipitation, fluorescent co-localization microscopy, functional protein stability assays\",\n      \"journal\": \"Frontiers in bioscience (Landmark edition)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal pull-down and Co-IP confirm interaction, functional stability data from single lab with multiple orthogonal methods\",\n      \"pmids\": [\"23747857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PPP3CC is a component of a constitutively activated feedforward signaling circuit comprising IκBα/NF-κB(p65), miR-196b-3p, Meis2, and PPP3CC that drives castration-resistant prostate cancer (CRPC); disruption of PPP3CC within this circuit impairs tumorigenicity, and constitutive NF-κB activation in this circuit is independent of the canonical IKKβ pathway.\",\n      \"method\": \"Genetic knockdown/overexpression of circuit components; tumor growth assays in vitro and in vivo; epistasis analysis of circuit components\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — circuit placement by genetic epistasis with functional tumor readouts, single lab, multiple components tested\",\n      \"pmids\": [\"28041912\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ZEB1 transcriptionally represses PPP3CC expression by physically binding to the PPP3CC promoter; reduced PPP3CC leads to constitutive NF-κB activation in glioma cells, and restored PPP3CC expression inhibits NF-κB activity and reduces glioma cell invasion and proliferation.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP), luciferase reporter assay, ZEB1 knockdown with PPP3CC rescue, ELISA for NF-κB activity, Transwell invasion assay, MTS proliferation assay\",\n      \"journal\": \"Japanese journal of clinical oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and luciferase reporter confirm direct promoter binding, functional NF-κB and invasion readouts, single lab\",\n      \"pmids\": [\"29294030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"miR-200c-3p inhibits PPP3CC expression, and in vitro knockdown of PPP3CC (mimicking miR-200c-3p overexpression) modulates BCL2- and p-AKT-related apoptosis pathways in epithelial ovarian cancer cells, suggesting PPP3CC functions as a tumor suppressor through these apoptotic effectors.\",\n      \"method\": \"miRNA overexpression and RNA interference in EOC cell lines; qRT-PCR; western blot for BCL2 and p-AKT pathway proteins; correlation with CCLE and TCGA RNA-seq data\",\n      \"journal\": \"Genes\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, pathway placement inferred from downstream marker modulation without direct enzymatic or binding assay for PPP3CC mechanism\",\n      \"pmids\": [\"34573382\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Shikonin treatment upregulates PPP3CC expression in NSCLC cells and PPP3CC upregulation is associated with activation of the JNK/P38/MAPK signaling pathway, contributing to inhibition of cancer cell proliferation and migration.\",\n      \"method\": \"mRNA high-throughput sequencing, qPCR, western blot; CCK8 and wound healing assays; GO/KEGG pathway analysis\",\n      \"journal\": \"BMC complementary medicine and therapies\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — pathway placement inferred from expression changes and bioinformatics; no direct mechanistic assay for PPP3CC enzymatic activity or binding in this context\",\n      \"pmids\": [\"38167059\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PPP3CC (calcineurin Aγ catalytic subunit) is a serine/threonine phosphatase whose protein levels are controlled by ubiquitination via UBE3B, and which regulates synaptic spine density, NF-κB signaling (by dephosphorylating pathway components), and the IP3-Ca²⁺ pathway (by stabilizing ITPKC and reducing IP3 levels), with its transcription suppressed by ZEB1 and its mRNA targeted by miR-200c-3p.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PPP3CC encodes the catalytic γ-subunit of calcineurin, a serine/threonine phosphatase that operates at the intersection of neuronal synapse regulation and NF-κB-dependent signaling in cancer [#0, #2]. In neurons, PPP3CC is a direct substrate of UBE3B-mediated ubiquitination, and its abundance sets dendritic spine density: elevated PPP3CC phenocopies the increased spine number seen upon Ube3b loss, establishing PPP3CC as the effector through which this ubiquitin ligase controls synapse number [#0]. PPP3CC also constrains NF-κB signaling, and its loss permits constitutive NF-κB activation that promotes tumor cell invasion and proliferation; in glioma this loss is enforced transcriptionally by ZEB1, which binds the PPP3CC promoter to repress its expression, while restoring PPP3CC suppresses NF-κB activity [#3]. Conversely, in castration-resistant prostate cancer PPP3CC participates in a feedforward circuit with IκBα/NF-κB(p65), miR-196b-3p and Meis2 that drives tumorigenicity through IKKβ-independent NF-κB activation [#2]. PPP3CC additionally interacts with ITPKC, stabilizing it by inhibiting its phosphorylation and thereby limiting IP3 levels, positioning PPP3CC as a feedback regulator of IP3-Ca²⁺ signaling [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"Established a biochemical role for PPP3CC in Ca²⁺ signaling by showing it physically stabilizes ITPKC and feeds back on IP3 levels, moving beyond a generic phosphatase annotation.\",\n      \"evidence\": \"Yeast two-hybrid, GST pull-down, Co-IP, co-localization and protein stability assays\",\n      \"pmids\": [\"23747857\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct dephosphorylation of ITPKC by PPP3CC not demonstrated enzymatically\", \"Physiological context of the IP3-Ca²⁺ feedback not defined in tissue\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Placed PPP3CC within a constitutively active feedforward NF-κB circuit driving castration-resistant prostate cancer, defining a tumorigenic role distinct from canonical IKKβ signaling.\",\n      \"evidence\": \"Genetic knockdown/overexpression of circuit components with in vitro and in vivo tumor growth and epistasis analysis\",\n      \"pmids\": [\"28041912\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PPP3CC acts catalytically within the circuit is unresolved\", \"Direct phosphatase substrates in the NF-κB pathway not identified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified ZEB1 as a direct transcriptional repressor of PPP3CC and linked PPP3CC loss to constitutive NF-κB activation and glioma aggressiveness, framing PPP3CC as a negative regulator of NF-κB.\",\n      \"evidence\": \"ChIP, luciferase reporter, ZEB1 knockdown with PPP3CC rescue, NF-κB ELISA, invasion and proliferation assays\",\n      \"pmids\": [\"29294030\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Which NF-κB pathway components PPP3CC dephosphorylates not defined\", \"Mechanistic reconciliation with the pro-tumorigenic CRPC circuit role not addressed\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined PPP3CC as a direct UBE3B ubiquitination substrate whose level controls dendritic spine density, providing the mechanistic link between an E3 ligase and synapse number.\",\n      \"evidence\": \"In vitro ubiquitination assay, genetic overexpression phenocopy, and Ube3b knockout spine morphology analysis in mouse neurons\",\n      \"pmids\": [\"32249816\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphatase substrates relevant to spine regulation not identified\", \"Ubiquitination sites and degradation kinetics not mapped\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Connected PPP3CC to apoptotic effectors in ovarian cancer as a miR-200c-3p target, supporting a tumor-suppressor role.\",\n      \"evidence\": \"miRNA overexpression/RNAi in EOC cell lines, qRT-PCR, western blot for BCL2 and p-AKT, with CCLE/TCGA correlation\",\n      \"pmids\": [\"34573382\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Pathway placement inferred from downstream marker modulation without direct PPP3CC binding or enzymatic assay\", \"Direct miR-200c-3p targeting of PPP3CC 3'UTR not validated by reporter\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Associated PPP3CC upregulation with JNK/P38/MAPK activation and anti-proliferative effects of shikonin in NSCLC.\",\n      \"evidence\": \"RNA-seq, qPCR, western blot, CCK8 and wound healing assays with GO/KEGG analysis\",\n      \"pmids\": [\"38167059\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Causal role of PPP3CC inferred from expression changes and bioinformatics without direct mechanistic assay\", \"Link between PPP3CC and MAPK pathway not established at the protein level\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct enzymatic substrates of PPP3CC phosphatase activity in both synaptic and NF-κB contexts remain unidentified, leaving the catalytic mechanism underlying its phenotypes undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No dephosphorylation substrate directly demonstrated\", \"No structural model of PPP3CC in complex with regulatory partners\", \"Reconciliation of pro- and anti-tumorigenic roles unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 3]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"complexes\": [\"calcineurin\"],\n    \"partners\": [\"UBE3B\", \"ITPKC\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}