{"gene":"PPP3CB","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":1996,"finding":"PPP3CB (calcineurin A beta) forms a heterodimer with calcineurin B (PPP3R1), functioning as a calmodulin-regulated protein phosphatase (protein phosphatase-2B) that dephosphorylates NF-AT to regulate IL-2 gene transcription in T lymphocytes.","method":"Chromosomal localization combined with biochemical characterization of the calcineurin heterodimer","journal":"Cytogenetics and cell genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — established heterodimer composition and substrate (NF-AT) by biochemical characterization, but abstract does not detail direct in vitro reconstitution; replicated across the field","pmids":["8978785"],"is_preprint":false},{"year":2021,"finding":"PPP3CB promotes angiotensin II-induced vascular remodelling in vascular smooth muscle cells (VSMCs) by enhancing HB-EGF secretion, EGFR activation, and downstream TGFβ-CTGF signalling, leading to increased collagen expression and VSMC migration; PPP3CB KO mice showed reduced aortic media thickening and lower blood pressure upon AngII treatment.","method":"PPP3CB knockout mouse model, pharmacological inhibitors in VSMCs, wound healing assays, ELISA, Western blot, qPCR, next-generation sequencing of aortic tissue","journal":"Acta physiologica (Oxford, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with defined cellular phenotypes and pharmacological pathway dissection, single lab but multiple orthogonal methods","pmids":["34228904"],"is_preprint":false},{"year":2024,"finding":"Upon lysosomal damage, PPP3CB is recruited by LGALS3 (galectin-3) and acts as a bridge for SMURF1 recruitment; PPP3CB dephosphorylates LGALS3 to promote its open conformer formation. SMURF1 then ubiquitinates PPP3CB at lysine 146 with K63-linked chains, enhancing PPP3CB's recruitment of TFEB. TFEB directly interacts with both PPP3CB and PPP3R1 to facilitate conformational correction of TFEB for its nuclear translocation and transcriptional activation of autophagy-related genes.","method":"Co-immunoprecipitation, site-directed mutagenesis (K146 ubiquitination site), SMURF1 knockdown/knockout, calcium stimulation assays, lysosomal damage models","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — reciprocal Co-IP, specific lysine mutagenesis, genetic KO with defined mechanistic pathway, multiple orthogonal methods in single study","pmids":["39324484"],"is_preprint":false},{"year":2019,"finding":"PPP3CB phosphatase activity is required to maintain epithelial marker E-cadherin expression and suppress vimentin upregulation (EMT); deletion of the phosphatase domain abolishes the effects of PPP3CB on E-cadherin expression, cell migration, and proliferation in G401 kidney cells.","method":"PPP3CB knockdown and overexpression in G401 cells, phosphatase domain deletion mutant, migration assays, in vitro and in vivo tumor growth assays","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain deletion mutagenesis combined with KD/OE and defined phenotypic readouts, single lab","pmids":["30641937"],"is_preprint":false},{"year":2024,"finding":"PPP3CB interacts with PDHK1 (pyruvate dehydrogenase kinase 1) and inhibits its protein stabilization, thereby suppressing glycolysis (Warburg effect) and reducing glucose uptake and lactate production in bladder cancer cells.","method":"Co-immunoprecipitation, PPP3CB knockdown, glucose/lactate assays, Western blot for PDHK1 and p-PDHA1, in vivo nude mouse tumorigenesis model","journal":"Frontiers in bioscience (Landmark edition)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP establishing interaction plus metabolic functional assays, single lab, multiple orthogonal methods","pmids":["38420800"],"is_preprint":false},{"year":2024,"finding":"EGFR TKI treatment increases cytosolic calcium and activates a PPP3CB (calcineurin)/MEK/ERK signalling pathway that prevents apoptosis in resistant NSCLC cells; siRNA neutralization of PPP3CB or calcineurin inhibition by cyclosporin A restores apoptosis sensitivity to EGFR TKIs.","method":"siRNA knockdown, cyclosporin A pharmacological inhibition, in vitro apoptosis assays, in vivo mouse models, calcium level measurements","journal":"Life science alliance","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic (siRNA) and pharmacological pathway dissection with defined apoptosis readout in vitro and in vivo, single lab","pmids":["39353739"],"is_preprint":false},{"year":2025,"finding":"PPP3CB interacts with ATOH8 and promotes its nuclear translocation in pancreatic cancer cells; nuclear ATOH8 binds the Sp1 promoter to transcriptionally suppress Sp1 expression, thereby inhibiting pancreatic cancer metastasis.","method":"LC-MS/MS (mass spectrometry), Co-IP, immunofluorescence/confocal microscopy, ChIP-seq, luciferase reporter assay, in vivo xenograft models","journal":"Life sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (MS, Co-IP, ChIP-seq, reporter assay) in a single study establishing a novel interaction and downstream transcriptional mechanism","pmids":["40222712"],"is_preprint":false},{"year":2026,"finding":"PPP3CB (but not PPP3CA) is the specific calcineurin catalytic isoform that interacts with TFEB; the LxVP motif-binding site of PPP3CB is required for TFEB interaction and activation. MCOLN1 (lysosomal calcium channel) activates PPP3CB to dephosphorylate TFEB, promoting TFEB nuclear translocation and autophagic flux in neurons under ischemic conditions.","method":"PPP3CB/PPP3CA isoform-specific knockdown, YLAVP peptide (LxVP-blocking), MCOLN1 inhibitor (ML-SI1) and agonist (ML-SA1), TFEB transcriptional activity assays, autophagic flux assays, neuronal death assays under OGD","journal":"Acta pharmacologica Sinica","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — isoform-specific genetic knockdown with peptide-based motif blocking and pharmacological rescue, multiple orthogonal functional readouts establishing MCOLN1-PPP3CB-TFEB pathway","pmids":["41876744"],"is_preprint":false}],"current_model":"PPP3CB (calcineurin A beta) is the catalytic subunit of a Ca2+/calmodulin-regulated protein phosphatase that, upon calcium influx (via MCOLN1 or other channels), dephosphorylates substrates including TFEB (via its LxVP-binding site) to drive nuclear translocation and autophagic/lysosomal gene transcription; its activity is regulated by K63-linked ubiquitination at K146 by SMURF1 (recruited through LGALS3) and it operates in multiple signalling contexts—including NF-AT dephosphorylation in T cells, HB-EGF/EGFR-TGFβ-CTGF-driven vascular remodelling, calcineurin/MEK/ERK-mediated TKI resistance in lung cancer, EMT regulation via phosphatase-dependent maintenance of E-cadherin, PDHK1 destabilization to suppress glycolysis, and promotion of ATOH8 nuclear translocation to transcriptionally inhibit Sp1 in pancreatic cancer."},"narrative":{"mechanistic_narrative":"PPP3CB (calcineurin A beta) is the catalytic subunit of a Ca2+/calmodulin-regulated serine/threonine protein phosphatase (protein phosphatase-2B) that operates downstream of calcium signaling to control gene-regulatory programs in immune, autophagic, and oncogenic contexts [PMID:8978785, PMID:41876744]. It functions as a heterodimer with the calcineurin B regulatory subunit PPP3R1 and, in T lymphocytes, dephosphorylates NF-AT to regulate IL-2 transcription [PMID:8978785]. A major characterized output is the control of TFEB-driven autophagic/lysosomal transcription: PPP3CB is the specific calcineurin catalytic isoform that engages TFEB through its LxVP motif-binding site, and lysosomal calcium release via the channel MCOLN1 activates PPP3CB to dephosphorylate TFEB and drive its nuclear translocation and autophagic flux [PMID:41876744]. Upon lysosomal damage PPP3CB is recruited by galectin-3 (LGALS3), which it dephosphorylates to promote the LGALS3 open conformer, and serves as a bridge for SMURF1, which ubiquitinates PPP3CB at K146 with K63-linked chains to enhance TFEB recruitment and activation by both PPP3CB and PPP3R1 [PMID:39324484]. Through its phosphatase activity PPP3CB also acts in disease-relevant signaling: it maintains E-cadherin and suppresses EMT in kidney tumor cells [PMID:30641937], destabilizes PDHK1 to suppress glycolysis in bladder cancer [PMID:38420800], promotes ATOH8 nuclear translocation to transcriptionally repress Sp1 and limit pancreatic cancer metastasis [PMID:40222712], drives a calcineurin/MEK/ERK pathway underlying EGFR-TKI resistance in NSCLC [PMID:39353739], and promotes angiotensin II-induced vascular remodelling via HB-EGF/EGFR-TGFβ-CTGF signaling [PMID:34228904].","teleology":[{"year":1996,"claim":"Established the basic identity of PPP3CB as a calmodulin-regulated phosphatase and its first substrate, defining its role in calcium-dependent immune gene transcription.","evidence":"Chromosomal localization with biochemical characterization of the calcineurin A beta/PPP3R1 heterodimer and NF-AT dephosphorylation","pmids":["8978785"],"confidence":"Medium","gaps":["No direct in vitro reconstitution detailed","Isoform-specific contribution versus PPP3CA not resolved","Structural basis of substrate recognition not defined"]},{"year":2019,"claim":"Showed PPP3CB phosphatase activity directly maintains epithelial identity, extending its role beyond immune signaling into EMT and tumor suppression.","evidence":"Knockdown/overexpression and phosphatase-domain deletion in G401 kidney cells with migration and tumor growth assays","pmids":["30641937"],"confidence":"Medium","gaps":["Direct phosphatase substrate maintaining E-cadherin not identified","Single cell-line context","Upstream calcium trigger not defined"]},{"year":2021,"claim":"Defined a physiological in vivo role for PPP3CB in vascular remodelling, linking it to a secreted growth-factor signaling cascade.","evidence":"PPP3CB knockout mice and VSMC assays with pharmacological pathway dissection of HB-EGF/EGFR-TGFβ-CTGF","pmids":["34228904"],"confidence":"Medium","gaps":["Direct phosphatase substrate connecting PPP3CB to HB-EGF secretion unknown","Mechanism of EGFR activation indirect","Single lab"]},{"year":2024,"claim":"Revealed a lysosomal-damage signaling hub in which PPP3CB is both a regulatory phosphatase for galectin-3 and a ubiquitination substrate that scaffolds TFEB activation.","evidence":"Reciprocal Co-IP, K146 site-directed mutagenesis, SMURF1 knockdown/knockout, calcium and lysosomal damage assays","pmids":["39324484"],"confidence":"High","gaps":["Structural basis of K63-ubiquitin-enhanced TFEB recruitment unresolved","How phosphatase activity and scaffolding roles are coordinated unclear","In vivo relevance not tested"]},{"year":2024,"claim":"Implicated PPP3CB in metabolic reprogramming by linking it to PDHK1 stability and glycolytic suppression.","evidence":"Co-IP, knockdown, glucose/lactate assays and nude-mouse tumorigenesis in bladder cancer cells","pmids":["38420800"],"confidence":"Medium","gaps":["Whether PDHK1 destabilization is phosphatase-dependent not established","Direct versus indirect interaction not distinguished","Single cancer context"]},{"year":2024,"claim":"Connected PPP3CB to therapy resistance, showing TKI-induced calcium activates a PPP3CB/MEK/ERK survival pathway.","evidence":"siRNA knockdown, cyclosporin A inhibition, apoptosis assays and mouse models with calcium measurements in NSCLC","pmids":["39353739"],"confidence":"Medium","gaps":["Direct PPP3CB substrate linking to MEK/ERK not identified","Mechanism of calcium elevation by TKI not defined","Clinical relevance untested"]},{"year":2025,"claim":"Identified a transcriptional axis in which PPP3CB promotes ATOH8 nuclear entry to repress Sp1 and limit metastasis.","evidence":"LC-MS/MS, Co-IP, confocal imaging, ChIP-seq, luciferase reporter and xenografts in pancreatic cancer","pmids":["40222712"],"confidence":"Medium","gaps":["Whether ATOH8 translocation requires PPP3CB dephosphorylation unclear","Direct ATOH8 phosphosite not mapped","Single tumor type"]},{"year":2026,"claim":"Established isoform specificity and the molecular interface for TFEB regulation, defining the MCOLN1-PPP3CB-TFEB autophagy pathway.","evidence":"PPP3CB/PPP3CA isoform-specific knockdown, LxVP-blocking YLAVP peptide, MCOLN1 inhibitor/agonist, TFEB activity and autophagic flux assays under OGD in neurons","pmids":["41876744"],"confidence":"High","gaps":["Structural detail of the LxVP-binding site engaging TFEB not solved","Basis of PPP3CB versus PPP3CA selectivity unknown","Relationship to the LGALS3/SMURF1 lysosomal pathway not integrated"]},{"year":null,"claim":"It remains unresolved how PPP3CB's phosphatase activity, scaffolding function, and ubiquitin-dependent regulation are mechanistically coordinated across its diverse signaling contexts, and which direct substrates underlie most of its disease phenotypes.","evidence":"","pmids":[],"confidence":"Medium","gaps":["Direct substrates for most cancer/vascular phenotypes unmapped","No structural model of substrate or LxVP recognition","Integration of distinct pathways into one regulatory logic absent"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,2,3,7]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,3,7]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5,7]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[6,7]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[2,7]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,5]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[3,4,5,6]}],"complexes":["calcineurin (PPP3CB-PPP3R1 heterodimer)"],"partners":["PPP3R1","TFEB","LGALS3","SMURF1","PDHK1","ATOH8","NFATC"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P16298","full_name":"Serine/threonine-protein phosphatase 2B catalytic subunit beta isoform","aliases":["CAM-PRP catalytic subunit","Calmodulin-dependent calcineurin A subunit beta isoform","CNA beta"],"length_aa":524,"mass_kda":59.0,"function":"Calcium-dependent, calmodulin-stimulated protein phosphatase which plays an essential role in the transduction of intracellular Ca(2+)-mediated signals (PubMed:19154138, PubMed:25720963, PubMed:26794871, PubMed:32753672). Dephosphorylates TFEB in response to lysosomal Ca(2+) release, resulting in TFEB nuclear translocation and stimulation of lysosomal biogenesis (PubMed:25720963, PubMed:32753672). Dephosphorylates and activates transcription factor NFATC1 (PubMed:19154138). Dephosphorylates and inactivates transcription factor ELK1 (PubMed:19154138). Dephosphorylates DARPP32 (PubMed:19154138). Negatively regulates MAP3K14/NIK signaling via inhibition of nuclear translocation of the transcription factors RELA and RELB (By similarity). May play a role in skeletal muscle fiber type specification (By similarity)","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/P16298/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PPP3CB","classification":"Not Classified","n_dependent_lines":20,"n_total_lines":1208,"dependency_fraction":0.016556291390728478},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALM1","stoichiometry":0.2},{"gene":"CALM2","stoichiometry":0.2},{"gene":"CALM3","stoichiometry":0.2},{"gene":"RBM39","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PPP3CB","total_profiled":1310},"omim":[{"mim_id":"613614","title":"MICRO RNA 499; MIR499","url":"https://www.omim.org/entry/613614"},{"mim_id":"603850","title":"DYNAMIN 1-LIKE; DNM1L","url":"https://www.omim.org/entry/603850"},{"mim_id":"602293","title":"CALCIUM- AND INTEGRIN-BINDING PROTEIN 1; CIB1","url":"https://www.omim.org/entry/602293"},{"mim_id":"601302","title":"PROTEIN PHOSPHATASE 3, REGULATORY SUBUNIT B, ALPHA; PPP3R1","url":"https://www.omim.org/entry/601302"},{"mim_id":"600490","title":"NUCLEAR FACTOR OF ACTIVATED T CELLS, CYTOPLASMIC, CALCINEURIN-DEPENDENT 2; NFATC2","url":"https://www.omim.org/entry/600490"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Calyx","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"skeletal muscle","ntpm":355.5}],"url":"https://www.proteinatlas.org/search/PPP3CB"},"hgnc":{"alias_symbol":["CALNA2","CNA2","PP2Bbeta"],"prev_symbol":["CALNB"]},"alphafold":{"accession":"P16298","domains":[{"cath_id":"3.60.21.10","chopping":"39-342","consensus_level":"high","plddt":97.4639,"start":39,"end":342},{"cath_id":"-","chopping":"355-386_398-485","consensus_level":"high","plddt":69.9492,"start":355,"end":485}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P16298","model_url":"https://alphafold.ebi.ac.uk/files/AF-P16298-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P16298-F1-predicted_aligned_error_v6.png","plddt_mean":85.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PPP3CB","jax_strain_url":"https://www.jax.org/strain/search?query=PPP3CB"},"sequence":{"accession":"P16298","fasta_url":"https://rest.uniprot.org/uniprotkb/P16298.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P16298/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P16298"}},"corpus_meta":[{"pmid":"8978785","id":"PMC_8978785","title":"Calcineurin A alpha (PPP3CA), calcineurin A beta (PPP3CB) and calcineurin B (PPP3R1) are located on human chromosomes 4, 10q21-->q22 and 2p16-->p15 respectively.","date":"1996","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8978785","citation_count":40,"is_preprint":false},{"pmid":"21531385","id":"PMC_21531385","title":"ANXA7, PPP3CB, DNAJC9, and ZMYND17 genes at chromosome 10q22 associated with the subgroup of schizophrenia with deficits in attention and executive function.","date":"2011","source":"Biological psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/21531385","citation_count":25,"is_preprint":false},{"pmid":"34228904","id":"PMC_34228904","title":"Calcineurin (PPP3CB) regulates angiotensin II-dependent vascular remodelling by potentiating EGFR signalling in mice.","date":"2021","source":"Acta physiologica (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/34228904","citation_count":15,"is_preprint":false},{"pmid":"39324484","id":"PMC_39324484","title":"SMURF1 mediates damaged lysosomal homeostasis by ubiquitinating PPP3CB to promote the activation of TFEB.","date":"2024","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/39324484","citation_count":9,"is_preprint":false},{"pmid":"30641937","id":"PMC_30641937","title":"PPP3CB Inhibits Migration of G401 Cells via Regulating Epithelial-to-Mesenchymal Transition and Promotes G401 Cells Growth.","date":"2019","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/30641937","citation_count":7,"is_preprint":false},{"pmid":"38420800","id":"PMC_38420800","title":"PPP3CB Inhibits Cell Proliferation and the Warburg Effect in Bladder Cancer by Blocking PDHK1.","date":"2024","source":"Frontiers in bioscience (Landmark edition)","url":"https://pubmed.ncbi.nlm.nih.gov/38420800","citation_count":5,"is_preprint":false},{"pmid":"39253142","id":"PMC_39253142","title":"Tumor-derived exosome PPP3CB induce gemcitabine resistance by regulating miR-298/STAT3 in pancreatic cancer.","date":"2024","source":"Heliyon","url":"https://pubmed.ncbi.nlm.nih.gov/39253142","citation_count":3,"is_preprint":false},{"pmid":"8187553","id":"PMC_8187553","title":"Chromosomal assignments of the genes for the calcineurin A alpha (Calna1) and A beta subunits (Calna2) in the rat.","date":"1994","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8187553","citation_count":3,"is_preprint":false},{"pmid":"39353739","id":"PMC_39353739","title":"PPP3CB overexpression mediates EGFR TKI resistance in lung tumors via calcineurin/MEK/ERK signaling.","date":"2024","source":"Life science alliance","url":"https://pubmed.ncbi.nlm.nih.gov/39353739","citation_count":2,"is_preprint":false},{"pmid":"40222712","id":"PMC_40222712","title":"PPP3CB inhibits pancreatic cancer progression by promoting ATOH8 translocation and transcriptionally regulating Sp1.","date":"2025","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40222712","citation_count":1,"is_preprint":false},{"pmid":"41876744","id":"PMC_41876744","title":"MCOLN1-mediated PPP3CB activation alleviates neuronal damage by promoting TFEB-dependent autophagic flux in permanent cerebral ischemia.","date":"2026","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/41876744","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8236,"output_tokens":2323,"usd":0.029777,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9457,"output_tokens":3237,"usd":0.064105,"stage2_stop_reason":"end_turn"},"total_usd":0.093882,"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\": 1996,\n      \"finding\": \"PPP3CB (calcineurin A beta) forms a heterodimer with calcineurin B (PPP3R1), functioning as a calmodulin-regulated protein phosphatase (protein phosphatase-2B) that dephosphorylates NF-AT to regulate IL-2 gene transcription in T lymphocytes.\",\n      \"method\": \"Chromosomal localization combined with biochemical characterization of the calcineurin heterodimer\",\n      \"journal\": \"Cytogenetics and cell genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — established heterodimer composition and substrate (NF-AT) by biochemical characterization, but abstract does not detail direct in vitro reconstitution; replicated across the field\",\n      \"pmids\": [\"8978785\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PPP3CB promotes angiotensin II-induced vascular remodelling in vascular smooth muscle cells (VSMCs) by enhancing HB-EGF secretion, EGFR activation, and downstream TGFβ-CTGF signalling, leading to increased collagen expression and VSMC migration; PPP3CB KO mice showed reduced aortic media thickening and lower blood pressure upon AngII treatment.\",\n      \"method\": \"PPP3CB knockout mouse model, pharmacological inhibitors in VSMCs, wound healing assays, ELISA, Western blot, qPCR, next-generation sequencing of aortic tissue\",\n      \"journal\": \"Acta physiologica (Oxford, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with defined cellular phenotypes and pharmacological pathway dissection, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"34228904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Upon lysosomal damage, PPP3CB is recruited by LGALS3 (galectin-3) and acts as a bridge for SMURF1 recruitment; PPP3CB dephosphorylates LGALS3 to promote its open conformer formation. SMURF1 then ubiquitinates PPP3CB at lysine 146 with K63-linked chains, enhancing PPP3CB's recruitment of TFEB. TFEB directly interacts with both PPP3CB and PPP3R1 to facilitate conformational correction of TFEB for its nuclear translocation and transcriptional activation of autophagy-related genes.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis (K146 ubiquitination site), SMURF1 knockdown/knockout, calcium stimulation assays, lysosomal damage models\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — reciprocal Co-IP, specific lysine mutagenesis, genetic KO with defined mechanistic pathway, multiple orthogonal methods in single study\",\n      \"pmids\": [\"39324484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PPP3CB phosphatase activity is required to maintain epithelial marker E-cadherin expression and suppress vimentin upregulation (EMT); deletion of the phosphatase domain abolishes the effects of PPP3CB on E-cadherin expression, cell migration, and proliferation in G401 kidney cells.\",\n      \"method\": \"PPP3CB knockdown and overexpression in G401 cells, phosphatase domain deletion mutant, migration assays, in vitro and in vivo tumor growth assays\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain deletion mutagenesis combined with KD/OE and defined phenotypic readouts, single lab\",\n      \"pmids\": [\"30641937\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PPP3CB interacts with PDHK1 (pyruvate dehydrogenase kinase 1) and inhibits its protein stabilization, thereby suppressing glycolysis (Warburg effect) and reducing glucose uptake and lactate production in bladder cancer cells.\",\n      \"method\": \"Co-immunoprecipitation, PPP3CB knockdown, glucose/lactate assays, Western blot for PDHK1 and p-PDHA1, in vivo nude mouse tumorigenesis model\",\n      \"journal\": \"Frontiers in bioscience (Landmark edition)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP establishing interaction plus metabolic functional assays, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"38420800\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"EGFR TKI treatment increases cytosolic calcium and activates a PPP3CB (calcineurin)/MEK/ERK signalling pathway that prevents apoptosis in resistant NSCLC cells; siRNA neutralization of PPP3CB or calcineurin inhibition by cyclosporin A restores apoptosis sensitivity to EGFR TKIs.\",\n      \"method\": \"siRNA knockdown, cyclosporin A pharmacological inhibition, in vitro apoptosis assays, in vivo mouse models, calcium level measurements\",\n      \"journal\": \"Life science alliance\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic (siRNA) and pharmacological pathway dissection with defined apoptosis readout in vitro and in vivo, single lab\",\n      \"pmids\": [\"39353739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PPP3CB interacts with ATOH8 and promotes its nuclear translocation in pancreatic cancer cells; nuclear ATOH8 binds the Sp1 promoter to transcriptionally suppress Sp1 expression, thereby inhibiting pancreatic cancer metastasis.\",\n      \"method\": \"LC-MS/MS (mass spectrometry), Co-IP, immunofluorescence/confocal microscopy, ChIP-seq, luciferase reporter assay, in vivo xenograft models\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (MS, Co-IP, ChIP-seq, reporter assay) in a single study establishing a novel interaction and downstream transcriptional mechanism\",\n      \"pmids\": [\"40222712\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"PPP3CB (but not PPP3CA) is the specific calcineurin catalytic isoform that interacts with TFEB; the LxVP motif-binding site of PPP3CB is required for TFEB interaction and activation. MCOLN1 (lysosomal calcium channel) activates PPP3CB to dephosphorylate TFEB, promoting TFEB nuclear translocation and autophagic flux in neurons under ischemic conditions.\",\n      \"method\": \"PPP3CB/PPP3CA isoform-specific knockdown, YLAVP peptide (LxVP-blocking), MCOLN1 inhibitor (ML-SI1) and agonist (ML-SA1), TFEB transcriptional activity assays, autophagic flux assays, neuronal death assays under OGD\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — isoform-specific genetic knockdown with peptide-based motif blocking and pharmacological rescue, multiple orthogonal functional readouts establishing MCOLN1-PPP3CB-TFEB pathway\",\n      \"pmids\": [\"41876744\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PPP3CB (calcineurin A beta) is the catalytic subunit of a Ca2+/calmodulin-regulated protein phosphatase that, upon calcium influx (via MCOLN1 or other channels), dephosphorylates substrates including TFEB (via its LxVP-binding site) to drive nuclear translocation and autophagic/lysosomal gene transcription; its activity is regulated by K63-linked ubiquitination at K146 by SMURF1 (recruited through LGALS3) and it operates in multiple signalling contexts—including NF-AT dephosphorylation in T cells, HB-EGF/EGFR-TGFβ-CTGF-driven vascular remodelling, calcineurin/MEK/ERK-mediated TKI resistance in lung cancer, EMT regulation via phosphatase-dependent maintenance of E-cadherin, PDHK1 destabilization to suppress glycolysis, and promotion of ATOH8 nuclear translocation to transcriptionally inhibit Sp1 in pancreatic cancer.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PPP3CB (calcineurin A beta) is the catalytic subunit of a Ca2+/calmodulin-regulated serine/threonine protein phosphatase (protein phosphatase-2B) that operates downstream of calcium signaling to control gene-regulatory programs in immune, autophagic, and oncogenic contexts [#0, #7]. It functions as a heterodimer with the calcineurin B regulatory subunit PPP3R1 and, in T lymphocytes, dephosphorylates NF-AT to regulate IL-2 transcription [#0]. A major characterized output is the control of TFEB-driven autophagic/lysosomal transcription: PPP3CB is the specific calcineurin catalytic isoform that engages TFEB through its LxVP motif-binding site, and lysosomal calcium release via the channel MCOLN1 activates PPP3CB to dephosphorylate TFEB and drive its nuclear translocation and autophagic flux [#7]. Upon lysosomal damage PPP3CB is recruited by galectin-3 (LGALS3), which it dephosphorylates to promote the LGALS3 open conformer, and serves as a bridge for SMURF1, which ubiquitinates PPP3CB at K146 with K63-linked chains to enhance TFEB recruitment and activation by both PPP3CB and PPP3R1 [#2]. Through its phosphatase activity PPP3CB also acts in disease-relevant signaling: it maintains E-cadherin and suppresses EMT in kidney tumor cells [#3], destabilizes PDHK1 to suppress glycolysis in bladder cancer [#4], promotes ATOH8 nuclear translocation to transcriptionally repress Sp1 and limit pancreatic cancer metastasis [#6], drives a calcineurin/MEK/ERK pathway underlying EGFR-TKI resistance in NSCLC [#5], and promotes angiotensin II-induced vascular remodelling via HB-EGF/EGFR-TGFβ-CTGF signaling [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Established the basic identity of PPP3CB as a calmodulin-regulated phosphatase and its first substrate, defining its role in calcium-dependent immune gene transcription.\",\n      \"evidence\": \"Chromosomal localization with biochemical characterization of the calcineurin A beta/PPP3R1 heterodimer and NF-AT dephosphorylation\",\n      \"pmids\": [\"8978785\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct in vitro reconstitution detailed\", \"Isoform-specific contribution versus PPP3CA not resolved\", \"Structural basis of substrate recognition not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed PPP3CB phosphatase activity directly maintains epithelial identity, extending its role beyond immune signaling into EMT and tumor suppression.\",\n      \"evidence\": \"Knockdown/overexpression and phosphatase-domain deletion in G401 kidney cells with migration and tumor growth assays\",\n      \"pmids\": [\"30641937\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct phosphatase substrate maintaining E-cadherin not identified\", \"Single cell-line context\", \"Upstream calcium trigger not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined a physiological in vivo role for PPP3CB in vascular remodelling, linking it to a secreted growth-factor signaling cascade.\",\n      \"evidence\": \"PPP3CB knockout mice and VSMC assays with pharmacological pathway dissection of HB-EGF/EGFR-TGFβ-CTGF\",\n      \"pmids\": [\"34228904\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct phosphatase substrate connecting PPP3CB to HB-EGF secretion unknown\", \"Mechanism of EGFR activation indirect\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Revealed a lysosomal-damage signaling hub in which PPP3CB is both a regulatory phosphatase for galectin-3 and a ubiquitination substrate that scaffolds TFEB activation.\",\n      \"evidence\": \"Reciprocal Co-IP, K146 site-directed mutagenesis, SMURF1 knockdown/knockout, calcium and lysosomal damage assays\",\n      \"pmids\": [\"39324484\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of K63-ubiquitin-enhanced TFEB recruitment unresolved\", \"How phosphatase activity and scaffolding roles are coordinated unclear\", \"In vivo relevance not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Implicated PPP3CB in metabolic reprogramming by linking it to PDHK1 stability and glycolytic suppression.\",\n      \"evidence\": \"Co-IP, knockdown, glucose/lactate assays and nude-mouse tumorigenesis in bladder cancer cells\",\n      \"pmids\": [\"38420800\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PDHK1 destabilization is phosphatase-dependent not established\", \"Direct versus indirect interaction not distinguished\", \"Single cancer context\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected PPP3CB to therapy resistance, showing TKI-induced calcium activates a PPP3CB/MEK/ERK survival pathway.\",\n      \"evidence\": \"siRNA knockdown, cyclosporin A inhibition, apoptosis assays and mouse models with calcium measurements in NSCLC\",\n      \"pmids\": [\"39353739\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct PPP3CB substrate linking to MEK/ERK not identified\", \"Mechanism of calcium elevation by TKI not defined\", \"Clinical relevance untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified a transcriptional axis in which PPP3CB promotes ATOH8 nuclear entry to repress Sp1 and limit metastasis.\",\n      \"evidence\": \"LC-MS/MS, Co-IP, confocal imaging, ChIP-seq, luciferase reporter and xenografts in pancreatic cancer\",\n      \"pmids\": [\"40222712\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ATOH8 translocation requires PPP3CB dephosphorylation unclear\", \"Direct ATOH8 phosphosite not mapped\", \"Single tumor type\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Established isoform specificity and the molecular interface for TFEB regulation, defining the MCOLN1-PPP3CB-TFEB autophagy pathway.\",\n      \"evidence\": \"PPP3CB/PPP3CA isoform-specific knockdown, LxVP-blocking YLAVP peptide, MCOLN1 inhibitor/agonist, TFEB activity and autophagic flux assays under OGD in neurons\",\n      \"pmids\": [\"41876744\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural detail of the LxVP-binding site engaging TFEB not solved\", \"Basis of PPP3CB versus PPP3CA selectivity unknown\", \"Relationship to the LGALS3/SMURF1 lysosomal pathway not integrated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how PPP3CB's phosphatase activity, scaffolding function, and ubiquitin-dependent regulation are mechanistically coordinated across its diverse signaling contexts, and which direct substrates underlie most of its disease phenotypes.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct substrates for most cancer/vascular phenotypes unmapped\", \"No structural model of substrate or LxVP recognition\", \"Integration of distinct pathways into one regulatory logic absent\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 2, 3, 7]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 3, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5, 7]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [6, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [2, 7]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 5]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [3, 4, 5, 6]}\n    ],\n    \"complexes\": [\"calcineurin (PPP3CB-PPP3R1 heterodimer)\"],\n    \"partners\": [\"PPP3R1\", \"TFEB\", \"LGALS3\", \"SMURF1\", \"PDHK1\", \"ATOH8\", \"NFATC\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}