{"gene":"PFDN2","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":2018,"finding":"PFDN2 is a β subunit of the URI prefoldin-like complex, a heterohexameric chaperone complex comprising two α subunits (URI and STAP1) and four β subunits (PFDN2, PFDN6, and PFDN4r, one likely in duplicate), identified by immunoprecipitation in mammalian cells.","method":"Immunoprecipitation / complex reconstitution (review citing original IP experiments)","journal":"Advances in experimental medicine and biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP evidence cited from original work; described in review, single lab origin for the original IP","pmids":["30484155"],"is_preprint":false},{"year":2016,"finding":"PFDN2 acts as an upstream regulator of γ-synuclein (SNCG) expression in retinal ganglion cells (RGCs); knockdown of Pfdn2 in primary murine RGCs significantly reduced Sncg expression, placing PFDN2 upstream of SNCG in the same pathway.","method":"Systems genetics (eQTL mapping), siRNA knockdown in primary murine RGCs, immunohistochemistry co-localization","journal":"The FEBS journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional KD with defined transcriptional phenotype in primary cells, corroborated by eQTL and IHC co-localization, single lab","pmids":["26663874"],"is_preprint":false},{"year":2017,"finding":"Downregulation of Pfdn2 in enriched murine RGCs causes a concomitant reduction in Sncg expression, confirming genetic epistasis with PFDN2 upstream of SNCG.","method":"siRNA knockdown in flow-cytometry-isolated primary RGCs, qPCR readout","journal":"Methods in molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct KD with specific molecular phenotype, replicates finding from PMID:26663874, single lab","pmids":["27933535"],"is_preprint":false},{"year":2023,"finding":"PFDN2 promotes cell cycle progression in gastric cancer by facilitating nuclear translocation of hnRNPD, which in turn upregulates MYBL2 transcription; this defines a PFDN2–hnRNPD–MYBL2 axis.","method":"Gain/loss-of-function experiments, nuclear fractionation, transcriptional reporter assays, co-immunoprecipitation","journal":"Frontiers in oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic pathway placement via KD/OE and nuclear translocation assay with defined downstream transcriptional phenotype, single lab","pmids":["37538116"],"is_preprint":false},{"year":2026,"finding":"PFDN2 physically interacts with PYCR2 (co-immunoprecipitation, cytoplasmic co-localization by immunofluorescence) and stabilizes PYCR2 protein by limiting proteasome-dependent degradation, as shown by cycloheximide chase and MG132 rescue experiments.","method":"Co-immunoprecipitation, immunofluorescence, cycloheximide chase, proteasome inhibitor (MG132) rescue, gain/loss-of-function","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (Co-IP, CHX chase, MG132 rescue) in single lab establishing direct binding and stabilization mechanism","pmids":["41656306"],"is_preprint":false},{"year":2026,"finding":"PFDN2-mediated stabilization of PYCR2 activates Wnt/β-catenin signaling, evidenced by increased TOP/FOPflash reporter activity, nuclear β-catenin accumulation, and upregulation of canonical Wnt targets; re-expression of PYCR2 partially rescues these readouts upon PFDN2 silencing.","method":"TOP/FOPflash luciferase reporter assay, Western blot for nuclear β-catenin, pharmacological Wnt inhibition, rescue experiments","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway epistasis established by reporter assay plus rescue, multiple readouts, single lab","pmids":["41656306"],"is_preprint":false},{"year":2026,"finding":"Plasma PFDN2 suppresses head and neck squamous cell carcinoma (HNSC) progression by interacting with CD64 (FCGR1A) on monocytes; molecular docking and dynamics simulations support a stable PFDN2–CD64 protein–protein interaction, and virtual knockout of PFDN2 selectively activated monocyte-associated inflammatory programs.","method":"Mendelian randomization, molecular docking and molecular dynamics simulation, single-cell RNA sequencing, scTenifoldKnk virtual knockout, immunofluorescence","journal":"Frontiers in immunology","confidence":"Low","confidence_rationale":"Tier 4 / Weak — interaction supported mainly by computational docking/simulation and virtual knockout; no direct biochemical binding assay for PFDN2–CD64 interaction","pmids":["41884853"],"is_preprint":false},{"year":2020,"finding":"PFDN2 was identified as a putative interaction partner of NEK10 kinase after zeocin-induced DNA damage, detected by co-immunoprecipitation with FLAG-NEK10 followed by LC-MS/MS.","method":"Co-immunoprecipitation with FLAG-NEK10, LC-MS/MS proteomics","journal":"Proteome science","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single co-IP/MS identification without functional follow-up specific to PFDN2; PFDN2 is one of many listed interactors","pmids":["32368190"],"is_preprint":false},{"year":2020,"finding":"PFDN2 was identified as one of 11 novel interaction partners of cardiac syndecan-2, verified in both rat left ventricle affinity purification/MS and HEK293 cell confirmation.","method":"Affinity purification combined with mass spectrometry, HEK293 verification","journal":"Frontiers in cell and developmental biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single AP-MS identification with cell-line verification but no functional characterization of the PFDN2–syndecan-2 interaction","pmids":["32984315"],"is_preprint":false}],"current_model":"PFDN2 is a β subunit of the URI prefoldin-like heterohexameric chaperone complex; it acts as an upstream transcriptional regulator of γ-synuclein (SNCG) in retinal ganglion cells, promotes cell cycle progression in gastric cancer by facilitating nuclear translocation of hnRNPD to drive MYBL2 transcription, and in colorectal cancer stabilizes PYCR2 protein against proteasomal degradation to activate Wnt/β-catenin signaling and promote proliferation and migration."},"narrative":{"mechanistic_narrative":"PFDN2 is a β subunit of the URI prefoldin-like heterohexameric chaperone complex, which contains two α subunits (URI and STAP1) and four β subunits (PFDN2, PFDN6, and PFDN4r) [PMID:30484155]. Beyond its structural role in this complex, PFDN2 functions as a transcriptional and signaling regulator across several cellular contexts. In retinal ganglion cells it acts upstream of γ-synuclein (SNCG), as knockdown reduces Sncg expression and places PFDN2 within the same regulatory pathway [PMID:26663874, PMID:27933535]. In gastric cancer, PFDN2 drives cell cycle progression through a PFDN2–hnRNPD–MYBL2 axis, facilitating nuclear translocation of hnRNPD to upregulate MYBL2 transcription [PMID:37538116]. In colorectal cancer, PFDN2 physically binds PYCR2 and stabilizes it against proteasome-dependent degradation, thereby activating Wnt/β-catenin signaling to promote proliferation and migration [PMID:41656306]. The mechanistic relationship between PFDN2's chaperone-complex membership and these context-specific regulatory activities has not been characterized in the available corpus.","teleology":[{"year":2016,"claim":"Established that PFDN2 functions as an upstream regulator of a specific transcriptional target, moving it beyond a presumed generic chaperone role into a defined gene-regulatory pathway in neurons.","evidence":"eQTL mapping plus siRNA knockdown in primary murine retinal ganglion cells with IHC co-localization","pmids":["26663874"],"confidence":"Medium","gaps":["Mechanism by which PFDN2 controls SNCG expression is undefined","No evidence whether this is direct or via the chaperone complex"]},{"year":2017,"claim":"Confirmed the PFDN2→SNCG epistatic relationship in an independent purified RGC system, solidifying the upstream placement of PFDN2.","evidence":"siRNA knockdown in flow-sorted primary RGCs with qPCR readout","pmids":["27933535"],"confidence":"Medium","gaps":["Does not establish a molecular mechanism linking PFDN2 to SNCG transcription"]},{"year":2018,"claim":"Defined PFDN2 as a β subunit of the URI prefoldin-like heterohexameric chaperone complex, establishing its structural assignment.","evidence":"Immunoprecipitation / complex reconstitution in mammalian cells (review citing original IP data)","pmids":["30484155"],"confidence":"Medium","gaps":["Chaperone substrates of the complex not defined here","Link between complex membership and PFDN2's regulatory functions unestablished"]},{"year":2020,"claim":"Catalogued PFDN2 among interactors of NEK10 and of cardiac syndecan-2, raising candidate roles in DNA-damage signaling and cardiac signaling that remain unvalidated.","evidence":"Co-IP/AP coupled to LC-MS/MS in cells and rat ventricle with HEK293 verification","pmids":["32368190","32984315"],"confidence":"Low","gaps":["Single AP-MS identifications without reciprocal validation","No functional characterization of either interaction specific to PFDN2"]},{"year":2023,"claim":"Placed PFDN2 within a cancer cell-cycle pathway by defining a PFDN2–hnRNPD–MYBL2 transcriptional axis, providing a mechanistic route from PFDN2 to proliferative gene expression.","evidence":"Gain/loss-of-function, nuclear fractionation, reporter assays, and co-IP in gastric cancer cells","pmids":["37538116"],"confidence":"Medium","gaps":["How PFDN2 promotes hnRNPD nuclear translocation is unresolved","Single lab, single cancer type"]},{"year":2026,"claim":"Demonstrated a protein-stabilization mechanism whereby PFDN2 binds PYCR2 and protects it from proteasomal degradation to activate Wnt/β-catenin signaling, connecting PFDN2 to oncogenic signaling in colorectal cancer.","evidence":"Co-IP, immunofluorescence, cycloheximide chase, MG132 rescue, TOP/FOPflash reporter and rescue assays","pmids":["41656306"],"confidence":"Medium","gaps":["Mechanism by which PFDN2 limits PYCR2 degradation (e.g., shielding from ubiquitination) not resolved","Whether this depends on the chaperone complex is unknown"]},{"year":2026,"claim":"Proposed a tumor-suppressive, extracellular role for plasma PFDN2 via interaction with monocyte CD64 in head and neck cancer, contrasting with its intracellular pro-proliferative roles.","evidence":"Mendelian randomization, molecular docking/dynamics, scRNA-seq, and scTenifoldKnk virtual knockout","pmids":["41884853"],"confidence":"Low","gaps":["Interaction supported only by computational docking/simulation with no direct biochemical binding assay","Extracellular localization and secretion of PFDN2 not biochemically established"]},{"year":null,"claim":"Whether PFDN2's chaperone-complex function mechanistically underlies its diverse transcriptional, protein-stabilization, and signaling activities remains unresolved.","evidence":"No discovery in the corpus links the URI prefoldin-like complex to the SNCG, hnRNPD–MYBL2, or PYCR2–Wnt activities","pmids":[],"confidence":"Low","gaps":["No unifying mechanistic model connecting chaperone role to gene-regulatory roles","No structural data on PFDN2 substrate or partner binding"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0044183","term_label":"protein folding chaperone","supporting_discovery_ids":[0]},{"term_id":"GO:0140313","term_label":"molecular sequestering activity","supporting_discovery_ids":[4]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[4]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[5]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[3]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,4]}],"complexes":["URI prefoldin-like complex"],"partners":["URI","STAP1","PFDN6","PFDN4R","HNRNPD","PYCR2","NEK10","SDC2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UHV9","full_name":"Prefoldin subunit 2","aliases":[],"length_aa":154,"mass_kda":16.6,"function":"Binds specifically to cytosolic chaperonin (c-CPN) and transfers target proteins to it. Binds to nascent polypeptide chain and promotes folding in an environment in which there are many competing pathways for nonnative proteins","subcellular_location":"Nucleus; Cytoplasm; Mitochondrion","url":"https://www.uniprot.org/uniprotkb/Q9UHV9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/PFDN2","classification":"Common Essential","n_dependent_lines":1203,"n_total_lines":1208,"dependency_fraction":0.9958609271523179},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"PFDN6","stoichiometry":10.0},{"gene":"POLR2E","stoichiometry":4.0},{"gene":"POLR2H","stoichiometry":4.0},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"POLR1C","stoichiometry":0.2},{"gene":"POLR2B","stoichiometry":0.2},{"gene":"POLR2K","stoichiometry":0.2},{"gene":"POLR3B","stoichiometry":0.2},{"gene":"PTGES3","stoichiometry":0.2},{"gene":"RPAP2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PFDN2","total_profiled":1310},"omim":[{"mim_id":"613466","title":"PREFOLDIN 2; PFDN2","url":"https://www.omim.org/entry/613466"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Mitochondria","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PFDN2"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q9UHV9","domains":[{"cath_id":"1.10.287.370","chopping":"24-121","consensus_level":"high","plddt":94.6902,"start":24,"end":121}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UHV9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UHV9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UHV9-F1-predicted_aligned_error_v6.png","plddt_mean":79.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PFDN2","jax_strain_url":"https://www.jax.org/strain/search?query=PFDN2"},"sequence":{"accession":"Q9UHV9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UHV9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UHV9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UHV9"}},"corpus_meta":[{"pmid":"24486590","id":"PMC_24486590","title":"Integrative analysis of 1q23.3 copy-number gain in metastatic urothelial carcinoma.","date":"2014","source":"Clinical cancer research : an official journal of the American Association for Cancer Research","url":"https://pubmed.ncbi.nlm.nih.gov/24486590","citation_count":70,"is_preprint":false},{"pmid":"32812032","id":"PMC_32812032","title":"WGCNA reveals key gene modules regulated by the combined treatment of colon cancer with PHY906 and CPT11.","date":"2020","source":"Bioscience reports","url":"https://pubmed.ncbi.nlm.nih.gov/32812032","citation_count":33,"is_preprint":false},{"pmid":"32368190","id":"PMC_32368190","title":"NEK10 interactome and depletion reveal new roles in mitochondria.","date":"2020","source":"Proteome science","url":"https://pubmed.ncbi.nlm.nih.gov/32368190","citation_count":26,"is_preprint":false},{"pmid":"21403392","id":"PMC_21403392","title":"Association of HSP70 and its co-chaperones with Alzheimer's disease.","date":"2011","source":"Journal of Alzheimer's disease : JAD","url":"https://pubmed.ncbi.nlm.nih.gov/21403392","citation_count":18,"is_preprint":false},{"pmid":"34840672","id":"PMC_34840672","title":"Identification of the susceptibility genes for COVID-19 in lung adenocarcinoma with global data and biological computation methods.","date":"2021","source":"Computational and structural biotechnology journal","url":"https://pubmed.ncbi.nlm.nih.gov/34840672","citation_count":17,"is_preprint":false},{"pmid":"26663874","id":"PMC_26663874","title":"Multipronged approach to identify and validate a novel upstream regulator of Sncg in mouse retinal ganglion cells.","date":"2016","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/26663874","citation_count":14,"is_preprint":false},{"pmid":"30484155","id":"PMC_30484155","title":"Roles and Functions of the Unconventional Prefoldin URI.","date":"2018","source":"Advances in experimental medicine and biology","url":"https://pubmed.ncbi.nlm.nih.gov/30484155","citation_count":13,"is_preprint":false},{"pmid":"33929667","id":"PMC_33929667","title":"Pharmacological inhibition of HDAC1/3-interacting proteins induced morphological changes, and hindered the cell proliferation and migration of hepatocellular carcinoma cells.","date":"2021","source":"Environmental science and pollution research international","url":"https://pubmed.ncbi.nlm.nih.gov/33929667","citation_count":9,"is_preprint":false},{"pmid":"37538116","id":"PMC_37538116","title":"PFDN2 promotes cell cycle progression via the hnRNPD-MYBL2 axis in gastric cancer.","date":"2023","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/37538116","citation_count":7,"is_preprint":false},{"pmid":"35096829","id":"PMC_35096829","title":"Identification and Validation of Key Genes of Differential Correlations in Gastric Cancer.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/35096829","citation_count":7,"is_preprint":false},{"pmid":"32984315","id":"PMC_32984315","title":"The Cardiac Syndecan-2 Interactome.","date":"2020","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/32984315","citation_count":7,"is_preprint":false},{"pmid":"27933535","id":"PMC_27933535","title":"Systems Genetics Analysis to Identify the Genetic Modulation of a Glaucoma-Associated Gene.","date":"2017","source":"Methods in molecular biology (Clifton, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/27933535","citation_count":3,"is_preprint":false},{"pmid":"41884853","id":"PMC_41884853","title":"Plasma PFDN2 suppresses head and neck squamous cell carcinoma progression by restricting CD64 on monocyte-driven inflammatory microenvironments.","date":"2026","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/41884853","citation_count":0,"is_preprint":false},{"pmid":"41656306","id":"PMC_41656306","title":"PFDN2 stabilizes PYCR2 to activate Wnt/β-catenin signaling and promote colorectal cancer progression.","date":"2026","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/41656306","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9249,"output_tokens":2069,"usd":0.029391,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9099,"output_tokens":2594,"usd":0.055172,"stage2_stop_reason":"end_turn"},"total_usd":0.084563,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"PFDN2 is a β subunit of the URI prefoldin-like complex, a heterohexameric chaperone complex comprising two α subunits (URI and STAP1) and four β subunits (PFDN2, PFDN6, and PFDN4r, one likely in duplicate), identified by immunoprecipitation in mammalian cells.\",\n      \"method\": \"Immunoprecipitation / complex reconstitution (review citing original IP experiments)\",\n      \"journal\": \"Advances in experimental medicine and biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP evidence cited from original work; described in review, single lab origin for the original IP\",\n      \"pmids\": [\"30484155\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PFDN2 acts as an upstream regulator of γ-synuclein (SNCG) expression in retinal ganglion cells (RGCs); knockdown of Pfdn2 in primary murine RGCs significantly reduced Sncg expression, placing PFDN2 upstream of SNCG in the same pathway.\",\n      \"method\": \"Systems genetics (eQTL mapping), siRNA knockdown in primary murine RGCs, immunohistochemistry co-localization\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional KD with defined transcriptional phenotype in primary cells, corroborated by eQTL and IHC co-localization, single lab\",\n      \"pmids\": [\"26663874\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Downregulation of Pfdn2 in enriched murine RGCs causes a concomitant reduction in Sncg expression, confirming genetic epistasis with PFDN2 upstream of SNCG.\",\n      \"method\": \"siRNA knockdown in flow-cytometry-isolated primary RGCs, qPCR readout\",\n      \"journal\": \"Methods in molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct KD with specific molecular phenotype, replicates finding from PMID:26663874, single lab\",\n      \"pmids\": [\"27933535\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PFDN2 promotes cell cycle progression in gastric cancer by facilitating nuclear translocation of hnRNPD, which in turn upregulates MYBL2 transcription; this defines a PFDN2–hnRNPD–MYBL2 axis.\",\n      \"method\": \"Gain/loss-of-function experiments, nuclear fractionation, transcriptional reporter assays, co-immunoprecipitation\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic pathway placement via KD/OE and nuclear translocation assay with defined downstream transcriptional phenotype, single lab\",\n      \"pmids\": [\"37538116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"PFDN2 physically interacts with PYCR2 (co-immunoprecipitation, cytoplasmic co-localization by immunofluorescence) and stabilizes PYCR2 protein by limiting proteasome-dependent degradation, as shown by cycloheximide chase and MG132 rescue experiments.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, cycloheximide chase, proteasome inhibitor (MG132) rescue, gain/loss-of-function\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (Co-IP, CHX chase, MG132 rescue) in single lab establishing direct binding and stabilization mechanism\",\n      \"pmids\": [\"41656306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"PFDN2-mediated stabilization of PYCR2 activates Wnt/β-catenin signaling, evidenced by increased TOP/FOPflash reporter activity, nuclear β-catenin accumulation, and upregulation of canonical Wnt targets; re-expression of PYCR2 partially rescues these readouts upon PFDN2 silencing.\",\n      \"method\": \"TOP/FOPflash luciferase reporter assay, Western blot for nuclear β-catenin, pharmacological Wnt inhibition, rescue experiments\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway epistasis established by reporter assay plus rescue, multiple readouts, single lab\",\n      \"pmids\": [\"41656306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Plasma PFDN2 suppresses head and neck squamous cell carcinoma (HNSC) progression by interacting with CD64 (FCGR1A) on monocytes; molecular docking and dynamics simulations support a stable PFDN2–CD64 protein–protein interaction, and virtual knockout of PFDN2 selectively activated monocyte-associated inflammatory programs.\",\n      \"method\": \"Mendelian randomization, molecular docking and molecular dynamics simulation, single-cell RNA sequencing, scTenifoldKnk virtual knockout, immunofluorescence\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — interaction supported mainly by computational docking/simulation and virtual knockout; no direct biochemical binding assay for PFDN2–CD64 interaction\",\n      \"pmids\": [\"41884853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PFDN2 was identified as a putative interaction partner of NEK10 kinase after zeocin-induced DNA damage, detected by co-immunoprecipitation with FLAG-NEK10 followed by LC-MS/MS.\",\n      \"method\": \"Co-immunoprecipitation with FLAG-NEK10, LC-MS/MS proteomics\",\n      \"journal\": \"Proteome science\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single co-IP/MS identification without functional follow-up specific to PFDN2; PFDN2 is one of many listed interactors\",\n      \"pmids\": [\"32368190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PFDN2 was identified as one of 11 novel interaction partners of cardiac syndecan-2, verified in both rat left ventricle affinity purification/MS and HEK293 cell confirmation.\",\n      \"method\": \"Affinity purification combined with mass spectrometry, HEK293 verification\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single AP-MS identification with cell-line verification but no functional characterization of the PFDN2–syndecan-2 interaction\",\n      \"pmids\": [\"32984315\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PFDN2 is a β subunit of the URI prefoldin-like heterohexameric chaperone complex; it acts as an upstream transcriptional regulator of γ-synuclein (SNCG) in retinal ganglion cells, promotes cell cycle progression in gastric cancer by facilitating nuclear translocation of hnRNPD to drive MYBL2 transcription, and in colorectal cancer stabilizes PYCR2 protein against proteasomal degradation to activate Wnt/β-catenin signaling and promote proliferation and migration.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PFDN2 is a β subunit of the URI prefoldin-like heterohexameric chaperone complex, which contains two α subunits (URI and STAP1) and four β subunits (PFDN2, PFDN6, and PFDN4r) [#0]. Beyond its structural role in this complex, PFDN2 functions as a transcriptional and signaling regulator across several cellular contexts. In retinal ganglion cells it acts upstream of γ-synuclein (SNCG), as knockdown reduces Sncg expression and places PFDN2 within the same regulatory pathway [#1, #2]. In gastric cancer, PFDN2 drives cell cycle progression through a PFDN2–hnRNPD–MYBL2 axis, facilitating nuclear translocation of hnRNPD to upregulate MYBL2 transcription [#3]. In colorectal cancer, PFDN2 physically binds PYCR2 and stabilizes it against proteasome-dependent degradation, thereby activating Wnt/β-catenin signaling to promote proliferation and migration [#4, #5]. The mechanistic relationship between PFDN2's chaperone-complex membership and these context-specific regulatory activities has not been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2016,\n      \"claim\": \"Established that PFDN2 functions as an upstream regulator of a specific transcriptional target, moving it beyond a presumed generic chaperone role into a defined gene-regulatory pathway in neurons.\",\n      \"evidence\": \"eQTL mapping plus siRNA knockdown in primary murine retinal ganglion cells with IHC co-localization\",\n      \"pmids\": [\"26663874\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which PFDN2 controls SNCG expression is undefined\", \"No evidence whether this is direct or via the chaperone complex\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Confirmed the PFDN2→SNCG epistatic relationship in an independent purified RGC system, solidifying the upstream placement of PFDN2.\",\n      \"evidence\": \"siRNA knockdown in flow-sorted primary RGCs with qPCR readout\",\n      \"pmids\": [\"27933535\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not establish a molecular mechanism linking PFDN2 to SNCG transcription\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined PFDN2 as a β subunit of the URI prefoldin-like heterohexameric chaperone complex, establishing its structural assignment.\",\n      \"evidence\": \"Immunoprecipitation / complex reconstitution in mammalian cells (review citing original IP data)\",\n      \"pmids\": [\"30484155\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Chaperone substrates of the complex not defined here\", \"Link between complex membership and PFDN2's regulatory functions unestablished\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Catalogued PFDN2 among interactors of NEK10 and of cardiac syndecan-2, raising candidate roles in DNA-damage signaling and cardiac signaling that remain unvalidated.\",\n      \"evidence\": \"Co-IP/AP coupled to LC-MS/MS in cells and rat ventricle with HEK293 verification\",\n      \"pmids\": [\"32368190\", \"32984315\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single AP-MS identifications without reciprocal validation\", \"No functional characterization of either interaction specific to PFDN2\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placed PFDN2 within a cancer cell-cycle pathway by defining a PFDN2–hnRNPD–MYBL2 transcriptional axis, providing a mechanistic route from PFDN2 to proliferative gene expression.\",\n      \"evidence\": \"Gain/loss-of-function, nuclear fractionation, reporter assays, and co-IP in gastric cancer cells\",\n      \"pmids\": [\"37538116\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How PFDN2 promotes hnRNPD nuclear translocation is unresolved\", \"Single lab, single cancer type\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Demonstrated a protein-stabilization mechanism whereby PFDN2 binds PYCR2 and protects it from proteasomal degradation to activate Wnt/β-catenin signaling, connecting PFDN2 to oncogenic signaling in colorectal cancer.\",\n      \"evidence\": \"Co-IP, immunofluorescence, cycloheximide chase, MG132 rescue, TOP/FOPflash reporter and rescue assays\",\n      \"pmids\": [\"41656306\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which PFDN2 limits PYCR2 degradation (e.g., shielding from ubiquitination) not resolved\", \"Whether this depends on the chaperone complex is unknown\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Proposed a tumor-suppressive, extracellular role for plasma PFDN2 via interaction with monocyte CD64 in head and neck cancer, contrasting with its intracellular pro-proliferative roles.\",\n      \"evidence\": \"Mendelian randomization, molecular docking/dynamics, scRNA-seq, and scTenifoldKnk virtual knockout\",\n      \"pmids\": [\"41884853\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Interaction supported only by computational docking/simulation with no direct biochemical binding assay\", \"Extracellular localization and secretion of PFDN2 not biochemically established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether PFDN2's chaperone-complex function mechanistically underlies its diverse transcriptional, protein-stabilization, and signaling activities remains unresolved.\",\n      \"evidence\": \"No discovery in the corpus links the URI prefoldin-like complex to the SNCG, hnRNPD–MYBL2, or PYCR2–Wnt activities\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No unifying mechanistic model connecting chaperone role to gene-regulatory roles\", \"No structural data on PFDN2 substrate or partner binding\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0140313\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"complexes\": [\"URI prefoldin-like complex\"],\n    \"partners\": [\"URI\", \"STAP1\", \"PFDN6\", \"PFDN4r\", \"hnRNPD\", \"PYCR2\", \"NEK10\", \"SDC2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}