{"gene":"PDRG1","run_date":"2026-06-10T05:19:53","timeline":{"discoveries":[{"year":2016,"finding":"PDRG1 physically interacts with MATα1 (the catalytic subunit of methionine adenosyltransferases MAT I and MAT III), as demonstrated by yeast two-hybrid, immunoprecipitation, and pull-down assays. Nuclear MATα1-PDRG1 interaction results in reduced DNA methylation levels, identifying downregulation of S-adenosylmethionine synthesis as the first functional effect directly ascribed to PDRG1.","method":"Yeast two-hybrid, co-immunoprecipitation, pull-down assays, DNA methylation assays","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and pull-down with functional readout (DNA methylation), single lab, multiple orthogonal methods","pmids":["27548429"],"is_preprint":false},{"year":2016,"finding":"PDRG1 promotes radioresistance in lung cancer cells via the ATM-p53 signaling pathway, as shown by gain- and loss-of-function experiments affecting cell viability, apoptosis, and protein expression.","method":"Gain-of-function and loss-of-function transfection, cell viability assays, apoptosis assays, Western blot","journal":"Biomedicine & pharmacotherapy","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — single lab, pathway placement via KD/OE with defined cellular phenotype, but no direct biochemical interaction with ATM demonstrated","pmids":["27610824"],"is_preprint":false},{"year":2017,"finding":"HIF1α directly targets the miR-519d promoter (chromatin immunoprecipitation and luciferase reporter assay), and miR-519d directly targets PDRG1 mRNA (luciferase reporter assay), placing PDRG1 downstream of a HIF1α-miR-519d axis in nasopharyngeal carcinoma radiosensitivity.","method":"Chromatin immunoprecipitation, luciferase reporter assay, stable overexpression/knockdown","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and luciferase reporter confirm direct transcriptional regulation, single lab","pmids":["28057028"],"is_preprint":false},{"year":2019,"finding":"PDRG1 silencing in gastric cancer cells activates the ATM/p53 pathway (increased p-ATM, p53, p21, p-cdc2, cleaved caspase-3), arrests the cell cycle at G2/M, and induces apoptosis; pharmacological ATM inhibition (KU55933) reverses these effects, establishing PDRG1 as an upstream suppressor of ATM/p53 signaling.","method":"siRNA knockdown, Western blot, flow cytometry, ATM inhibitor rescue, xenograft model","journal":"Pathology, research and practice","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway placement confirmed by pharmacological epistasis (KU55933 rescue), single lab, multiple readouts","pmids":["31383535"],"is_preprint":false},{"year":2019,"finding":"PDRG1 knockdown in esophageal cancer cells suppresses the Wnt signaling pathway, as evidenced by reduced cyclinD1 and β-catenin expression, increased apoptosis, and enhanced cisplatin sensitivity.","method":"shRNA knockdown, overexpression, Western blot, cell viability and apoptosis assays","journal":"Annals of clinical and laboratory science","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single-method pathway inference from protein expression changes without direct interaction evidence","pmids":["31882431"],"is_preprint":false},{"year":2021,"finding":"PDRG1 promotes proliferation and migration of GBM cells via the MEK/ERK/CD44 pathway; PDRG1 knockdown reduces CD44 expression and transcriptome analysis confirmed enrichment of adhesion and motility gene sets.","method":"shRNA knockdown, transcriptome sequencing, Western blot, in vitro migration/proliferation assays, in vivo xenograft","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — pathway placement by KD with transcriptomic readout and in vivo validation, but no direct biochemical interaction with MEK/ERK components demonstrated; single lab","pmids":["34812552"],"is_preprint":false},{"year":2025,"finding":"In Arabidopsis, PDRG1 functions primarily as a subunit of the prefoldin-like complex (PFDLc); in vivo interactome (AP-MS) shows PFDLc subunits (UXT, URI) are its main interactors with overlapping interactomes including nuclear RNA polymerase subunits and spliceosome components. PDRG1 impairment causes embryonic lethality, equivalent to loss of other PFDLc subunits.","method":"In vivo co-immunoprecipitation/AP-MS, genetic loss-of-function (embryonic lethal phenotype), interactome comparison","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal interactome mapping with functional genetic validation in plant model, single lab; plant ortholog context limits direct translation to human protein","pmids":["40026265"],"is_preprint":false},{"year":2026,"finding":"PDRG1 directly interacts with EZH2 (co-immunoprecipitation), and this interaction increases H3K27me3 enrichment at the p21 (CDKN1A) promoter (ChIP-qPCR), suppressing p21 transcription and allowing bypass of cellular senescence. Domain mapping identified PDRG1 N-terminal residues 36–70 as required for EZH2 binding. Restoration of p21 rescues the anti-proliferative phenotype caused by PDRG1 knockdown.","method":"Co-immunoprecipitation, ChIP-qPCR, RNA-seq, domain-mapping mutagenesis, rescue experiments, xenograft model","journal":"International journal of biological sciences","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct protein interaction confirmed by Co-IP, epigenetic mechanism validated by ChIP-qPCR, domain mapping, and rescue experiments; multiple orthogonal methods in single lab","pmids":["41943853"],"is_preprint":false},{"year":2026,"finding":"Transcription factor SP1 directly binds the PDRG1 promoter at the E3 site (−1927 to −1917) and activates PDRG1 transcription; SP1-driven pro-tumor effects are rescued by PDRG1 silencing. PDRG1 in turn activates Wnt/β-catenin signaling (elevated β-catenin, c-Myc, phospho-GSK-3β), and Wnt inhibitor XAV939 reverses PDRG1 oncogenic effects in HCC.","method":"ChIP, luciferase reporter assay (implied by promoter binding), Western blot, Wnt pathway inhibitor rescue, KD/OE in vitro and in vivo","journal":"MedScience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — upstream transcriptional regulation confirmed by promoter binding assay and rescue experiments; Wnt pathway placement supported by pharmacological epistasis; single lab","pmids":["42243436"],"is_preprint":false}],"current_model":"PDRG1 is a small oncogenic protein that functions as a subunit of the prefoldin-like complex (binding UXT/URI and associating with RNA polymerase II and spliceosome components), interacts with and suppresses methionine adenosyltransferases (MAT I/III) to reduce nuclear S-adenosylmethionine and DNA methylation, directly binds EZH2 via its N-terminal residues 36–70 to promote H3K27me3-mediated repression of p21 and senescence bypass, and is transcriptionally activated by SP1; downstream, PDRG1 suppresses ATM/p53 pathway activity and activates MEK/ERK/CD44 and Wnt/β-catenin signaling to drive proliferation, migration, and therapy resistance in multiple cancer contexts."},"narrative":{"mechanistic_narrative":"PDRG1 is a small protein with dual roles in chromatin/epigenetic regulation and oncogenic signaling, acting both as a subunit of the prefoldin-like complex and as a modulator of DNA and histone methylation [PMID:40026265, PMID:27548429, PMID:41943853]. As a structural component, PDRG1 associates principally with the prefoldin-like complex subunits UXT and URI, with an overlapping interactome that includes nuclear RNA polymerase subunits and spliceosome components, and its loss is developmentally lethal [PMID:40026265]. PDRG1 lowers genomic methylation by physically binding MATα1, the catalytic subunit of methionine adenosyltransferases MAT I/III, reducing S-adenosylmethionine availability and DNA methylation [PMID:27548429]. In parallel, PDRG1 directly binds EZH2 through its N-terminal residues 36–70, increasing H3K27me3 deposition at the CDKN1A (p21) promoter to repress p21 transcription and enable bypass of cellular senescence; restoring p21 reverses the growth arrest caused by PDRG1 loss [PMID:41943853]. PDRG1 is transcriptionally activated by SP1 binding at its promoter [PMID:42243436] and is held downstream of a HIF1α–miR-519d regulatory axis [PMID:28057028]. Through these activities PDRG1 functions as an oncogenic driver: it suppresses ATM/p53 signaling to promote radioresistance and survival [PMID:27610824, PMID:31383535] and activates MEK/ERK/CD44 and Wnt/β-catenin signaling to drive proliferation and migration across multiple cancer contexts [PMID:34812552, PMID:42243436].","teleology":[{"year":2016,"claim":"The first molecular function for PDRG1 was established by showing it binds the MAT catalytic subunit and lowers DNA methylation, linking the protein to methionine/SAM metabolism.","evidence":"Yeast two-hybrid, reciprocal Co-IP, pull-down, and DNA methylation assays identifying MATα1 interaction","pmids":["27548429"],"confidence":"High","gaps":["Does not establish how the interaction inhibits MAT enzymatic activity mechanistically","Nuclear versus cytoplasmic partitioning of the effect not fully resolved"]},{"year":2016,"claim":"PDRG1 was placed as a determinant of radioresistance by showing gain/loss of function alters survival through the ATM-p53 axis, beginning its characterization as a stress-response modulator.","evidence":"Gain- and loss-of-function transfection with viability, apoptosis assays and Western blot in lung cancer cells","pmids":["27610824"],"confidence":"Medium","gaps":["No direct biochemical interaction with ATM demonstrated","Mechanism by which PDRG1 modulates ATM activity unknown"]},{"year":2017,"claim":"Upstream regulation of PDRG1 was clarified by positioning it downstream of a HIF1α–miR-519d axis controlling radiosensitivity.","evidence":"ChIP and luciferase reporter assays confirming HIF1α binding to miR-519d promoter and miR-519d targeting of PDRG1 mRNA in nasopharyngeal carcinoma","pmids":["28057028"],"confidence":"Medium","gaps":["Does not address how PDRG1 protein level changes translate to downstream effectors","Generality of the axis beyond nasopharyngeal carcinoma untested"]},{"year":2019,"claim":"Pharmacological epistasis confirmed PDRG1 as an upstream suppressor of ATM/p53 signaling, consolidating its anti-apoptotic role.","evidence":"siRNA knockdown with ATM inhibitor (KU55933) rescue, flow cytometry, Western blot, and xenografts in gastric cancer","pmids":["31383535"],"confidence":"Medium","gaps":["Direct molecular link between PDRG1 and ATM still missing","Whether the MAT/SAM or EZH2 activities feed into ATM suppression not tested"]},{"year":2019,"claim":"PDRG1 was linked to Wnt signaling and chemosensitivity, expanding its oncogenic pathway repertoire.","evidence":"shRNA knockdown and overexpression with Western blot of β-catenin/cyclinD1 and cisplatin sensitivity assays in esophageal cancer","pmids":["31882431"],"confidence":"Low","gaps":["Pathway inference rests on protein expression changes without direct interaction evidence","No epistasis or rescue experiment to establish causality"]},{"year":2021,"claim":"Transcriptomic and in vivo work placed PDRG1 upstream of MEK/ERK/CD44 signaling driving glioblastoma proliferation and migration.","evidence":"shRNA knockdown, transcriptome sequencing, Western blot, migration/proliferation assays, and xenografts","pmids":["34812552"],"confidence":"Medium","gaps":["No direct biochemical interaction with MEK/ERK components shown","Mechanism connecting PDRG1 to CD44 induction unresolved"]},{"year":2025,"claim":"The core structural identity of PDRG1 was defined as a prefoldin-like complex subunit, providing a conserved framework for its nuclear functions.","evidence":"In vivo AP-MS interactome mapping and genetic loss-of-function (embryonic lethal) in Arabidopsis showing UXT/URI as main interactors with RNA Pol and spliceosome overlap","pmids":["40026265"],"confidence":"Medium","gaps":["Plant ortholog context limits direct translation to human PDRG1","How PFDLc membership relates to the MAT and EZH2 activities not integrated"]},{"year":2026,"claim":"A direct epigenetic mechanism was established: PDRG1 binds EZH2 via defined N-terminal residues to drive H3K27me3-mediated p21 repression and senescence bypass.","evidence":"Co-IP, ChIP-qPCR, RNA-seq, domain-mapping mutagenesis, p21 rescue, and xenografts","pmids":["41943853"],"confidence":"High","gaps":["Whether EZH2 binding cooperates with the DNA methylation effect via MAT not tested","Structural basis of the residue 36–70 interaction not resolved"]},{"year":2026,"claim":"SP1 was identified as a direct transcriptional activator of PDRG1, and PDRG1 was confirmed to act through Wnt/β-catenin in hepatocellular carcinoma, completing an upstream-to-downstream signaling loop.","evidence":"ChIP/promoter binding, Western blot of Wnt effectors, XAV939 inhibitor rescue, and KD/OE in vitro and in vivo","pmids":["42243436"],"confidence":"Medium","gaps":["Direct PDRG1–Wnt component interaction not demonstrated","Whether SP1 induction operates across other PDRG1-driven cancers untested"]},{"year":null,"claim":"How PDRG1's prefoldin-like complex membership mechanistically unifies its distinct roles in DNA methylation, H3K27me3 deposition, and multiple oncogenic signaling pathways remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of human PDRG1 in complex with EZH2, MATα1, or PFDLc partners","Direct biochemical links to ATM, MEK/ERK, and Wnt components are absent","Integration of metabolic (SAM) and chromatin activities into a single pathway is undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,7]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[6]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,7]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[7]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[5,8]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,3,5,8]}],"complexes":["prefoldin-like complex (PFDLc)"],"partners":["UXT","URI","MAT1A","EZH2","SP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NUG6","full_name":"p53 and DNA damage-regulated protein 1","aliases":[],"length_aa":133,"mass_kda":15.5,"function":"May play a role in chaperone-mediated protein folding","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q9NUG6/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/PDRG1","classification":"Common Essential","n_dependent_lines":1204,"n_total_lines":1208,"dependency_fraction":0.9966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"POLR2H","stoichiometry":10.0},{"gene":"POLR2E","stoichiometry":4.0},{"gene":"PFDN6","stoichiometry":0.2},{"gene":"POLR2B","stoichiometry":0.2},{"gene":"POLR2K","stoichiometry":0.2},{"gene":"PTGES3","stoichiometry":0.2},{"gene":"RNF40","stoichiometry":0.2},{"gene":"RPAP2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PDRG1","total_profiled":1310},"omim":[{"mim_id":"610789","title":"p53 AND DNA DAMAGE-REGULATED 1; PDRG1","url":"https://www.omim.org/entry/610789"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Actin filaments","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PDRG1"},"hgnc":{"alias_symbol":["dJ310O13.3"],"prev_symbol":["C20orf126"]},"alphafold":{"accession":"Q9NUG6","domains":[{"cath_id":"-","chopping":"3-51_85-130","consensus_level":"high","plddt":93.0609,"start":3,"end":130}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NUG6","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NUG6-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NUG6-F1-predicted_aligned_error_v6.png","plddt_mean":91.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PDRG1","jax_strain_url":"https://www.jax.org/strain/search?query=PDRG1"},"sequence":{"accession":"Q9NUG6","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NUG6.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NUG6/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NUG6"}},"corpus_meta":[{"pmid":"28057028","id":"PMC_28057028","title":"Oleuropein enhances radiation sensitivity of nasopharyngeal carcinoma by downregulating PDRG1 through HIF1α-repressed microRNA-519d.","date":"2017","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/28057028","citation_count":36,"is_preprint":false},{"pmid":"27548429","id":"PMC_27548429","title":"The Oncogene PDRG1 Is an Interaction Target of Methionine Adenosyltransferases.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/27548429","citation_count":18,"is_preprint":false},{"pmid":"32390762","id":"PMC_32390762","title":"Long non-coding RNA LINC01419 mediates miR-519a-3p/PDRG1 axis to promote cell progression in osteosarcoma.","date":"2020","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/32390762","citation_count":14,"is_preprint":false},{"pmid":"32489325","id":"PMC_32489325","title":"lncRNA FOXD2-AS1 promotes hemangioma progression through the miR-324-3p/PDRG1 pathway.","date":"2020","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/32489325","citation_count":14,"is_preprint":false},{"pmid":"34812552","id":"PMC_34812552","title":"PDRG1 promotes the proliferation and migration of GBM cells by the MEK/ERK/CD44 pathway.","date":"2021","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/34812552","citation_count":13,"is_preprint":false},{"pmid":"27610824","id":"PMC_27610824","title":"The PDRG1 is an oncogene in lung cancer cells, promoting radioresistance via the ATM-P53 signaling pathway.","date":"2016","source":"Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie","url":"https://pubmed.ncbi.nlm.nih.gov/27610824","citation_count":12,"is_preprint":false},{"pmid":"31383535","id":"PMC_31383535","title":"PDRG1 gene silencing contributes to inhibit the growth and induce apoptosis of gastric cancer cells.","date":"2019","source":"Pathology, research and practice","url":"https://pubmed.ncbi.nlm.nih.gov/31383535","citation_count":11,"is_preprint":false},{"pmid":"29225734","id":"PMC_29225734","title":"PDRG1 at the interface between intermediary metabolism and oncogenesis.","date":"2017","source":"World journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/29225734","citation_count":9,"is_preprint":false},{"pmid":"29301330","id":"PMC_29301330","title":"The Potential Roles of the Apoptosis-Related Protein PDRG1 in Diapause Embryo Restarting of Artemia sinica.","date":"2018","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/29301330","citation_count":7,"is_preprint":false},{"pmid":"31882431","id":"PMC_31882431","title":"Knockdown of PDRG1 Could Inhibit the Wnt Signaling Pathway in Esophageal Cancer Cells.","date":"2019","source":"Annals of clinical and laboratory science","url":"https://pubmed.ncbi.nlm.nih.gov/31882431","citation_count":3,"is_preprint":false},{"pmid":"28257526","id":"PMC_28257526","title":"Molecular cloning, characterization and expression analysis of a novel PDRG1 gene from black tiger shrimp (Penaeus monodon).","date":"2017","source":"Genetics and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/28257526","citation_count":2,"is_preprint":false},{"pmid":"40026265","id":"PMC_40026265","title":"PDRG1 is essential for early plant development as a component of the prefoldin-like complex.","date":"2025","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/40026265","citation_count":1,"is_preprint":false},{"pmid":"41943853","id":"PMC_41943853","title":"Identification of a Novel PDRG1-EZH2-p21 Pathway Controlling Senescence and Tumor Progression in Hepatocellular Carcinoma.","date":"2026","source":"International journal of biological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41943853","citation_count":0,"is_preprint":false},{"pmid":"42243436","id":"PMC_42243436","title":"PDRG1 induced by SP1 facilitates the proliferation and metastasis of hepatocellular carcinoma by activating the Wnt/β-catenin pathway.","date":"2026","source":"MedScience","url":"https://pubmed.ncbi.nlm.nih.gov/42243436","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9106,"output_tokens":2381,"usd":0.031517,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9515,"output_tokens":3295,"usd":0.064975,"stage2_stop_reason":"end_turn"},"total_usd":0.096492,"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\": 2016,\n      \"finding\": \"PDRG1 physically interacts with MATα1 (the catalytic subunit of methionine adenosyltransferases MAT I and MAT III), as demonstrated by yeast two-hybrid, immunoprecipitation, and pull-down assays. Nuclear MATα1-PDRG1 interaction results in reduced DNA methylation levels, identifying downregulation of S-adenosylmethionine synthesis as the first functional effect directly ascribed to PDRG1.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, pull-down assays, DNA methylation assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and pull-down with functional readout (DNA methylation), single lab, multiple orthogonal methods\",\n      \"pmids\": [\"27548429\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PDRG1 promotes radioresistance in lung cancer cells via the ATM-p53 signaling pathway, as shown by gain- and loss-of-function experiments affecting cell viability, apoptosis, and protein expression.\",\n      \"method\": \"Gain-of-function and loss-of-function transfection, cell viability assays, apoptosis assays, Western blot\",\n      \"journal\": \"Biomedicine & pharmacotherapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — single lab, pathway placement via KD/OE with defined cellular phenotype, but no direct biochemical interaction with ATM demonstrated\",\n      \"pmids\": [\"27610824\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HIF1α directly targets the miR-519d promoter (chromatin immunoprecipitation and luciferase reporter assay), and miR-519d directly targets PDRG1 mRNA (luciferase reporter assay), placing PDRG1 downstream of a HIF1α-miR-519d axis in nasopharyngeal carcinoma radiosensitivity.\",\n      \"method\": \"Chromatin immunoprecipitation, luciferase reporter assay, stable overexpression/knockdown\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and luciferase reporter confirm direct transcriptional regulation, single lab\",\n      \"pmids\": [\"28057028\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PDRG1 silencing in gastric cancer cells activates the ATM/p53 pathway (increased p-ATM, p53, p21, p-cdc2, cleaved caspase-3), arrests the cell cycle at G2/M, and induces apoptosis; pharmacological ATM inhibition (KU55933) reverses these effects, establishing PDRG1 as an upstream suppressor of ATM/p53 signaling.\",\n      \"method\": \"siRNA knockdown, Western blot, flow cytometry, ATM inhibitor rescue, xenograft model\",\n      \"journal\": \"Pathology, research and practice\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway placement confirmed by pharmacological epistasis (KU55933 rescue), single lab, multiple readouts\",\n      \"pmids\": [\"31383535\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PDRG1 knockdown in esophageal cancer cells suppresses the Wnt signaling pathway, as evidenced by reduced cyclinD1 and β-catenin expression, increased apoptosis, and enhanced cisplatin sensitivity.\",\n      \"method\": \"shRNA knockdown, overexpression, Western blot, cell viability and apoptosis assays\",\n      \"journal\": \"Annals of clinical and laboratory science\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single-method pathway inference from protein expression changes without direct interaction evidence\",\n      \"pmids\": [\"31882431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PDRG1 promotes proliferation and migration of GBM cells via the MEK/ERK/CD44 pathway; PDRG1 knockdown reduces CD44 expression and transcriptome analysis confirmed enrichment of adhesion and motility gene sets.\",\n      \"method\": \"shRNA knockdown, transcriptome sequencing, Western blot, in vitro migration/proliferation assays, in vivo xenograft\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — pathway placement by KD with transcriptomic readout and in vivo validation, but no direct biochemical interaction with MEK/ERK components demonstrated; single lab\",\n      \"pmids\": [\"34812552\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In Arabidopsis, PDRG1 functions primarily as a subunit of the prefoldin-like complex (PFDLc); in vivo interactome (AP-MS) shows PFDLc subunits (UXT, URI) are its main interactors with overlapping interactomes including nuclear RNA polymerase subunits and spliceosome components. PDRG1 impairment causes embryonic lethality, equivalent to loss of other PFDLc subunits.\",\n      \"method\": \"In vivo co-immunoprecipitation/AP-MS, genetic loss-of-function (embryonic lethal phenotype), interactome comparison\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal interactome mapping with functional genetic validation in plant model, single lab; plant ortholog context limits direct translation to human protein\",\n      \"pmids\": [\"40026265\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"PDRG1 directly interacts with EZH2 (co-immunoprecipitation), and this interaction increases H3K27me3 enrichment at the p21 (CDKN1A) promoter (ChIP-qPCR), suppressing p21 transcription and allowing bypass of cellular senescence. Domain mapping identified PDRG1 N-terminal residues 36–70 as required for EZH2 binding. Restoration of p21 rescues the anti-proliferative phenotype caused by PDRG1 knockdown.\",\n      \"method\": \"Co-immunoprecipitation, ChIP-qPCR, RNA-seq, domain-mapping mutagenesis, rescue experiments, xenograft model\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct protein interaction confirmed by Co-IP, epigenetic mechanism validated by ChIP-qPCR, domain mapping, and rescue experiments; multiple orthogonal methods in single lab\",\n      \"pmids\": [\"41943853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Transcription factor SP1 directly binds the PDRG1 promoter at the E3 site (−1927 to −1917) and activates PDRG1 transcription; SP1-driven pro-tumor effects are rescued by PDRG1 silencing. PDRG1 in turn activates Wnt/β-catenin signaling (elevated β-catenin, c-Myc, phospho-GSK-3β), and Wnt inhibitor XAV939 reverses PDRG1 oncogenic effects in HCC.\",\n      \"method\": \"ChIP, luciferase reporter assay (implied by promoter binding), Western blot, Wnt pathway inhibitor rescue, KD/OE in vitro and in vivo\",\n      \"journal\": \"MedScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — upstream transcriptional regulation confirmed by promoter binding assay and rescue experiments; Wnt pathway placement supported by pharmacological epistasis; single lab\",\n      \"pmids\": [\"42243436\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PDRG1 is a small oncogenic protein that functions as a subunit of the prefoldin-like complex (binding UXT/URI and associating with RNA polymerase II and spliceosome components), interacts with and suppresses methionine adenosyltransferases (MAT I/III) to reduce nuclear S-adenosylmethionine and DNA methylation, directly binds EZH2 via its N-terminal residues 36–70 to promote H3K27me3-mediated repression of p21 and senescence bypass, and is transcriptionally activated by SP1; downstream, PDRG1 suppresses ATM/p53 pathway activity and activates MEK/ERK/CD44 and Wnt/β-catenin signaling to drive proliferation, migration, and therapy resistance in multiple cancer contexts.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PDRG1 is a small protein with dual roles in chromatin/epigenetic regulation and oncogenic signaling, acting both as a subunit of the prefoldin-like complex and as a modulator of DNA and histone methylation [#6, #0, #7]. As a structural component, PDRG1 associates principally with the prefoldin-like complex subunits UXT and URI, with an overlapping interactome that includes nuclear RNA polymerase subunits and spliceosome components, and its loss is developmentally lethal [#6]. PDRG1 lowers genomic methylation by physically binding MAT\\u03b11, the catalytic subunit of methionine adenosyltransferases MAT I/III, reducing S-adenosylmethionine availability and DNA methylation [#0]. In parallel, PDRG1 directly binds EZH2 through its N-terminal residues 36\\u201370, increasing H3K27me3 deposition at the CDKN1A (p21) promoter to repress p21 transcription and enable bypass of cellular senescence; restoring p21 reverses the growth arrest caused by PDRG1 loss [#7]. PDRG1 is transcriptionally activated by SP1 binding at its promoter [#8] and is held downstream of a HIF1\\u03b1\\u2013miR-519d regulatory axis [#2]. Through these activities PDRG1 functions as an oncogenic driver: it suppresses ATM/p53 signaling to promote radioresistance and survival [#1, #3] and activates MEK/ERK/CD44 and Wnt/\\u03b2-catenin signaling to drive proliferation and migration across multiple cancer contexts [#5, #8].\",\n  \"teleology\": [\n    {\n      \"year\": 2016,\n      \"claim\": \"The first molecular function for PDRG1 was established by showing it binds the MAT catalytic subunit and lowers DNA methylation, linking the protein to methionine/SAM metabolism.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal Co-IP, pull-down, and DNA methylation assays identifying MAT\\u03b11 interaction\",\n      \"pmids\": [\"27548429\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not establish how the interaction inhibits MAT enzymatic activity mechanistically\", \"Nuclear versus cytoplasmic partitioning of the effect not fully resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"PDRG1 was placed as a determinant of radioresistance by showing gain/loss of function alters survival through the ATM-p53 axis, beginning its characterization as a stress-response modulator.\",\n      \"evidence\": \"Gain- and loss-of-function transfection with viability, apoptosis assays and Western blot in lung cancer cells\",\n      \"pmids\": [\"27610824\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct biochemical interaction with ATM demonstrated\", \"Mechanism by which PDRG1 modulates ATM activity unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Upstream regulation of PDRG1 was clarified by positioning it downstream of a HIF1\\u03b1\\u2013miR-519d axis controlling radiosensitivity.\",\n      \"evidence\": \"ChIP and luciferase reporter assays confirming HIF1\\u03b1 binding to miR-519d promoter and miR-519d targeting of PDRG1 mRNA in nasopharyngeal carcinoma\",\n      \"pmids\": [\"28057028\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not address how PDRG1 protein level changes translate to downstream effectors\", \"Generality of the axis beyond nasopharyngeal carcinoma untested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Pharmacological epistasis confirmed PDRG1 as an upstream suppressor of ATM/p53 signaling, consolidating its anti-apoptotic role.\",\n      \"evidence\": \"siRNA knockdown with ATM inhibitor (KU55933) rescue, flow cytometry, Western blot, and xenografts in gastric cancer\",\n      \"pmids\": [\"31383535\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between PDRG1 and ATM still missing\", \"Whether the MAT/SAM or EZH2 activities feed into ATM suppression not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"PDRG1 was linked to Wnt signaling and chemosensitivity, expanding its oncogenic pathway repertoire.\",\n      \"evidence\": \"shRNA knockdown and overexpression with Western blot of \\u03b2-catenin/cyclinD1 and cisplatin sensitivity assays in esophageal cancer\",\n      \"pmids\": [\"31882431\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Pathway inference rests on protein expression changes without direct interaction evidence\", \"No epistasis or rescue experiment to establish causality\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Transcriptomic and in vivo work placed PDRG1 upstream of MEK/ERK/CD44 signaling driving glioblastoma proliferation and migration.\",\n      \"evidence\": \"shRNA knockdown, transcriptome sequencing, Western blot, migration/proliferation assays, and xenografts\",\n      \"pmids\": [\"34812552\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct biochemical interaction with MEK/ERK components shown\", \"Mechanism connecting PDRG1 to CD44 induction unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The core structural identity of PDRG1 was defined as a prefoldin-like complex subunit, providing a conserved framework for its nuclear functions.\",\n      \"evidence\": \"In vivo AP-MS interactome mapping and genetic loss-of-function (embryonic lethal) in Arabidopsis showing UXT/URI as main interactors with RNA Pol and spliceosome overlap\",\n      \"pmids\": [\"40026265\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Plant ortholog context limits direct translation to human PDRG1\", \"How PFDLc membership relates to the MAT and EZH2 activities not integrated\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"A direct epigenetic mechanism was established: PDRG1 binds EZH2 via defined N-terminal residues to drive H3K27me3-mediated p21 repression and senescence bypass.\",\n      \"evidence\": \"Co-IP, ChIP-qPCR, RNA-seq, domain-mapping mutagenesis, p21 rescue, and xenografts\",\n      \"pmids\": [\"41943853\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether EZH2 binding cooperates with the DNA methylation effect via MAT not tested\", \"Structural basis of the residue 36\\u201370 interaction not resolved\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"SP1 was identified as a direct transcriptional activator of PDRG1, and PDRG1 was confirmed to act through Wnt/\\u03b2-catenin in hepatocellular carcinoma, completing an upstream-to-downstream signaling loop.\",\n      \"evidence\": \"ChIP/promoter binding, Western blot of Wnt effectors, XAV939 inhibitor rescue, and KD/OE in vitro and in vivo\",\n      \"pmids\": [\"42243436\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct PDRG1\\u2013Wnt component interaction not demonstrated\", \"Whether SP1 induction operates across other PDRG1-driven cancers untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PDRG1's prefoldin-like complex membership mechanistically unifies its distinct roles in DNA methylation, H3K27me3 deposition, and multiple oncogenic signaling pathways remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of human PDRG1 in complex with EZH2, MAT\\u03b11, or PFDLc partners\", \"Direct biochemical links to ATM, MEK/ERK, and Wnt components are absent\", \"Integration of metabolic (SAM) and chromatin activities into a single pathway is undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 7]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5, 8]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 3, 5, 8]}\n    ],\n    \"complexes\": [\"prefoldin-like complex (PFDLc)\"],\n    \"partners\": [\"UXT\", \"URI\", \"MAT1A\", \"EZH2\", \"SP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"faith_supported":6,"faith_total":6,"faith_pct":100.0}}