{"gene":"DDA1","run_date":"2026-06-09T23:54:41","timeline":{"discoveries":[{"year":2009,"finding":"DDA1 is a chromatin-associated core subunit of multiple CRL4 (Cul4-DDB1) E3 ubiquitin ligase complexes. Cells depleted of DDA1 spontaneously accumulated double-stranded DNA breaks similarly to Cul4A-, Cul4B-, or Wdr23-depleted cells, indicating DDA1 interacts physically and functionally with CRL4 complexes.","method":"Mass spectrometric interrogation of mammalian COP9 signalosome (CSN) subunit interaction networks; RNAi depletion with DNA damage readout (γH2AX/DSB accumulation)","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal mass spectrometry interactome plus functional depletion phenotype with orthogonal readout, single lab but two orthogonal methods","pmids":["19295130"],"is_preprint":false},{"year":2017,"finding":"c-Abl non-receptor kinase phosphorylates DDB1 at Tyr-316, which recruits DDA1 to the CRL4 ubiquitin ligase complex and leads to increased ubiquitination of CRL4 substrates including IKZF1 and IKZF3 in lenalidomide-treated multiple myeloma cells. Pharmacological inhibition or genetic ablation of the Abl-DDB1-DDA1 axis decreases substrate ubiquitination.","method":"Biochemical assays for DDB1 phosphorylation (site-specific mutagenesis at Tyr-316); co-immunoprecipitation of DDA1 with CRL4; ubiquitination assays for IKZF1/IKZF3; pharmacological (imatinib) and genetic (Abl KO) ablation in multiple myeloma cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — site-directed mutagenesis, biochemical ubiquitination assays, and genetic/pharmacological epistasis in same study; single lab but multiple orthogonal methods","pmids":["28087699"],"is_preprint":false},{"year":2024,"finding":"DDA1 is an integral structural component of the CRL4CSA ubiquitin ligase complex (composed of DDB1, CUL4A/B, RBX1, and CSA) and coordinates ubiquitination dynamics during transcription-coupled nucleotide excision repair (TC-NER). DDA1 is required for efficient turnover and progression of TC-NER at DNA damage-stalled RNA polymerase II.","method":"Single-step protein-complex isolation coupled to mass spectrometry; cryo-EM structural analysis; functional depletion assays measuring TC-NER dynamics and ubiquitination of TC-NER substrates","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure plus biochemical reconstitution plus functional depletion with mechanistic readout, published in peer-reviewed journal and consistent with companion preprint","pmids":["39075067"],"is_preprint":false},{"year":2023,"finding":"DDA1 identified as a CSA interacting protein that is an integral component of CRL4CSA; coordinates ubiquitination dynamics during TC-NER and is required for efficient turnover and progression of this process. (Preprint version of the 2024 Nature Communications study.)","method":"Single-step protein-complex isolation coupled to mass spectrometry; cryo-EM; functional depletion assays for TC-NER dynamics","journal":"Research square","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — cryo-EM plus mass spectrometry plus functional assays, but preprint not yet peer-reviewed at time of posting; results consistent with published version","pmids":["37886519"],"is_preprint":true},{"year":2016,"finding":"DDA1 overexpression in colon cancer cells promotes cell proliferation, facilitates cell cycle progression, inhibits apoptosis, and activates the NFκB/COP9 signalosome 2 (CSN2)/GSK-3β signaling pathway. DDA1 suppression inhibited tumor progression in vivo.","method":"Overexpression and knockdown in colon cancer cell lines; in vivo xenograft; pathway analysis (NFκB reporter, GSK-3β activity assay)","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — loss- and gain-of-function with defined pathway readout (NFκB/CSN2/GSK-3β), in vitro and in vivo, single lab","pmids":["26942699"],"is_preprint":false},{"year":2017,"finding":"DDA1 overexpression promotes lung cancer cell proliferation and cell cycle progression in vitro and xenograft tumor progression in vivo, associated with upregulation of cyclins D1, D3, and E1, placing DDA1 as a positive regulator of S-phase entry.","method":"Overexpression and loss-of-function in lung cancer lines; cell cycle analysis (flow cytometry); cyclin western blot; subcutaneous xenograft in vivo","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — gain- and loss-of-function with cell cycle and molecular readouts, consistent in vivo data, single lab","pmids":["28211159"],"is_preprint":false},{"year":2023,"finding":"STAT3 transcriptionally regulates DDA1 expression (measured by dual-luciferase reporter assay). DDA1 knockdown inhibited cyclin expression, promoted G0/G1 arrest, restrained proliferation, and induced apoptosis in cisplatin-resistant breast cancer cells. DHA suppressed STAT3 phosphorylation to repress DDA1, reversing cisplatin resistance.","method":"Dual-luciferase reporter assay for STAT3-DDA1 interaction; STAT3 knockdown; DDA1 knockdown; flow cytometry for cell cycle and apoptosis; western blot for cyclin and p-STAT3","journal":"The American journal of Chinese medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — dual-luciferase reporter plus KD phenotype with molecular readout, single lab, multiple methods","pmids":["36891981"],"is_preprint":false},{"year":2007,"finding":"Bacterial two-hybrid screening identified ACTN4 (alpha-actinin-4), PSAP (prosaposin), and EIF3S10 as candidate binding partners of DDA1/PCIA1. Three additional interacting genes had unknown function at the time.","method":"Bacterial two-hybrid system (BacterioMatch); fetal kidney cDNA library screening; DNA sequencing validation","journal":"Chinese journal of medical genetics","confidence":"Low","confidence_rationale":"Tier 4 / Weak — bacterial two-hybrid only, no reciprocal validation, single method, single lab","pmids":["17557237"],"is_preprint":false}],"current_model":"DDA1 (also known as PCIA1/C19orf58) is a small, evolutionarily conserved protein that functions as a core regulatory subunit of multiple CRL4 (Cullin4-DDB1-RBX1) E3 ubiquitin ligase complexes; its recruitment to CRL4 is promoted by c-Abl-mediated phosphorylation of DDB1 at Tyr-316, and within the CRL4CSA complex—whose structure has been resolved by cryo-EM—DDA1 coordinates ubiquitination dynamics during transcription-coupled nucleotide excision repair (TC-NER), with loss of DDA1 causing spontaneous DNA double-strand breaks and impaired TC-NER progression."},"narrative":{"mechanistic_narrative":"DDA1 is a small, evolutionarily conserved chromatin-associated protein that functions as a core regulatory subunit of CRL4 (Cul4-DDB1) E3 ubiquitin ligase complexes, where it supports genome stability through control of substrate ubiquitination [PMID:19295130]. Depletion of DDA1 phenocopies loss of other CRL4 components by causing spontaneous accumulation of double-stranded DNA breaks, establishing it as a physical and functional partner of these ligases [PMID:19295130]. Its incorporation into CRL4 is governed by c-Abl-mediated phosphorylation of DDB1 at Tyr-316, which recruits DDA1 and drives ubiquitination of CRL4 substrates such as IKZF1 and IKZF3 [PMID:28087699]. Within the CRL4CSA complex (DDB1, CUL4A/B, RBX1, and CSA), DDA1 is an integral structural component resolved by cryo-EM that coordinates ubiquitination dynamics during transcription-coupled nucleotide excision repair, being required for efficient turnover and progression of TC-NER at DNA damage-stalled RNA polymerase II [PMID:39075067]. Independent of its ligase role, DDA1 acts as a positive regulator of proliferation and cell-cycle progression in cancer cells, where its overexpression upregulates cyclins and engages NFkB/CSN2/GSK-3beta signaling and where it is transcriptionally controlled by STAT3 [PMID:26942699, PMID:28211159, PMID:36891981].","teleology":[{"year":2009,"claim":"Established DDA1 as a bona fide CRL4-associated subunit by linking its physical interaction to a shared loss-of-function genome-stability phenotype, defining its role rather than merely cataloguing an interaction.","evidence":"Mass spectrometric CSN interactome plus RNAi depletion with gammaH2AX/DSB readout in mammalian cells","pmids":["19295130"],"confidence":"High","gaps":["Did not define which CRL4 substrates or repair pathway DDA1 acts upon","Structural basis of DDA1 incorporation into CRL4 unresolved","Mechanism connecting DDA1 loss to DSB accumulation not delineated"]},{"year":2017,"claim":"Resolved how DDA1 is recruited to CRL4, showing that c-Abl phosphorylation of DDB1 at Tyr-316 is the regulatory switch controlling DDA1 incorporation and downstream substrate ubiquitination.","evidence":"Site-directed mutagenesis of DDB1 Tyr-316, Co-IP, IKZF1/IKZF3 ubiquitination assays, and Abl pharmacological/genetic ablation in multiple myeloma cells","pmids":["28087699"],"confidence":"High","gaps":["Whether the same recruitment mechanism operates in DNA-repair CRL4 complexes not tested","Structural consequence of DDB1 phosphorylation on DDA1 binding not visualized","Generality across other CRL4 substrate receptors unknown"]},{"year":2023,"claim":"Identified DDA1 as a CSA-interacting integral component of CRL4CSA and implicated it in TC-NER dynamics, extending its function to a specific repair complex (preprint).","evidence":"Single-step protein-complex isolation with mass spectrometry, cryo-EM, and functional TC-NER depletion assays (Research Square preprint)","pmids":["37886519"],"confidence":"Medium","gaps":["Preprint not yet peer-reviewed at time of posting","Quantitative kinetics of TC-NER turnover not fully defined"]},{"year":2024,"claim":"Established the structural and functional basis of DDA1 within CRL4CSA, showing it is required for efficient ubiquitination turnover and TC-NER progression at stalled RNA Pol II.","evidence":"Cryo-EM structure of CRL4CSA, complex isolation with mass spectrometry, and functional depletion assays measuring TC-NER dynamics","pmids":["39075067"],"confidence":"High","gaps":["Precise enzymatic step DDA1 modulates within the ubiquitination cycle not fully isolated","In vivo physiological consequences of DDA1-specific TC-NER defects not characterized"]},{"year":2017,"claim":"Characterized a proliferative, oncogenic dimension of DDA1 distinct from its ligase role, linking its overexpression to cyclin-driven S-phase entry and tumor growth.","evidence":"Gain- and loss-of-function in colon and lung cancer lines, cyclin western blots, flow cytometry, NFkB/CSN2/GSK-3beta pathway assays, and xenografts","pmids":["26942699","28211159"],"confidence":"Medium","gaps":["Whether proliferative effects require CRL4 ligase activity not resolved","Direct molecular targets connecting DDA1 to cyclin upregulation undefined"]},{"year":2023,"claim":"Placed DDA1 downstream of STAT3 transcriptional control and within a drug-resistance circuit, linking its expression to chemoresistance.","evidence":"Dual-luciferase reporter for STAT3-DDA1, STAT3 and DDA1 knockdown, cell-cycle/apoptosis flow cytometry, and p-STAT3/cyclin western blots in cisplatin-resistant breast cancer cells","pmids":["36891981"],"confidence":"Medium","gaps":["Direct STAT3 binding to the DDA1 promoter not confirmed by ChIP","Mechanistic link between DDA1 and cisplatin resistance not established"]},{"year":2007,"claim":"Earliest attempt to define DDA1/PCIA1 binding partners, nominating ACTN4, PSAP, and EIF3S10 as candidate interactors.","evidence":"Bacterial two-hybrid (BacterioMatch) screening of a fetal kidney cDNA library with sequencing validation","pmids":["17557237"],"confidence":"Low","gaps":["Bacterial two-hybrid only, no reciprocal validation or co-IP confirmation","Functional significance of these interactions never established","Not integrated with later CRL4-centric understanding of DDA1"]},{"year":null,"claim":"Whether DDA1's proliferative/oncogenic activities depend on its CRL4 ligase function, and how its repair and growth-regulatory roles are mechanistically connected, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No experiment links the CRL4-subunit role to the cyclin/NFkB proliferative phenotype","Substrate spectrum of DDA1-containing CRL4 complexes incompletely defined","Physiological and disease consequences of DDA1 loss in vivo uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,2]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,2]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,2]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[4,5]}],"complexes":["CRL4 (Cul4-DDB1-RBX1) E3 ubiquitin ligase","CRL4CSA"],"partners":["DDB1","CUL4A","CUL4B","RBX1","CSA","ACTN4","PSAP","EIF3S10"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BW61","full_name":"DET1- and DDB1-associated protein 1","aliases":["Placenta cross-immune reaction antigen 1","PCIA-1"],"length_aa":102,"mass_kda":11.8,"function":"Functions as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins (PubMed:17452440, PubMed:28302793, PubMed:28437394, PubMed:31686031, PubMed:31819272). In the DCX complexes, acts as a scaffolding subunit required to stabilize the complex (PubMed:31686031, PubMed:31819272)","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q9BW61/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DDA1","classification":"Not Classified","n_dependent_lines":322,"n_total_lines":1208,"dependency_fraction":0.26655629139072845},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"DYNLL2","stoichiometry":4.0},{"gene":"DDB1","stoichiometry":0.2},{"gene":"DYNLL1","stoichiometry":0.2},{"gene":"MIF","stoichiometry":0.2},{"gene":"SRP14","stoichiometry":0.2},{"gene":"SRP9","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/DDA1","total_profiled":1310},"omim":[{"mim_id":"620109","title":"DDB1- AND CUL4-ASSOCIATED FACTOR 15; DCAF15","url":"https://www.omim.org/entry/620109"},{"mim_id":"604739","title":"RNA-BINDING MOTIF PROTEIN 39; RBM39","url":"https://www.omim.org/entry/604739"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Nucleoli","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/DDA1"},"hgnc":{"alias_symbol":["PCIA1","MGC2594"],"prev_symbol":["C19orf58"]},"alphafold":{"accession":"Q9BW61","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BW61","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BW61-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BW61-F1-predicted_aligned_error_v6.png","plddt_mean":66.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DDA1","jax_strain_url":"https://www.jax.org/strain/search?query=DDA1"},"sequence":{"accession":"Q9BW61","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BW61.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BW61/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BW61"}},"corpus_meta":[{"pmid":"17634358","id":"PMC_17634358","title":"D1 dopamine receptor dDA1 is required in the mushroom body neurons for aversive and appetitive learning in Drosophila.","date":"2007","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/17634358","citation_count":291,"is_preprint":false},{"pmid":"12711555","id":"PMC_12711555","title":"Expression of a D1 dopamine receptor dDA1/DmDOP1 in the central nervous system of Drosophila melanogaster.","date":"2003","source":"Gene expression patterns : GEP","url":"https://pubmed.ncbi.nlm.nih.gov/12711555","citation_count":92,"is_preprint":false},{"pmid":"19295130","id":"PMC_19295130","title":"An interaction network of the mammalian COP9 signalosome identifies Dda1 as a core subunit of multiple Cul4-based E3 ligases.","date":"2009","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/19295130","citation_count":71,"is_preprint":false},{"pmid":"20797997","id":"PMC_20797997","title":"Misregulation of the LOB domain gene DDA1 suggests possible functions in auxin signalling and photomorphogenesis.","date":"2010","source":"Journal of experimental botany","url":"https://pubmed.ncbi.nlm.nih.gov/20797997","citation_count":45,"is_preprint":false},{"pmid":"36891981","id":"PMC_36891981","title":"Dihydroartemisinin Affects STAT3/DDA1 Signaling Pathway and Reverses Breast Cancer Resistance to Cisplatin.","date":"2023","source":"The American journal of Chinese medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36891981","citation_count":20,"is_preprint":false},{"pmid":"28211159","id":"PMC_28211159","title":"DDA1, a novel oncogene, promotes lung cancer progression through regulation of cell cycle.","date":"2017","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/28211159","citation_count":18,"is_preprint":false},{"pmid":"39075067","id":"PMC_39075067","title":"The small CRL4CSA ubiquitin ligase component DDA1 regulates transcription-coupled repair dynamics.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/39075067","citation_count":12,"is_preprint":false},{"pmid":"26942699","id":"PMC_26942699","title":"DDA1 promotes stage IIB-IIC colon cancer progression by activating NFκB/CSN2/GSK-3β signaling.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26942699","citation_count":9,"is_preprint":false},{"pmid":"28087699","id":"PMC_28087699","title":"Activation of c-Abl Kinase Potentiates the Anti-myeloma Drug Lenalidomide by Promoting DDA1 Protein Recruitment to the CRL4 Ubiquitin Ligase.","date":"2017","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/28087699","citation_count":8,"is_preprint":false},{"pmid":"17557237","id":"PMC_17557237","title":"[Searching for genes interacting with human PCIA1 gene by using the bacterial two-hybrid system].","date":"2007","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/17557237","citation_count":2,"is_preprint":false},{"pmid":"16761402","id":"PMC_16761402","title":"[The establishment and identification of the stable transfectant of HeLa cell expressing human new gene (PCIA1)].","date":"2006","source":"Sichuan da xue xue bao. Yi xue ban = Journal of Sichuan University. Medical science edition","url":"https://pubmed.ncbi.nlm.nih.gov/16761402","citation_count":2,"is_preprint":false},{"pmid":"37886519","id":"PMC_37886519","title":"DDA1, a novel factor in transcription-coupled repair, modulates CRL4CSA dynamics at DNA damage-stalled RNA polymerase II.","date":"2023","source":"Research square","url":"https://pubmed.ncbi.nlm.nih.gov/37886519","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.06.09.658656","title":"Nighttime Caffeine Intake Increases Motor Impulsivity","date":"2025-06-13","source":"bioRxiv","url":"https://doi.org/10.1101/2025.06.09.658656","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7775,"output_tokens":2194,"usd":0.028118,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9280,"output_tokens":3019,"usd":0.060937,"stage2_stop_reason":"end_turn"},"total_usd":0.089055,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"DDA1 is a chromatin-associated core subunit of multiple CRL4 (Cul4-DDB1) E3 ubiquitin ligase complexes. Cells depleted of DDA1 spontaneously accumulated double-stranded DNA breaks similarly to Cul4A-, Cul4B-, or Wdr23-depleted cells, indicating DDA1 interacts physically and functionally with CRL4 complexes.\",\n      \"method\": \"Mass spectrometric interrogation of mammalian COP9 signalosome (CSN) subunit interaction networks; RNAi depletion with DNA damage readout (γH2AX/DSB accumulation)\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal mass spectrometry interactome plus functional depletion phenotype with orthogonal readout, single lab but two orthogonal methods\",\n      \"pmids\": [\"19295130\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"c-Abl non-receptor kinase phosphorylates DDB1 at Tyr-316, which recruits DDA1 to the CRL4 ubiquitin ligase complex and leads to increased ubiquitination of CRL4 substrates including IKZF1 and IKZF3 in lenalidomide-treated multiple myeloma cells. Pharmacological inhibition or genetic ablation of the Abl-DDB1-DDA1 axis decreases substrate ubiquitination.\",\n      \"method\": \"Biochemical assays for DDB1 phosphorylation (site-specific mutagenesis at Tyr-316); co-immunoprecipitation of DDA1 with CRL4; ubiquitination assays for IKZF1/IKZF3; pharmacological (imatinib) and genetic (Abl KO) ablation in multiple myeloma cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — site-directed mutagenesis, biochemical ubiquitination assays, and genetic/pharmacological epistasis in same study; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"28087699\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DDA1 is an integral structural component of the CRL4CSA ubiquitin ligase complex (composed of DDB1, CUL4A/B, RBX1, and CSA) and coordinates ubiquitination dynamics during transcription-coupled nucleotide excision repair (TC-NER). DDA1 is required for efficient turnover and progression of TC-NER at DNA damage-stalled RNA polymerase II.\",\n      \"method\": \"Single-step protein-complex isolation coupled to mass spectrometry; cryo-EM structural analysis; functional depletion assays measuring TC-NER dynamics and ubiquitination of TC-NER substrates\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure plus biochemical reconstitution plus functional depletion with mechanistic readout, published in peer-reviewed journal and consistent with companion preprint\",\n      \"pmids\": [\"39075067\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DDA1 identified as a CSA interacting protein that is an integral component of CRL4CSA; coordinates ubiquitination dynamics during TC-NER and is required for efficient turnover and progression of this process. (Preprint version of the 2024 Nature Communications study.)\",\n      \"method\": \"Single-step protein-complex isolation coupled to mass spectrometry; cryo-EM; functional depletion assays for TC-NER dynamics\",\n      \"journal\": \"Research square\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — cryo-EM plus mass spectrometry plus functional assays, but preprint not yet peer-reviewed at time of posting; results consistent with published version\",\n      \"pmids\": [\"37886519\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"DDA1 overexpression in colon cancer cells promotes cell proliferation, facilitates cell cycle progression, inhibits apoptosis, and activates the NFκB/COP9 signalosome 2 (CSN2)/GSK-3β signaling pathway. DDA1 suppression inhibited tumor progression in vivo.\",\n      \"method\": \"Overexpression and knockdown in colon cancer cell lines; in vivo xenograft; pathway analysis (NFκB reporter, GSK-3β activity assay)\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — loss- and gain-of-function with defined pathway readout (NFκB/CSN2/GSK-3β), in vitro and in vivo, single lab\",\n      \"pmids\": [\"26942699\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"DDA1 overexpression promotes lung cancer cell proliferation and cell cycle progression in vitro and xenograft tumor progression in vivo, associated with upregulation of cyclins D1, D3, and E1, placing DDA1 as a positive regulator of S-phase entry.\",\n      \"method\": \"Overexpression and loss-of-function in lung cancer lines; cell cycle analysis (flow cytometry); cyclin western blot; subcutaneous xenograft in vivo\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — gain- and loss-of-function with cell cycle and molecular readouts, consistent in vivo data, single lab\",\n      \"pmids\": [\"28211159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"STAT3 transcriptionally regulates DDA1 expression (measured by dual-luciferase reporter assay). DDA1 knockdown inhibited cyclin expression, promoted G0/G1 arrest, restrained proliferation, and induced apoptosis in cisplatin-resistant breast cancer cells. DHA suppressed STAT3 phosphorylation to repress DDA1, reversing cisplatin resistance.\",\n      \"method\": \"Dual-luciferase reporter assay for STAT3-DDA1 interaction; STAT3 knockdown; DDA1 knockdown; flow cytometry for cell cycle and apoptosis; western blot for cyclin and p-STAT3\",\n      \"journal\": \"The American journal of Chinese medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — dual-luciferase reporter plus KD phenotype with molecular readout, single lab, multiple methods\",\n      \"pmids\": [\"36891981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Bacterial two-hybrid screening identified ACTN4 (alpha-actinin-4), PSAP (prosaposin), and EIF3S10 as candidate binding partners of DDA1/PCIA1. Three additional interacting genes had unknown function at the time.\",\n      \"method\": \"Bacterial two-hybrid system (BacterioMatch); fetal kidney cDNA library screening; DNA sequencing validation\",\n      \"journal\": \"Chinese journal of medical genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — bacterial two-hybrid only, no reciprocal validation, single method, single lab\",\n      \"pmids\": [\"17557237\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DDA1 (also known as PCIA1/C19orf58) is a small, evolutionarily conserved protein that functions as a core regulatory subunit of multiple CRL4 (Cullin4-DDB1-RBX1) E3 ubiquitin ligase complexes; its recruitment to CRL4 is promoted by c-Abl-mediated phosphorylation of DDB1 at Tyr-316, and within the CRL4CSA complex—whose structure has been resolved by cryo-EM—DDA1 coordinates ubiquitination dynamics during transcription-coupled nucleotide excision repair (TC-NER), with loss of DDA1 causing spontaneous DNA double-strand breaks and impaired TC-NER progression.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"DDA1 is a small, evolutionarily conserved chromatin-associated protein that functions as a core regulatory subunit of CRL4 (Cul4-DDB1) E3 ubiquitin ligase complexes, where it supports genome stability through control of substrate ubiquitination [#0]. Depletion of DDA1 phenocopies loss of other CRL4 components by causing spontaneous accumulation of double-stranded DNA breaks, establishing it as a physical and functional partner of these ligases [#0]. Its incorporation into CRL4 is governed by c-Abl-mediated phosphorylation of DDB1 at Tyr-316, which recruits DDA1 and drives ubiquitination of CRL4 substrates such as IKZF1 and IKZF3 [#1]. Within the CRL4CSA complex (DDB1, CUL4A/B, RBX1, and CSA), DDA1 is an integral structural component resolved by cryo-EM that coordinates ubiquitination dynamics during transcription-coupled nucleotide excision repair, being required for efficient turnover and progression of TC-NER at DNA damage-stalled RNA polymerase II [#2]. Independent of its ligase role, DDA1 acts as a positive regulator of proliferation and cell-cycle progression in cancer cells, where its overexpression upregulates cyclins and engages NFkB/CSN2/GSK-3beta signaling and where it is transcriptionally controlled by STAT3 [#4, #5, #6].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Established DDA1 as a bona fide CRL4-associated subunit by linking its physical interaction to a shared loss-of-function genome-stability phenotype, defining its role rather than merely cataloguing an interaction.\",\n      \"evidence\": \"Mass spectrometric CSN interactome plus RNAi depletion with gammaH2AX/DSB readout in mammalian cells\",\n      \"pmids\": [\"19295130\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not define which CRL4 substrates or repair pathway DDA1 acts upon\",\n        \"Structural basis of DDA1 incorporation into CRL4 unresolved\",\n        \"Mechanism connecting DDA1 loss to DSB accumulation not delineated\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Resolved how DDA1 is recruited to CRL4, showing that c-Abl phosphorylation of DDB1 at Tyr-316 is the regulatory switch controlling DDA1 incorporation and downstream substrate ubiquitination.\",\n      \"evidence\": \"Site-directed mutagenesis of DDB1 Tyr-316, Co-IP, IKZF1/IKZF3 ubiquitination assays, and Abl pharmacological/genetic ablation in multiple myeloma cells\",\n      \"pmids\": [\"28087699\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the same recruitment mechanism operates in DNA-repair CRL4 complexes not tested\",\n        \"Structural consequence of DDB1 phosphorylation on DDA1 binding not visualized\",\n        \"Generality across other CRL4 substrate receptors unknown\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified DDA1 as a CSA-interacting integral component of CRL4CSA and implicated it in TC-NER dynamics, extending its function to a specific repair complex (preprint).\",\n      \"evidence\": \"Single-step protein-complex isolation with mass spectrometry, cryo-EM, and functional TC-NER depletion assays (Research Square preprint)\",\n      \"pmids\": [\"37886519\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Preprint not yet peer-reviewed at time of posting\",\n        \"Quantitative kinetics of TC-NER turnover not fully defined\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established the structural and functional basis of DDA1 within CRL4CSA, showing it is required for efficient ubiquitination turnover and TC-NER progression at stalled RNA Pol II.\",\n      \"evidence\": \"Cryo-EM structure of CRL4CSA, complex isolation with mass spectrometry, and functional depletion assays measuring TC-NER dynamics\",\n      \"pmids\": [\"39075067\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Precise enzymatic step DDA1 modulates within the ubiquitination cycle not fully isolated\",\n        \"In vivo physiological consequences of DDA1-specific TC-NER defects not characterized\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Characterized a proliferative, oncogenic dimension of DDA1 distinct from its ligase role, linking its overexpression to cyclin-driven S-phase entry and tumor growth.\",\n      \"evidence\": \"Gain- and loss-of-function in colon and lung cancer lines, cyclin western blots, flow cytometry, NFkB/CSN2/GSK-3beta pathway assays, and xenografts\",\n      \"pmids\": [\"26942699\", \"28211159\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether proliferative effects require CRL4 ligase activity not resolved\",\n        \"Direct molecular targets connecting DDA1 to cyclin upregulation undefined\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placed DDA1 downstream of STAT3 transcriptional control and within a drug-resistance circuit, linking its expression to chemoresistance.\",\n      \"evidence\": \"Dual-luciferase reporter for STAT3-DDA1, STAT3 and DDA1 knockdown, cell-cycle/apoptosis flow cytometry, and p-STAT3/cyclin western blots in cisplatin-resistant breast cancer cells\",\n      \"pmids\": [\"36891981\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct STAT3 binding to the DDA1 promoter not confirmed by ChIP\",\n        \"Mechanistic link between DDA1 and cisplatin resistance not established\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Earliest attempt to define DDA1/PCIA1 binding partners, nominating ACTN4, PSAP, and EIF3S10 as candidate interactors.\",\n      \"evidence\": \"Bacterial two-hybrid (BacterioMatch) screening of a fetal kidney cDNA library with sequencing validation\",\n      \"pmids\": [\"17557237\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Bacterial two-hybrid only, no reciprocal validation or co-IP confirmation\",\n        \"Functional significance of these interactions never established\",\n        \"Not integrated with later CRL4-centric understanding of DDA1\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether DDA1's proliferative/oncogenic activities depend on its CRL4 ligase function, and how its repair and growth-regulatory roles are mechanistically connected, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No experiment links the CRL4-subunit role to the cyclin/NFkB proliferative phenotype\",\n        \"Substrate spectrum of DDA1-containing CRL4 complexes incompletely defined\",\n        \"Physiological and disease consequences of DDA1 loss in vivo uncharacterized\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [4, 5]}\n    ],\n    \"complexes\": [\"CRL4 (Cul4-DDB1-RBX1) E3 ubiquitin ligase\", \"CRL4CSA\"],\n    \"partners\": [\"DDB1\", \"CUL4A\", \"CUL4B\", \"RBX1\", \"CSA\", \"ACTN4\", \"PSAP\", \"EIF3S10\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}