{"gene":"DNAJC24","run_date":"2026-04-28T17:46:03","timeline":{"discoveries":[{"year":2004,"finding":"DPH4 (DNAJC24) encodes a CSL zinc finger-containing DnaJ-like protein required for diphthamide biosynthesis on translation elongation factor 2 (EF2); human DPH4 has sequence homology to yeast Dph4 and functions in this conserved pathway.","method":"Genetic identification and functional complementation in yeast; sequence homology analysis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — foundational identification paper with >100 citations, replicated across multiple subsequent studies","pmids":["15485916"],"is_preprint":false},{"year":2008,"finding":"Mouse Dph4 (ortholog of human DNAJC24) is required for diphthamide modification of eEF2; cells from homozygous mutant embryos lacked diphthamide on eEF2 and were resistant to diphtheria toxin killing. Reporter-tagged DPH4 localized to the cytoskeleton, distinct from DPH1 localization, consistent with DPH4 not being part of the DPH1-DPH2-DPH3 complex.","method":"Mouse knockout model; diphtheria toxin resistance assay; reporter-tagged protein localization imaging","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined cellular phenotype (diphthamide loss, DT resistance) plus direct localization experiment; replicated by other labs","pmids":["18765564"],"is_preprint":false},{"year":2012,"finding":"Human DPH4 (DNAJC24) is a type III J-protein with an NMR-determined two-domain structure: a conserved J-domain and a CSL-domain connected by a flexible linker-helix. The CSL-domain binds iron in tetrahedral coordination via cysteines, forming an Fe-Dph4 species with rubredoxin-like spectral properties. Fe-Dph4 undergoes oligomerization and exhibits redox/electron carrier activity critical for diphthamide biosynthesis. Iron binding also enhances Hsp70-stimulatory (J-domain) function.","method":"NMR solution structure; UV-visible spectroscopy; EPR spectroscopy; in vitro iron-binding assay; redox activity assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — NMR structure combined with multiple orthogonal biochemical methods (EPR, UV-vis, redox assay) in a single rigorous study","pmids":["22367199"],"is_preprint":false},{"year":2014,"finding":"Yeast Dph3 (ortholog of human DPH3/KTI11, a CSL zinc finger protein closely related to DPH4/DNAJC24) functions as an electron donor to reduce the Fe-S cluster in the Dph1-Dph2 complex during the first step of diphthamide biosynthesis, establishing that Dph3/Dph4-family CSL proteins serve as electron carriers in this pathway.","method":"In vitro reconstitution of diphthamide biosynthesis; EPR spectroscopy; iron-binding assay","journal":"Journal of the American Chemical Society","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro reconstitution with EPR validation; this paper focuses on Dph3 but establishes mechanistic context for the CSL-domain electron carrier function shared with Dph4/DNAJC24","pmids":["24422557"],"is_preprint":false},{"year":2015,"finding":"Complete knockout of DPH4 in MCF7 cells generates viable cells with unmodified eEF2 (no diphthamide), rendering cells resistant to Pseudomonas exotoxin A and diphtheria toxin ADP-ribosylation, but pre-sensitizing cells to TNF-mediated apoptosis via NF-κB and death receptor pathway activation.","method":"CRISPR/gene knockout; ADP-ribosylation assay; toxin sensitivity assay; apoptosis assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — clean KO with multiple defined phenotypic readouts (diphthamide loss, toxin resistance, TNF hypersensitivity), multiple orthogonal methods","pmids":["26261303"],"is_preprint":false},{"year":2012,"finding":"Immunotoxin resistance in an ALL cell line is caused by epigenetic silencing of DPH4 (DNAJC24) via CpG island hypermethylation of its promoter, reducing DPH4 mRNA and protein levels, which prevents diphthamide biosynthesis and renders EF2 refractory to ADP-ribosylation by Pseudomonas exotoxin A.","method":"CpG methylation analysis; RT-PCR; protein expression analysis; ADP-ribosylation assay; methylation inhibitor rescue (5-azacytidine)","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods linking DPH4 promoter methylation to diphthamide loss and toxin resistance, with pharmacological rescue","pmids":["22509046"],"is_preprint":false},{"year":2019,"finding":"Knockdown of DPH4 (DNAJC24) in human podocytes (via shRNA or CRISPR-Cas9 KO) increases adhesion to fibronectin and sFLT1/Fc substrates and causes a cell-spreading defect, establishing a role for diphthamide biosynthesis genes including DPH4 in regulating podocyte adhesion.","method":"Genome-scale RNAi screen; CRISPR-Cas9 knockout; adhesion assay; cell-spreading assay","journal":"American journal of physiology. Renal physiology","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with defined cellular phenotype; functional role placed within diphthamide biosynthesis pathway context","pmids":["31566424"],"is_preprint":false},{"year":2021,"finding":"CRISPR/Cas9 pooled screen in pig PK-15 cells confirmed DNAJC24 as a host factor essential for diphtheria toxin-induced cell death, with individual gene knockout validating that loss of DNAJC24 confers DT resistance by blocking diphthamide biosynthesis.","method":"Genome-scale CRISPR/Cas9 screen; individual gene knockout; diphtheria toxin cytotoxicity assay","journal":"Biotechnology journal","confidence":"Medium","confidence_rationale":"Tier 2 — functional validation of CRISPR screen hit with individual KO and defined phenotypic readout","pmids":["34705337"],"is_preprint":false},{"year":2022,"finding":"DNAJC24 knockdown in HCC cells reduces proliferation and motility; its expression is transcriptionally upregulated by HSF2 under hypoxia, starvation, and heat stress. Targeting DNAJC24 under normal conditions affects HCC cell proliferation and autophagy by interfering with ammonia metabolism.","method":"siRNA knockdown; cell proliferation and migration assays; transcription factor knockdown (HSF2); ammonia metabolism assay; autophagy assay","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2-3 — multiple cellular phenotype readouts with pathway placement (ammonia metabolism/autophagy), single lab","pmids":["35606363"],"is_preprint":false},{"year":2024,"finding":"DNAJC24 directly interacts with PCNA (confirmed by Co-IP and mass spectrometry) and promotes lung adenocarcinoma (LUAD) cell proliferation and invasion by activating AKT phosphorylation via the PI3K/AKT signaling pathway.","method":"Co-immunoprecipitation; mass spectrometry; AKT phosphorylation assay; cell proliferation and invasion assays in A549 and NCI-H1299 cell lines","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP plus MS identification of PCNA interaction, with functional phosphorylation readout; single lab","pmids":["38713100"],"is_preprint":false}],"current_model":"DNAJC24 (DPH4) is a type III J-protein cochaperone that functions in diphthamide biosynthesis on eEF2 by acting through its CSL-domain, which binds iron in tetrahedral coordination to mediate redox/electron carrier activity required for the Dph1-Dph2 catalytic complex; it also stimulates Hsp70 ATPase activity via its J-domain, localizes to the cytoskeleton independently of the DPH1-DPH2-DPH3 complex, regulates podocyte adhesion and HCC/LUAD cell proliferation through ammonia metabolism and a PCNA/PI3K/AKT axis, and its promoter is subject to reversible CpG methylation that controls diphthamide biosynthesis and toxin sensitivity."},"narrative":{"teleology":[{"year":2004,"claim":"Identification of DPH4/DNAJC24 as a conserved gene required for diphthamide biosynthesis established that a DnaJ-like protein with a CSL zinc-finger domain participates in this post-translational modification pathway.","evidence":"Genetic identification and functional complementation of yeast dph4 mutants; sequence homology to human DNAJC24","pmids":["15485916"],"confidence":"High","gaps":["Biochemical mechanism of DPH4 contribution unknown","No structural information","Relationship to other DPH factors unresolved"]},{"year":2008,"claim":"Mouse knockout demonstrated that Dph4 is essential for diphthamide modification in mammalian cells and revealed that DPH4 localizes to the cytoskeleton independently of the DPH1–DPH2–DPH3 complex, indicating a non-overlapping subcellular role.","evidence":"Dph4 knockout mouse embryonic cells; diphtheria toxin resistance assay; reporter-tagged protein localization imaging","pmids":["18765564"],"confidence":"High","gaps":["Functional significance of cytoskeletal localization unclear","Whether DPH4 physically interacts with the DPH1-DPH2 complex not tested"]},{"year":2012,"claim":"Structural and spectroscopic characterization revealed DPH4 as a two-domain protein whose CSL-domain binds iron in tetrahedral coordination with rubredoxin-like properties, functioning as a redox/electron carrier, while its J-domain stimulates Hsp70 — establishing the molecular mechanism by which DPH4 supports diphthamide biosynthesis.","evidence":"NMR solution structure; UV-visible and EPR spectroscopy; in vitro iron-binding and redox activity assays","pmids":["22367199"],"confidence":"High","gaps":["Direct electron transfer to Dph1-Dph2 Fe-S cluster not reconstituted for human DPH4","In vivo iron loading mechanism unknown","Relationship between Hsp70 stimulation and diphthamide biosynthesis unclear"]},{"year":2012,"claim":"Epigenetic silencing of DPH4 via CpG island hypermethylation was shown to be a physiologically relevant mechanism for abolishing diphthamide biosynthesis and conferring immunotoxin resistance, reversible by demethylating agents.","evidence":"CpG methylation analysis, RT-PCR, ADP-ribosylation assay, and 5-azacytidine rescue in an ALL cell line","pmids":["22509046"],"confidence":"High","gaps":["Frequency of DPH4 methylation-based silencing in primary tumors unknown","Whether other DPH genes are co-silenced not addressed"]},{"year":2015,"claim":"Complete DPH4 knockout in human cells confirmed loss of diphthamide and toxin resistance while uncovering that diphthamide-deficient cells are pre-sensitized to TNF-induced apoptosis via NF-κB and death receptor pathways, linking diphthamide status to cell survival signaling.","evidence":"CRISPR knockout in MCF7 cells; ADP-ribosylation assay; toxin sensitivity and apoptosis assays","pmids":["26261303"],"confidence":"High","gaps":["Mechanism connecting unmodified eEF2 to NF-κB/death receptor activation not defined","Whether TNF sensitization is eEF2-dependent or a DPH4-autonomous effect unclear"]},{"year":2019,"claim":"DPH4 knockdown in podocytes increased adhesion and impaired cell spreading, establishing a role for diphthamide pathway components in regulating integrin-mediated adhesion beyond canonical translational fidelity.","evidence":"Genome-scale RNAi screen and CRISPR-Cas9 knockout in human podocytes; fibronectin adhesion assay","pmids":["31566424"],"confidence":"Medium","gaps":["Whether adhesion phenotype is mediated through eEF2 translation defects or a DPH4-autonomous function unclear","In vivo podocyte/kidney phenotype not examined"]},{"year":2022,"claim":"DNAJC24 was found to promote HCC cell proliferation and motility, with its transcription upregulated by HSF2 under stress, and its knockdown impairing ammonia metabolism and autophagy — suggesting functions beyond diphthamide biosynthesis.","evidence":"siRNA knockdown in HCC cell lines; proliferation, migration, ammonia metabolism, and autophagy assays; HSF2 knockdown","pmids":["35606363"],"confidence":"Medium","gaps":["Ammonia metabolism link is correlative; direct enzymatic target unknown","Whether proliferation effect is diphthamide-dependent not tested","Single lab, no independent replication"]},{"year":2024,"claim":"Identification of a direct DNAJC24–PCNA interaction and downstream PI3K/AKT activation in lung adenocarcinoma cells expanded the functional repertoire of DNAJC24 to include a signaling axis promoting tumor cell proliferation and invasion.","evidence":"Co-immunoprecipitation and mass spectrometry in A549 and NCI-H1299 cells; AKT phosphorylation assay; proliferation and invasion assays","pmids":["38713100"],"confidence":"Medium","gaps":["PCNA interaction not validated by reciprocal Co-IP or structural methods","Whether PCNA interaction is J-domain or CSL-domain mediated unknown","Relationship between PCNA binding and diphthamide biosynthesis not addressed"]},{"year":null,"claim":"Key unresolved questions include: (1) whether DPH4 directly donates electrons to the Dph1-Dph2 Fe-S cluster in vivo, (2) the functional significance of its cytoskeletal localization, (3) whether its cancer-associated proliferative roles are diphthamide-dependent or reflect independent functions of its J-domain or PCNA interaction, and (4) whether Hsp70 cochaperone activity is required for diphthamide biosynthesis or other cellular processes.","evidence":"","pmids":[],"confidence":"Low","gaps":["No in vivo reconstitution of electron transfer from DPH4 to Dph1-Dph2","No crystal or cryo-EM structure of DPH4 in complex with partners","In vivo relevance of PCNA interaction and PI3K/AKT activation not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0044183","term_label":"protein folding chaperone","supporting_discovery_ids":[0,2]},{"term_id":"GO:0016491","term_label":"oxidoreductase activity","supporting_discovery_ids":[2,3]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[1]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,4]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,1,2,4]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[9]}],"complexes":[],"partners":["PCNA","DPH1","DPH2","HSF2"],"other_free_text":[]},"mechanistic_narrative":"DNAJC24 (DPH4) is a type III J-protein cochaperone essential for diphthamide biosynthesis on eukaryotic translation elongation factor 2 (eEF2). Its two-domain architecture comprises a J-domain that stimulates Hsp70 ATPase activity and a CSL-domain that coordinates iron in a rubredoxin-like tetrahedral geometry, enabling redox/electron carrier activity required for the radical SAM reaction catalyzed by the Dph1–Dph2 complex [PMID:22367199, PMID:15485916]. Loss of DNAJC24 abolishes diphthamide modification of eEF2, conferring resistance to diphtheria toxin and Pseudomonas exotoxin A while sensitizing cells to TNF-mediated apoptosis; its promoter is subject to CpG methylation-based silencing that reversibly controls diphthamide levels and toxin sensitivity [PMID:26261303, PMID:22509046]. Beyond diphthamide biosynthesis, DNAJC24 regulates podocyte adhesion, and in cancer cells it interacts with PCNA and promotes proliferation through PI3K/AKT signaling [PMID:31566424, PMID:38713100]."},"prefetch_data":{"uniprot":{"accession":"Q6P3W2","full_name":"DnaJ homolog subfamily C member 24","aliases":["CSL-type zinc finger-containing protein 3","Diphthamide biosynthesis protein 4"],"length_aa":149,"mass_kda":17.1,"function":"Stimulates the ATPase activity of several Hsp70-type chaperones. This ability is enhanced by iron-binding. The iron-bound form is redox-active and can function as electron carrier. Plays a role in the diphthamide biosynthesis, a post-translational modification of histidine which occurs in translation elongation factor 2 (EEF2) which can be ADP-ribosylated by diphtheria toxin and by Pseudomonas exotoxin A (Eta)","subcellular_location":"Cytoplasm, cytoskeleton","url":"https://www.uniprot.org/uniprotkb/Q6P3W2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DNAJC24","classification":"Not Classified","n_dependent_lines":17,"n_total_lines":1208,"dependency_fraction":0.014072847682119206},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000170946","cell_line_id":"CID000030","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"nucleoplasm","grade":2}],"interactors":[{"gene":"DNAJA2","stoichiometry":0.2},{"gene":"NUP88","stoichiometry":0.2},{"gene":"ASPSCR1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000030","total_profiled":1310},"omim":[{"mim_id":"617141","title":"ANIRIDIA 2; AN2","url":"https://www.omim.org/entry/617141"},{"mim_id":"616902","title":"CHROMOSOME 11p13 DELETION SYNDROME, DISTAL","url":"https://www.omim.org/entry/616902"},{"mim_id":"611072","title":"DNAJ/HSP40 HOMOLOG, SUBFAMILY C, MEMBER 24; DNAJC24","url":"https://www.omim.org/entry/611072"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/DNAJC24"},"hgnc":{"alias_symbol":["JJJ3"],"prev_symbol":["ZCSL3","DPH4"]},"alphafold":{"accession":"Q6P3W2","domains":[{"cath_id":"1.10.287.110","chopping":"12-86","consensus_level":"high","plddt":76.5996,"start":12,"end":86},{"cath_id":"3.10.660.10","chopping":"91-145","consensus_level":"high","plddt":80.4533,"start":91,"end":145}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6P3W2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6P3W2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6P3W2-F1-predicted_aligned_error_v6.png","plddt_mean":74.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DNAJC24","jax_strain_url":"https://www.jax.org/strain/search?query=DNAJC24"},"sequence":{"accession":"Q6P3W2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6P3W2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6P3W2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6P3W2"}},"corpus_meta":[{"pmid":"15485916","id":"PMC_15485916","title":"Identification of the proteins required for biosynthesis of diphthamide, the target of bacterial ADP-ribosylating toxins on translation elongation factor 2.","date":"2004","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15485916","citation_count":145,"is_preprint":false},{"pmid":"17438278","id":"PMC_17438278","title":"Network of general and specialty J protein chaperones of the yeast cytosol.","date":"2007","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/17438278","citation_count":126,"is_preprint":false},{"pmid":"24422557","id":"PMC_24422557","title":"Dph3 is an electron donor for Dph1-Dph2 in the first step of eukaryotic diphthamide biosynthesis.","date":"2014","source":"Journal of the American Chemical Society","url":"https://pubmed.ncbi.nlm.nih.gov/24422557","citation_count":58,"is_preprint":false},{"pmid":"18765564","id":"PMC_18765564","title":"Diphthamide modification of eEF2 requires a J-domain protein and is essential for normal development.","date":"2008","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/18765564","citation_count":57,"is_preprint":false},{"pmid":"26261303","id":"PMC_26261303","title":"Loss of diphthamide pre-activates NF-κB and death receptor pathways and renders MCF7 cells hypersensitive to tumor necrosis factor.","date":"2015","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/26261303","citation_count":49,"is_preprint":false},{"pmid":"22509046","id":"PMC_22509046","title":"Immunotoxin resistance via reversible methylation of the DPH4 promoter is a unique survival strategy.","date":"2012","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/22509046","citation_count":43,"is_preprint":false},{"pmid":"16572726","id":"PMC_16572726","title":"A genomewide analysis of genes for the heat shock protein 70 chaperone system in the ascidian Ciona intestinalis.","date":"2006","source":"Cell stress & chaperones","url":"https://pubmed.ncbi.nlm.nih.gov/16572726","citation_count":30,"is_preprint":false},{"pmid":"22367199","id":"PMC_22367199","title":"Structure and mechanistic insights into novel iron-mediated moonlighting functions of human J-protein cochaperone, Dph4.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22367199","citation_count":27,"is_preprint":false},{"pmid":"22851130","id":"PMC_22851130","title":"Synthetic lethal interactions in yeast reveal functional roles of J protein co-chaperones.","date":"2012","source":"Molecular bioSystems","url":"https://pubmed.ncbi.nlm.nih.gov/22851130","citation_count":26,"is_preprint":false},{"pmid":"21321669","id":"PMC_21321669","title":"A 556 kb deletion in the downstream region of the PAX6 gene causes familial aniridia and other eye anomalies in a Chinese 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Reporter-tagged DPH4 localized to the cytoskeleton, distinct from DPH1 localization, consistent with DPH4 not being part of the DPH1-DPH2-DPH3 complex.\",\n      \"method\": \"Mouse knockout model; diphtheria toxin resistance assay; reporter-tagged protein localization imaging\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular phenotype (diphthamide loss, DT resistance) plus direct localization experiment; replicated by other labs\",\n      \"pmids\": [\"18765564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Human DPH4 (DNAJC24) is a type III J-protein with an NMR-determined two-domain structure: a conserved J-domain and a CSL-domain connected by a flexible linker-helix. The CSL-domain binds iron in tetrahedral coordination via cysteines, forming an Fe-Dph4 species with rubredoxin-like spectral properties. Fe-Dph4 undergoes oligomerization and exhibits redox/electron carrier activity critical for diphthamide biosynthesis. Iron binding also enhances Hsp70-stimulatory (J-domain) function.\",\n      \"method\": \"NMR solution structure; UV-visible spectroscopy; EPR spectroscopy; in vitro iron-binding assay; redox activity assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structure combined with multiple orthogonal biochemical methods (EPR, UV-vis, redox assay) in a single rigorous study\",\n      \"pmids\": [\"22367199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Yeast Dph3 (ortholog of human DPH3/KTI11, a CSL zinc finger protein closely related to DPH4/DNAJC24) functions as an electron donor to reduce the Fe-S cluster in the Dph1-Dph2 complex during the first step of diphthamide biosynthesis, establishing that Dph3/Dph4-family CSL proteins serve as electron carriers in this pathway.\",\n      \"method\": \"In vitro reconstitution of diphthamide biosynthesis; EPR spectroscopy; iron-binding assay\",\n      \"journal\": \"Journal of the American Chemical Society\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with EPR validation; this paper focuses on Dph3 but establishes mechanistic context for the CSL-domain electron carrier function shared with Dph4/DNAJC24\",\n      \"pmids\": [\"24422557\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Complete knockout of DPH4 in MCF7 cells generates viable cells with unmodified eEF2 (no diphthamide), rendering cells resistant to Pseudomonas exotoxin A and diphtheria toxin ADP-ribosylation, but pre-sensitizing cells to TNF-mediated apoptosis via NF-κB and death receptor pathway activation.\",\n      \"method\": \"CRISPR/gene knockout; ADP-ribosylation assay; toxin sensitivity assay; apoptosis assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple defined phenotypic readouts (diphthamide loss, toxin resistance, TNF hypersensitivity), multiple orthogonal methods\",\n      \"pmids\": [\"26261303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Immunotoxin resistance in an ALL cell line is caused by epigenetic silencing of DPH4 (DNAJC24) via CpG island hypermethylation of its promoter, reducing DPH4 mRNA and protein levels, which prevents diphthamide biosynthesis and renders EF2 refractory to ADP-ribosylation by Pseudomonas exotoxin A.\",\n      \"method\": \"CpG methylation analysis; RT-PCR; protein expression analysis; ADP-ribosylation assay; methylation inhibitor rescue (5-azacytidine)\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods linking DPH4 promoter methylation to diphthamide loss and toxin resistance, with pharmacological rescue\",\n      \"pmids\": [\"22509046\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Knockdown of DPH4 (DNAJC24) in human podocytes (via shRNA or CRISPR-Cas9 KO) increases adhesion to fibronectin and sFLT1/Fc substrates and causes a cell-spreading defect, establishing a role for diphthamide biosynthesis genes including DPH4 in regulating podocyte adhesion.\",\n      \"method\": \"Genome-scale RNAi screen; CRISPR-Cas9 knockout; adhesion assay; cell-spreading assay\",\n      \"journal\": \"American journal of physiology. Renal physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular phenotype; functional role placed within diphthamide biosynthesis pathway context\",\n      \"pmids\": [\"31566424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CRISPR/Cas9 pooled screen in pig PK-15 cells confirmed DNAJC24 as a host factor essential for diphtheria toxin-induced cell death, with individual gene knockout validating that loss of DNAJC24 confers DT resistance by blocking diphthamide biosynthesis.\",\n      \"method\": \"Genome-scale CRISPR/Cas9 screen; individual gene knockout; diphtheria toxin cytotoxicity assay\",\n      \"journal\": \"Biotechnology journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional validation of CRISPR screen hit with individual KO and defined phenotypic readout\",\n      \"pmids\": [\"34705337\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"DNAJC24 knockdown in HCC cells reduces proliferation and motility; its expression is transcriptionally upregulated by HSF2 under hypoxia, starvation, and heat stress. Targeting DNAJC24 under normal conditions affects HCC cell proliferation and autophagy by interfering with ammonia metabolism.\",\n      \"method\": \"siRNA knockdown; cell proliferation and migration assays; transcription factor knockdown (HSF2); ammonia metabolism assay; autophagy assay\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — multiple cellular phenotype readouts with pathway placement (ammonia metabolism/autophagy), single lab\",\n      \"pmids\": [\"35606363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DNAJC24 directly interacts with PCNA (confirmed by Co-IP and mass spectrometry) and promotes lung adenocarcinoma (LUAD) cell proliferation and invasion by activating AKT phosphorylation via the PI3K/AKT signaling pathway.\",\n      \"method\": \"Co-immunoprecipitation; mass spectrometry; AKT phosphorylation assay; cell proliferation and invasion assays in A549 and NCI-H1299 cell lines\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP plus MS identification of PCNA interaction, with functional phosphorylation readout; single lab\",\n      \"pmids\": [\"38713100\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DNAJC24 (DPH4) is a type III J-protein cochaperone that functions in diphthamide biosynthesis on eEF2 by acting through its CSL-domain, which binds iron in tetrahedral coordination to mediate redox/electron carrier activity required for the Dph1-Dph2 catalytic complex; it also stimulates Hsp70 ATPase activity via its J-domain, localizes to the cytoskeleton independently of the DPH1-DPH2-DPH3 complex, regulates podocyte adhesion and HCC/LUAD cell proliferation through ammonia metabolism and a PCNA/PI3K/AKT axis, and its promoter is subject to reversible CpG methylation that controls diphthamide biosynthesis and toxin sensitivity.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"DNAJC24 (DPH4) is a type III J-protein cochaperone essential for diphthamide biosynthesis on eukaryotic translation elongation factor 2 (eEF2). Its two-domain architecture comprises a J-domain that stimulates Hsp70 ATPase activity and a CSL-domain that coordinates iron in a rubredoxin-like tetrahedral geometry, enabling redox/electron carrier activity required for the radical SAM reaction catalyzed by the Dph1–Dph2 complex [PMID:22367199, PMID:15485916]. Loss of DNAJC24 abolishes diphthamide modification of eEF2, conferring resistance to diphtheria toxin and Pseudomonas exotoxin A while sensitizing cells to TNF-mediated apoptosis; its promoter is subject to CpG methylation-based silencing that reversibly controls diphthamide levels and toxin sensitivity [PMID:26261303, PMID:22509046]. Beyond diphthamide biosynthesis, DNAJC24 regulates podocyte adhesion, and in cancer cells it interacts with PCNA and promotes proliferation through PI3K/AKT signaling [PMID:31566424, PMID:38713100].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Identification of DPH4/DNAJC24 as a conserved gene required for diphthamide biosynthesis established that a DnaJ-like protein with a CSL zinc-finger domain participates in this post-translational modification pathway.\",\n      \"evidence\": \"Genetic identification and functional complementation of yeast dph4 mutants; sequence homology to human DNAJC24\",\n      \"pmids\": [\"15485916\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biochemical mechanism of DPH4 contribution unknown\", \"No structural information\", \"Relationship to other DPH factors unresolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Mouse knockout demonstrated that Dph4 is essential for diphthamide modification in mammalian cells and revealed that DPH4 localizes to the cytoskeleton independently of the DPH1–DPH2–DPH3 complex, indicating a non-overlapping subcellular role.\",\n      \"evidence\": \"Dph4 knockout mouse embryonic cells; diphtheria toxin resistance assay; reporter-tagged protein localization imaging\",\n      \"pmids\": [\"18765564\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional significance of cytoskeletal localization unclear\", \"Whether DPH4 physically interacts with the DPH1-DPH2 complex not tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Structural and spectroscopic characterization revealed DPH4 as a two-domain protein whose CSL-domain binds iron in tetrahedral coordination with rubredoxin-like properties, functioning as a redox/electron carrier, while its J-domain stimulates Hsp70 — establishing the molecular mechanism by which DPH4 supports diphthamide biosynthesis.\",\n      \"evidence\": \"NMR solution structure; UV-visible and EPR spectroscopy; in vitro iron-binding and redox activity assays\",\n      \"pmids\": [\"22367199\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct electron transfer to Dph1-Dph2 Fe-S cluster not reconstituted for human DPH4\", \"In vivo iron loading mechanism unknown\", \"Relationship between Hsp70 stimulation and diphthamide biosynthesis unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Epigenetic silencing of DPH4 via CpG island hypermethylation was shown to be a physiologically relevant mechanism for abolishing diphthamide biosynthesis and conferring immunotoxin resistance, reversible by demethylating agents.\",\n      \"evidence\": \"CpG methylation analysis, RT-PCR, ADP-ribosylation assay, and 5-azacytidine rescue in an ALL cell line\",\n      \"pmids\": [\"22509046\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Frequency of DPH4 methylation-based silencing in primary tumors unknown\", \"Whether other DPH genes are co-silenced not addressed\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Complete DPH4 knockout in human cells confirmed loss of diphthamide and toxin resistance while uncovering that diphthamide-deficient cells are pre-sensitized to TNF-induced apoptosis via NF-κB and death receptor pathways, linking diphthamide status to cell survival signaling.\",\n      \"evidence\": \"CRISPR knockout in MCF7 cells; ADP-ribosylation assay; toxin sensitivity and apoptosis assays\",\n      \"pmids\": [\"26261303\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism connecting unmodified eEF2 to NF-κB/death receptor activation not defined\", \"Whether TNF sensitization is eEF2-dependent or a DPH4-autonomous effect unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"DPH4 knockdown in podocytes increased adhesion and impaired cell spreading, establishing a role for diphthamide pathway components in regulating integrin-mediated adhesion beyond canonical translational fidelity.\",\n      \"evidence\": \"Genome-scale RNAi screen and CRISPR-Cas9 knockout in human podocytes; fibronectin adhesion assay\",\n      \"pmids\": [\"31566424\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether adhesion phenotype is mediated through eEF2 translation defects or a DPH4-autonomous function unclear\", \"In vivo podocyte/kidney phenotype not examined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"DNAJC24 was found to promote HCC cell proliferation and motility, with its transcription upregulated by HSF2 under stress, and its knockdown impairing ammonia metabolism and autophagy — suggesting functions beyond diphthamide biosynthesis.\",\n      \"evidence\": \"siRNA knockdown in HCC cell lines; proliferation, migration, ammonia metabolism, and autophagy assays; HSF2 knockdown\",\n      \"pmids\": [\"35606363\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ammonia metabolism link is correlative; direct enzymatic target unknown\", \"Whether proliferation effect is diphthamide-dependent not tested\", \"Single lab, no independent replication\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identification of a direct DNAJC24–PCNA interaction and downstream PI3K/AKT activation in lung adenocarcinoma cells expanded the functional repertoire of DNAJC24 to include a signaling axis promoting tumor cell proliferation and invasion.\",\n      \"evidence\": \"Co-immunoprecipitation and mass spectrometry in A549 and NCI-H1299 cells; AKT phosphorylation assay; proliferation and invasion assays\",\n      \"pmids\": [\"38713100\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"PCNA interaction not validated by reciprocal Co-IP or structural methods\", \"Whether PCNA interaction is J-domain or CSL-domain mediated unknown\", \"Relationship between PCNA binding and diphthamide biosynthesis not addressed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: (1) whether DPH4 directly donates electrons to the Dph1-Dph2 Fe-S cluster in vivo, (2) the functional significance of its cytoskeletal localization, (3) whether its cancer-associated proliferative roles are diphthamide-dependent or reflect independent functions of its J-domain or PCNA interaction, and (4) whether Hsp70 cochaperone activity is required for diphthamide biosynthesis or other cellular processes.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No in vivo reconstitution of electron transfer from DPH4 to Dph1-Dph2\", \"No crystal or cryo-EM structure of DPH4 in complex with partners\", \"In vivo relevance of PCNA interaction and PI3K/AKT activation not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 1, 2, 4]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"PCNA\",\n      \"DPH1\",\n      \"DPH2\",\n      \"HSF2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}