{"gene":"CCDC8","run_date":"2026-06-09T22:57:17","timeline":{"discoveries":[{"year":2011,"finding":"CCDC8 physically interacts with OBSL1 but not CUL7, placing CCDC8 in a pathway with CUL7 and OBSL1 to control mammalian growth; identified via coimmunoprecipitation.","method":"Coimmunoprecipitation (Co-IP)","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single Co-IP experiment showing CCDC8-OBSL1 interaction but not CCDC8-CUL7; replicated conceptually by subsequent studies","pmids":["21737058"],"is_preprint":false},{"year":2012,"finding":"In CCDC8-deficient (CCDC8−/−) fibroblasts, GH-stimulated STAT5b and MAPK activation is reduced compared to controls, while IGF1-stimulated AKT activation is normal, indicating CCDC8 loss specifically impairs GH signaling downstream.","method":"Signaling assays in patient-derived fibroblast cell lines (CCDC8−/−) with GH and IGF1 stimulation; Western blot readouts for STAT5b, MAPK, AKT phosphorylation","journal":"Journal of molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean loss-of-function cell lines with defined pathway readouts, single lab, multiple signaling endpoints","pmids":["23018678"],"is_preprint":false},{"year":2015,"finding":"The ankyrin repeats of ANKRA2 recognize a PxLPxL motif at the C-terminal region of CCDC8, establishing CCDC8 as a major binding partner of ANKRA2 (but not the paralog RFXANK) in cells; the N-terminal region of CCDC8 interacts with OBSL1 to form a CUL7 ligase complex.","method":"Binding assays, structural analysis (crystal/structural data), coimmunoprecipitation in cells","journal":"Structure","confidence":"High","confidence_rationale":"Tier 1 / Strong — structural analysis combined with binding assays and cell-based Co-IP, multiple orthogonal methods identifying specific motif-mediated interaction","pmids":["25752541"],"is_preprint":false},{"year":2019,"finding":"JMJD2A (a histone lysine demethylase) directly interacts with CCDC8 and regulates its expression; CCDC8 is a downstream pro-apoptotic target of JMJD2A, and CCDC8 inhibition restores drug resistance in gastric cancer cells.","method":"Immunoprecipitation, whole-gene expression array after JMJD2A knockdown, siRNA knockdown of CCDC8 with cell viability assays","journal":"Gastric cancer","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single Co-IP plus expression array and functional rescue, single lab, multiple methods","pmids":["31677131"],"is_preprint":false},{"year":2020,"finding":"Overexpressed CCDC8 inhibits HIV-1 production by causing newly assembled HIV-1 Gag particles on the plasma membrane to be endocytosed and degraded in lysosomes rather than budding out; CCDC8 is a membrane-associated protein and its N-terminal domain is critical for membrane binding and inhibition of Gag assembly. CCDC8 is phosphorylated at T87 and S261 and mono-methylated at K491, but alanine mutations at these sites do not affect anti-HIV activity.","method":"Live-cell imaging, overexpression studies, deletion mutant analysis, subcellular fractionation/co-localization with organelle markers, site-directed mutagenesis","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live-cell imaging with functional consequence plus domain deletion mutants and PTM mutagenesis, single lab","pmids":["32651437"],"is_preprint":false},{"year":2021,"finding":"G9a-mediated H3K9me3 binds to the CCDC8 promoter and suppresses CCDC8 expression, linking G9a epigenetic activity to CCDC8 regulation; CCDC8 dysregulation mediates G9a-driven radioresistance in lung cancer cells.","method":"Chromatin immunoprecipitation (ChIP) assay, Western blotting, siRNA knockdown, cell proliferation and apoptosis assays","journal":"OncoTargets and therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP directly demonstrates H3K9me3 enrichment at CCDC8 promoter, functional rescue experiments, single lab","pmids":["34140780"],"is_preprint":false},{"year":2024,"finding":"CCDC8 promotes cardiomyocyte apoptosis via the TNF signaling pathway; silencing CCDC8 suppresses TNF-α-induced apoptosis and ROS production in cardiomyocytes under hypoxia-reoxygenation conditions.","method":"AAV9 overexpression and siRNA knockdown in vivo and in vitro, mRNA sequencing, KEGG pathway analysis, flow cytometry for apoptosis, TNF-α stimulation assays","journal":"Life sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo and in vitro loss/gain of function with pathway identification via transcriptomics, single lab","pmids":["39424266"],"is_preprint":false},{"year":2026,"finding":"CCDC8 interacts with the E3 ubiquitin ligase scaffold CUL7 and facilitates proteasome-dependent degradation of p53, thereby suppressing p53 downstream effectors P21 and BAX; pharmacological inhibition of neddylation (MLN4924) restores p53 levels and reverses CCDC8-driven oncogenic effects.","method":"Co-immunoprecipitation, functional overexpression and knockdown studies in vitro and in vivo, neddylation inhibitor (MLN4924) rescue experiments, Western blotting for p53/P21/BAX","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus pharmacological rescue plus in vivo tumor model, single lab, multiple orthogonal methods","pmids":["41644704"],"is_preprint":false}],"current_model":"CCDC8 is a membrane-associated scaffold protein that physically interacts with OBSL1 (via its N-terminal region) and CUL7 to form an E3 ubiquitin ligase complex that facilitates p53 degradation and regulates GH/IGF1 signaling; its C-terminal PxLPxL motif is recognized by the ankyrin repeats of ANKRA2; it is transcriptionally repressed by G9a-mediated H3K9me3 and regulated by JMJD2A; and it promotes apoptosis via the TNF signaling pathway while also restricting HIV-1 replication by redirecting Gag to lysosomal degradation."},"narrative":{"mechanistic_narrative":"CCDC8 is a membrane-associated scaffold protein that operates within a CUL7–OBSL1 E3 ubiquitin ligase axis controlling mammalian growth and proteostasis [PMID:21737058, PMID:25752541]. It binds OBSL1 through its N-terminal region and associates with the CUL7 ligase scaffold, where it facilitates proteasome-dependent degradation of p53 and thereby represses the p53 effectors P21 and BAX; this activity is neddylation-dependent and reversible by MLN4924 [PMID:25752541, PMID:41644704]. A C-terminal PxLPxL motif in CCDC8 is specifically recognized by the ankyrin repeats of ANKRA2, defining a distinct motif-mediated interaction [PMID:25752541]. Loss of CCDC8 selectively impairs growth hormone–driven STAT5b and MAPK signaling while sparing IGF1-stimulated AKT activation, placing it downstream in GH signaling [PMID:23018678]. CCDC8 expression is epigenetically constrained, being repressed by G9a-mediated H3K9me3 at its promoter and regulated through interaction with the demethylase JMJD2A, contexts in which CCDC8 acts as a pro-apoptotic effector influencing cancer cell drug and radiation resistance [PMID:31677131, PMID:34140780]. CCDC8 also promotes apoptosis via the TNF signaling pathway in cardiomyocytes [PMID:39424266] and restricts HIV-1 by redirecting plasma-membrane Gag particles to lysosomal degradation through its membrane-binding N-terminal domain [PMID:32651437].","teleology":[{"year":2011,"claim":"Established that CCDC8 is not an isolated factor but a member of a growth-regulatory module by showing it physically partners with OBSL1.","evidence":"Co-immunoprecipitation linking CCDC8, OBSL1, and CUL7 in a growth pathway","pmids":["21737058"],"confidence":"Medium","gaps":["Direct CCDC8-CUL7 interaction not detected in this study","Molecular function within the complex undefined"]},{"year":2012,"claim":"Resolved which signaling arm CCDC8 supports by showing its loss specifically blunts GH-driven STAT5b/MAPK activation but leaves IGF1-AKT intact.","evidence":"GH and IGF1 stimulation assays in CCDC8-deficient patient fibroblasts with phospho-Western readouts","pmids":["23018678"],"confidence":"Medium","gaps":["Molecular step at which CCDC8 acts in GH signaling unknown","Single lab"]},{"year":2015,"claim":"Defined the structural basis of CCDC8 interactions, mapping a C-terminal PxLPxL motif recognized by ANKRA2 ankyrin repeats and an N-terminal OBSL1/CUL7 interface.","evidence":"Structural analysis combined with binding assays and cellular Co-IP","pmids":["25752541"],"confidence":"High","gaps":["Functional consequence of ANKRA2 binding not established","Whether ANKRA2 and OBSL1 binding are mutually exclusive unknown"]},{"year":2019,"claim":"Connected CCDC8 to chromatin-modifier control by showing JMJD2A interacts with and regulates CCDC8, which acts as a pro-apoptotic, drug-sensitizing target.","evidence":"Immunoprecipitation, expression array after JMJD2A knockdown, and siRNA rescue in gastric cancer cells","pmids":["31677131"],"confidence":"Medium","gaps":["Mechanism by which CCDC8 promotes apoptosis not defined","Single Co-IP without reciprocal validation"]},{"year":2020,"claim":"Identified an antiviral function, showing CCDC8 is membrane-associated and redirects HIV-1 Gag to lysosomal degradation via its N-terminal domain.","evidence":"Live-cell imaging, deletion mutants, subcellular fractionation, and PTM site mutagenesis in overexpression systems","pmids":["32651437"],"confidence":"Medium","gaps":["Relies on overexpression rather than endogenous levels","Mapped PTMs (T87, S261, K491) have no demonstrated functional role in antiviral activity"]},{"year":2021,"claim":"Showed CCDC8 is epigenetically repressed by G9a-deposited H3K9me3 at its promoter, linking its silencing to radioresistance.","evidence":"ChIP for H3K9me3 at the CCDC8 promoter plus siRNA and apoptosis assays in lung cancer cells","pmids":["34140780"],"confidence":"Medium","gaps":["Downstream effectors of CCDC8 in radioresistance not defined","Single lab"]},{"year":2024,"claim":"Demonstrated a pro-apoptotic role through TNF signaling, where CCDC8 silencing suppresses TNF-α-induced apoptosis and ROS in cardiomyocytes.","evidence":"AAV9 overexpression and siRNA knockdown in vivo/in vitro, mRNA-seq with KEGG analysis, and flow cytometry under hypoxia-reoxygenation","pmids":["39424266"],"confidence":"Medium","gaps":["Direct molecular link between CCDC8 and TNF pathway components not established","Single lab"]},{"year":2026,"claim":"Mechanistically united CCDC8 with the CUL7 ligase by showing it drives neddylation-dependent proteasomal degradation of p53, suppressing P21 and BAX.","evidence":"Co-IP, gain/loss-of-function in vitro and in vivo, and MLN4924 neddylation-inhibitor rescue with p53/P21/BAX Westerns","pmids":["41644704"],"confidence":"Medium","gaps":["Whether CCDC8 directly recruits p53 as substrate versus acting indirectly unresolved","Single lab"]},{"year":null,"claim":"It remains unresolved how CCDC8's distinct activities — GH signaling, p53 degradation, antiviral defense, and TNF-driven apoptosis — are mechanistically integrated within a single protein.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of CCDC8 within an assembled CUL7-OBSL1 complex","No defined enzymatic activity intrinsic to CCDC8","Determinants selecting between its growth, antiviral, and apoptotic roles unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,2,7]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[4]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[7]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,6]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[3,6,7]}],"complexes":["CUL7-OBSL1-CCDC8 E3 ubiquitin ligase complex"],"partners":["OBSL1","CUL7","ANKRA2","JMJD2A"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9H0W5","full_name":"Coiled-coil domain-containing protein 8","aliases":[],"length_aa":538,"mass_kda":59.4,"function":"Core component of the 3M complex, a complex required to regulate microtubule dynamics and genome integrity. It is unclear how the 3M complex regulates microtubules, it could act by controlling the level of a microtubule stabilizer (PubMed:24793695, PubMed:24793696). Required for localization of CUL7 to the centrosome (PubMed:24793695)","subcellular_location":"Cytoplasm; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome","url":"https://www.uniprot.org/uniprotkb/Q9H0W5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CCDC8","classification":"Not Classified","n_dependent_lines":6,"n_total_lines":1208,"dependency_fraction":0.004966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALM1","stoichiometry":0.2},{"gene":"CALM2","stoichiometry":0.2},{"gene":"CALM3","stoichiometry":0.2},{"gene":"NPM1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/CCDC8","total_profiled":1310},"omim":[{"mim_id":"614205","title":"THREE M SYNDROME 3; 3M3","url":"https://www.omim.org/entry/614205"},{"mim_id":"614145","title":"COILED-COIL DOMAIN-CONTAINING PROTEIN 8; CCDC8","url":"https://www.omim.org/entry/614145"},{"mim_id":"273750","title":"THREE M SYNDROME 1; 3M1","url":"https://www.omim.org/entry/273750"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"ovary","ntpm":35.3}],"url":"https://www.proteinatlas.org/search/CCDC8"},"hgnc":{"alias_symbol":["DKFZp564K0322","3M3","PPP1R20","p90"],"prev_symbol":[]},"alphafold":{"accession":"Q9H0W5","domains":[{"cath_id":"-","chopping":"33-63","consensus_level":"medium","plddt":70.0119,"start":33,"end":63}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H0W5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H0W5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H0W5-F1-predicted_aligned_error_v6.png","plddt_mean":46.41},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CCDC8","jax_strain_url":"https://www.jax.org/strain/search?query=CCDC8"},"sequence":{"accession":"Q9H0W5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H0W5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H0W5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H0W5"}},"corpus_meta":[{"pmid":"21737058","id":"PMC_21737058","title":"Exome sequencing identifies CCDC8 mutations in 3-M syndrome, suggesting that CCDC8 contributes in a pathway with CUL7 and OBSL1 to control human growth.","date":"2011","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21737058","citation_count":95,"is_preprint":false},{"pmid":"26052355","id":"PMC_26052355","title":"The GALNT9, BNC1 and CCDC8 genes are frequently epigenetically dysregulated in breast tumours that metastasise to the brain.","date":"2015","source":"Clinical epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/26052355","citation_count":78,"is_preprint":false},{"pmid":"23018678","id":"PMC_23018678","title":"Mutations in CUL7, OBSL1 and CCDC8 in 3-M syndrome lead to disordered growth factor signalling.","date":"2012","source":"Journal of molecular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/23018678","citation_count":50,"is_preprint":false},{"pmid":"31677131","id":"PMC_31677131","title":"JMJD2A sensitizes gastric cancer to chemotherapy by cooperating with CCDC8.","date":"2019","source":"Gastric cancer : official journal of the International Gastric Cancer Association and the Japanese Gastric Cancer Association","url":"https://pubmed.ncbi.nlm.nih.gov/31677131","citation_count":24,"is_preprint":false},{"pmid":"25752541","id":"PMC_25752541","title":"Ankyrin repeats of ANKRA2 recognize a PxLPxL motif on the 3M syndrome protein CCDC8.","date":"2015","source":"Structure (London, England : 1993)","url":"https://pubmed.ncbi.nlm.nih.gov/25752541","citation_count":16,"is_preprint":false},{"pmid":"34140780","id":"PMC_34140780","title":"G9a Regulates Cell Sensitivity to Radiotherapy via Histone H3 Lysine 9 Trimethylation and CCDC8 in Lung Cancer.","date":"2021","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/34140780","citation_count":11,"is_preprint":false},{"pmid":"28675896","id":"PMC_28675896","title":"Two Siblings with a Mutation in CCDC8 Presenting with Mild Short Stature: A Case of 3-M Syndrome.","date":"2017","source":"Hormone research in paediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/28675896","citation_count":7,"is_preprint":false},{"pmid":"32651437","id":"PMC_32651437","title":"Overexpressed coiled-coil domain containing protein 8 (CCDC8) mediates newly synthesized HIV-1 Gag lysosomal degradation.","date":"2020","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/32651437","citation_count":5,"is_preprint":false},{"pmid":"41644704","id":"PMC_41644704","title":"Interstitial cystitis-related gene CCDC8 accelerates tumorigenesis by participating in CUL7-mediated degradation of P53 in bladder cancer.","date":"2026","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/41644704","citation_count":2,"is_preprint":false},{"pmid":"39424266","id":"PMC_39424266","title":"Ablation of CCDC8 provides cardioprotection against cardiomyocyte apoptosis via TNF signaling pathway in myocardial ischemia reperfusion injury.","date":"2024","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39424266","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7315,"output_tokens":2029,"usd":0.02619,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8977,"output_tokens":2826,"usd":0.057767,"stage2_stop_reason":"end_turn"},"total_usd":0.083957,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"CCDC8 physically interacts with OBSL1 but not CUL7, placing CCDC8 in a pathway with CUL7 and OBSL1 to control mammalian growth; identified via coimmunoprecipitation.\",\n      \"method\": \"Coimmunoprecipitation (Co-IP)\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single Co-IP experiment showing CCDC8-OBSL1 interaction but not CCDC8-CUL7; replicated conceptually by subsequent studies\",\n      \"pmids\": [\"21737058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In CCDC8-deficient (CCDC8−/−) fibroblasts, GH-stimulated STAT5b and MAPK activation is reduced compared to controls, while IGF1-stimulated AKT activation is normal, indicating CCDC8 loss specifically impairs GH signaling downstream.\",\n      \"method\": \"Signaling assays in patient-derived fibroblast cell lines (CCDC8−/−) with GH and IGF1 stimulation; Western blot readouts for STAT5b, MAPK, AKT phosphorylation\",\n      \"journal\": \"Journal of molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean loss-of-function cell lines with defined pathway readouts, single lab, multiple signaling endpoints\",\n      \"pmids\": [\"23018678\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The ankyrin repeats of ANKRA2 recognize a PxLPxL motif at the C-terminal region of CCDC8, establishing CCDC8 as a major binding partner of ANKRA2 (but not the paralog RFXANK) in cells; the N-terminal region of CCDC8 interacts with OBSL1 to form a CUL7 ligase complex.\",\n      \"method\": \"Binding assays, structural analysis (crystal/structural data), coimmunoprecipitation in cells\",\n      \"journal\": \"Structure\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — structural analysis combined with binding assays and cell-based Co-IP, multiple orthogonal methods identifying specific motif-mediated interaction\",\n      \"pmids\": [\"25752541\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"JMJD2A (a histone lysine demethylase) directly interacts with CCDC8 and regulates its expression; CCDC8 is a downstream pro-apoptotic target of JMJD2A, and CCDC8 inhibition restores drug resistance in gastric cancer cells.\",\n      \"method\": \"Immunoprecipitation, whole-gene expression array after JMJD2A knockdown, siRNA knockdown of CCDC8 with cell viability assays\",\n      \"journal\": \"Gastric cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single Co-IP plus expression array and functional rescue, single lab, multiple methods\",\n      \"pmids\": [\"31677131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Overexpressed CCDC8 inhibits HIV-1 production by causing newly assembled HIV-1 Gag particles on the plasma membrane to be endocytosed and degraded in lysosomes rather than budding out; CCDC8 is a membrane-associated protein and its N-terminal domain is critical for membrane binding and inhibition of Gag assembly. CCDC8 is phosphorylated at T87 and S261 and mono-methylated at K491, but alanine mutations at these sites do not affect anti-HIV activity.\",\n      \"method\": \"Live-cell imaging, overexpression studies, deletion mutant analysis, subcellular fractionation/co-localization with organelle markers, site-directed mutagenesis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live-cell imaging with functional consequence plus domain deletion mutants and PTM mutagenesis, single lab\",\n      \"pmids\": [\"32651437\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"G9a-mediated H3K9me3 binds to the CCDC8 promoter and suppresses CCDC8 expression, linking G9a epigenetic activity to CCDC8 regulation; CCDC8 dysregulation mediates G9a-driven radioresistance in lung cancer cells.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) assay, Western blotting, siRNA knockdown, cell proliferation and apoptosis assays\",\n      \"journal\": \"OncoTargets and therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP directly demonstrates H3K9me3 enrichment at CCDC8 promoter, functional rescue experiments, single lab\",\n      \"pmids\": [\"34140780\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CCDC8 promotes cardiomyocyte apoptosis via the TNF signaling pathway; silencing CCDC8 suppresses TNF-α-induced apoptosis and ROS production in cardiomyocytes under hypoxia-reoxygenation conditions.\",\n      \"method\": \"AAV9 overexpression and siRNA knockdown in vivo and in vitro, mRNA sequencing, KEGG pathway analysis, flow cytometry for apoptosis, TNF-α stimulation assays\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo and in vitro loss/gain of function with pathway identification via transcriptomics, single lab\",\n      \"pmids\": [\"39424266\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"CCDC8 interacts with the E3 ubiquitin ligase scaffold CUL7 and facilitates proteasome-dependent degradation of p53, thereby suppressing p53 downstream effectors P21 and BAX; pharmacological inhibition of neddylation (MLN4924) restores p53 levels and reverses CCDC8-driven oncogenic effects.\",\n      \"method\": \"Co-immunoprecipitation, functional overexpression and knockdown studies in vitro and in vivo, neddylation inhibitor (MLN4924) rescue experiments, Western blotting for p53/P21/BAX\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus pharmacological rescue plus in vivo tumor model, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"41644704\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CCDC8 is a membrane-associated scaffold protein that physically interacts with OBSL1 (via its N-terminal region) and CUL7 to form an E3 ubiquitin ligase complex that facilitates p53 degradation and regulates GH/IGF1 signaling; its C-terminal PxLPxL motif is recognized by the ankyrin repeats of ANKRA2; it is transcriptionally repressed by G9a-mediated H3K9me3 and regulated by JMJD2A; and it promotes apoptosis via the TNF signaling pathway while also restricting HIV-1 replication by redirecting Gag to lysosomal degradation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CCDC8 is a membrane-associated scaffold protein that operates within a CUL7–OBSL1 E3 ubiquitin ligase axis controlling mammalian growth and proteostasis [#0, #2]. It binds OBSL1 through its N-terminal region and associates with the CUL7 ligase scaffold, where it facilitates proteasome-dependent degradation of p53 and thereby represses the p53 effectors P21 and BAX; this activity is neddylation-dependent and reversible by MLN4924 [#2, #7]. A C-terminal PxLPxL motif in CCDC8 is specifically recognized by the ankyrin repeats of ANKRA2, defining a distinct motif-mediated interaction [#2]. Loss of CCDC8 selectively impairs growth hormone–driven STAT5b and MAPK signaling while sparing IGF1-stimulated AKT activation, placing it downstream in GH signaling [#1]. CCDC8 expression is epigenetically constrained, being repressed by G9a-mediated H3K9me3 at its promoter and regulated through interaction with the demethylase JMJD2A, contexts in which CCDC8 acts as a pro-apoptotic effector influencing cancer cell drug and radiation resistance [#3, #5]. CCDC8 also promotes apoptosis via the TNF signaling pathway in cardiomyocytes [#6] and restricts HIV-1 by redirecting plasma-membrane Gag particles to lysosomal degradation through its membrane-binding N-terminal domain [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Established that CCDC8 is not an isolated factor but a member of a growth-regulatory module by showing it physically partners with OBSL1.\",\n      \"evidence\": \"Co-immunoprecipitation linking CCDC8, OBSL1, and CUL7 in a growth pathway\",\n      \"pmids\": [\"21737058\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct CCDC8-CUL7 interaction not detected in this study\", \"Molecular function within the complex undefined\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Resolved which signaling arm CCDC8 supports by showing its loss specifically blunts GH-driven STAT5b/MAPK activation but leaves IGF1-AKT intact.\",\n      \"evidence\": \"GH and IGF1 stimulation assays in CCDC8-deficient patient fibroblasts with phospho-Western readouts\",\n      \"pmids\": [\"23018678\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular step at which CCDC8 acts in GH signaling unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined the structural basis of CCDC8 interactions, mapping a C-terminal PxLPxL motif recognized by ANKRA2 ankyrin repeats and an N-terminal OBSL1/CUL7 interface.\",\n      \"evidence\": \"Structural analysis combined with binding assays and cellular Co-IP\",\n      \"pmids\": [\"25752541\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of ANKRA2 binding not established\", \"Whether ANKRA2 and OBSL1 binding are mutually exclusive unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Connected CCDC8 to chromatin-modifier control by showing JMJD2A interacts with and regulates CCDC8, which acts as a pro-apoptotic, drug-sensitizing target.\",\n      \"evidence\": \"Immunoprecipitation, expression array after JMJD2A knockdown, and siRNA rescue in gastric cancer cells\",\n      \"pmids\": [\"31677131\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which CCDC8 promotes apoptosis not defined\", \"Single Co-IP without reciprocal validation\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified an antiviral function, showing CCDC8 is membrane-associated and redirects HIV-1 Gag to lysosomal degradation via its N-terminal domain.\",\n      \"evidence\": \"Live-cell imaging, deletion mutants, subcellular fractionation, and PTM site mutagenesis in overexpression systems\",\n      \"pmids\": [\"32651437\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relies on overexpression rather than endogenous levels\", \"Mapped PTMs (T87, S261, K491) have no demonstrated functional role in antiviral activity\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed CCDC8 is epigenetically repressed by G9a-deposited H3K9me3 at its promoter, linking its silencing to radioresistance.\",\n      \"evidence\": \"ChIP for H3K9me3 at the CCDC8 promoter plus siRNA and apoptosis assays in lung cancer cells\",\n      \"pmids\": [\"34140780\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream effectors of CCDC8 in radioresistance not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrated a pro-apoptotic role through TNF signaling, where CCDC8 silencing suppresses TNF-α-induced apoptosis and ROS in cardiomyocytes.\",\n      \"evidence\": \"AAV9 overexpression and siRNA knockdown in vivo/in vitro, mRNA-seq with KEGG analysis, and flow cytometry under hypoxia-reoxygenation\",\n      \"pmids\": [\"39424266\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between CCDC8 and TNF pathway components not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Mechanistically united CCDC8 with the CUL7 ligase by showing it drives neddylation-dependent proteasomal degradation of p53, suppressing P21 and BAX.\",\n      \"evidence\": \"Co-IP, gain/loss-of-function in vitro and in vivo, and MLN4924 neddylation-inhibitor rescue with p53/P21/BAX Westerns\",\n      \"pmids\": [\"41644704\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether CCDC8 directly recruits p53 as substrate versus acting indirectly unresolved\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how CCDC8's distinct activities — GH signaling, p53 degradation, antiviral defense, and TNF-driven apoptosis — are mechanistically integrated within a single protein.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of CCDC8 within an assembled CUL7-OBSL1 complex\", \"No defined enzymatic activity intrinsic to CCDC8\", \"Determinants selecting between its growth, antiviral, and apoptotic roles unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2, 7]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 6]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [3, 6, 7]}\n    ],\n    \"complexes\": [\"CUL7-OBSL1-CCDC8 E3 ubiquitin ligase complex\"],\n    \"partners\": [\"OBSL1\", \"CUL7\", \"ANKRA2\", \"JMJD2A\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}