{"gene":"OCIAD2","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2013,"finding":"OCIAD2 interacts with nicastrin to stimulate γ-secretase activity, promotes formation of an active γ-secretase complex, enhances subcellular localization of γ-secretase components to lipid rafts, increases the interaction of nicastrin with C99, and stimulates APP processing via γ-secretase activation without affecting Notch processing. A cell-permeable Tat-OCIAD2 peptide that blocked the OCIAD2–nicastrin interaction interrupted γ-secretase-mediated AICD production.","method":"Genome-wide functional screen (cDNA library, 6,178 genes), ectopic expression and knockdown assays, co-immunoprecipitation, lipid raft fractionation, cell-permeable inhibitory peptide (Tat-OCIAD2)","journal":"Cellular and molecular life sciences : CMLS","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (functional screen, co-IP, lipid raft fractionation, peptide interference, KD/OE) in one focused study establishing a direct mechanistic interaction","pmids":["24270855"],"is_preprint":false},{"year":2018,"finding":"OCIAD2 localizes to early endosomes and mitochondria, interacts with OCIAD1/Asrij and STAT3, and is essential for STAT3 activation and cell migration. A double helical motif within the OCIA domain is necessary and sufficient for its subcellular localization, protein–protein interactions, and STAT3 activation.","method":"Subcellular fractionation/immunofluorescence localization, co-immunoprecipitation, knockdown and overexpression studies, structure prediction with protein disruption and biochemical assays","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, KD/OE with defined phenotype, domain disruption studies, multiple orthogonal methods in a single focused study","pmids":["29743632"],"is_preprint":false},{"year":2022,"finding":"OCIAD2 is a mitochondrial inner membrane assembly factor specifically required for dimeric complex III (CIII2) and supercomplex III2+IV biogenesis. Complete loss of OCIAD2 by gene editing in HEK293 cells caused abnormal mitochondrial morphology, substantial decrease of CIII2 and supercomplex III2+IV, reduction in CIII enzymatic activity, and interaction of OCIAD2 with electron transport chain proteins.","method":"CRISPR-Cas9 knockout in HEK293 cells, co-immunoprecipitation with ETC proteins, blue native PAGE / BN-PAGE for supercomplex assessment, enzymatic activity assay, mitochondrial morphology imaging","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean KO with defined biochemical phenotype, multiple orthogonal methods (KO, Co-IP, BN-PAGE, enzymatic assay) in a single focused study","pmids":["35080992"],"is_preprint":false},{"year":2021,"finding":"OCIAD2 is a proviral host cofactor for HCV replication: it is recruited into the HCV RNA replication complex through direct interaction with the viral non-structural protein NS4B, and also interacts with PREB and NS5A but not NS5B or Surfeit 4. An OCIAD2 mutant lacking NS4B-binding ability did not promote HCV replication. HCV infection in turn induces OCIAD2 expression.","method":"siRNA knockdown screen, co-immunoprecipitation, overexpression of wild-type vs. binding-deficient OCIAD2 mutant, HCV replication assays","journal":"International journal of biological macromolecules","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP identifying interaction, mutant rescue experiment, and KD dose-response in a single lab study","pmids":["34371038"],"is_preprint":false},{"year":2017,"finding":"Knockdown of OCIAD2 in HCC cell lines increased colony formation, migration, and invasion, accompanied by enhanced MMP9 expression and activation of AKT and FAK. Pharmacological inhibition of AKT restored the OCIAD2-dependent changes in clonogenic growth, migration, and invasion, placing OCIAD2 upstream of AKT/FAK signaling.","method":"siRNA knockdown, colony formation assay, migration/invasion assay, western blot for AKT/FAK activation, AKT inhibitor rescue experiment","journal":"Carcinogenesis","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD with defined cellular phenotype and pharmacological epistasis placing OCIAD2 upstream of AKT, single lab","pmids":["28911005"],"is_preprint":false},{"year":2026,"finding":"OCIAD2 directly interacts with integrin β1 (by Co-IP/MS) and binds SNX17 to enhance SNX17–integrin β1 association, promoting recycling of integrin β1 to lipid raft-enriched plasma membrane regions and preventing its lysosomal degradation. This stabilizes integrin β1 protein expression and sustains FAK–PI3K–AKT–mTOR signaling, conferring cisplatin resistance in HNSCC. Genetic silencing of OCIAD2 sensitized tumors to cisplatin in preclinical models.","method":"Co-immunoprecipitation coupled with mass spectrometry, transcriptomic analysis, lysosomal degradation assays, lipid raft fractionation, western blot for FAK/PI3K/AKT/mTOR, genetic silencing (shRNA/siRNA), in vivo xenograft models","journal":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP/MS identifying direct interaction, multiple orthogonal mechanistic assays (trafficking, lipid raft fractionation, signaling pathway), in vivo validation","pmids":["41655222"],"is_preprint":false},{"year":2025,"finding":"OCIAD2 directly interacts with IQGAP1 via its double helical motif (identified by immunoprecipitation-coupled mass spectrometry and validated by protein–protein interaction assays), and this binding activates the PI3K/AKT pathway, suppresses oxidative stress, maintains mitochondrial function, and inhibits mitochondria-mediated apoptosis in pancreatic ductal adenocarcinoma cells.","method":"Immunoprecipitation-coupled mass spectrometry, co-immunoprecipitation validation, transcriptomic profiling, mitochondrial morphology and function assays, redox homeostasis assays, apoptosis assays, subcutaneous and orthotopic xenograft models","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP/MS identifying direct interaction, multiple functional assays and in vivo models, single lab","pmids":["41197887"],"is_preprint":false},{"year":2025,"finding":"OCIAD2 depletion in human embryonic stem cells impairs mesendoderm induction and causes an incomplete epithelial-to-mesenchymal transition (EMT), with transcriptional repression of TGFβ signaling and downregulation of fatty acid oxidation (FAO) genes. OCIAD2 KO cells exhibited hyperfused mitochondria. Pharmacological restoration of FAO (acetate supplementation) rescued mesendoderm specification capacity in KO cells, indicating OCIAD2 coordinates metabolic cues with TGFβ pathway activation during EMT.","method":"CRISPR-Cas9 KO and overexpression in hESCs, transcriptome analysis, immunoblotting, localization studies, pharmacological FAO restoration (acetate supplementation), differentiation assays","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO/OE with defined differentiation phenotype, transcriptomics, pharmacological rescue; preprint, not yet peer-reviewed","pmids":["bio_10.1101_2025.11.10.687537"],"is_preprint":true},{"year":2025,"finding":"OCIAD2 impairs oxidative phosphorylation (OXPHOS) function and induces a metabolic shift toward glycolysis in lung adenocarcinoma cells, as demonstrated by mitochondrial metabolic assay. OCIAD2 silencing decreased cell migration, invasion, and colony-forming abilities.","method":"siRNA silencing, mitochondrial metabolic assay (Seahorse or equivalent), colony formation, migration/invasion assays, GSEA","journal":"Journal of proteome research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct mitochondrial metabolic measurement with functional cellular assays, single lab study","pmids":["40690206"],"is_preprint":false}],"current_model":"OCIAD2 is a mitochondrial inner membrane protein with a conserved double helical OCIA domain that functions as a complex III assembly factor (required for CIII2 and supercomplex III2+IV biogenesis and activity), activates γ-secretase by binding nicastrin to enhance Aβ production and lipid raft localization of the complex, promotes JAK/STAT3 and PI3K/AKT/FAK signaling through interactions with STAT3, IQGAP1, and integrin β1 (the latter stabilized via SNX17-mediated endosomal recycling to lipid rafts), modulates mitochondrial metabolism and EMT by integrating TGFβ signaling with fatty acid oxidation, and serves as a proviral cofactor for HCV replication through interaction with NS4B within the viral replication complex."},"narrative":{"mechanistic_narrative":"OCIAD2 is a dual-localized protein found in mitochondria and early endosomes whose conserved double helical motif within the OCIA domain mediates its subcellular targeting and protein-protein interactions, linking mitochondrial bioenergetics to membrane signaling [PMID:29743632, PMID:35080992]. At the mitochondrial inner membrane it acts as an assembly factor specifically required for dimeric complex III (CIII2) and the III2+IV supercomplex, with its loss reducing CIII enzymatic activity and producing abnormal mitochondrial morphology [PMID:35080992]. Through its OCIA double helical motif OCIAD2 engages a series of signaling partners — STAT3, IQGAP1, and integrin β1 — to drive JAK/STAT3 and PI3K/AKT/FAK signaling, promoting cell migration; integrin β1 is stabilized by OCIAD2 binding to SNX17, which routes the integrin through endosomal recycling to lipid raft membrane regions and away from lysosomal degradation [PMID:29743632, PMID:41655222, PMID:41197887]. OCIAD2 also stimulates γ-secretase activity by binding nicastrin, enhancing lipid raft localization of the complex and APP processing toward Aβ production without affecting Notch cleavage [PMID:24270855]. By coupling fatty acid oxidation and OXPHOS to TGFβ signaling, OCIAD2 further modulates mitochondrial metabolism and epithelial-to-mesenchymal transition [PMID:bio_10.1101_2025.11.10.687537, PMID:40690206]. Independently, OCIAD2 serves as a proviral host cofactor for HCV replication via direct interaction with the viral NS4B protein in the replication complex [PMID:34371038].","teleology":[{"year":2013,"claim":"Established the first molecular function for OCIAD2 by showing it activates γ-secretase, addressing how an uncharacterized protein could influence amyloidogenic APP processing.","evidence":"Genome-wide functional cDNA screen, co-IP, lipid raft fractionation, and a cell-permeable inhibitory peptide in cell lines","pmids":["24270855"],"confidence":"High","gaps":["No structural basis for the nicastrin interaction","Selectivity for APP over Notch not mechanistically explained","In vivo relevance to amyloid pathology untested"]},{"year":2017,"claim":"Placed OCIAD2 upstream of AKT/FAK signaling in cancer, addressing whether it functions as a signaling regulator beyond γ-secretase.","evidence":"siRNA knockdown, clonogenic/migration/invasion assays, and AKT inhibitor epistasis in HCC cell lines","pmids":["28911005"],"confidence":"Medium","gaps":["Direct molecular partner linking OCIAD2 to AKT not identified","Knockdown rather than clean genetic loss","Single tumor type"]},{"year":2018,"claim":"Defined the OCIA double helical motif as the determinant of OCIAD2 localization and interactions and connected it to STAT3 activation, addressing the structure-function basis of its dual roles.","evidence":"Subcellular fractionation/IF, reciprocal co-IP, domain disruption, and KD/OE migration assays","pmids":["29743632"],"confidence":"High","gaps":["No experimental structure of the OCIA domain","Mechanism by which the motif drives both mitochondrial and endosomal targeting unresolved"]},{"year":2021,"claim":"Identified OCIAD2 as a proviral host cofactor, addressing how it is co-opted by HCV.","evidence":"siRNA screen, co-IP mapping NS4B/NS5A/PREB interactions, and a binding-deficient mutant rescue in HCV replication assays","pmids":["34371038"],"confidence":"Medium","gaps":["Structural detail of the NS4B interface unknown","How OCIAD2 mechanistically supports replication complex function unclear","Single lab"]},{"year":2022,"claim":"Defined OCIAD2 as a mitochondrial inner membrane complex III assembly factor, addressing its native bioenergetic function.","evidence":"CRISPR-Cas9 knockout in HEK293, co-IP with ETC proteins, BN-PAGE, and CIII enzymatic assay","pmids":["35080992"],"confidence":"High","gaps":["Step in the CIII assembly pathway at which OCIAD2 acts not defined","No structural model of OCIAD2 within assembly intermediates","Relationship between assembly role and signaling roles unexplored"]},{"year":2025,"claim":"Linked OCIAD2 to IQGAP1 and to mitochondrial/metabolic control, addressing how it suppresses apoptosis and sustains PI3K/AKT signaling.","evidence":"IP-MS, co-IP validation, mitochondrial function and apoptosis assays, and xenografts in PDAC; plus Seahorse metabolic assays in lung adenocarcinoma","pmids":["41197887","40690206"],"confidence":"Medium","gaps":["Whether metabolic effects derive from the CIII assembly role versus signaling not separated","Direct versus indirect IQGAP1 binding interface not mapped"]},{"year":2025,"claim":"Connected OCIAD2 to TGFβ-coupled fatty acid oxidation during EMT and developmental differentiation, addressing how it integrates metabolic and signaling cues.","evidence":"CRISPR-Cas9 KO/OE in hESCs, transcriptomics, and pharmacological FAO restoration (preprint)","pmids":["bio_10.1101_2025.11.10.687537"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Direct molecular link between OCIAD2 and TGFβ transcription undefined","Causality between hyperfused mitochondria and differentiation defect unresolved"]},{"year":2026,"claim":"Resolved a trafficking mechanism by which OCIAD2 stabilizes integrin β1, addressing how it sustains FAK-PI3K-AKT-mTOR signaling and drug resistance.","evidence":"Co-IP/MS, lysosomal degradation and lipid raft fractionation assays, signaling immunoblots, and shRNA silencing with xenografts in HNSCC","pmids":["41655222"],"confidence":"High","gaps":["Whether SNX17 recruitment uses the OCIA double helical motif not stated","How endosomal OCIAD2 pool relates to mitochondrial pool unclear"]},{"year":null,"claim":"It remains unknown how OCIAD2's mitochondrial complex III assembly function mechanistically relates to its endosomal trafficking and signaling activities, and whether these reflect distinct subpopulations or a single integrating mechanism.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying structural or biochemical model spanning both compartments","No experimental structure of the OCIA domain","Substrate/client specificity of the assembly factor role undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2,5]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,5]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[1,2]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1,5]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,5]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,4,5,6]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[2,7,8]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[3,5]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[5]}],"complexes":["mitochondrial respiratory complex III (CIII2)","supercomplex III2+IV","γ-secretase complex"],"partners":["NCSTN","STAT3","OCIAD1","IQGAP1","ITGB1","SNX17","NS4B","PREB"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q56VL3","full_name":"OCIA domain-containing protein 2","aliases":["Ovarian carcinoma immunoreactive antigen-like protein"],"length_aa":154,"mass_kda":17.0,"function":"Has an essential role in the assembly of mitochondrial respiratory chain complex III (PubMed:35080992). Is also required for STAT3 activation and plays a role in cell migration (PubMed:29743632)","subcellular_location":"Endosome; Mitochondrion; Mitochondrion inner membrane","url":"https://www.uniprot.org/uniprotkb/Q56VL3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/OCIAD2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/OCIAD2","total_profiled":1310},"omim":[{"mim_id":"619633","title":"OCIA DOMAIN-CONTAINING PROTEIN 2; OCIAD2","url":"https://www.omim.org/entry/619633"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Mitochondria","reliability":"Enhanced"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"kidney","ntpm":144.9}],"url":"https://www.proteinatlas.org/search/OCIAD2"},"hgnc":{"alias_symbol":["MGC45416"],"prev_symbol":[]},"alphafold":{"accession":"Q56VL3","domains":[{"cath_id":"-","chopping":"34-119","consensus_level":"high","plddt":63.7356,"start":34,"end":119}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q56VL3","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q56VL3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q56VL3-F1-predicted_aligned_error_v6.png","plddt_mean":57.34},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=OCIAD2","jax_strain_url":"https://www.jax.org/strain/search?query=OCIAD2"},"sequence":{"accession":"Q56VL3","fasta_url":"https://rest.uniprot.org/uniprotkb/Q56VL3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q56VL3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q56VL3"}},"corpus_meta":[{"pmid":"28911005","id":"PMC_28911005","title":"OCIAD2 suppressed tumor growth and invasion via AKT pathway in Hepatocelluar carcinoma.","date":"2017","source":"Carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/28911005","citation_count":26,"is_preprint":false},{"pmid":"29743632","id":"PMC_29743632","title":"A double helical motif in OCIAD2 is essential for its localization, interactions and STAT3 activation.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/29743632","citation_count":24,"is_preprint":false},{"pmid":"24270855","id":"PMC_24270855","title":"OCIAD2 activates γ-secretase to enhance amyloid β production by interacting with nicastrin.","date":"2013","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/24270855","citation_count":21,"is_preprint":false},{"pmid":"25376185","id":"PMC_25376185","title":"Immunocytochemical staining for stratifin and OCIAD2 in bronchial washing specimens increases sensitivity for diagnosis of lung cancer.","date":"2014","source":"Cytopathology : official journal of the British Society for Clinical Cytology","url":"https://pubmed.ncbi.nlm.nih.gov/25376185","citation_count":18,"is_preprint":false},{"pmid":"35080992","id":"PMC_35080992","title":"Ovarian carcinoma immunoreactive antigen-like protein 2 (OCIAD2) is a novel complex III-specific assembly factor in mitochondria.","date":"2022","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/35080992","citation_count":14,"is_preprint":false},{"pmid":"35920378","id":"PMC_35920378","title":"Aberrant OCIAD2 demethylation in lung adenocarcinoma is associated with outcome.","date":"2022","source":"Pathology international","url":"https://pubmed.ncbi.nlm.nih.gov/35920378","citation_count":9,"is_preprint":false},{"pmid":"38944166","id":"PMC_38944166","title":"OCIAD2 promotes pancreatic cancer progression through the AKT signaling pathway.","date":"2024","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/38944166","citation_count":8,"is_preprint":false},{"pmid":"34371038","id":"PMC_34371038","title":"Cellular OCIAD2 protein is a proviral factor for hepatitis C virus replication.","date":"2021","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/34371038","citation_count":6,"is_preprint":false},{"pmid":"39076095","id":"PMC_39076095","title":"Knockdown of Anoikis-Associated Gene OCIAD2 Reduces Proliferation and Migration of Glioblastoma Cell Lines.","date":"2025","source":"Combinatorial chemistry & high throughput screening","url":"https://pubmed.ncbi.nlm.nih.gov/39076095","citation_count":1,"is_preprint":false},{"pmid":"36640474","id":"PMC_36640474","title":"Generation of an OCIAD2 overexpressing transgenic human embryonic stem cell line, BJNhem20-OCIAD2-OV.","date":"2023","source":"Stem cell research","url":"https://pubmed.ncbi.nlm.nih.gov/36640474","citation_count":1,"is_preprint":false},{"pmid":"40690206","id":"PMC_40690206","title":"OCIAD2 Promotes Cancer Progression via Metabolic Reprogramming in Lung Adenocarcinoma.","date":"2025","source":"Journal of proteome research","url":"https://pubmed.ncbi.nlm.nih.gov/40690206","citation_count":0,"is_preprint":false},{"pmid":"36642056","id":"PMC_36642056","title":"Generation of OCIAD2 homozygous knockout (BJNhem20-OCIAD2-CRISPR-33) and heterozygous knockout (BJNhem20-OCIAD2-CRISPR-40) human embryonic stem cell lines using CRISPR-Cas9 mediated targeting.","date":"2023","source":"Stem cell research","url":"https://pubmed.ncbi.nlm.nih.gov/36642056","citation_count":0,"is_preprint":false},{"pmid":"41655222","id":"PMC_41655222","title":"OCIAD2 Stabilizes Integrin β1 Signaling Through SNX17-Mediated Endosomal Recycling to Lipid Rafts and Modulates Cisplatin Response in HNSCC.","date":"2026","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/41655222","citation_count":0,"is_preprint":false},{"pmid":"41197887","id":"PMC_41197887","title":"OCIAD2-IQGAP1 interaction promotes pancreatic cancer progression by suppressing oxidative stress and mitochondria-mediated apoptosis.","date":"2025","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/41197887","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.10.687537","title":"TGFβ-dependent upregulation of OCIAD2 is essential for epithelial-to-mesenchymal transition during mesendoderm differentiation","date":"2025-11-11","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.10.687537","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9096,"output_tokens":2700,"usd":0.033894,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10086,"output_tokens":3264,"usd":0.066015,"stage2_stop_reason":"end_turn"},"total_usd":0.099909,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2013,\n      \"finding\": \"OCIAD2 interacts with nicastrin to stimulate γ-secretase activity, promotes formation of an active γ-secretase complex, enhances subcellular localization of γ-secretase components to lipid rafts, increases the interaction of nicastrin with C99, and stimulates APP processing via γ-secretase activation without affecting Notch processing. A cell-permeable Tat-OCIAD2 peptide that blocked the OCIAD2–nicastrin interaction interrupted γ-secretase-mediated AICD production.\",\n      \"method\": \"Genome-wide functional screen (cDNA library, 6,178 genes), ectopic expression and knockdown assays, co-immunoprecipitation, lipid raft fractionation, cell-permeable inhibitory peptide (Tat-OCIAD2)\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (functional screen, co-IP, lipid raft fractionation, peptide interference, KD/OE) in one focused study establishing a direct mechanistic interaction\",\n      \"pmids\": [\"24270855\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"OCIAD2 localizes to early endosomes and mitochondria, interacts with OCIAD1/Asrij and STAT3, and is essential for STAT3 activation and cell migration. A double helical motif within the OCIA domain is necessary and sufficient for its subcellular localization, protein–protein interactions, and STAT3 activation.\",\n      \"method\": \"Subcellular fractionation/immunofluorescence localization, co-immunoprecipitation, knockdown and overexpression studies, structure prediction with protein disruption and biochemical assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, KD/OE with defined phenotype, domain disruption studies, multiple orthogonal methods in a single focused study\",\n      \"pmids\": [\"29743632\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"OCIAD2 is a mitochondrial inner membrane assembly factor specifically required for dimeric complex III (CIII2) and supercomplex III2+IV biogenesis. Complete loss of OCIAD2 by gene editing in HEK293 cells caused abnormal mitochondrial morphology, substantial decrease of CIII2 and supercomplex III2+IV, reduction in CIII enzymatic activity, and interaction of OCIAD2 with electron transport chain proteins.\",\n      \"method\": \"CRISPR-Cas9 knockout in HEK293 cells, co-immunoprecipitation with ETC proteins, blue native PAGE / BN-PAGE for supercomplex assessment, enzymatic activity assay, mitochondrial morphology imaging\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined biochemical phenotype, multiple orthogonal methods (KO, Co-IP, BN-PAGE, enzymatic assay) in a single focused study\",\n      \"pmids\": [\"35080992\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"OCIAD2 is a proviral host cofactor for HCV replication: it is recruited into the HCV RNA replication complex through direct interaction with the viral non-structural protein NS4B, and also interacts with PREB and NS5A but not NS5B or Surfeit 4. An OCIAD2 mutant lacking NS4B-binding ability did not promote HCV replication. HCV infection in turn induces OCIAD2 expression.\",\n      \"method\": \"siRNA knockdown screen, co-immunoprecipitation, overexpression of wild-type vs. binding-deficient OCIAD2 mutant, HCV replication assays\",\n      \"journal\": \"International journal of biological macromolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP identifying interaction, mutant rescue experiment, and KD dose-response in a single lab study\",\n      \"pmids\": [\"34371038\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Knockdown of OCIAD2 in HCC cell lines increased colony formation, migration, and invasion, accompanied by enhanced MMP9 expression and activation of AKT and FAK. Pharmacological inhibition of AKT restored the OCIAD2-dependent changes in clonogenic growth, migration, and invasion, placing OCIAD2 upstream of AKT/FAK signaling.\",\n      \"method\": \"siRNA knockdown, colony formation assay, migration/invasion assay, western blot for AKT/FAK activation, AKT inhibitor rescue experiment\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD with defined cellular phenotype and pharmacological epistasis placing OCIAD2 upstream of AKT, single lab\",\n      \"pmids\": [\"28911005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"OCIAD2 directly interacts with integrin β1 (by Co-IP/MS) and binds SNX17 to enhance SNX17–integrin β1 association, promoting recycling of integrin β1 to lipid raft-enriched plasma membrane regions and preventing its lysosomal degradation. This stabilizes integrin β1 protein expression and sustains FAK–PI3K–AKT–mTOR signaling, conferring cisplatin resistance in HNSCC. Genetic silencing of OCIAD2 sensitized tumors to cisplatin in preclinical models.\",\n      \"method\": \"Co-immunoprecipitation coupled with mass spectrometry, transcriptomic analysis, lysosomal degradation assays, lipid raft fractionation, western blot for FAK/PI3K/AKT/mTOR, genetic silencing (shRNA/siRNA), in vivo xenograft models\",\n      \"journal\": \"Advanced science (Weinheim, Baden-Wurttemberg, Germany)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/MS identifying direct interaction, multiple orthogonal mechanistic assays (trafficking, lipid raft fractionation, signaling pathway), in vivo validation\",\n      \"pmids\": [\"41655222\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"OCIAD2 directly interacts with IQGAP1 via its double helical motif (identified by immunoprecipitation-coupled mass spectrometry and validated by protein–protein interaction assays), and this binding activates the PI3K/AKT pathway, suppresses oxidative stress, maintains mitochondrial function, and inhibits mitochondria-mediated apoptosis in pancreatic ductal adenocarcinoma cells.\",\n      \"method\": \"Immunoprecipitation-coupled mass spectrometry, co-immunoprecipitation validation, transcriptomic profiling, mitochondrial morphology and function assays, redox homeostasis assays, apoptosis assays, subcutaneous and orthotopic xenograft models\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/MS identifying direct interaction, multiple functional assays and in vivo models, single lab\",\n      \"pmids\": [\"41197887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"OCIAD2 depletion in human embryonic stem cells impairs mesendoderm induction and causes an incomplete epithelial-to-mesenchymal transition (EMT), with transcriptional repression of TGFβ signaling and downregulation of fatty acid oxidation (FAO) genes. OCIAD2 KO cells exhibited hyperfused mitochondria. Pharmacological restoration of FAO (acetate supplementation) rescued mesendoderm specification capacity in KO cells, indicating OCIAD2 coordinates metabolic cues with TGFβ pathway activation during EMT.\",\n      \"method\": \"CRISPR-Cas9 KO and overexpression in hESCs, transcriptome analysis, immunoblotting, localization studies, pharmacological FAO restoration (acetate supplementation), differentiation assays\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO/OE with defined differentiation phenotype, transcriptomics, pharmacological rescue; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.11.10.687537\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"OCIAD2 impairs oxidative phosphorylation (OXPHOS) function and induces a metabolic shift toward glycolysis in lung adenocarcinoma cells, as demonstrated by mitochondrial metabolic assay. OCIAD2 silencing decreased cell migration, invasion, and colony-forming abilities.\",\n      \"method\": \"siRNA silencing, mitochondrial metabolic assay (Seahorse or equivalent), colony formation, migration/invasion assays, GSEA\",\n      \"journal\": \"Journal of proteome research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct mitochondrial metabolic measurement with functional cellular assays, single lab study\",\n      \"pmids\": [\"40690206\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"OCIAD2 is a mitochondrial inner membrane protein with a conserved double helical OCIA domain that functions as a complex III assembly factor (required for CIII2 and supercomplex III2+IV biogenesis and activity), activates γ-secretase by binding nicastrin to enhance Aβ production and lipid raft localization of the complex, promotes JAK/STAT3 and PI3K/AKT/FAK signaling through interactions with STAT3, IQGAP1, and integrin β1 (the latter stabilized via SNX17-mediated endosomal recycling to lipid rafts), modulates mitochondrial metabolism and EMT by integrating TGFβ signaling with fatty acid oxidation, and serves as a proviral cofactor for HCV replication through interaction with NS4B within the viral replication complex.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"OCIAD2 is a dual-localized protein found in mitochondria and early endosomes whose conserved double helical motif within the OCIA domain mediates its subcellular targeting and protein-protein interactions, linking mitochondrial bioenergetics to membrane signaling [#1, #2]. At the mitochondrial inner membrane it acts as an assembly factor specifically required for dimeric complex III (CIII2) and the III2+IV supercomplex, with its loss reducing CIII enzymatic activity and producing abnormal mitochondrial morphology [#2]. Through its OCIA double helical motif OCIAD2 engages a series of signaling partners — STAT3, IQGAP1, and integrin \\u03b21 — to drive JAK/STAT3 and PI3K/AKT/FAK signaling, promoting cell migration; integrin \\u03b21 is stabilized by OCIAD2 binding to SNX17, which routes the integrin through endosomal recycling to lipid raft membrane regions and away from lysosomal degradation [#1, #5, #6]. OCIAD2 also stimulates \\u03b3-secretase activity by binding nicastrin, enhancing lipid raft localization of the complex and APP processing toward A\\u03b2 production without affecting Notch cleavage [#0]. By coupling fatty acid oxidation and OXPHOS to TGF\\u03b2 signaling, OCIAD2 further modulates mitochondrial metabolism and epithelial-to-mesenchymal transition [#7, #8]. Independently, OCIAD2 serves as a proviral host cofactor for HCV replication via direct interaction with the viral NS4B protein in the replication complex [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"Established the first molecular function for OCIAD2 by showing it activates \\u03b3-secretase, addressing how an uncharacterized protein could influence amyloidogenic APP processing.\",\n      \"evidence\": \"Genome-wide functional cDNA screen, co-IP, lipid raft fractionation, and a cell-permeable inhibitory peptide in cell lines\",\n      \"pmids\": [\"24270855\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structural basis for the nicastrin interaction\", \"Selectivity for APP over Notch not mechanistically explained\", \"In vivo relevance to amyloid pathology untested\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Placed OCIAD2 upstream of AKT/FAK signaling in cancer, addressing whether it functions as a signaling regulator beyond \\u03b3-secretase.\",\n      \"evidence\": \"siRNA knockdown, clonogenic/migration/invasion assays, and AKT inhibitor epistasis in HCC cell lines\",\n      \"pmids\": [\"28911005\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular partner linking OCIAD2 to AKT not identified\", \"Knockdown rather than clean genetic loss\", \"Single tumor type\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the OCIA double helical motif as the determinant of OCIAD2 localization and interactions and connected it to STAT3 activation, addressing the structure-function basis of its dual roles.\",\n      \"evidence\": \"Subcellular fractionation/IF, reciprocal co-IP, domain disruption, and KD/OE migration assays\",\n      \"pmids\": [\"29743632\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No experimental structure of the OCIA domain\", \"Mechanism by which the motif drives both mitochondrial and endosomal targeting unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified OCIAD2 as a proviral host cofactor, addressing how it is co-opted by HCV.\",\n      \"evidence\": \"siRNA screen, co-IP mapping NS4B/NS5A/PREB interactions, and a binding-deficient mutant rescue in HCV replication assays\",\n      \"pmids\": [\"34371038\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural detail of the NS4B interface unknown\", \"How OCIAD2 mechanistically supports replication complex function unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined OCIAD2 as a mitochondrial inner membrane complex III assembly factor, addressing its native bioenergetic function.\",\n      \"evidence\": \"CRISPR-Cas9 knockout in HEK293, co-IP with ETC proteins, BN-PAGE, and CIII enzymatic assay\",\n      \"pmids\": [\"35080992\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Step in the CIII assembly pathway at which OCIAD2 acts not defined\", \"No structural model of OCIAD2 within assembly intermediates\", \"Relationship between assembly role and signaling roles unexplored\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked OCIAD2 to IQGAP1 and to mitochondrial/metabolic control, addressing how it suppresses apoptosis and sustains PI3K/AKT signaling.\",\n      \"evidence\": \"IP-MS, co-IP validation, mitochondrial function and apoptosis assays, and xenografts in PDAC; plus Seahorse metabolic assays in lung adenocarcinoma\",\n      \"pmids\": [\"41197887\", \"40690206\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether metabolic effects derive from the CIII assembly role versus signaling not separated\", \"Direct versus indirect IQGAP1 binding interface not mapped\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected OCIAD2 to TGF\\u03b2-coupled fatty acid oxidation during EMT and developmental differentiation, addressing how it integrates metabolic and signaling cues.\",\n      \"evidence\": \"CRISPR-Cas9 KO/OE in hESCs, transcriptomics, and pharmacological FAO restoration (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.11.10.687537\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Direct molecular link between OCIAD2 and TGF\\u03b2 transcription undefined\", \"Causality between hyperfused mitochondria and differentiation defect unresolved\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Resolved a trafficking mechanism by which OCIAD2 stabilizes integrin \\u03b21, addressing how it sustains FAK-PI3K-AKT-mTOR signaling and drug resistance.\",\n      \"evidence\": \"Co-IP/MS, lysosomal degradation and lipid raft fractionation assays, signaling immunoblots, and shRNA silencing with xenografts in HNSCC\",\n      \"pmids\": [\"41655222\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SNX17 recruitment uses the OCIA double helical motif not stated\", \"How endosomal OCIAD2 pool relates to mitochondrial pool unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how OCIAD2's mitochondrial complex III assembly function mechanistically relates to its endosomal trafficking and signaling activities, and whether these reflect distinct subpopulations or a single integrating mechanism.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying structural or biochemical model spanning both compartments\", \"No experimental structure of the OCIA domain\", \"Substrate/client specificity of the assembly factor role undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 2, 5]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005743\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [1, 5]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 4, 5, 6]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [2, 7, 8]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [3, 5]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [\"mitochondrial respiratory complex III (CIII2)\", \"supercomplex III2+IV\", \"\\u03b3-secretase complex\"],\n    \"partners\": [\"NCSTN\", \"STAT3\", \"OCIAD1\", \"IQGAP1\", \"ITGB1\", \"SNX17\", \"NS4B\", \"PREB\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}