{"gene":"CIAO1","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2005,"finding":"Yeast Cia1 (ortholog of human CIAO1) is an essential WD40 repeat protein required for Fe/S cluster assembly on cytosolic and nuclear, but not mitochondrial, Fe/S proteins. Genetic epistasis showed that Nbp35 and Nar1 can assemble their own Fe/S clusters in the absence of Cia1, placing Cia1 in a late step of the CIA pathway, after Nbp35 and Nar1. Co-immunoprecipitation demonstrated a specific physical interaction between Cia1 and Nar1.","method":"Genetic epistasis (conditional depletion), coimmunoprecipitation, in vivo Fe/S assembly assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, genetic epistasis with multiple Fe/S substrates, replicated across several experimental conditions in a focused study","pmids":["16314508"],"is_preprint":false},{"year":2007,"finding":"Crystal structure of yeast Cia1 (ortholog of human CIAO1) resolved to 1.7 Å reveals a seven-bladed beta-propeller WD40 fold. Site-directed mutagenesis identified conserved top-surface residue R127 as functionally critical; R127 mutant cells grew slowly and were impaired in cytosolic Fe/S protein assembly. Human CIAO1 was shown to functionally replace yeast Cia1 and support cytosolic Fe/S protein biogenesis, confirming structural and functional conservation.","method":"X-ray crystallography (1.7 Å), site-directed mutagenesis, in vivo complementation assay","journal":"Structure","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus mutagenesis plus functional complementation in a single rigorous study","pmids":["17937914"],"is_preprint":false},{"year":2018,"finding":"The human CIA2A-CIAO1 heterotrimeric complex (two CIA2A molecules + one CIAO1) binds one [4Fe-4S] cluster, with Cys90 of CIA2A serving as a cluster ligand. The holo trimeric complex can transfer the [4Fe-4S] cluster to apo-IRP1 (cytosolic aconitase) to generate the active form of aconitase.","method":"NMR spectroscopy, UV-vis absorption, EPR spectroscopy, in vitro Fe/S cluster transfer assay","journal":"Biochimica et biophysica acta. General subjects","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple orthogonal biophysical methods (NMR, UV-vis, EPR) plus functional reconstitution of cluster transfer in a single study","pmids":["29842905"],"is_preprint":false},{"year":2018,"finding":"Cytosolic HSC20 (C-HSC20) mediates complex formation between components of the cytosolic Fe-S biogenesis pathway (primary scaffold ISCU1 and cysteine desulfurase NFS1) and the CIA targeting complex (CIAO1, FAM96B, MMS19), thereby integrating de novo Fe-S biosynthesis with the CIA-mediated transfer of Fe-S clusters to cytoplasmic and nuclear recipient proteins.","method":"Co-immunoprecipitation, interaction mapping, functional Fe-S cluster delivery assays in human cells","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP interactions plus functional assays in a single lab, multiple pathway components tested","pmids":["29309586"],"is_preprint":false},{"year":2016,"finding":"Human CIAO1 physically interacts with POLE1 (the catalytic subunit of DNA polymerase ε) as a CIA complex component, facilitating Fe-S cluster acquisition by POLE1. The interaction between POLE1 and CIAO1 does not require POLE1 serine-1940 (in contrast to MMS19, which does require S1940 phosphorylation).","method":"Co-immunoprecipitation, mutagenesis of POLE1 S1940","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP interaction validated with phosphorylation-site mutant, single lab, two methods","pmids":["27235625"],"is_preprint":false},{"year":2024,"finding":"Patients with biallelic loss-of-function CIAO1 variants develop a neuromuscular disorder; functional assays showed that disease-associated CIAO1 variants fail to recruit Fe-S recipient proteins to the CIA complex, resulting in compromised activities of CIA-dependent DNA helicases, polymerases, and repair enzymes. Lentivirus-mediated restoration of CIAO1 expression reversed all patient-derived cellular abnormalities, establishing CIAO1 as essential for CIA targeting complex function in vivo.","method":"Mutational stability analysis, functional recruitment assays, enzymatic activity assays, lentiviral rescue in patient-derived cells","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal functional assays, lentiviral rescue as causal validation, patient variants characterized alongside WT controls","pmids":["38950322"],"is_preprint":false},{"year":2024,"finding":"Loss of CIAO1 in patient-derived fibroblasts caused profound alterations in proteome, metabolome, and lipidome, consistent with general failure of cytosolic and nuclear iron-sulfur protein maturation. Zebrafish ciao1-deficiency models confirmed the detrimental effects, implicating CIAO1 in antiviral host defense through Fe-S protein maturation.","method":"Genome sequencing, proteomics/metabolomics/lipidomics of patient fibroblasts, zebrafish loss-of-function models","journal":"Genetics in medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multi-omic functional characterization plus orthologous animal model, single study","pmids":["38411040"],"is_preprint":false},{"year":2020,"finding":"In Drosophila, Ciao1 physically interacts with Crumbs intracellular domain (Crbintra), Galla, and Xpd (DNA helicase/CIA target). Loss of Ciao1 reduces Cyclin E and Diap1 levels in imaginal discs and increases apoptotic cell death. Genetic epistasis placed Ciao1 and Xpd in the same growth-regulatory pathway; CycE overexpression rescued Ciao1 RNAi phenotypes, and reduced CycE in Ciao1 mutants was shown to be secondary to loss of Diap1.","method":"Co-immunoprecipitation, RNAi knockdown, clonal analysis in imaginal discs, epistasis rescue experiments, CycE/Diap1 overexpression","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal genetic and physical interaction data with functional epistasis, single lab","pmids":["32404863"],"is_preprint":false},{"year":2025,"finding":"The TCR (targeting complex recognition) peptide found in up to 25% of CIA client proteins docks at the conserved interface between Cia1 and Cia2 subunits of the CIA targeting complex, even in the absence of the Fe-S cluster. The same Cia1-Cia2 interface also mediates binding of apo-Nar1 (proposed Fe-S carrier). Mutations disrupting this interface, including the disease-linked R65W Cia1 variant, impair TCR-dependent client recruitment. In vitro evidence supports Nar1's role as a cluster trafficking protein in the CIA pathway.","method":"Computational docking, biochemical interaction assays, mutagenesis of Cia1-Cia2 interface, in vitro TCR peptide binding assays","journal":"Journal of the American Chemical Society","confidence":"High","confidence_rationale":"Tier 1 / Moderate — integrated computational and biochemical reconstitution with mutagenesis including a disease variant, multiple orthogonal approaches in a single focused study","pmids":["40924805"],"is_preprint":false},{"year":2025,"finding":"The Cia1-Cia2 interface mediates recognition of apo-Fe-S client proteins bearing a C-terminal TCR motif; mutations destabilizing this interface disrupt TCR-based client identification. Human CIAO2A (Cia2a paralog) in complex with CIAO1 can also recruit TCR-motif-bearing clients, suggesting a broader role for CIAO2A in Fe-S protein maturation beyond IRP1.","method":"Computational, biochemical, and biophysical approaches; in vitro TCR peptide binding; mutagenesis","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — preprint with reconstitution and mutagenesis but not yet peer reviewed; largely overlapping findings with PMID 40924805","pmids":["40196589"],"is_preprint":true},{"year":2021,"finding":"A heterozygous CIAO1 variant (Val67Ile) increases the physical interaction of CIAO1 protein with immature (but not mature or soluble) amyloid-β protein precursor (AβPP), suggesting CIAO1 involvement in AβPP processing.","method":"Biochemical interaction assay (co-immunoprecipitation/pull-down) comparing WT and Val67Ile CIAO1 with AβPP forms","journal":"Journal of Alzheimer's disease","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP experiment, single lab, no mechanistic follow-up beyond the interaction","pmids":["34569959"],"is_preprint":false}],"current_model":"CIAO1 is an essential WD40 beta-propeller protein that functions as a core subunit of the cytosolic iron-sulfur cluster assembly (CIA) targeting complex together with MMS19 and FAM96B/CIA2B; it acts in a late step of the CIA pathway—after the scaffold proteins Nbp35 and Nar1—by recruiting apo-Fe-S client proteins via a conserved Cia1-Cia2 interface that recognizes a C-terminal TCR motif on substrates, thereby facilitating Fe-S cluster insertion into >30 cytoplasmic and nuclear targets including DNA helicases, polymerases, and repair enzymes essential for genome maintenance, and disease-linked mutations that disrupt this interface impair client recruitment and cause a human neuromuscular and neurodegenerative disorder."},"narrative":{"mechanistic_narrative":"CIAO1 is an essential WD40 β-propeller protein that acts in a late step of the cytosolic iron-sulfur cluster assembly (CIA) pathway, functioning downstream of the scaffold proteins Nbp35 and Nar1 to deliver Fe-S clusters specifically to cytosolic and nuclear, but not mitochondrial, target proteins [PMID:16314508]. Its seven-bladed WD40 fold presents a conserved top surface required for cytosolic Fe-S protein biogenesis, and the protein is functionally conserved between yeast and humans [PMID:17937914]. As a subunit of the CIA targeting complex together with FAM96B and MMS19, CIAO1 recruits apo-Fe-S client proteins—including DNA polymerase ε catalytic subunit POLE1 and DNA helicases—and the Cia1-Cia2 interface recognizes a C-terminal TCR motif present in a large fraction of CIA clients, an interaction that occurs even without the Fe-S cluster and that also engages the carrier protein Nar1 [PMID:27235625, PMID:40924805]. The de novo cytosolic Fe-S biosynthesis machinery (ISCU1/NFS1) is bridged to this targeting complex via cytosolic HSC20, integrating cluster synthesis with delivery [PMID:29309586], and the holo CIA2A-CIAO1 complex coordinates a [4Fe-4S] cluster that it transfers to apo-IRP1/cytosolic aconitase [PMID:29842905]. Biallelic loss-of-function CIAO1 variants cause a human neuromuscular disorder: disease-associated variants fail to recruit Fe-S recipient proteins and compromise the activities of CIA-dependent helicases, polymerases, and repair enzymes, with lentiviral restoration reversing patient cellular defects [PMID:38950322].","teleology":[{"year":2005,"claim":"Established where CIAO1's ortholog acts within the iron-sulfur assembly machinery, distinguishing it from earlier scaffold steps and from mitochondrial Fe-S biogenesis.","evidence":"Genetic epistasis, conditional depletion, and reciprocal Co-IP in yeast","pmids":["16314508"],"confidence":"High","gaps":["Did not resolve the structural basis of client or partner recognition","Mechanism of cluster handoff from Nar1 to clients unaddressed"]},{"year":2007,"claim":"Defined the molecular architecture as a seven-bladed WD40 β-propeller and identified a functionally critical top-surface residue, while demonstrating yeast-to-human functional conservation.","evidence":"1.7 Å X-ray crystallography, site-directed mutagenesis, and cross-species complementation","pmids":["17937914"],"confidence":"High","gaps":["Did not identify which surface engages clients versus partner subunits","No structure of CIAO1 within an assembled targeting complex"]},{"year":2016,"claim":"Showed CIAO1 directly engages a specific client, POLE1, and that this engagement uses a recognition mode distinct from MMS19's phosphorylation-dependent binding.","evidence":"Co-IP and POLE1 S1940 phosphosite mutagenesis in human cells","pmids":["27235625"],"confidence":"Medium","gaps":["Did not map the CIAO1 surface contacting POLE1","Generality of phosphorylation-independent recruitment across clients untested"]},{"year":2018,"claim":"Demonstrated that CIAO1-containing subcomplexes can bind and transfer an actual [4Fe-4S] cluster to a physiological recipient, providing biochemical proof of cluster-delivery activity.","evidence":"NMR, UV-vis, EPR spectroscopy and in vitro cluster transfer to apo-IRP1 with the CIA2A-CIAO1 trimer","pmids":["29842905"],"confidence":"High","gaps":["Cysteine ligand contributed by CIAO1 itself not defined","Did not address transfer to nuclear genome-maintenance clients"]},{"year":2018,"claim":"Connected upstream de novo Fe-S biosynthesis to the CIA targeting complex, explaining how synthesized clusters reach CIAO1-dependent delivery.","evidence":"Co-IP, interaction mapping, and Fe-S delivery assays in human cells","pmids":["29309586"],"confidence":"Medium","gaps":["Single-lab interaction data without orthogonal structural confirmation","Stoichiometry and dynamics of the bridged assembly unresolved"]},{"year":2020,"claim":"Placed CIAO1 within a cell-growth and survival circuit in an animal model, linking its Fe-S target Xpd to CyclinE/Diap1-dependent control of apoptosis.","evidence":"Co-IP, RNAi, clonal imaginal-disc analysis, and epistasis/rescue in Drosophila","pmids":["32404863"],"confidence":"Medium","gaps":["Whether growth effects are wholly attributable to Fe-S client maturation not fully isolated","Relevance of Crumbs-domain interaction to CIA function unclear"]},{"year":2024,"claim":"Established CIAO1 as the cause of a human disease and linked the molecular defect (failed client recruitment) to functional loss of genome-maintenance Fe-S enzymes, with causal rescue.","evidence":"Patient variant characterization, recruitment and enzymatic activity assays, and lentiviral rescue in patient-derived cells","pmids":["38950322"],"confidence":"High","gaps":["Genotype-phenotype relationships across variants not delineated","Tissue-specific vulnerability of neuromuscular system not mechanistically explained"]},{"year":2024,"claim":"Mapped the system-wide cellular consequences of CIAO1 loss and extended its role to antiviral host defense via Fe-S protein maturation.","evidence":"Genome sequencing, multi-omics of patient fibroblasts, and zebrafish loss-of-function models","pmids":["38411040"],"confidence":"Medium","gaps":["Specific Fe-S clients driving the antiviral phenotype not identified","Causality from omic correlations to individual client failures incomplete"]},{"year":2025,"claim":"Resolved the molecular logic of client selection, showing a TCR peptide docks at the Cia1-Cia2 interface independent of the cluster, and that the disease-linked R65W variant disrupts this recruitment.","evidence":"Computational docking, biochemical TCR peptide-binding and interface mutagenesis including a disease variant","pmids":["40924805"],"confidence":"High","gaps":["High-resolution experimental structure of the docked complex not reported","Determinants of TCR-motif specificity across the >30 clients not exhaustively defined"]},{"year":2025,"claim":"Extended the TCR-interface recognition model to the CIAO2A-CIAO1 complex, indicating CIAO2A participates in maturing TCR-bearing clients beyond IRP1.","evidence":"Computational, biochemical, and biophysical TCR peptide binding and mutagenesis (preprint)","pmids":["40196589"],"confidence":"Medium","gaps":["Preprint, not yet peer reviewed and largely overlapping with the JACS study","Physiological client repertoire of CIAO2A-CIAO1 versus FAM96B-CIAO1 untested"]},{"year":null,"claim":"How CIAO1 coordinates timed cluster handoff from Nar1 to specific apo-clients, and what determines tissue-specific disease vulnerability, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No experimental structure of an intact CIAO1-bound targeting complex with a client","Order and kinetics of cluster transfer versus client docking undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,4]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,8]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[4,7]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,2]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[5]}],"complexes":["CIA targeting complex (CIAO1-MMS19-FAM96B)","CIA2A-CIAO1 complex"],"partners":["MMS19","FAM96B","CIA2A","NAR1","POLE1","HSC20","XPD","ISCU1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O76071","full_name":"Probable cytosolic iron-sulfur protein assembly protein CIAO1","aliases":["WD repeat-containing protein 39"],"length_aa":339,"mass_kda":37.8,"function":"Key component of the cytosolic iron-sulfur protein assembly (CIA) complex, a multiprotein complex that mediates the incorporation of iron-sulfur cluster into extramitochondrial Fe/S proteins (PubMed:17937914, PubMed:23891004, PubMed:38950322). As a CIA complex component, interacts specifically with CIAO2A or CIAO2B and MMS19 to assist different branches of iron-sulfur protein assembly, depending of its interactors. The complex CIAO1:CIAO2B:MMS19 binds to and facilitates the assembly of most cytosolic-nuclear Fe/S proteins. CIAO1:CIAO2A specifically matures ACO1 and stabilizes IREB2 (PubMed:23891004). Seems to specifically modulate the transactivation activity of WT1 (PubMed:9556563). As part of the mitotic spindle-associated MMXD complex it may play a role in chromosome segregation (PubMed:20797633)","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/O76071/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/CIAO1","classification":"Common Essential","n_dependent_lines":1179,"n_total_lines":1208,"dependency_fraction":0.9759933774834437},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CIAO1","total_profiled":1310},"omim":[{"mim_id":"620960","title":"MULTIPLE MITOCHONDRIAL DYSFUNCTIONS SYNDROME 10; MMDS10","url":"https://www.omim.org/entry/620960"},{"mim_id":"618382","title":"CYTOSOLIC IRON-SULFUR ASSEMBLY COMPONENT 2A; CIAO2A","url":"https://www.omim.org/entry/618382"},{"mim_id":"614778","title":"CYTOSOLIC IRON-SULFUR ASSEMBLY COMPONENT 2B; CIAO2B","url":"https://www.omim.org/entry/614778"},{"mim_id":"614777","title":"MMS19 HOMOLOG, CYTOSOLIC IRON-SULFUR ASSEMBLY COMPONENT; MMS19","url":"https://www.omim.org/entry/614777"},{"mim_id":"604333","title":"WD40 REPEAT-CONTAINING PROTEIN CIAO1; CIAO1","url":"https://www.omim.org/entry/604333"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CIAO1"},"hgnc":{"alias_symbol":["CIA1"],"prev_symbol":["WDR39"]},"alphafold":{"accession":"O76071","domains":[{"cath_id":"2.130.10.10","chopping":"4-332","consensus_level":"medium","plddt":97.35,"start":4,"end":332}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O76071","model_url":"https://alphafold.ebi.ac.uk/files/AF-O76071-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O76071-F1-predicted_aligned_error_v6.png","plddt_mean":96.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CIAO1","jax_strain_url":"https://www.jax.org/strain/search?query=CIAO1"},"sequence":{"accession":"O76071","fasta_url":"https://rest.uniprot.org/uniprotkb/O76071.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O76071/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O76071"}},"corpus_meta":[{"pmid":"16314508","id":"PMC_16314508","title":"The essential WD40 protein Cia1 is involved in a late step of cytosolic and nuclear iron-sulfur protein assembly.","date":"2005","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/16314508","citation_count":114,"is_preprint":false},{"pmid":"11737265","id":"PMC_11737265","title":"Cell death with predominant apoptotic features in Saccharomyces cerevisiae mediated by deletion of the histone chaperone ASF1/CIA1.","date":"2001","source":"Genes to cells : devoted to molecular & cellular mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/11737265","citation_count":82,"is_preprint":false},{"pmid":"17937914","id":"PMC_17937914","title":"Structure of the yeast WD40 domain protein Cia1, a component acting late in iron-sulfur protein biogenesis.","date":"2007","source":"Structure (London, England : 1993)","url":"https://pubmed.ncbi.nlm.nih.gov/17937914","citation_count":63,"is_preprint":false},{"pmid":"11856374","id":"PMC_11856374","title":"Polyanionic stretch-deleted histone chaperone cia1/Asf1p is functional both in vivo and in vitro.","date":"2002","source":"Genes to cells : devoted to molecular & cellular mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/11856374","citation_count":57,"is_preprint":false},{"pmid":"29309586","id":"PMC_29309586","title":"Cytosolic HSC20 integrates de novo iron-sulfur cluster biogenesis with the CIAO1-mediated transfer to recipients.","date":"2018","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29309586","citation_count":39,"is_preprint":false},{"pmid":"8363513","id":"PMC_8363513","title":"Depletion of CD4+ and CD8+ T lymphocyte subpopulations by CIA-1, a chicken infectious anemia virus.","date":"1993","source":"Avian diseases","url":"https://pubmed.ncbi.nlm.nih.gov/8363513","citation_count":27,"is_preprint":false},{"pmid":"22083470","id":"PMC_22083470","title":"Characterization of CIA-1, an Ambler class A extended-spectrum β-lactamase from Chryseobacterium indologenes.","date":"2011","source":"Antimicrobial agents and chemotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/22083470","citation_count":23,"is_preprint":false},{"pmid":"29842905","id":"PMC_29842905","title":"Investigating the role of the human CIA2A-CIAO1 complex in the maturation of aconitase.","date":"2018","source":"Biochimica et biophysica acta. General subjects","url":"https://pubmed.ncbi.nlm.nih.gov/29842905","citation_count":18,"is_preprint":false},{"pmid":"38950322","id":"PMC_38950322","title":"CIAO1 loss of function causes a neuromuscular disorder with compromise of nucleocytoplasmic Fe-S enzymes.","date":"2024","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/38950322","citation_count":13,"is_preprint":false},{"pmid":"38411040","id":"PMC_38411040","title":"CIAO1 and MMS19 deficiency: A lethal neurodegenerative phenotype caused by cytosolic Fe-S cluster protein assembly disorders.","date":"2024","source":"Genetics in medicine : official journal of the American College of Medical Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38411040","citation_count":9,"is_preprint":false},{"pmid":"17673937","id":"PMC_17673937","title":"Genetic regulation of T regulatory, CD4, and CD8 cell numbers by the arthritis severity loci Cia5a, Cia5d, and the MHC/Cia1 in the rat.","date":"2007","source":"Molecular medicine (Cambridge, Mass.)","url":"https://pubmed.ncbi.nlm.nih.gov/17673937","citation_count":8,"is_preprint":false},{"pmid":"32404863","id":"PMC_32404863","title":"Ciao1 interacts with Crumbs and Xpd to regulate organ growth in Drosophila.","date":"2020","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/32404863","citation_count":5,"is_preprint":false},{"pmid":"27235625","id":"PMC_27235625","title":"Human DNA polymerase ε is phosphorylated at serine-1940 after DNA damage and interacts with the iron-sulfur complex chaperones CIAO1 and MMS19.","date":"2016","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/27235625","citation_count":5,"is_preprint":false},{"pmid":"40924805","id":"PMC_40924805","title":"A Conserved Cia1-Cia2 Interface Mediates Client Recruitment in the Cytosolic Iron-Sulfur Cluster Assembly Pathway.","date":"2025","source":"Journal of the American Chemical Society","url":"https://pubmed.ncbi.nlm.nih.gov/40924805","citation_count":4,"is_preprint":false},{"pmid":"34569959","id":"PMC_34569959","title":"A Novel Heterozygous Missense Variant in the CIAO1 Gene in a Family with Alzheimer's Disease: The Val67Ile Variant Promotes the Interaction of CIAO1 and Amyloid-β Protein Precursor.","date":"2021","source":"Journal of Alzheimer's disease : JAD","url":"https://pubmed.ncbi.nlm.nih.gov/34569959","citation_count":2,"is_preprint":false},{"pmid":"38196629","id":"PMC_38196629","title":"Loss of Function of the Cytoplasmic Fe-S Assembly Protein CIAO1 Causes a Neuromuscular Disorder with Compromise of Nucleocytoplasmic Fe-S Enzymes.","date":"2023","source":"medRxiv : the preprint server for health sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38196629","citation_count":2,"is_preprint":false},{"pmid":"16511210","id":"PMC_16511210","title":"Purification, crystallization and preliminary X-ray diffraction analysis of the histone chaperone cia1 from fission yeast.","date":"2005","source":"Acta crystallographica. Section F, Structural biology and crystallization communications","url":"https://pubmed.ncbi.nlm.nih.gov/16511210","citation_count":2,"is_preprint":false},{"pmid":"40697348","id":"PMC_40697348","title":"CIAO1 as a crucial signature gene of cuproptosis in gastric cancer.","date":"2025","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/40697348","citation_count":1,"is_preprint":false},{"pmid":"40196589","id":"PMC_40196589","title":"The Cia1 and Cia2 subunits of the CTC mediate recognition of apo-FeS proteins with a C-terminal targeting complex recognition motif.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/40196589","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.12.30.24317177","title":"Clear Cell Renal Cell Carcinoma: Unveiling Age-Linked Genetic Signatures, Relative Disease Aggressiveness, and Predictive Impact on Systemic Therapy","date":"2024-12-31","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.30.24317177","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12065,"output_tokens":2987,"usd":0.0405,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10451,"output_tokens":3394,"usd":0.068553,"stage2_stop_reason":"end_turn"},"total_usd":0.109053,"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\": 2005,\n      \"finding\": \"Yeast Cia1 (ortholog of human CIAO1) is an essential WD40 repeat protein required for Fe/S cluster assembly on cytosolic and nuclear, but not mitochondrial, Fe/S proteins. Genetic epistasis showed that Nbp35 and Nar1 can assemble their own Fe/S clusters in the absence of Cia1, placing Cia1 in a late step of the CIA pathway, after Nbp35 and Nar1. Co-immunoprecipitation demonstrated a specific physical interaction between Cia1 and Nar1.\",\n      \"method\": \"Genetic epistasis (conditional depletion), coimmunoprecipitation, in vivo Fe/S assembly assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, genetic epistasis with multiple Fe/S substrates, replicated across several experimental conditions in a focused study\",\n      \"pmids\": [\"16314508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Crystal structure of yeast Cia1 (ortholog of human CIAO1) resolved to 1.7 Å reveals a seven-bladed beta-propeller WD40 fold. Site-directed mutagenesis identified conserved top-surface residue R127 as functionally critical; R127 mutant cells grew slowly and were impaired in cytosolic Fe/S protein assembly. Human CIAO1 was shown to functionally replace yeast Cia1 and support cytosolic Fe/S protein biogenesis, confirming structural and functional conservation.\",\n      \"method\": \"X-ray crystallography (1.7 Å), site-directed mutagenesis, in vivo complementation assay\",\n      \"journal\": \"Structure\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus mutagenesis plus functional complementation in a single rigorous study\",\n      \"pmids\": [\"17937914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The human CIA2A-CIAO1 heterotrimeric complex (two CIA2A molecules + one CIAO1) binds one [4Fe-4S] cluster, with Cys90 of CIA2A serving as a cluster ligand. The holo trimeric complex can transfer the [4Fe-4S] cluster to apo-IRP1 (cytosolic aconitase) to generate the active form of aconitase.\",\n      \"method\": \"NMR spectroscopy, UV-vis absorption, EPR spectroscopy, in vitro Fe/S cluster transfer assay\",\n      \"journal\": \"Biochimica et biophysica acta. General subjects\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple orthogonal biophysical methods (NMR, UV-vis, EPR) plus functional reconstitution of cluster transfer in a single study\",\n      \"pmids\": [\"29842905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Cytosolic HSC20 (C-HSC20) mediates complex formation between components of the cytosolic Fe-S biogenesis pathway (primary scaffold ISCU1 and cysteine desulfurase NFS1) and the CIA targeting complex (CIAO1, FAM96B, MMS19), thereby integrating de novo Fe-S biosynthesis with the CIA-mediated transfer of Fe-S clusters to cytoplasmic and nuclear recipient proteins.\",\n      \"method\": \"Co-immunoprecipitation, interaction mapping, functional Fe-S cluster delivery assays in human cells\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP interactions plus functional assays in a single lab, multiple pathway components tested\",\n      \"pmids\": [\"29309586\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Human CIAO1 physically interacts with POLE1 (the catalytic subunit of DNA polymerase ε) as a CIA complex component, facilitating Fe-S cluster acquisition by POLE1. The interaction between POLE1 and CIAO1 does not require POLE1 serine-1940 (in contrast to MMS19, which does require S1940 phosphorylation).\",\n      \"method\": \"Co-immunoprecipitation, mutagenesis of POLE1 S1940\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP interaction validated with phosphorylation-site mutant, single lab, two methods\",\n      \"pmids\": [\"27235625\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Patients with biallelic loss-of-function CIAO1 variants develop a neuromuscular disorder; functional assays showed that disease-associated CIAO1 variants fail to recruit Fe-S recipient proteins to the CIA complex, resulting in compromised activities of CIA-dependent DNA helicases, polymerases, and repair enzymes. Lentivirus-mediated restoration of CIAO1 expression reversed all patient-derived cellular abnormalities, establishing CIAO1 as essential for CIA targeting complex function in vivo.\",\n      \"method\": \"Mutational stability analysis, functional recruitment assays, enzymatic activity assays, lentiviral rescue in patient-derived cells\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal functional assays, lentiviral rescue as causal validation, patient variants characterized alongside WT controls\",\n      \"pmids\": [\"38950322\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Loss of CIAO1 in patient-derived fibroblasts caused profound alterations in proteome, metabolome, and lipidome, consistent with general failure of cytosolic and nuclear iron-sulfur protein maturation. Zebrafish ciao1-deficiency models confirmed the detrimental effects, implicating CIAO1 in antiviral host defense through Fe-S protein maturation.\",\n      \"method\": \"Genome sequencing, proteomics/metabolomics/lipidomics of patient fibroblasts, zebrafish loss-of-function models\",\n      \"journal\": \"Genetics in medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multi-omic functional characterization plus orthologous animal model, single study\",\n      \"pmids\": [\"38411040\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In Drosophila, Ciao1 physically interacts with Crumbs intracellular domain (Crbintra), Galla, and Xpd (DNA helicase/CIA target). Loss of Ciao1 reduces Cyclin E and Diap1 levels in imaginal discs and increases apoptotic cell death. Genetic epistasis placed Ciao1 and Xpd in the same growth-regulatory pathway; CycE overexpression rescued Ciao1 RNAi phenotypes, and reduced CycE in Ciao1 mutants was shown to be secondary to loss of Diap1.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, clonal analysis in imaginal discs, epistasis rescue experiments, CycE/Diap1 overexpression\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal genetic and physical interaction data with functional epistasis, single lab\",\n      \"pmids\": [\"32404863\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The TCR (targeting complex recognition) peptide found in up to 25% of CIA client proteins docks at the conserved interface between Cia1 and Cia2 subunits of the CIA targeting complex, even in the absence of the Fe-S cluster. The same Cia1-Cia2 interface also mediates binding of apo-Nar1 (proposed Fe-S carrier). Mutations disrupting this interface, including the disease-linked R65W Cia1 variant, impair TCR-dependent client recruitment. In vitro evidence supports Nar1's role as a cluster trafficking protein in the CIA pathway.\",\n      \"method\": \"Computational docking, biochemical interaction assays, mutagenesis of Cia1-Cia2 interface, in vitro TCR peptide binding assays\",\n      \"journal\": \"Journal of the American Chemical Society\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — integrated computational and biochemical reconstitution with mutagenesis including a disease variant, multiple orthogonal approaches in a single focused study\",\n      \"pmids\": [\"40924805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The Cia1-Cia2 interface mediates recognition of apo-Fe-S client proteins bearing a C-terminal TCR motif; mutations destabilizing this interface disrupt TCR-based client identification. Human CIAO2A (Cia2a paralog) in complex with CIAO1 can also recruit TCR-motif-bearing clients, suggesting a broader role for CIAO2A in Fe-S protein maturation beyond IRP1.\",\n      \"method\": \"Computational, biochemical, and biophysical approaches; in vitro TCR peptide binding; mutagenesis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — preprint with reconstitution and mutagenesis but not yet peer reviewed; largely overlapping findings with PMID 40924805\",\n      \"pmids\": [\"40196589\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"A heterozygous CIAO1 variant (Val67Ile) increases the physical interaction of CIAO1 protein with immature (but not mature or soluble) amyloid-β protein precursor (AβPP), suggesting CIAO1 involvement in AβPP processing.\",\n      \"method\": \"Biochemical interaction assay (co-immunoprecipitation/pull-down) comparing WT and Val67Ile CIAO1 with AβPP forms\",\n      \"journal\": \"Journal of Alzheimer's disease\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP experiment, single lab, no mechanistic follow-up beyond the interaction\",\n      \"pmids\": [\"34569959\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CIAO1 is an essential WD40 beta-propeller protein that functions as a core subunit of the cytosolic iron-sulfur cluster assembly (CIA) targeting complex together with MMS19 and FAM96B/CIA2B; it acts in a late step of the CIA pathway—after the scaffold proteins Nbp35 and Nar1—by recruiting apo-Fe-S client proteins via a conserved Cia1-Cia2 interface that recognizes a C-terminal TCR motif on substrates, thereby facilitating Fe-S cluster insertion into >30 cytoplasmic and nuclear targets including DNA helicases, polymerases, and repair enzymes essential for genome maintenance, and disease-linked mutations that disrupt this interface impair client recruitment and cause a human neuromuscular and neurodegenerative disorder.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CIAO1 is an essential WD40 β-propeller protein that acts in a late step of the cytosolic iron-sulfur cluster assembly (CIA) pathway, functioning downstream of the scaffold proteins Nbp35 and Nar1 to deliver Fe-S clusters specifically to cytosolic and nuclear, but not mitochondrial, target proteins [#0]. Its seven-bladed WD40 fold presents a conserved top surface required for cytosolic Fe-S protein biogenesis, and the protein is functionally conserved between yeast and humans [#1]. As a subunit of the CIA targeting complex together with FAM96B and MMS19, CIAO1 recruits apo-Fe-S client proteins—including DNA polymerase ε catalytic subunit POLE1 and DNA helicases—and the Cia1-Cia2 interface recognizes a C-terminal TCR motif present in a large fraction of CIA clients, an interaction that occurs even without the Fe-S cluster and that also engages the carrier protein Nar1 [#4, #8]. The de novo cytosolic Fe-S biosynthesis machinery (ISCU1/NFS1) is bridged to this targeting complex via cytosolic HSC20, integrating cluster synthesis with delivery [#3], and the holo CIA2A-CIAO1 complex coordinates a [4Fe-4S] cluster that it transfers to apo-IRP1/cytosolic aconitase [#2]. Biallelic loss-of-function CIAO1 variants cause a human neuromuscular disorder: disease-associated variants fail to recruit Fe-S recipient proteins and compromise the activities of CIA-dependent helicases, polymerases, and repair enzymes, with lentiviral restoration reversing patient cellular defects [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Established where CIAO1's ortholog acts within the iron-sulfur assembly machinery, distinguishing it from earlier scaffold steps and from mitochondrial Fe-S biogenesis.\",\n      \"evidence\": \"Genetic epistasis, conditional depletion, and reciprocal Co-IP in yeast\",\n      \"pmids\": [\"16314508\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the structural basis of client or partner recognition\", \"Mechanism of cluster handoff from Nar1 to clients unaddressed\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined the molecular architecture as a seven-bladed WD40 β-propeller and identified a functionally critical top-surface residue, while demonstrating yeast-to-human functional conservation.\",\n      \"evidence\": \"1.7 Å X-ray crystallography, site-directed mutagenesis, and cross-species complementation\",\n      \"pmids\": [\"17937914\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify which surface engages clients versus partner subunits\", \"No structure of CIAO1 within an assembled targeting complex\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed CIAO1 directly engages a specific client, POLE1, and that this engagement uses a recognition mode distinct from MMS19's phosphorylation-dependent binding.\",\n      \"evidence\": \"Co-IP and POLE1 S1940 phosphosite mutagenesis in human cells\",\n      \"pmids\": [\"27235625\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not map the CIAO1 surface contacting POLE1\", \"Generality of phosphorylation-independent recruitment across clients untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrated that CIAO1-containing subcomplexes can bind and transfer an actual [4Fe-4S] cluster to a physiological recipient, providing biochemical proof of cluster-delivery activity.\",\n      \"evidence\": \"NMR, UV-vis, EPR spectroscopy and in vitro cluster transfer to apo-IRP1 with the CIA2A-CIAO1 trimer\",\n      \"pmids\": [\"29842905\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cysteine ligand contributed by CIAO1 itself not defined\", \"Did not address transfer to nuclear genome-maintenance clients\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected upstream de novo Fe-S biosynthesis to the CIA targeting complex, explaining how synthesized clusters reach CIAO1-dependent delivery.\",\n      \"evidence\": \"Co-IP, interaction mapping, and Fe-S delivery assays in human cells\",\n      \"pmids\": [\"29309586\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab interaction data without orthogonal structural confirmation\", \"Stoichiometry and dynamics of the bridged assembly unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Placed CIAO1 within a cell-growth and survival circuit in an animal model, linking its Fe-S target Xpd to CyclinE/Diap1-dependent control of apoptosis.\",\n      \"evidence\": \"Co-IP, RNAi, clonal imaginal-disc analysis, and epistasis/rescue in Drosophila\",\n      \"pmids\": [\"32404863\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether growth effects are wholly attributable to Fe-S client maturation not fully isolated\", \"Relevance of Crumbs-domain interaction to CIA function unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established CIAO1 as the cause of a human disease and linked the molecular defect (failed client recruitment) to functional loss of genome-maintenance Fe-S enzymes, with causal rescue.\",\n      \"evidence\": \"Patient variant characterization, recruitment and enzymatic activity assays, and lentiviral rescue in patient-derived cells\",\n      \"pmids\": [\"38950322\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Genotype-phenotype relationships across variants not delineated\", \"Tissue-specific vulnerability of neuromuscular system not mechanistically explained\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Mapped the system-wide cellular consequences of CIAO1 loss and extended its role to antiviral host defense via Fe-S protein maturation.\",\n      \"evidence\": \"Genome sequencing, multi-omics of patient fibroblasts, and zebrafish loss-of-function models\",\n      \"pmids\": [\"38411040\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific Fe-S clients driving the antiviral phenotype not identified\", \"Causality from omic correlations to individual client failures incomplete\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Resolved the molecular logic of client selection, showing a TCR peptide docks at the Cia1-Cia2 interface independent of the cluster, and that the disease-linked R65W variant disrupts this recruitment.\",\n      \"evidence\": \"Computational docking, biochemical TCR peptide-binding and interface mutagenesis including a disease variant\",\n      \"pmids\": [\"40924805\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"High-resolution experimental structure of the docked complex not reported\", \"Determinants of TCR-motif specificity across the >30 clients not exhaustively defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended the TCR-interface recognition model to the CIAO2A-CIAO1 complex, indicating CIAO2A participates in maturing TCR-bearing clients beyond IRP1.\",\n      \"evidence\": \"Computational, biochemical, and biophysical TCR peptide binding and mutagenesis (preprint)\",\n      \"pmids\": [\"40196589\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer reviewed and largely overlapping with the JACS study\", \"Physiological client repertoire of CIAO2A-CIAO1 versus FAM96B-CIAO1 untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CIAO1 coordinates timed cluster handoff from Nar1 to specific apo-clients, and what determines tissue-specific disease vulnerability, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No experimental structure of an intact CIAO1-bound targeting complex with a client\", \"Order and kinetics of cluster transfer versus client docking undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 4]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 8]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [4, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [\"CIA targeting complex (CIAO1-MMS19-FAM96B)\", \"CIA2A-CIAO1 complex\"],\n    \"partners\": [\"MMS19\", \"FAM96B\", \"CIA2A\", \"NAR1\", \"POLE1\", \"HSC20\", \"XPD\", \"ISCU1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}