{"gene":"ZXDC","run_date":"2026-06-11T09:02:07","timeline":{"discoveries":[{"year":2006,"finding":"ZXDC (zinc finger X-linked duplicated family member C) was identified as a novel CIITA-binding protein via yeast two-hybrid screening. The 858-amino acid ZXDC protein contains 10 zinc fingers and a transcriptional activation domain, and binds the leucine-rich repeat region of CIITA. Overexpression of ZXDC in human cell lines caused super-activation of MHC class I and class II promoters by CIITA, while siRNA knockdown of ZXDC reduced CIITA-mediated MHC class II transcriptional activation.","method":"Yeast two-hybrid, co-immunoprecipitation, overexpression and siRNA knockdown in human cell lines with MHC promoter reporter assays","journal":"Molecular immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal protein interaction assay (Y2H + Co-IP), functional overexpression and loss-of-function in human cells with defined transcriptional readout, two orthogonal methods in a single focused study","pmids":["16600381"],"is_preprint":false},{"year":2007,"finding":"ZXDA and ZXDC can self-associate and also heterodimerize with each other through their zinc finger-containing regions. The ZXDA-ZXDC complex, rather than either protein alone, interacts with CIITA. Knockdown and overexpression of ZXDA demonstrated its importance in MHC II transcriptional activation. ChIP showed ZXDC is present at MHC II promoters in HeLa cells both before and after IFN-γ treatment.","method":"Co-immunoprecipitation, knockdown/overexpression reporter assays, chromatin immunoprecipitation (ChIP)","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP for complex formation, ChIP for promoter occupancy, functional knockdown/OE with defined transcriptional phenotype; multiple orthogonal methods in one focused study","pmids":["17493635"],"is_preprint":false},{"year":2007,"finding":"ZXDC is sumoylated at a single lysine residue within its transcriptional activation domain. All three SUMO proteins (SUMO-1, -2, and -3) can modify ZXDC. Multiple SUMO E3 ligase enzymes and HDAC4 can facilitate this modification; the E3 ligase PIASy interacts with a specific region of ZXDC. Sumoylation does not disrupt ZXDC interactions with its binding partners (ZXDA, CIITA), but is required for full activity of the ZXDC transcriptional activation domain.","method":"Western blot (two-species detection), co-immunoprecipitation with SUMO proteins and E3 ligases, mutagenesis of sumoylation site, transcriptional reporter assays","journal":"Biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — site-specific mutagenesis combined with Co-IP and functional reporter assays; multiple SUMO isoforms and E3 ligases tested; single lab but multiple orthogonal methods","pmids":["17696781"],"is_preprint":false},{"year":2009,"finding":"An alternatively spliced isoform of ZXDC, named ZXDC2, is produced from a transcript that initiates in the first exon and terminates within the seventh intron, yielding a protein truncated at both N- and C-termini. ZXDC2 represses IFN-γ-induced MHC class II transcription in HeLa cells, and interacts with both ZXDA and full-length ZXDC, suggesting a dominant-negative mechanism of MHC II transcriptional repression.","method":"Molecular cloning of isoform, transfection/overexpression in HeLa cells with IFN-γ treatment and MHC II reporter assays, co-immunoprecipitation","journal":"Molecular and cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional reporter assay and Co-IP for isoform; single lab, limited validation of the mechanism","pmids":["19777325"],"is_preprint":false},{"year":2023,"finding":"ZXDC promotes cervical cancer cell metastasis by activating the RhoA/ROCK signaling pathway, leading to enhanced cytoskeleton remodeling. IGF2BP3 plays an essential role in this pathway by stabilizing RhoA mRNA downstream of ZXDC. Overexpression of ZXDC promotes metastasis both in vitro and in vivo, while silencing ZXDC inhibits it.","method":"Overexpression and siRNA knockdown in cervical cancer cell lines, in vitro migration/invasion assays, in vivo metastasis models, RhoA/ROCK pathway readouts, IGF2BP3 interaction/mRNA stability assays","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss- and gain-of-function with defined cellular phenotype and pathway placement via IGF2BP3/RhoA/ROCK; in vitro and in vivo validation; single lab","pmids":["37599824"],"is_preprint":false}],"current_model":"ZXDC is a zinc-finger transcription co-activator that forms a heterodimeric complex with ZXDA (via their zinc finger domains) and recruits CIITA through its leucine-rich repeat region to drive MHC class I and II gene transcription; its transcriptional activation domain is positively regulated by sumoylation (at a single lysine, facilitated by SUMO-1/-2/-3 and E3 ligases including PIASy), while an alternatively spliced short isoform (ZXDC2) represses MHC II transcription by sequestering ZXDA and full-length ZXDC; beyond immune gene regulation, ZXDC also promotes cancer cell metastasis by activating the IGF2BP3/RhoA/ROCK signaling axis to remodel the cytoskeleton."},"narrative":{"mechanistic_narrative":"ZXDC is a multi-zinc-finger transcriptional co-activator that drives MHC class I and class II gene expression by partnering with the master regulator CIITA [PMID:16600381]. It was identified as a CIITA-binding protein that contacts the leucine-rich repeat region of CIITA, and its overexpression super-activates MHC promoters while its knockdown blunts CIITA-mediated MHC II transcription [PMID:16600381]. ZXDC functions not alone but as part of a complex: it self-associates and heterodimerizes with ZXDA through their zinc-finger regions, and it is the ZXDA-ZXDC complex that engages CIITA and occupies MHC II promoters before and after IFN-γ stimulation [PMID:17493635]. The activity of its transcriptional activation domain is tuned by SUMO modification at a single lysine, a modification required for full activation-domain function without disrupting its binding to ZXDA or CIITA [PMID:17696781]. A truncated, alternatively spliced isoform (ZXDC2) acts as a dominant-negative repressor of IFN-γ-induced MHC II transcription by sequestering ZXDA and full-length ZXDC [PMID:19777325]. Beyond immune gene regulation, ZXDC promotes cervical cancer cell metastasis by activating IGF2BP3-dependent stabilization of RhoA mRNA and downstream RhoA/ROCK signaling to remodel the cytoskeleton [PMID:37599824].","teleology":[{"year":2006,"claim":"Established ZXDC as a physical and functional partner of CIITA, defining a previously unknown co-activator of MHC gene transcription.","evidence":"Yeast two-hybrid screen plus Co-IP and overexpression/siRNA reporter assays in human cells","pmids":["16600381"],"confidence":"High","gaps":["Did not resolve which zinc fingers mediate CIITA binding versus DNA contact","No structural model of the ZXDC-CIITA interface"]},{"year":2007,"claim":"Showed that ZXDC operates as a heterodimer with ZXDA at MHC II promoters, redefining the functional unit of activation as the ZXDA-ZXDC complex rather than ZXDC alone.","evidence":"Reciprocal Co-IP, knockdown/overexpression reporter assays, and ChIP for promoter occupancy in HeLa cells","pmids":["17493635"],"confidence":"High","gaps":["Stoichiometry of the ZXDA-ZXDC-CIITA assembly not defined","Whether ZXDC contacts promoter DNA directly is unresolved"]},{"year":2007,"claim":"Defined SUMO modification at a single lysine as a positive regulator of the ZXDC activation domain, linking post-translational modification to co-activator output.","evidence":"Site-directed mutagenesis, Co-IP with SUMO isoforms and E3 ligases (PIASy), and transcriptional reporter assays","pmids":["17696781"],"confidence":"High","gaps":["Mechanism by which sumoylation enhances activation-domain activity not established","Physiological signals controlling ZXDC sumoylation unknown"]},{"year":2009,"claim":"Identified an alternatively spliced isoform (ZXDC2) that acts as a dominant-negative repressor, revealing autoregulation of the MHC II activation program.","evidence":"Isoform cloning, overexpression with IFN-γ and MHC II reporter assays, and Co-IP in HeLa cells","pmids":["19777325"],"confidence":"Medium","gaps":["Dominant-negative mechanism inferred from overexpression rather than endogenous isoform manipulation","Regulation and abundance of endogenous ZXDC2 not characterized"]},{"year":2023,"claim":"Extended ZXDC function beyond immune transcription to cancer metastasis via an IGF2BP3/RhoA/ROCK cytoskeletal axis.","evidence":"Gain- and loss-of-function in cervical cancer cells with migration/invasion assays, in vivo metastasis models, and IGF2BP3/RhoA mRNA-stability readouts","pmids":["37599824"],"confidence":"Medium","gaps":["Whether ZXDC acts transcriptionally on IGF2BP3 or through another mechanism not fully defined","Relationship between the MHC co-activator role and the pro-metastatic role unclear","Single cancer-type validation"]},{"year":null,"claim":"How ZXDC integrates its CIITA co-activator role with cell-cycle- or context-dependent functions, and the direct DNA-binding role of its zinc fingers, remain open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No direct DNA-binding target sequence defined for the zinc fingers","No structural characterization of any ZXDC complex","Mechanistic link between immune and metastatic functions unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[4]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,1,3]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4]}],"complexes":["ZXDA-ZXDC heterodimer"],"partners":["ZXDA","CIITA","PIASY","HDAC4","IGF2BP3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q2QGD7","full_name":"Zinc finger protein ZXDC","aliases":["ZXD-like zinc finger protein"],"length_aa":858,"mass_kda":90.0,"function":"Cooperates with CIITA to promote transcription of MHC class I and MHC class II genes","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q2QGD7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ZXDC","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ZXDC","total_profiled":1310},"omim":[{"mim_id":"615746","title":"ZXD FAMILY ZINC FINGER PROTEIN C; ZXDC","url":"https://www.omim.org/entry/615746"},{"mim_id":"606118","title":"HPS3 BIOGENESIS OF LYSOSOMAL ORGANELLES COMPLEX 2, SUBUNIT 1; HPS3","url":"https://www.omim.org/entry/606118"},{"mim_id":"600005","title":"CLASS II MAJOR HISTOCOMPATIBILITY COMPLEX TRANSACTIVATOR; CIITA","url":"https://www.omim.org/entry/600005"},{"mim_id":"300235","title":"ZINC FINGER-ENCODING GENE, X-LINKED, DUPLICATED, A; ZXDA","url":"https://www.omim.org/entry/300235"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoli","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"bone marrow","ntpm":37.2}],"url":"https://www.proteinatlas.org/search/ZXDC"},"hgnc":{"alias_symbol":["MGC11349","FLJ13861"],"prev_symbol":[]},"alphafold":{"accession":"Q2QGD7","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q2QGD7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q2QGD7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q2QGD7-F1-predicted_aligned_error_v6.png","plddt_mean":51.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ZXDC","jax_strain_url":"https://www.jax.org/strain/search?query=ZXDC"},"sequence":{"accession":"Q2QGD7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q2QGD7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q2QGD7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q2QGD7"}},"corpus_meta":[{"pmid":"26530418","id":"PMC_26530418","title":"Disease Variant Landscape of a Large Multiethnic Population of Moyamoya Patients by Exome Sequencing.","date":"2015","source":"G3 (Bethesda, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/26530418","citation_count":42,"is_preprint":false},{"pmid":"20651356","id":"PMC_20651356","title":"Proteomic analysis for nuclear proteins related to tumour malignant progression: a comparative proteomic study between malignant progressive cells and regressive cells.","date":"2010","source":"Anticancer research","url":"https://pubmed.ncbi.nlm.nih.gov/20651356","citation_count":26,"is_preprint":false},{"pmid":"16600381","id":"PMC_16600381","title":"ZXDC, a novel zinc finger protein that binds CIITA and activates MHC gene transcription.","date":"2006","source":"Molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/16600381","citation_count":24,"is_preprint":false},{"pmid":"17493635","id":"PMC_17493635","title":"The zinc finger proteins ZXDA and ZXDC form a complex that binds CIITA and regulates MHC II gene transcription.","date":"2007","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17493635","citation_count":23,"is_preprint":false},{"pmid":"37493860","id":"PMC_37493860","title":"Pan-primate studies of age and sex.","date":"2023","source":"GeroScience","url":"https://pubmed.ncbi.nlm.nih.gov/37493860","citation_count":20,"is_preprint":false},{"pmid":"38154557","id":"PMC_38154557","title":"Glomerular transcriptomics predicts long term outcome and identifies therapeutic strategies for patients with assumed benign IgA nephropathy.","date":"2023","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/38154557","citation_count":13,"is_preprint":false},{"pmid":"28427458","id":"PMC_28427458","title":"Whole-exome sequencing identifies novel candidate predisposition genes for familial polycythemia vera.","date":"2017","source":"Human genomics","url":"https://pubmed.ncbi.nlm.nih.gov/28427458","citation_count":12,"is_preprint":false},{"pmid":"17696781","id":"PMC_17696781","title":"Sumoylation of the zinc finger protein ZXDC enhances the function of its transcriptional activation domain.","date":"2007","source":"Biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17696781","citation_count":7,"is_preprint":false},{"pmid":"37599824","id":"PMC_37599824","title":"ZXDC enhances cervical cancer metastasis through IGF2BP3-mediated activation of RhoA/ROCK signaling.","date":"2023","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/37599824","citation_count":6,"is_preprint":false},{"pmid":"28993696","id":"PMC_28993696","title":"An eQTL variant of ZXDC is associated with IFN-γ production following Mycobacterium tuberculosis antigen-specific stimulation.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28993696","citation_count":6,"is_preprint":false},{"pmid":"19777325","id":"PMC_19777325","title":"An N- and C-terminal truncated isoform of zinc finger X-linked duplicated C protein represses MHC class II transcription.","date":"2009","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19777325","citation_count":4,"is_preprint":false},{"pmid":"39072829","id":"PMC_39072829","title":"X centromeric drive may explain the prevalence of polycystic ovary syndrome and other conditions: Genomic structure of the human X chromosome pericentromeric region is consistent with meiotic drive associated with PCOS and other conditions.","date":"2024","source":"BioEssays : news and reviews in molecular, cellular and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/39072829","citation_count":2,"is_preprint":false},{"pmid":"20684234","id":"PMC_20684234","title":"[Changes in genes expression caused by overexpression of the transcription factor ZXDC in embryonic kidney cell line HEK293].","date":"2010","source":"Ukrains'kyi biokhimichnyi zhurnal (1999 )","url":"https://pubmed.ncbi.nlm.nih.gov/20684234","citation_count":1,"is_preprint":false},{"pmid":"41637780","id":"PMC_41637780","title":"6PPD-Q exposure promotes hepatocellular carcinoma progression and confers resistance to ferroptosis.","date":"2026","source":"Ecotoxicology and environmental safety","url":"https://pubmed.ncbi.nlm.nih.gov/41637780","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8407,"output_tokens":1661,"usd":0.025068,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8431,"output_tokens":2196,"usd":0.048528,"stage2_stop_reason":"end_turn"},"total_usd":0.073596,"stage1_batch_id":"msgbatch_01UT1AahFPCAyn2uVweS7A9z","stage2_batch_id":"msgbatch_01HuKWtKNT4Pqj1bc8eEP5RV","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"ZXDC (zinc finger X-linked duplicated family member C) was identified as a novel CIITA-binding protein via yeast two-hybrid screening. The 858-amino acid ZXDC protein contains 10 zinc fingers and a transcriptional activation domain, and binds the leucine-rich repeat region of CIITA. Overexpression of ZXDC in human cell lines caused super-activation of MHC class I and class II promoters by CIITA, while siRNA knockdown of ZXDC reduced CIITA-mediated MHC class II transcriptional activation.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, overexpression and siRNA knockdown in human cell lines with MHC promoter reporter assays\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal protein interaction assay (Y2H + Co-IP), functional overexpression and loss-of-function in human cells with defined transcriptional readout, two orthogonal methods in a single focused study\",\n      \"pmids\": [\"16600381\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ZXDA and ZXDC can self-associate and also heterodimerize with each other through their zinc finger-containing regions. The ZXDA-ZXDC complex, rather than either protein alone, interacts with CIITA. Knockdown and overexpression of ZXDA demonstrated its importance in MHC II transcriptional activation. ChIP showed ZXDC is present at MHC II promoters in HeLa cells both before and after IFN-γ treatment.\",\n      \"method\": \"Co-immunoprecipitation, knockdown/overexpression reporter assays, chromatin immunoprecipitation (ChIP)\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP for complex formation, ChIP for promoter occupancy, functional knockdown/OE with defined transcriptional phenotype; multiple orthogonal methods in one focused study\",\n      \"pmids\": [\"17493635\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ZXDC is sumoylated at a single lysine residue within its transcriptional activation domain. All three SUMO proteins (SUMO-1, -2, and -3) can modify ZXDC. Multiple SUMO E3 ligase enzymes and HDAC4 can facilitate this modification; the E3 ligase PIASy interacts with a specific region of ZXDC. Sumoylation does not disrupt ZXDC interactions with its binding partners (ZXDA, CIITA), but is required for full activity of the ZXDC transcriptional activation domain.\",\n      \"method\": \"Western blot (two-species detection), co-immunoprecipitation with SUMO proteins and E3 ligases, mutagenesis of sumoylation site, transcriptional reporter assays\",\n      \"journal\": \"Biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-specific mutagenesis combined with Co-IP and functional reporter assays; multiple SUMO isoforms and E3 ligases tested; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"17696781\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"An alternatively spliced isoform of ZXDC, named ZXDC2, is produced from a transcript that initiates in the first exon and terminates within the seventh intron, yielding a protein truncated at both N- and C-termini. ZXDC2 represses IFN-γ-induced MHC class II transcription in HeLa cells, and interacts with both ZXDA and full-length ZXDC, suggesting a dominant-negative mechanism of MHC II transcriptional repression.\",\n      \"method\": \"Molecular cloning of isoform, transfection/overexpression in HeLa cells with IFN-γ treatment and MHC II reporter assays, co-immunoprecipitation\",\n      \"journal\": \"Molecular and cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional reporter assay and Co-IP for isoform; single lab, limited validation of the mechanism\",\n      \"pmids\": [\"19777325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ZXDC promotes cervical cancer cell metastasis by activating the RhoA/ROCK signaling pathway, leading to enhanced cytoskeleton remodeling. IGF2BP3 plays an essential role in this pathway by stabilizing RhoA mRNA downstream of ZXDC. Overexpression of ZXDC promotes metastasis both in vitro and in vivo, while silencing ZXDC inhibits it.\",\n      \"method\": \"Overexpression and siRNA knockdown in cervical cancer cell lines, in vitro migration/invasion assays, in vivo metastasis models, RhoA/ROCK pathway readouts, IGF2BP3 interaction/mRNA stability assays\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss- and gain-of-function with defined cellular phenotype and pathway placement via IGF2BP3/RhoA/ROCK; in vitro and in vivo validation; single lab\",\n      \"pmids\": [\"37599824\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ZXDC is a zinc-finger transcription co-activator that forms a heterodimeric complex with ZXDA (via their zinc finger domains) and recruits CIITA through its leucine-rich repeat region to drive MHC class I and II gene transcription; its transcriptional activation domain is positively regulated by sumoylation (at a single lysine, facilitated by SUMO-1/-2/-3 and E3 ligases including PIASy), while an alternatively spliced short isoform (ZXDC2) represses MHC II transcription by sequestering ZXDA and full-length ZXDC; beyond immune gene regulation, ZXDC also promotes cancer cell metastasis by activating the IGF2BP3/RhoA/ROCK signaling axis to remodel the cytoskeleton.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ZXDC is a multi-zinc-finger transcriptional co-activator that drives MHC class I and class II gene expression by partnering with the master regulator CIITA [#0]. It was identified as a CIITA-binding protein that contacts the leucine-rich repeat region of CIITA, and its overexpression super-activates MHC promoters while its knockdown blunts CIITA-mediated MHC II transcription [#0]. ZXDC functions not alone but as part of a complex: it self-associates and heterodimerizes with ZXDA through their zinc-finger regions, and it is the ZXDA-ZXDC complex that engages CIITA and occupies MHC II promoters before and after IFN-\\u03b3 stimulation [#1]. The activity of its transcriptional activation domain is tuned by SUMO modification at a single lysine, a modification required for full activation-domain function without disrupting its binding to ZXDA or CIITA [#2]. A truncated, alternatively spliced isoform (ZXDC2) acts as a dominant-negative repressor of IFN-\\u03b3-induced MHC II transcription by sequestering ZXDA and full-length ZXDC [#3]. Beyond immune gene regulation, ZXDC promotes cervical cancer cell metastasis by activating IGF2BP3-dependent stabilization of RhoA mRNA and downstream RhoA/ROCK signaling to remodel the cytoskeleton [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established ZXDC as a physical and functional partner of CIITA, defining a previously unknown co-activator of MHC gene transcription.\",\n      \"evidence\": \"Yeast two-hybrid screen plus Co-IP and overexpression/siRNA reporter assays in human cells\",\n      \"pmids\": [\"16600381\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which zinc fingers mediate CIITA binding versus DNA contact\", \"No structural model of the ZXDC-CIITA interface\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Showed that ZXDC operates as a heterodimer with ZXDA at MHC II promoters, redefining the functional unit of activation as the ZXDA-ZXDC complex rather than ZXDC alone.\",\n      \"evidence\": \"Reciprocal Co-IP, knockdown/overexpression reporter assays, and ChIP for promoter occupancy in HeLa cells\",\n      \"pmids\": [\"17493635\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of the ZXDA-ZXDC-CIITA assembly not defined\", \"Whether ZXDC contacts promoter DNA directly is unresolved\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined SUMO modification at a single lysine as a positive regulator of the ZXDC activation domain, linking post-translational modification to co-activator output.\",\n      \"evidence\": \"Site-directed mutagenesis, Co-IP with SUMO isoforms and E3 ligases (PIASy), and transcriptional reporter assays\",\n      \"pmids\": [\"17696781\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which sumoylation enhances activation-domain activity not established\", \"Physiological signals controlling ZXDC sumoylation unknown\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identified an alternatively spliced isoform (ZXDC2) that acts as a dominant-negative repressor, revealing autoregulation of the MHC II activation program.\",\n      \"evidence\": \"Isoform cloning, overexpression with IFN-\\u03b3 and MHC II reporter assays, and Co-IP in HeLa cells\",\n      \"pmids\": [\"19777325\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Dominant-negative mechanism inferred from overexpression rather than endogenous isoform manipulation\", \"Regulation and abundance of endogenous ZXDC2 not characterized\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended ZXDC function beyond immune transcription to cancer metastasis via an IGF2BP3/RhoA/ROCK cytoskeletal axis.\",\n      \"evidence\": \"Gain- and loss-of-function in cervical cancer cells with migration/invasion assays, in vivo metastasis models, and IGF2BP3/RhoA mRNA-stability readouts\",\n      \"pmids\": [\"37599824\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ZXDC acts transcriptionally on IGF2BP3 or through another mechanism not fully defined\", \"Relationship between the MHC co-activator role and the pro-metastatic role unclear\", \"Single cancer-type validation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ZXDC integrates its CIITA co-activator role with cell-cycle- or context-dependent functions, and the direct DNA-binding role of its zinc fingers, remain open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct DNA-binding target sequence defined for the zinc fingers\", \"No structural characterization of any ZXDC complex\", \"Mechanistic link between immune and metastatic functions unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [\"ZXDA-ZXDC heterodimer\"],\n    \"partners\": [\"ZXDA\", \"CIITA\", \"PIASy\", \"HDAC4\", \"IGF2BP3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}