{"gene":"ZHX1","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":1996,"finding":"ZHX1 (zhx-1) encodes a novel protein of 873 amino acids containing two C2-H2 zinc fingers and five homeodomains, classifying it as a ZF-class homeodomain transcription factor; mRNA is widely expressed in adult mouse with preferential expression in brain.","method":"cDNA cloning, ORF sequencing, Northern blot analysis","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — foundational molecular characterization by direct sequencing and Northern blot, replicated across mouse and human","pmids":["8713137"],"is_preprint":false},{"year":1999,"finding":"Human ZHX1 was isolated as a direct binding partner of the NF-YA subunit of the heterotrimeric transcription factor NF-Y (CCAAT-binding protein); interaction identified by yeast two-hybrid screening of a human liver cDNA library using NF-YA as bait.","method":"Yeast two-hybrid screen, cDNA library screening, Northern blot","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — yeast two-hybrid single method, but replicated in subsequent studies confirming NF-YA interaction","pmids":["10441475"],"is_preprint":false},{"year":2002,"finding":"ZHX1 functions as a transcriptional repressor: its acidic C-terminal region (amino acids 831–873) is the repressor domain; homodimerization via homeodomain 1 (amino acids 272–432) is required for full repressor activity; nuclear localization signal maps to an arginine-rich region (amino acids 734–768).","method":"Mammalian one-hybrid assay, GFP-fusion transfection into HEK293 cells, protein-protein interaction assays with truncation mutants","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (one-hybrid, GFP localization, interaction assays) with domain-mapping mutagenesis in a single study","pmids":["12237128"],"is_preprint":false},{"year":2002,"finding":"Rat ZHX1 forms a homodimer, as identified by yeast two-hybrid screening of an ovarian granulosa cell cDNA library; full-length ZHX1 fused to GFP localizes to the nucleus in HEK293 cells.","method":"Yeast two-hybrid, GFP fusion transfection, Northern blot","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — yeast two-hybrid for homodimerization plus direct GFP localization, consistent with independent report (PMID:12237128)","pmids":["12062805"],"is_preprint":false},{"year":2003,"finding":"Transcription of the mouse ZHX1 gene is driven by two positive cis-acting elements (Box A and Box B) in the proximal promoter; PEA3 binds Box A and YY1 binds Box B, and they synergistically stimulate ZHX1 transcription.","method":"Luciferase reporter assays with 5'- and 3'-deletion constructs, electrophoretic mobility shift assay (EMSA) with antibodies and specific competitors","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA with antibody supershift plus functional reporter assays, single lab","pmids":["12527199"],"is_preprint":false},{"year":2007,"finding":"ZHX1 directly binds DNMT3B; the N-terminal PWWP domain of DNMT3B interacts with the homeobox motifs of ZHX1; both proteins co-localize in the nucleus; ZHX1 enhances DNMT3B-mediated transcriptional repression when DNMT3B is directly targeted to DNA.","method":"Yeast two-hybrid, co-immunoprecipitation (in vivo and in vitro), co-localization, transcriptional repression assay","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP in vivo and in vitro, co-localization, and functional transcriptional assay in a single study","pmids":["17303076"],"is_preprint":false},{"year":2007,"finding":"Corepressor BS69 interacts with ZHX1 through its C-terminal MYND domain binding to the PxLxP motif of ZHX1; this interaction suppresses BS69-mediated transcriptional activation in HEK293 cells.","method":"Co-transfection with wild-type and PxLxP-mutant ZHX1, transcriptional reporter assay, domain mapping","journal":"Frontiers in bioscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — domain-specific mutant used to confirm interaction and functional consequence, single lab","pmids":["17127430"],"is_preprint":false},{"year":2013,"finding":"ZHX1 is SUMOylated by the SUMO E2 conjugating enzyme Ubc9 at lysine residues K159, K454, and K626 using SUMO1; SUMOylation regulates ZHX1 protein stability, ubiquitination, and transcriptional repression activity.","method":"Yeast two-hybrid (interaction screen), co-immunoprecipitation, co-localization, site-directed mutagenesis of SUMO acceptor sites, SUMOylation assay","journal":"Journal of cellular biochemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods including site-directed mutagenesis of SUMO sites plus Co-IP and functional assays in a single study","pmids":["23686912"],"is_preprint":false},{"year":2014,"finding":"Solution NMR structures of a ZHX1 homeodomain were solved, providing structural characterization of this domain.","method":"Solution NMR structure determination","journal":"Journal of structural and functional genomics","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — high-quality NMR structure, but no functional validation of the specific homeodomain was performed in this study","pmids":["24941917"],"is_preprint":false},{"year":2016,"finding":"ZHX1 induces G1/S cell-cycle arrest by decreasing cyclin D1 and cyclin E expression, and induces apoptosis by downregulating Bcl2 and upregulating Bax and cleaved caspase-3 in gastric cancer cells.","method":"siRNA knockdown and overexpression in gastric cancer cell lines, cell-cycle analysis, Western blot for cyclins and apoptosis markers","journal":"Journal of Cancer","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — loss-of-function and gain-of-function with defined molecular readouts, single lab","pmids":["26722361"],"is_preprint":false},{"year":2016,"finding":"ZHX1 knockdown decreases cholangiocarcinoma cell proliferation, migration, and invasion; EGR1 was identified as a partial downstream mediator of ZHX1's effect on CCA cell proliferation.","method":"siRNA knockdown, overexpression, in silico analysis, immunohistochemistry, proliferation/migration/invasion assays","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 3 / Weak — EGR1 mediation suggested from results but not mechanistically validated beyond correlation; single lab, single method for pathway placement","pmids":["27835650"],"is_preprint":false},{"year":2017,"finding":"ZHX1 acts upstream of PUMA in a pro-apoptotic pathway in hepatocellular carcinoma cells; targeting ZHX1 with siRNA inhibits PUMA upregulation following miR-199a-3p overexpression, reversing effects on Bcl2, Bax, and cleaved caspase-3.","method":"siRNA transfection, Western blot, in vivo xenograft model","journal":"American journal of translational research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — epistasis-like experiment placing ZHX1 upstream of PUMA, confirmed in vitro and in vivo, single lab","pmids":["28559996"],"is_preprint":false},{"year":2023,"finding":"Zhx1 directly interacts with hnRNPA1 via amino acid residues Thr111–His120 of its second zinc finger domain; the Zhx1/hnRNPA1 complex co-activates transcription of genes required for cardiac progenitor specification during cardiomyocyte differentiation from embryonic stem cells.","method":"Co-immunoprecipitation, domain-level interaction mapping, loss-of-function experiments in mouse and human ESC differentiation models, transcriptomics","journal":"Cell death discovery","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with domain-level residue mapping, functional validation in two species (mouse and human ESCs), single lab with multiple orthogonal methods","pmids":["37452012"],"is_preprint":false},{"year":2026,"finding":"ZHX1 promotes transcription of mitochondrial ribosomal protein genes Mrps15 and Mrps21; ZHX1 overexpression or pharmacological activation with mithramycin ameliorates mitochondrial dysfunction in hypertensive heart disease, and combined silencing of Mrps15/Mrps21 abrogates ZHX1's cardioprotective effect.","method":"ZHX1 overexpression, mithramycin treatment, combined Mrps15/Mrps21 siRNA rescue experiment, mitochondrial respiration assay, membrane potential assay, in vivo L-NAME mouse model","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistasis rescue experiment plus in vivo model, single lab","pmids":["42162768"],"is_preprint":false}],"current_model":"ZHX1 is a nuclear transcriptional repressor containing two zinc fingers and five homeodomains that homodimerizes via its first homeodomain, localizes to the nucleus via a C-terminal arginine-rich NLS, and represses transcription through a C-terminal acidic domain; it interacts with NF-YA, DNMT3B (enhancing its repression), and the corepressor BS69, is post-translationally regulated by Ubc9-mediated SUMOylation at K159/K454/K626 (affecting its stability and activity), and can also act as a transcriptional activator in specific contexts (e.g., co-activating gene expression with hnRNPA1 during cardiac progenitor specification and driving Mrps15/Mrps21 transcription to protect mitochondrial function)."},"narrative":{"mechanistic_narrative":"ZHX1 is a nuclear zinc-finger/homeodomain transcription factor that functions principally as a transcriptional repressor but can also act as a context-specific activator [PMID:8713137, PMID:12237128]. It harbors two C2-H2 zinc fingers and five homeodomains, and represses transcription through an acidic C-terminal domain (residues 831–873), homodimerizes via its first homeodomain (residues 272–432) as a requirement for full repressor activity, and enters the nucleus through an arginine-rich C-terminal NLS (residues 734–768) [PMID:12237128]. ZHX1 was first identified as a direct binding partner of the NF-YA subunit of the CCAAT-binding factor NF-Y [PMID:10441475], and it integrates into repressive transcriptional machinery by binding the de novo DNA methyltransferase DNMT3B—engaging the DNMT3B PWWP domain through its homeobox motifs and enhancing DNMT3B-mediated repression—and by binding the corepressor BS69 via a PxLxP motif [PMID:17303076, PMID:17127430]. ZHX1 activity and stability are tuned by Ubc9-mediated SUMOylation at K159, K454, and K626, which modulates its ubiquitination and repressor function [PMID:23686912]. Beyond repression, ZHX1 acts as a co-activator: it partners with hnRNPA1 through residues in its second zinc finger to drive a transcriptional program for cardiac progenitor specification [PMID:37452012], and it promotes transcription of the mitochondrial ribosomal protein genes Mrps15 and Mrps21 to protect mitochondrial function in hypertensive heart disease [PMID:42162768]. In cancer cells ZHX1 restrains proliferation by enforcing G1/S arrest and promoting apoptosis [PMID:26722361, PMID:28559996].","teleology":[{"year":1996,"claim":"Establishing that ZHX1 encodes a zinc-finger-class homeodomain protein defined it as a candidate transcription factor and set the structural framework for all later mechanistic work.","evidence":"cDNA cloning and ORF sequencing with Northern blot expression profiling in mouse","pmids":["8713137"],"confidence":"High","gaps":["No DNA-binding specificity or target genes identified","Function inferred from domain content, not tested"]},{"year":1999,"claim":"Identifying ZHX1 as a direct NF-YA interactor connected it to the CCAAT-binding transcriptional machinery, giving its first defined molecular partner.","evidence":"Yeast two-hybrid screen of a human liver cDNA library using NF-YA as bait","pmids":["10441475"],"confidence":"Medium","gaps":["Single-method interaction without reciprocal in-cell validation","Functional consequence of NF-YA binding not defined"]},{"year":2002,"claim":"Domain mapping defined ZHX1 as a repressor and assigned its repression, dimerization, and nuclear-targeting functions to discrete regions, converting it from a presumed factor to a mechanistically dissected one.","evidence":"Mammalian one-hybrid, GFP-fusion localization and truncation interaction assays in HEK293; independent yeast two-hybrid homodimerization with GFP localization","pmids":["12237128","12062805"],"confidence":"High","gaps":["Direct DNA target sequences not identified","Cofactors mediating repression not yet known"]},{"year":2003,"claim":"Mapping the ZHX1 promoter showed how ZHX1 expression is itself controlled, identifying PEA3 and YY1 as synergistic upstream activators.","evidence":"Luciferase reporter deletion analysis and EMSA with supershift in mouse","pmids":["12527199"],"confidence":"Medium","gaps":["Regulation in physiological/disease contexts not tested","Single lab"]},{"year":2007,"claim":"Discovery of DNMT3B and BS69 partnerships placed ZHX1 within repressive chromatin/corepressor machinery, explaining how it executes repression mechanistically.","evidence":"Reciprocal Co-IP, co-localization and transcriptional repression assays (DNMT3B); domain-mapped PxLxP-MYND interaction and reporter assays (BS69)","pmids":["17303076","17127430"],"confidence":"Medium","gaps":["Endogenous target genes co-regulated by these complexes not defined","Whether DNMT3B recruitment alters DNA methylation at ZHX1 targets untested"]},{"year":2013,"claim":"Identifying Ubc9-mediated SUMOylation at three lysines established a post-translational control layer governing ZHX1 stability and activity.","evidence":"Yeast two-hybrid, Co-IP, site-directed mutagenesis of SUMO acceptor sites and SUMOylation assays","pmids":["23686912"],"confidence":"High","gaps":["Signals triggering ZHX1 SUMOylation unknown","SUMO-dependent partner switching not characterized"]},{"year":2014,"claim":"A solution NMR structure of a ZHX1 homeodomain provided atomic-level structural information for one of its functional modules.","evidence":"Solution NMR structure determination","pmids":["24941917"],"confidence":"Medium","gaps":["No functional validation of the solved homeodomain","Full-length or multi-domain architecture unresolved"]},{"year":2016,"claim":"Loss- and gain-of-function studies in cancer cells linked ZHX1 to cell-cycle arrest and apoptosis, assigning it a tumor-suppressive cellular role.","evidence":"siRNA/overexpression in gastric and cholangiocarcinoma cells with cell-cycle, apoptosis and invasion readouts","pmids":["26722361","27835650"],"confidence":"Medium","gaps":["Direct transcriptional targets driving these effects not defined","EGR1 mediation only correlative"]},{"year":2017,"claim":"Epistasis placing ZHX1 upstream of PUMA defined a specific pro-apoptotic effector pathway downstream of ZHX1 in hepatocellular carcinoma.","evidence":"siRNA, Western blot and xenograft model","pmids":["28559996"],"confidence":"Medium","gaps":["Whether ZHX1 directly transcribes PUMA untested","Single lab"]},{"year":2023,"claim":"Identifying the ZHX1/hnRNPA1 co-activator complex demonstrated that ZHX1 can activate transcription and drive a developmental program for cardiac progenitor specification.","evidence":"Reciprocal Co-IP, residue-level domain mapping, and loss-of-function in mouse and human ESC differentiation with transcriptomics","pmids":["37452012"],"confidence":"High","gaps":["Direct target promoters bound by the complex not fully mapped","Mechanism of repressor-to-activator switch unknown"]},{"year":2026,"claim":"Demonstrating that ZHX1 drives Mrps15/Mrps21 transcription to protect mitochondria established a concrete activator target set and a cardioprotective function.","evidence":"Overexpression, mithramycin activation, combined Mrps15/Mrps21 siRNA rescue, mitochondrial respiration assays and in vivo L-NAME model","pmids":["42162768"],"confidence":"Medium","gaps":["Direct binding of ZHX1 to Mrps15/Mrps21 promoters not shown","Coactivator partners in this context not identified"]},{"year":null,"claim":"What determines whether ZHX1 acts as a repressor versus an activator at a given locus, and the genome-wide set of its direct DNA targets, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No genome-wide ZHX1 binding map","Molecular basis of the repressor/activator switch unknown","Direct DNA recognition sequence undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,2,12,13]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,2]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[2,3,5]}],"pathway":[{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[2,5,12,13]}],"complexes":[],"partners":["NFYA","DNMT3B","BS69","UBE2I","HNRNPA1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UKY1","full_name":"Zinc fingers and homeoboxes protein 1","aliases":[],"length_aa":873,"mass_kda":98.1,"function":"Acts as a transcriptional repressor. Increases DNMT3B-mediated repressive transcriptional activity when DNMT3B is tethered to DNA. May link molecule between DNMT3B and other co-repressor proteins","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9UKY1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ZHX1","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CAPZB","stoichiometry":0.2},{"gene":"CSNK2B","stoichiometry":0.2},{"gene":"HDAC1","stoichiometry":0.2},{"gene":"HDAC2","stoichiometry":0.2},{"gene":"RBBP4","stoichiometry":0.2},{"gene":"RIOK1","stoichiometry":0.2},{"gene":"YY1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/ZHX1","total_profiled":1310},"omim":[{"mim_id":"609598","title":"ZINC FINGER AND HOMEODOMAIN PROTEIN 3; ZHX3","url":"https://www.omim.org/entry/609598"},{"mim_id":"609185","title":"ZINC FINGER AND HOMEODOMAIN PROTEIN 2; ZHX2","url":"https://www.omim.org/entry/609185"},{"mim_id":"608119","title":"HOMEODOMAIN LEUCINE ZIPPER-CONTAINING FACTOR; HOMEZ","url":"https://www.omim.org/entry/608119"},{"mim_id":"604764","title":"ZINC FINGER AND HOMEODOMAIN PROTEIN 1; ZHX1","url":"https://www.omim.org/entry/604764"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ZHX1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q9UKY1","domains":[{"cath_id":"3.30.160","chopping":"69-147","consensus_level":"medium","plddt":79.9806,"start":69,"end":147},{"cath_id":"1.10.10","chopping":"282-355","consensus_level":"high","plddt":86.6645,"start":282,"end":355},{"cath_id":"1.10.10.60","chopping":"472-524","consensus_level":"high","plddt":90.2177,"start":472,"end":524},{"cath_id":"1.10.10.60","chopping":"576-632","consensus_level":"high","plddt":86.4604,"start":576,"end":632},{"cath_id":"1.10.10.60","chopping":"668-731","consensus_level":"high","plddt":88.7658,"start":668,"end":731},{"cath_id":"1.10.10","chopping":"781-832","consensus_level":"high","plddt":87.9973,"start":781,"end":832}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UKY1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UKY1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UKY1-F1-predicted_aligned_error_v6.png","plddt_mean":60.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ZHX1","jax_strain_url":"https://www.jax.org/strain/search?query=ZHX1"},"sequence":{"accession":"Q9UKY1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UKY1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UKY1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UKY1"}},"corpus_meta":[{"pmid":"31648104","id":"PMC_31648104","title":"Blocking lncRNA MALAT1/miR-199a/ZHX1 Axis Inhibits Glioblastoma Proliferation and Progression.","date":"2019","source":"Molecular therapy. Nucleic acids","url":"https://pubmed.ncbi.nlm.nih.gov/31648104","citation_count":89,"is_preprint":false},{"pmid":"25448600","id":"PMC_25448600","title":"MiR-199a-3p promotes gastric cancer progression by targeting ZHX1.","date":"2014","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/25448600","citation_count":83,"is_preprint":false},{"pmid":"30231238","id":"PMC_30231238","title":"lncRNA DLG1-AS1 Promotes Cell Proliferation by Competitively Binding with miR-107 and Up-Regulating ZHX1 Expression in Cervical Cancer.","date":"2018","source":"Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/30231238","citation_count":48,"is_preprint":false},{"pmid":"8713137","id":"PMC_8713137","title":"zhx-1: a novel mouse homeodomain protein containing two zinc-fingers and five homeodomains.","date":"1996","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/8713137","citation_count":47,"is_preprint":false},{"pmid":"26722361","id":"PMC_26722361","title":"ZHX1 Inhibits Gastric Cancer Cell Growth through Inducing Cell-Cycle Arrest and Apoptosis.","date":"2016","source":"Journal of Cancer","url":"https://pubmed.ncbi.nlm.nih.gov/26722361","citation_count":43,"is_preprint":false},{"pmid":"10441475","id":"PMC_10441475","title":"Human ZHX1: cloning, chromosomal location, and interaction with transcription factor NF-Y.","date":"1999","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/10441475","citation_count":41,"is_preprint":false},{"pmid":"17303076","id":"PMC_17303076","title":"Zinc-fingers and homeoboxes 1 (ZHX1) binds DNA methyltransferase (DNMT) 3B to enhance DNMT3B-mediated transcriptional repression.","date":"2007","source":"Biochemical and biophysical research 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therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32184618","citation_count":13,"is_preprint":false},{"pmid":"37452012","id":"PMC_37452012","title":"Cooperative regulation of Zhx1 and hnRNPA1 drives the cardiac progenitor-specific transcriptional activation during cardiomyocyte differentiation.","date":"2023","source":"Cell death discovery","url":"https://pubmed.ncbi.nlm.nih.gov/37452012","citation_count":5,"is_preprint":false},{"pmid":"24941917","id":"PMC_24941917","title":"Solution NMR structures of homeodomains from human proteins ALX4, ZHX1, and CASP8AP2 contribute to the structural coverage of the Human Cancer Protein Interaction Network.","date":"2014","source":"Journal of structural and functional genomics","url":"https://pubmed.ncbi.nlm.nih.gov/24941917","citation_count":1,"is_preprint":false},{"pmid":"39011138","id":"PMC_39011138","title":"LncRNA LINC01140 Inhibits Glioma Cell Migration and Invasion via Modulation of miR-199a-3p/ZHX1 Axis [Retraction].","date":"2024","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/39011138","citation_count":0,"is_preprint":false},{"pmid":"42162768","id":"PMC_42162768","title":"Mrps15/Mrps21 induced by Zhx1 protects mice from hypertensive heart disease by restoring mitochondrial translation.","date":"2026","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/42162768","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10900,"output_tokens":3167,"usd":0.040102,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10562,"output_tokens":3293,"usd":0.067568,"stage2_stop_reason":"end_turn"},"total_usd":0.10767,"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\": 1996,\n      \"finding\": \"ZHX1 (zhx-1) encodes a novel protein of 873 amino acids containing two C2-H2 zinc fingers and five homeodomains, classifying it as a ZF-class homeodomain transcription factor; mRNA is widely expressed in adult mouse with preferential expression in brain.\",\n      \"method\": \"cDNA cloning, ORF sequencing, Northern blot analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — foundational molecular characterization by direct sequencing and Northern blot, replicated across mouse and human\",\n      \"pmids\": [\"8713137\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Human ZHX1 was isolated as a direct binding partner of the NF-YA subunit of the heterotrimeric transcription factor NF-Y (CCAAT-binding protein); interaction identified by yeast two-hybrid screening of a human liver cDNA library using NF-YA as bait.\",\n      \"method\": \"Yeast two-hybrid screen, cDNA library screening, Northern blot\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — yeast two-hybrid single method, but replicated in subsequent studies confirming NF-YA interaction\",\n      \"pmids\": [\"10441475\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"ZHX1 functions as a transcriptional repressor: its acidic C-terminal region (amino acids 831–873) is the repressor domain; homodimerization via homeodomain 1 (amino acids 272–432) is required for full repressor activity; nuclear localization signal maps to an arginine-rich region (amino acids 734–768).\",\n      \"method\": \"Mammalian one-hybrid assay, GFP-fusion transfection into HEK293 cells, protein-protein interaction assays with truncation mutants\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (one-hybrid, GFP localization, interaction assays) with domain-mapping mutagenesis in a single study\",\n      \"pmids\": [\"12237128\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Rat ZHX1 forms a homodimer, as identified by yeast two-hybrid screening of an ovarian granulosa cell cDNA library; full-length ZHX1 fused to GFP localizes to the nucleus in HEK293 cells.\",\n      \"method\": \"Yeast two-hybrid, GFP fusion transfection, Northern blot\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — yeast two-hybrid for homodimerization plus direct GFP localization, consistent with independent report (PMID:12237128)\",\n      \"pmids\": [\"12062805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Transcription of the mouse ZHX1 gene is driven by two positive cis-acting elements (Box A and Box B) in the proximal promoter; PEA3 binds Box A and YY1 binds Box B, and they synergistically stimulate ZHX1 transcription.\",\n      \"method\": \"Luciferase reporter assays with 5'- and 3'-deletion constructs, electrophoretic mobility shift assay (EMSA) with antibodies and specific competitors\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA with antibody supershift plus functional reporter assays, single lab\",\n      \"pmids\": [\"12527199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ZHX1 directly binds DNMT3B; the N-terminal PWWP domain of DNMT3B interacts with the homeobox motifs of ZHX1; both proteins co-localize in the nucleus; ZHX1 enhances DNMT3B-mediated transcriptional repression when DNMT3B is directly targeted to DNA.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation (in vivo and in vitro), co-localization, transcriptional repression assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP in vivo and in vitro, co-localization, and functional transcriptional assay in a single study\",\n      \"pmids\": [\"17303076\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Corepressor BS69 interacts with ZHX1 through its C-terminal MYND domain binding to the PxLxP motif of ZHX1; this interaction suppresses BS69-mediated transcriptional activation in HEK293 cells.\",\n      \"method\": \"Co-transfection with wild-type and PxLxP-mutant ZHX1, transcriptional reporter assay, domain mapping\",\n      \"journal\": \"Frontiers in bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain-specific mutant used to confirm interaction and functional consequence, single lab\",\n      \"pmids\": [\"17127430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"ZHX1 is SUMOylated by the SUMO E2 conjugating enzyme Ubc9 at lysine residues K159, K454, and K626 using SUMO1; SUMOylation regulates ZHX1 protein stability, ubiquitination, and transcriptional repression activity.\",\n      \"method\": \"Yeast two-hybrid (interaction screen), co-immunoprecipitation, co-localization, site-directed mutagenesis of SUMO acceptor sites, SUMOylation assay\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods including site-directed mutagenesis of SUMO sites plus Co-IP and functional assays in a single study\",\n      \"pmids\": [\"23686912\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Solution NMR structures of a ZHX1 homeodomain were solved, providing structural characterization of this domain.\",\n      \"method\": \"Solution NMR structure determination\",\n      \"journal\": \"Journal of structural and functional genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — high-quality NMR structure, but no functional validation of the specific homeodomain was performed in this study\",\n      \"pmids\": [\"24941917\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ZHX1 induces G1/S cell-cycle arrest by decreasing cyclin D1 and cyclin E expression, and induces apoptosis by downregulating Bcl2 and upregulating Bax and cleaved caspase-3 in gastric cancer cells.\",\n      \"method\": \"siRNA knockdown and overexpression in gastric cancer cell lines, cell-cycle analysis, Western blot for cyclins and apoptosis markers\",\n      \"journal\": \"Journal of Cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — loss-of-function and gain-of-function with defined molecular readouts, single lab\",\n      \"pmids\": [\"26722361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ZHX1 knockdown decreases cholangiocarcinoma cell proliferation, migration, and invasion; EGR1 was identified as a partial downstream mediator of ZHX1's effect on CCA cell proliferation.\",\n      \"method\": \"siRNA knockdown, overexpression, in silico analysis, immunohistochemistry, proliferation/migration/invasion assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — EGR1 mediation suggested from results but not mechanistically validated beyond correlation; single lab, single method for pathway placement\",\n      \"pmids\": [\"27835650\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ZHX1 acts upstream of PUMA in a pro-apoptotic pathway in hepatocellular carcinoma cells; targeting ZHX1 with siRNA inhibits PUMA upregulation following miR-199a-3p overexpression, reversing effects on Bcl2, Bax, and cleaved caspase-3.\",\n      \"method\": \"siRNA transfection, Western blot, in vivo xenograft model\",\n      \"journal\": \"American journal of translational research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — epistasis-like experiment placing ZHX1 upstream of PUMA, confirmed in vitro and in vivo, single lab\",\n      \"pmids\": [\"28559996\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Zhx1 directly interacts with hnRNPA1 via amino acid residues Thr111–His120 of its second zinc finger domain; the Zhx1/hnRNPA1 complex co-activates transcription of genes required for cardiac progenitor specification during cardiomyocyte differentiation from embryonic stem cells.\",\n      \"method\": \"Co-immunoprecipitation, domain-level interaction mapping, loss-of-function experiments in mouse and human ESC differentiation models, transcriptomics\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with domain-level residue mapping, functional validation in two species (mouse and human ESCs), single lab with multiple orthogonal methods\",\n      \"pmids\": [\"37452012\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ZHX1 promotes transcription of mitochondrial ribosomal protein genes Mrps15 and Mrps21; ZHX1 overexpression or pharmacological activation with mithramycin ameliorates mitochondrial dysfunction in hypertensive heart disease, and combined silencing of Mrps15/Mrps21 abrogates ZHX1's cardioprotective effect.\",\n      \"method\": \"ZHX1 overexpression, mithramycin treatment, combined Mrps15/Mrps21 siRNA rescue experiment, mitochondrial respiration assay, membrane potential assay, in vivo L-NAME mouse model\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistasis rescue experiment plus in vivo model, single lab\",\n      \"pmids\": [\"42162768\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ZHX1 is a nuclear transcriptional repressor containing two zinc fingers and five homeodomains that homodimerizes via its first homeodomain, localizes to the nucleus via a C-terminal arginine-rich NLS, and represses transcription through a C-terminal acidic domain; it interacts with NF-YA, DNMT3B (enhancing its repression), and the corepressor BS69, is post-translationally regulated by Ubc9-mediated SUMOylation at K159/K454/K626 (affecting its stability and activity), and can also act as a transcriptional activator in specific contexts (e.g., co-activating gene expression with hnRNPA1 during cardiac progenitor specification and driving Mrps15/Mrps21 transcription to protect mitochondrial function).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ZHX1 is a nuclear zinc-finger/homeodomain transcription factor that functions principally as a transcriptional repressor but can also act as a context-specific activator [#0, #2]. It harbors two C2-H2 zinc fingers and five homeodomains, and represses transcription through an acidic C-terminal domain (residues 831–873), homodimerizes via its first homeodomain (residues 272–432) as a requirement for full repressor activity, and enters the nucleus through an arginine-rich C-terminal NLS (residues 734–768) [#2]. ZHX1 was first identified as a direct binding partner of the NF-YA subunit of the CCAAT-binding factor NF-Y [#1], and it integrates into repressive transcriptional machinery by binding the de novo DNA methyltransferase DNMT3B—engaging the DNMT3B PWWP domain through its homeobox motifs and enhancing DNMT3B-mediated repression—and by binding the corepressor BS69 via a PxLxP motif [#5, #6]. ZHX1 activity and stability are tuned by Ubc9-mediated SUMOylation at K159, K454, and K626, which modulates its ubiquitination and repressor function [#7]. Beyond repression, ZHX1 acts as a co-activator: it partners with hnRNPA1 through residues in its second zinc finger to drive a transcriptional program for cardiac progenitor specification [#12], and it promotes transcription of the mitochondrial ribosomal protein genes Mrps15 and Mrps21 to protect mitochondrial function in hypertensive heart disease [#13]. In cancer cells ZHX1 restrains proliferation by enforcing G1/S arrest and promoting apoptosis [#9, #11].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Establishing that ZHX1 encodes a zinc-finger-class homeodomain protein defined it as a candidate transcription factor and set the structural framework for all later mechanistic work.\",\n      \"evidence\": \"cDNA cloning and ORF sequencing with Northern blot expression profiling in mouse\",\n      \"pmids\": [\"8713137\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No DNA-binding specificity or target genes identified\", \"Function inferred from domain content, not tested\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Identifying ZHX1 as a direct NF-YA interactor connected it to the CCAAT-binding transcriptional machinery, giving its first defined molecular partner.\",\n      \"evidence\": \"Yeast two-hybrid screen of a human liver cDNA library using NF-YA as bait\",\n      \"pmids\": [\"10441475\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-method interaction without reciprocal in-cell validation\", \"Functional consequence of NF-YA binding not defined\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Domain mapping defined ZHX1 as a repressor and assigned its repression, dimerization, and nuclear-targeting functions to discrete regions, converting it from a presumed factor to a mechanistically dissected one.\",\n      \"evidence\": \"Mammalian one-hybrid, GFP-fusion localization and truncation interaction assays in HEK293; independent yeast two-hybrid homodimerization with GFP localization\",\n      \"pmids\": [\"12237128\", \"12062805\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct DNA target sequences not identified\", \"Cofactors mediating repression not yet known\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Mapping the ZHX1 promoter showed how ZHX1 expression is itself controlled, identifying PEA3 and YY1 as synergistic upstream activators.\",\n      \"evidence\": \"Luciferase reporter deletion analysis and EMSA with supershift in mouse\",\n      \"pmids\": [\"12527199\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Regulation in physiological/disease contexts not tested\", \"Single lab\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Discovery of DNMT3B and BS69 partnerships placed ZHX1 within repressive chromatin/corepressor machinery, explaining how it executes repression mechanistically.\",\n      \"evidence\": \"Reciprocal Co-IP, co-localization and transcriptional repression assays (DNMT3B); domain-mapped PxLxP-MYND interaction and reporter assays (BS69)\",\n      \"pmids\": [\"17303076\", \"17127430\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Endogenous target genes co-regulated by these complexes not defined\", \"Whether DNMT3B recruitment alters DNA methylation at ZHX1 targets untested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identifying Ubc9-mediated SUMOylation at three lysines established a post-translational control layer governing ZHX1 stability and activity.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP, site-directed mutagenesis of SUMO acceptor sites and SUMOylation assays\",\n      \"pmids\": [\"23686912\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signals triggering ZHX1 SUMOylation unknown\", \"SUMO-dependent partner switching not characterized\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"A solution NMR structure of a ZHX1 homeodomain provided atomic-level structural information for one of its functional modules.\",\n      \"evidence\": \"Solution NMR structure determination\",\n      \"pmids\": [\"24941917\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional validation of the solved homeodomain\", \"Full-length or multi-domain architecture unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Loss- and gain-of-function studies in cancer cells linked ZHX1 to cell-cycle arrest and apoptosis, assigning it a tumor-suppressive cellular role.\",\n      \"evidence\": \"siRNA/overexpression in gastric and cholangiocarcinoma cells with cell-cycle, apoptosis and invasion readouts\",\n      \"pmids\": [\"26722361\", \"27835650\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct transcriptional targets driving these effects not defined\", \"EGR1 mediation only correlative\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Epistasis placing ZHX1 upstream of PUMA defined a specific pro-apoptotic effector pathway downstream of ZHX1 in hepatocellular carcinoma.\",\n      \"evidence\": \"siRNA, Western blot and xenograft model\",\n      \"pmids\": [\"28559996\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ZHX1 directly transcribes PUMA untested\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identifying the ZHX1/hnRNPA1 co-activator complex demonstrated that ZHX1 can activate transcription and drive a developmental program for cardiac progenitor specification.\",\n      \"evidence\": \"Reciprocal Co-IP, residue-level domain mapping, and loss-of-function in mouse and human ESC differentiation with transcriptomics\",\n      \"pmids\": [\"37452012\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct target promoters bound by the complex not fully mapped\", \"Mechanism of repressor-to-activator switch unknown\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Demonstrating that ZHX1 drives Mrps15/Mrps21 transcription to protect mitochondria established a concrete activator target set and a cardioprotective function.\",\n      \"evidence\": \"Overexpression, mithramycin activation, combined Mrps15/Mrps21 siRNA rescue, mitochondrial respiration assays and in vivo L-NAME model\",\n      \"pmids\": [\"42162768\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding of ZHX1 to Mrps15/Mrps21 promoters not shown\", \"Coactivator partners in this context not identified\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"What determines whether ZHX1 acts as a repressor versus an activator at a given locus, and the genome-wide set of its direct DNA targets, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No genome-wide ZHX1 binding map\", \"Molecular basis of the repressor/activator switch unknown\", \"Direct DNA recognition sequence undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 2, 12, 13]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [2, 3, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [2, 5, 12, 13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"NFYA\", \"DNMT3B\", \"BS69\", \"UBE2I\", \"HNRNPA1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}