{"gene":"BAHD1","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2009,"finding":"BAHD1 is a nuclear heterochromatinization factor that interacts with HP1, MBD1, HDAC5, and the transcription factor SP1. Overexpression directs HP1 to specific nuclear sites, promotes formation of large heterochromatic domains enriched in H3K27me3 and lacking acetyl-H4. The BAH domain is required for BAHD1 colocalization with H3K27me3. BAHD1 represses target genes (including IGF2) by recruiting MBD1 and HDAC5 to CpG-rich promoters.","method":"Co-immunoprecipitation, immunofluorescence/electron microscopy, genome-wide microarray of knockdown cells, ChIP, overexpression studies with domain mutants","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, domain mutagenesis, direct localization experiments, genome-wide functional readout; multiple orthogonal methods in a single rigorous study","pmids":["19666599"],"is_preprint":false},{"year":2011,"finding":"The secreted Listeria monocytogenes virulence factor LntA targets BAHD1 in the host cell nucleus. The BAHD1-chromatin-associated complex represses interferon-stimulated genes (ISGs) downstream of IFN-λ; LntA prevents BAHD1 recruitment to ISG loci and thereby stimulates their expression, modulating IFN-λ-mediated immune response.","method":"Bacterial infection assays (wild-type vs. ΔlntA Listeria), chromatin immunoprecipitation, BAHD1(+/-) mouse infection model, co-immunoprecipitation","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal approaches (ChIP, genetic mouse model, bacterial genetics), independently corroborated in follow-up structural study","pmids":["21252314"],"is_preprint":false},{"year":2014,"finding":"LntA inhibits BAHD1 through a direct protein–protein interaction: a dilysine motif (K180/K181) in the elbow region of LntA contacts a central proline-rich region of BAHD1. Mutation of K180/K181 abolishes LntA recruitment to BAHD1-associated nuclear foci and abrogates LntA-mediated stimulation of interferon responses during infection. Crystal structure of the K180D/K181D mutant at 2.2-Å resolution reveals redistribution of surface charges near a groove implicated in target recognition.","method":"Crystal structure determination (2.2 Å), site-directed mutagenesis, in vitro binding assays, transfection/infection experiments in human cells","journal":"mBio","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus mutagenesis plus functional validation in vitro and in cellulo, multiple orthogonal methods","pmids":["24449750"],"is_preprint":false},{"year":2016,"finding":"BAHD1 forms a multiprotein chromatin-repressive complex containing MIER1, MIER3, histone deacetylases (HDAC1/2), and methyltransferases. MIER proteins are novel BAHD1 partners; BAHD1-MIER interaction acts as a hub for these epigenetic regulators. BAHD1 and MIER1/3 repress estrogen receptor ESR1 and progesterone receptor PGR gene expression, and BAHD1 overexpression increases MIER1 enrichment on the inactive X chromosome. Bahd1 knockout in mice causes placental growth restriction, hypocholesterolemia, hypoglycemia, and altered steroid/lipid metabolism gene expression.","method":"Biochemical co-purification/mass spectrometry of BAHD1-associated complex, Bahd1 knockout mouse phenotyping, transcriptome profiling (microarray), ChIP, stable overexpression cell lines","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — biochemical complex purification with MS, genetic KO mouse with defined phenotype, ChIP, transcriptomic readout; multiple orthogonal methods","pmids":["26938916"],"is_preprint":false},{"year":2021,"finding":"The BAH domain of BAHD1 directly reads H3K27me3; this interaction is required for overall BAHD1 targeting to chromatin and for optimal repression of H3K27me3-demarcated Polycomb target genes. Point mutations disrupting BAH–H3K27me3 binding lead to increased histone acetylation at Polycomb targets. Mice carrying the H3K27me3-interaction-defective Bahd1BAH mutation show marked embryonic lethality.","method":"Point mutagenesis of BAH domain, chromatin immunoprecipitation, histone modification profiling, knock-in mouse model","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — mutagenesis plus ChIP plus in vivo knock-in mouse model with developmental phenotype; multiple orthogonal methods","pmids":["33823544"],"is_preprint":false},{"year":2021,"finding":"The E3 ubiquitin ligase FBXO11 targets BAHD1 for proteolysis during erythroid maturation. BAHD1 is an H3K27me3 reader that recruits transcriptional corepressors and physically interacts with PRC2. Loss of FBXO11 causes BAHD1 accumulation at bivalent gene promoters, preventing GATA1 recruitment and blocking erythroid gene activation. Depletion of either BAHD1 or PRC2 restores erythroid gene expression in FBXO11-/- cells.","method":"FBXO11 knockout erythroblasts, co-immunoprecipitation of BAHD1-PRC2 complex, ChIP for BAHD1 and GATA1 at target promoters, rescue experiments (BAHD1/PRC2 depletion)","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, genetic KO with defined cellular phenotype, ChIP, epistasis rescue experiments; multiple orthogonal methods","pmids":["33156908"],"is_preprint":false},{"year":2015,"finding":"BAHD1 overexpression in HEK293 cells induces de novo DNA methylation at autosomes (predominantly at satellites, interspersed repeats, and intergenic regions) and causes hypomethylation on the X chromosome (at gene bodies and enhancers), organized in large chromosomal domains overlapping lamina-associated domains, linking BAHD1-mediated heterochromatin formation to DNA methylation patterning.","method":"Whole-genome bisulfite sequencing (BS-seq) comparing isogenic HEK293 cells with stable BAHD1 overexpression vs. control","journal":"Frontiers in genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide bisulfite sequencing with isogenic cell lines, single lab, single primary method","pmids":["26648976"],"is_preprint":false},{"year":2024,"finding":"BAHD1 contributes to heterochromatin compaction (H3K9me3 and H3K27me3) in radioresistant cancer cells; siRNA knockdown of BAHD1 preferentially reduces H3K9me3 and H3K27me3 in radioresistant but not wild-type cells, reverses radioresistance in clonogenic assays, and reduces DNA double-strand break repair.","method":"siRNA knockdown, clonogenic survival assays, histone modification immunoblotting (H3K9me3, H3K27me3), comparison of radioresistant vs. wild-type isogenic cell lines","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with defined molecular (histone marks) and functional (clonogenic) readouts, single lab, multiple orthogonal methods","pmids":["39719436"],"is_preprint":false}],"current_model":"BAHD1 is a nuclear chromatin-repressive factor whose BAH domain directly reads H3K27me3 to target it to Polycomb-repressed loci, where it recruits a multiprotein complex containing HP1, MBD1, MIER1/3, HDAC1/2/5, and PRC2 to promote heterochromatin formation, histone deacetylation, and transcriptional silencing of developmental and immune genes; its activity is antagonized by direct binding of the Listeria nucleomodulin LntA and is terminated during erythropoiesis through FBXO11-mediated ubiquitin-proteasomal degradation."},"narrative":{"mechanistic_narrative":"BAHD1 is a nuclear chromatin-repressive factor that nucleates heterochromatin and transcriptional silencing at Polycomb-regulated loci [PMID:19666599, PMID:33823544]. Its BAH domain directly reads the repressive histone mark H3K27me3, and this recognition is required to target BAHD1 to chromatin and to silence H3K27me3-demarcated Polycomb targets; disrupting the BAH–H3K27me3 interaction increases histone acetylation at these loci and is embryonic-lethal in mice [PMID:33823544]. Once recruited, BAHD1 assembles a multiprotein corepressor complex—directing HP1 to nuclear sites and recruiting MBD1, HDAC5, MIER1/MIER3, HDAC1/2, and PRC2—to drive histone deacetylation and formation of large H3K27me3-enriched heterochromatic domains, thereby repressing target genes including IGF2, ESR1, and PGR [PMID:19666599, PMID:26938916, PMID:33156908]. Through this activity BAHD1 governs developmental and metabolic programs, with Bahd1 knockout causing placental growth restriction and altered steroid/lipid metabolism [PMID:26938916], and it represses interferon-stimulated genes downstream of IFN-λ, an immune silencing function antagonized by direct binding of the Listeria nucleomodulin LntA, which contacts BAHD1 via a dilysine motif to block its recruitment to ISG loci [PMID:21252314, PMID:24449750]. BAHD1 abundance is controlled by FBXO11-mediated ubiquitin-proteasomal degradation, which during erythroid maturation clears BAHD1 from bivalent promoters to permit GATA1 recruitment and erythroid gene activation [PMID:33156908].","teleology":[{"year":2009,"claim":"Established BAHD1 as a heterochromatinization factor, defining its core corepressor partners and showing the BAH domain links it to H3K27me3-marked chromatin and CpG-rich promoter silencing.","evidence":"Co-IP, immunofluorescence/EM, genome-wide microarray of knockdown cells, ChIP, and domain-mutant overexpression in human cells","pmids":["19666599"],"confidence":"High","gaps":["Did not establish whether the BAH domain binds H3K27me3 directly versus via complex members","Mechanism connecting heterochromatin formation to DNA methylation not addressed"]},{"year":2011,"claim":"Revealed an immune-silencing role by showing the BAHD1 complex represses interferon-stimulated genes downstream of IFN-λ and is targeted by the Listeria nucleomodulin LntA, framing BAHD1 as a host chromatin target of a bacterial effector.","evidence":"Listeria infection assays (WT vs. ΔlntA), ChIP, Bahd1(+/-) mouse infection model, and Co-IP","pmids":["21252314"],"confidence":"High","gaps":["Structural basis of the LntA-BAHD1 interaction not yet defined","Scope of physiological ISGs controlled by BAHD1 not fully mapped"]},{"year":2014,"claim":"Defined the molecular interface of LntA antagonism, mapping a dilysine motif on LntA to a proline-rich region of BAHD1 and validating that this contact is required for LntA-mediated derepression of interferon responses.","evidence":"2.2-Å crystal structure of an LntA mutant, site-directed mutagenesis, in vitro binding, and infection/transfection in human cells","pmids":["24449750"],"confidence":"High","gaps":["No structure of the BAHD1 region engaged by LntA","Does not address how LntA binding sterically or allosterically blocks chromatin recruitment"]},{"year":2015,"claim":"Connected BAHD1-driven heterochromatin to DNA methylation patterning, showing overexpression reprograms autosomal and X-chromosomal methylation in large domains overlapping lamina-associated regions.","evidence":"Whole-genome bisulfite sequencing of isogenic HEK293 cells with stable BAHD1 overexpression vs. control","pmids":["26648976"],"confidence":"Medium","gaps":["Single primary method from one lab","Causal mechanism linking BAHD1 to DNA methyltransferase activity not demonstrated","Overexpression context may not reflect endogenous patterning"]},{"year":2016,"claim":"Expanded the BAHD1 corepressor complex by identifying MIER1/MIER3 as a partner hub bridging HDAC1/2 and methyltransferases, and tied BAHD1 to hormone-receptor gene repression and to systemic metabolic and placental phenotypes in vivo.","evidence":"Co-purification/mass spectrometry, Bahd1 knockout mouse phenotyping, transcriptomics, and ChIP","pmids":["26938916"],"confidence":"High","gaps":["Stoichiometry and assembly order of the complex not resolved","Direct enzymatic contribution of the associated methyltransferases not defined"]},{"year":2021,"claim":"Demonstrated that the BAH domain directly reads H3K27me3 and that this recognition is functionally required, linking the reader activity to repression of Polycomb targets and to embryonic viability.","evidence":"BAH-domain point mutagenesis, ChIP, histone modification profiling, and an H3K27me3-binding-defective knock-in mouse","pmids":["33823544"],"confidence":"High","gaps":["Atomic structure of the BAH-H3K27me3 complex not reported here","Relationship between H3K27me3 reading and the previously observed DNA methylation changes not addressed"]},{"year":2021,"claim":"Identified post-translational control of BAHD1 by FBXO11-mediated degradation and showed BAHD1 physically associates with PRC2, establishing that timely BAHD1 clearance from bivalent promoters licenses GATA1-driven erythroid gene activation.","evidence":"FBXO11 knockout erythroblasts, BAHD1-PRC2 Co-IP, ChIP for BAHD1 and GATA1, and BAHD1/PRC2 depletion rescue experiments","pmids":["33156908"],"confidence":"High","gaps":["Degron and ubiquitination sites on BAHD1 not mapped","Whether FBXO11 control of BAHD1 operates outside erythropoiesis unknown"]},{"year":2024,"claim":"Implicated BAHD1 in cancer radioresistance, showing it sustains H3K9me3/H3K27me3 heterochromatin compaction and supports double-strand break repair selectively in radioresistant cells.","evidence":"siRNA knockdown, clonogenic survival assays, and histone-mark immunoblotting in radioresistant vs. wild-type isogenic cell lines","pmids":["39719436"],"confidence":"Medium","gaps":["Mechanism linking BAHD1 to H3K9me3 (versus its established H3K27me3 reading) not defined","Single-lab, knockdown-only evidence without in vivo validation"]},{"year":null,"claim":"How BAHD1-templated heterochromatin is mechanistically coupled to de novo DNA methylation and H3K9me3 deposition, and the high-resolution structural basis of its BAH-H3K27me3 reading, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No atomic structure of BAHD1 BAH domain bound to H3K27me3","Enzyme(s) BAHD1 recruits to write DNA methylation not identified","Direct mechanistic link between BAHD1 and H3K9me3 unestablished"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[0,4]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,3,5]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,3]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,1]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[0,4]}],"pathway":[{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[0,4,7]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,3,5]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[1,2]}],"complexes":["BAHD1 chromatin-repressive complex","PRC2 (associated)"],"partners":["HP1","MBD1","HDAC5","MIER1","MIER3","HDAC1","PRC2","FBXO11"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8TBE0","full_name":"Bromo adjacent homology domain-containing 1 protein","aliases":[],"length_aa":780,"mass_kda":84.7,"function":"Heterochromatin protein that acts as a transcription repressor and has the ability to promote the formation of large heterochromatic domains. May act by recruiting heterochromatin proteins such as CBX5 (HP1 alpha), HDAC5 and MBD1. Represses IGF2 expression by binding to its CpG-rich P3 promoter and recruiting heterochromatin proteins. At specific stages of Listeria infection, in complex with TRIM28, corepresses interferon-stimulated genes, including IFNL1, IFNL2 and IFNL3","subcellular_location":"Nucleus; Chromosome","url":"https://www.uniprot.org/uniprotkb/Q8TBE0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/BAHD1","classification":"Not Classified","n_dependent_lines":12,"n_total_lines":1208,"dependency_fraction":0.009933774834437087},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"HDAC1","stoichiometry":0.2},{"gene":"HDAC2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/BAHD1","total_profiled":1310},"omim":[{"mim_id":"613880","title":"BROMO-ADJACENT HOMOLOGY DOMAIN-CONTAINING PROTEIN 1; BAHD1","url":"https://www.omim.org/entry/613880"}],"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/BAHD1"},"hgnc":{"alias_symbol":["KIAA0945"],"prev_symbol":[]},"alphafold":{"accession":"Q8TBE0","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TBE0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TBE0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TBE0-F1-predicted_aligned_error_v6.png","plddt_mean":50.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=BAHD1","jax_strain_url":"https://www.jax.org/strain/search?query=BAHD1"},"sequence":{"accession":"Q8TBE0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TBE0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TBE0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TBE0"}},"corpus_meta":[{"pmid":"21252314","id":"PMC_21252314","title":"A bacterial protein targets the BAHD1 chromatin complex to stimulate type III interferon response.","date":"2011","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/21252314","citation_count":139,"is_preprint":false},{"pmid":"19666599","id":"PMC_19666599","title":"Human BAHD1 promotes heterochromatic gene silencing.","date":"2009","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/19666599","citation_count":73,"is_preprint":false},{"pmid":"24449750","id":"PMC_24449750","title":"Structural basis for the inhibition of the chromatin repressor BAHD1 by the bacterial nucleomodulin LntA.","date":"2014","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/24449750","citation_count":34,"is_preprint":false},{"pmid":"33156908","id":"PMC_33156908","title":"FBXO11-mediated proteolysis of BAHD1 relieves PRC2-dependent transcriptional repression in erythropoiesis.","date":"2021","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/33156908","citation_count":31,"is_preprint":false},{"pmid":"26938916","id":"PMC_26938916","title":"Role of the BAHD1 Chromatin-Repressive Complex in Placental Development and Regulation of Steroid Metabolism.","date":"2016","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26938916","citation_count":29,"is_preprint":false},{"pmid":"33823544","id":"PMC_33823544","title":"A conserved BAH module within mammalian BAHD1 connects H3K27me3 to Polycomb gene silencing.","date":"2021","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/33823544","citation_count":25,"is_preprint":false},{"pmid":"26648976","id":"PMC_26648976","title":"Overexpression of the Heterochromatinization Factor BAHD1 in HEK293 Cells Differentially Reshapes the DNA Methylome on Autosomes and X Chromosome.","date":"2015","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26648976","citation_count":18,"is_preprint":false},{"pmid":"26183847","id":"PMC_26183847","title":"Computational Prediction and Validation of BAHD1 as a Novel Molecule for Ulcerative Colitis.","date":"2015","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26183847","citation_count":17,"is_preprint":false},{"pmid":"30352868","id":"PMC_30352868","title":"Mapping of breakpoints in balanced chromosomal translocations by shallow whole-genome sequencing points to EFNA5, BAHD1 and PPP2R5E as novel candidates for genes causing human Mendelian disorders.","date":"2018","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30352868","citation_count":14,"is_preprint":false},{"pmid":"35048286","id":"PMC_35048286","title":"BAHD1 serves as a critical regulator of breast cancer cell proliferation and invasion.","date":"2022","source":"Breast cancer (Tokyo, Japan)","url":"https://pubmed.ncbi.nlm.nih.gov/35048286","citation_count":6,"is_preprint":false},{"pmid":"32407325","id":"PMC_32407325","title":"BAHD1 haploinsufficiency results in anxiety-like phenotypes in male mice.","date":"2020","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/32407325","citation_count":6,"is_preprint":false},{"pmid":"39719436","id":"PMC_39719436","title":"Genomic and transcriptomic profiling of radioresistant prostate and head and neck cancers implicate a BAHD1-dependent modification of DNA damage at the heterochromatin.","date":"2024","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/39719436","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8453,"output_tokens":2467,"usd":0.031182,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9582,"output_tokens":3333,"usd":0.065617,"stage2_stop_reason":"end_turn"},"total_usd":0.096799,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"BAHD1 is a nuclear heterochromatinization factor that interacts with HP1, MBD1, HDAC5, and the transcription factor SP1. Overexpression directs HP1 to specific nuclear sites, promotes formation of large heterochromatic domains enriched in H3K27me3 and lacking acetyl-H4. The BAH domain is required for BAHD1 colocalization with H3K27me3. BAHD1 represses target genes (including IGF2) by recruiting MBD1 and HDAC5 to CpG-rich promoters.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence/electron microscopy, genome-wide microarray of knockdown cells, ChIP, overexpression studies with domain mutants\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, domain mutagenesis, direct localization experiments, genome-wide functional readout; multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"19666599\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The secreted Listeria monocytogenes virulence factor LntA targets BAHD1 in the host cell nucleus. The BAHD1-chromatin-associated complex represses interferon-stimulated genes (ISGs) downstream of IFN-λ; LntA prevents BAHD1 recruitment to ISG loci and thereby stimulates their expression, modulating IFN-λ-mediated immune response.\",\n      \"method\": \"Bacterial infection assays (wild-type vs. ΔlntA Listeria), chromatin immunoprecipitation, BAHD1(+/-) mouse infection model, co-immunoprecipitation\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal approaches (ChIP, genetic mouse model, bacterial genetics), independently corroborated in follow-up structural study\",\n      \"pmids\": [\"21252314\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"LntA inhibits BAHD1 through a direct protein–protein interaction: a dilysine motif (K180/K181) in the elbow region of LntA contacts a central proline-rich region of BAHD1. Mutation of K180/K181 abolishes LntA recruitment to BAHD1-associated nuclear foci and abrogates LntA-mediated stimulation of interferon responses during infection. Crystal structure of the K180D/K181D mutant at 2.2-Å resolution reveals redistribution of surface charges near a groove implicated in target recognition.\",\n      \"method\": \"Crystal structure determination (2.2 Å), site-directed mutagenesis, in vitro binding assays, transfection/infection experiments in human cells\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus mutagenesis plus functional validation in vitro and in cellulo, multiple orthogonal methods\",\n      \"pmids\": [\"24449750\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"BAHD1 forms a multiprotein chromatin-repressive complex containing MIER1, MIER3, histone deacetylases (HDAC1/2), and methyltransferases. MIER proteins are novel BAHD1 partners; BAHD1-MIER interaction acts as a hub for these epigenetic regulators. BAHD1 and MIER1/3 repress estrogen receptor ESR1 and progesterone receptor PGR gene expression, and BAHD1 overexpression increases MIER1 enrichment on the inactive X chromosome. Bahd1 knockout in mice causes placental growth restriction, hypocholesterolemia, hypoglycemia, and altered steroid/lipid metabolism gene expression.\",\n      \"method\": \"Biochemical co-purification/mass spectrometry of BAHD1-associated complex, Bahd1 knockout mouse phenotyping, transcriptome profiling (microarray), ChIP, stable overexpression cell lines\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — biochemical complex purification with MS, genetic KO mouse with defined phenotype, ChIP, transcriptomic readout; multiple orthogonal methods\",\n      \"pmids\": [\"26938916\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The BAH domain of BAHD1 directly reads H3K27me3; this interaction is required for overall BAHD1 targeting to chromatin and for optimal repression of H3K27me3-demarcated Polycomb target genes. Point mutations disrupting BAH–H3K27me3 binding lead to increased histone acetylation at Polycomb targets. Mice carrying the H3K27me3-interaction-defective Bahd1BAH mutation show marked embryonic lethality.\",\n      \"method\": \"Point mutagenesis of BAH domain, chromatin immunoprecipitation, histone modification profiling, knock-in mouse model\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — mutagenesis plus ChIP plus in vivo knock-in mouse model with developmental phenotype; multiple orthogonal methods\",\n      \"pmids\": [\"33823544\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The E3 ubiquitin ligase FBXO11 targets BAHD1 for proteolysis during erythroid maturation. BAHD1 is an H3K27me3 reader that recruits transcriptional corepressors and physically interacts with PRC2. Loss of FBXO11 causes BAHD1 accumulation at bivalent gene promoters, preventing GATA1 recruitment and blocking erythroid gene activation. Depletion of either BAHD1 or PRC2 restores erythroid gene expression in FBXO11-/- cells.\",\n      \"method\": \"FBXO11 knockout erythroblasts, co-immunoprecipitation of BAHD1-PRC2 complex, ChIP for BAHD1 and GATA1 at target promoters, rescue experiments (BAHD1/PRC2 depletion)\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, genetic KO with defined cellular phenotype, ChIP, epistasis rescue experiments; multiple orthogonal methods\",\n      \"pmids\": [\"33156908\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"BAHD1 overexpression in HEK293 cells induces de novo DNA methylation at autosomes (predominantly at satellites, interspersed repeats, and intergenic regions) and causes hypomethylation on the X chromosome (at gene bodies and enhancers), organized in large chromosomal domains overlapping lamina-associated domains, linking BAHD1-mediated heterochromatin formation to DNA methylation patterning.\",\n      \"method\": \"Whole-genome bisulfite sequencing (BS-seq) comparing isogenic HEK293 cells with stable BAHD1 overexpression vs. control\",\n      \"journal\": \"Frontiers in genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide bisulfite sequencing with isogenic cell lines, single lab, single primary method\",\n      \"pmids\": [\"26648976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"BAHD1 contributes to heterochromatin compaction (H3K9me3 and H3K27me3) in radioresistant cancer cells; siRNA knockdown of BAHD1 preferentially reduces H3K9me3 and H3K27me3 in radioresistant but not wild-type cells, reverses radioresistance in clonogenic assays, and reduces DNA double-strand break repair.\",\n      \"method\": \"siRNA knockdown, clonogenic survival assays, histone modification immunoblotting (H3K9me3, H3K27me3), comparison of radioresistant vs. wild-type isogenic cell lines\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with defined molecular (histone marks) and functional (clonogenic) readouts, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"39719436\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"BAHD1 is a nuclear chromatin-repressive factor whose BAH domain directly reads H3K27me3 to target it to Polycomb-repressed loci, where it recruits a multiprotein complex containing HP1, MBD1, MIER1/3, HDAC1/2/5, and PRC2 to promote heterochromatin formation, histone deacetylation, and transcriptional silencing of developmental and immune genes; its activity is antagonized by direct binding of the Listeria nucleomodulin LntA and is terminated during erythropoiesis through FBXO11-mediated ubiquitin-proteasomal degradation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"BAHD1 is a nuclear chromatin-repressive factor that nucleates heterochromatin and transcriptional silencing at Polycomb-regulated loci [#0, #4]. Its BAH domain directly reads the repressive histone mark H3K27me3, and this recognition is required to target BAHD1 to chromatin and to silence H3K27me3-demarcated Polycomb targets; disrupting the BAH–H3K27me3 interaction increases histone acetylation at these loci and is embryonic-lethal in mice [#4]. Once recruited, BAHD1 assembles a multiprotein corepressor complex—directing HP1 to nuclear sites and recruiting MBD1, HDAC5, MIER1/MIER3, HDAC1/2, and PRC2—to drive histone deacetylation and formation of large H3K27me3-enriched heterochromatic domains, thereby repressing target genes including IGF2, ESR1, and PGR [#0, #3, #5]. Through this activity BAHD1 governs developmental and metabolic programs, with Bahd1 knockout causing placental growth restriction and altered steroid/lipid metabolism [#3], and it represses interferon-stimulated genes downstream of IFN-\\u03bb, an immune silencing function antagonized by direct binding of the Listeria nucleomodulin LntA, which contacts BAHD1 via a dilysine motif to block its recruitment to ISG loci [#1, #2]. BAHD1 abundance is controlled by FBXO11-mediated ubiquitin-proteasomal degradation, which during erythroid maturation clears BAHD1 from bivalent promoters to permit GATA1 recruitment and erythroid gene activation [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Established BAHD1 as a heterochromatinization factor, defining its core corepressor partners and showing the BAH domain links it to H3K27me3-marked chromatin and CpG-rich promoter silencing.\",\n      \"evidence\": \"Co-IP, immunofluorescence/EM, genome-wide microarray of knockdown cells, ChIP, and domain-mutant overexpression in human cells\",\n      \"pmids\": [\"19666599\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish whether the BAH domain binds H3K27me3 directly versus via complex members\", \"Mechanism connecting heterochromatin formation to DNA methylation not addressed\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealed an immune-silencing role by showing the BAHD1 complex represses interferon-stimulated genes downstream of IFN-\\u03bb and is targeted by the Listeria nucleomodulin LntA, framing BAHD1 as a host chromatin target of a bacterial effector.\",\n      \"evidence\": \"Listeria infection assays (WT vs. \\u0394lntA), ChIP, Bahd1(+/-) mouse infection model, and Co-IP\",\n      \"pmids\": [\"21252314\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the LntA-BAHD1 interaction not yet defined\", \"Scope of physiological ISGs controlled by BAHD1 not fully mapped\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined the molecular interface of LntA antagonism, mapping a dilysine motif on LntA to a proline-rich region of BAHD1 and validating that this contact is required for LntA-mediated derepression of interferon responses.\",\n      \"evidence\": \"2.2-\\u00c5 crystal structure of an LntA mutant, site-directed mutagenesis, in vitro binding, and infection/transfection in human cells\",\n      \"pmids\": [\"24449750\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structure of the BAHD1 region engaged by LntA\", \"Does not address how LntA binding sterically or allosterically blocks chromatin recruitment\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected BAHD1-driven heterochromatin to DNA methylation patterning, showing overexpression reprograms autosomal and X-chromosomal methylation in large domains overlapping lamina-associated regions.\",\n      \"evidence\": \"Whole-genome bisulfite sequencing of isogenic HEK293 cells with stable BAHD1 overexpression vs. control\",\n      \"pmids\": [\"26648976\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single primary method from one lab\", \"Causal mechanism linking BAHD1 to DNA methyltransferase activity not demonstrated\", \"Overexpression context may not reflect endogenous patterning\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Expanded the BAHD1 corepressor complex by identifying MIER1/MIER3 as a partner hub bridging HDAC1/2 and methyltransferases, and tied BAHD1 to hormone-receptor gene repression and to systemic metabolic and placental phenotypes in vivo.\",\n      \"evidence\": \"Co-purification/mass spectrometry, Bahd1 knockout mouse phenotyping, transcriptomics, and ChIP\",\n      \"pmids\": [\"26938916\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and assembly order of the complex not resolved\", \"Direct enzymatic contribution of the associated methyltransferases not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrated that the BAH domain directly reads H3K27me3 and that this recognition is functionally required, linking the reader activity to repression of Polycomb targets and to embryonic viability.\",\n      \"evidence\": \"BAH-domain point mutagenesis, ChIP, histone modification profiling, and an H3K27me3-binding-defective knock-in mouse\",\n      \"pmids\": [\"33823544\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic structure of the BAH-H3K27me3 complex not reported here\", \"Relationship between H3K27me3 reading and the previously observed DNA methylation changes not addressed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified post-translational control of BAHD1 by FBXO11-mediated degradation and showed BAHD1 physically associates with PRC2, establishing that timely BAHD1 clearance from bivalent promoters licenses GATA1-driven erythroid gene activation.\",\n      \"evidence\": \"FBXO11 knockout erythroblasts, BAHD1-PRC2 Co-IP, ChIP for BAHD1 and GATA1, and BAHD1/PRC2 depletion rescue experiments\",\n      \"pmids\": [\"33156908\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Degron and ubiquitination sites on BAHD1 not mapped\", \"Whether FBXO11 control of BAHD1 operates outside erythropoiesis unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Implicated BAHD1 in cancer radioresistance, showing it sustains H3K9me3/H3K27me3 heterochromatin compaction and supports double-strand break repair selectively in radioresistant cells.\",\n      \"evidence\": \"siRNA knockdown, clonogenic survival assays, and histone-mark immunoblotting in radioresistant vs. wild-type isogenic cell lines\",\n      \"pmids\": [\"39719436\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking BAHD1 to H3K9me3 (versus its established H3K27me3 reading) not defined\", \"Single-lab, knockdown-only evidence without in vivo validation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How BAHD1-templated heterochromatin is mechanistically coupled to de novo DNA methylation and H3K9me3 deposition, and the high-resolution structural basis of its BAH-H3K27me3 reading, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No atomic structure of BAHD1 BAH domain bound to H3K27me3\", \"Enzyme(s) BAHD1 recruits to write DNA methylation not identified\", \"Direct mechanistic link between BAHD1 and H3K9me3 unestablished\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 3, 5]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [0, 4, 7]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 3, 5]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"complexes\": [\"BAHD1 chromatin-repressive complex\", \"PRC2 (associated)\"],\n    \"partners\": [\"HP1\", \"MBD1\", \"HDAC5\", \"MIER1\", \"MIER3\", \"HDAC1\", \"PRC2\", \"FBXO11\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}