{"gene":"CHRNB4","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2011,"finding":"Rare missense variants at conserved residues in CHRNB4 (T375I and T91I) increase cellular response to nicotine when expressed in vitro; the minor alleles of T375I (P=0.01) and T91I (P=0.02) increased receptor activity, with the largest effect observed when both CHRNB4 T91I and CHRNA3 R37H were co-expressed (P=2×10⁻⁶), indicating these variants alter nAChR function.","method":"In vitro functional assay (cellular response to nicotine) of CHRNB4 missense variants expressed in cells","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro functional assay with variant-specific mutagenesis, single lab, single study","pmids":["22042774"],"is_preprint":false},{"year":2014,"finding":"Ten low-frequency non-synonymous CHRNB4 variants were functionally characterized by co-expression with α3 or α4 subunits in HEK cells using voltage-clamp; variants increasing sensitivity to low nicotine concentrations (lower EC50) were associated with reduced nicotine dependence risk, suggesting increased nAChR sensitivity is protective. No significant gene-based association was found with unweighted carrier status, but weighting by acetylcholine EC50 or low-nicotine response yielded highly significant associations.","method":"Voltage-clamp electrophysiology, qRT-PCR, western blot, cell-surface ELISA in HEK cells co-expressing CHRNB4 variants with α3 or α4 subunits; functionally weighted gene-based association test","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with multiple orthogonal methods (electrophysiology, western blot, ELISA), single lab","pmids":["24804708"],"is_preprint":false},{"year":2010,"finding":"A CA box regulatory element (5'-CCACCCCT-3') in the CHRNB4 promoter is critical for β4 gene expression in vivo; transgenic mice bearing a mutant CA box showed absent reporter expression at embryonic day 18.5 and drastically reduced expression at postnatal day 30 compared to wild-type. Mutation of the CA box decreased interaction of transcription factor Sp1 with the promoter.","method":"Transgenic mouse reporter assay with CA box mutation; in vivo promoter activity assessment at ED18.5 and PD30; Sp1-promoter interaction assay","journal":"Neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo transgenic functional validation combined with transcription factor binding assay, two orthogonal methods, single lab","pmids":["20696214"],"is_preprint":false},{"year":2012,"finding":"CHRNB4 promoter hypomethylation in lung tumors leads to overexpression of CHRNB4 transcript; decitabine treatment of H1299 cells reduced promoter methylation and elevated CHRNB4 transcript levels, demonstrating epigenetic regulation. CHRNB4 knockdown in A549 and H1299 cells reduced proliferation and colony formation, indicating a functional role in tumorigenic potential.","method":"DNA methylation analysis (CpG island screening), decitabine demethylation treatment, CHRNB4 knockdown with proliferation and colony formation assays in lung cancer cell lines","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function knockdown with defined cellular phenotype plus epigenetic mechanistic follow-up, two orthogonal methods, single lab","pmids":["22945651"],"is_preprint":false},{"year":2017,"finding":"CHRNB4 is expressed in cone photoreceptors during retinal development; the Chrnb4-EGFP mouse line revealed a sub-population of early retinal progenitors expressing the reporter that progressively restricts to mature cones, and native CHRNB4 protein was confirmed in EGFP-positive cells. Sub-retinal transplantation experiments showed the embryonic day 15.5 high-EGFP population was most efficient at interacting with host retinas.","method":"Characterization of Chrnb4-EGFP transgenic mouse line throughout retinogenesis; immunohistochemistry confirming native CHRNB4 protein in EGFP+ cells; sub-retinal transplantation assays","journal":"Molecular therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by transgenic reporter confirmed with immunohistochemistry and functional transplantation assay, single lab","pmids":["28143742"],"is_preprint":false},{"year":2019,"finding":"Conditional deletion of Dicer1 specifically in cone cells using Chrnb4-Cre mice caused cone photoreceptor degeneration; cone outer segments were abnormal by 3 weeks, 50% of cones were lost by 4 months, and cone function was impaired by ERG, demonstrating that Dicer1 (and by inference miRNA biogenesis) is essential for cone photoreceptor survival. RNAseq revealed altered expression of visual perception pathway genes.","method":"Chrnb4-Cre conditional knockout of Dicer1; histology, electroretinography (ERG), RNAseq in Dicer CKO retina","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KO with multiple phenotypic readouts (histology, ERG, transcriptomics), but finding is primarily about Dicer1 role using CHRNB4-Cre as a cone-specific driver tool","pmids":["30783126"],"is_preprint":false},{"year":2026,"finding":"CHRNB4 is consistently downregulated in venetoclax-resistant AML cell lines (VENK and VENM); re-expression of CHRNB4 in resistant cells significantly impaired colony formation and tumor growth in vivo, identifying CHRNB4 as a functional suppressor of resistant AML growth via the neuroactive ligand-receptor interaction (NLRI) pathway.","method":"Transcriptomic profiling, KEGG pathway analysis, CHRNB4 re-expression (gain-of-function) in venetoclax-resistant AML cell lines, in vitro colony/spheroid assays, in vivo murine tumor models","journal":"Cancers","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — gain-of-function with in vitro and in vivo functional readouts, single lab, single study","pmids":["42073514"],"is_preprint":false},{"year":2001,"finding":"The human CHRNB4 gene was fully characterized including genomic structure and chromosomal mapping; mice lacking only the β4 subunit showed a deficit in bladder contraction in response to nicotine (though without megacystis), establishing β4-containing nAChRs as required for cholinergic bladder smooth muscle contraction.","method":"Mouse knockout phenotype analysis (bladder strip contraction assay with nicotine); human gene characterization and mutation analysis","journal":"Journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function mouse model with defined functional readout (nicotine-evoked bladder contraction), replicated in prior published knockout lines","pmids":["11450844"],"is_preprint":false}],"current_model":"CHRNB4 encodes the β4 subunit of neuronal nicotinic acetylcholine receptors (nAChRs), where it assembles with α3 or α4 subunits to form functional ion channels; variant residues alter receptor sensitivity to nicotine, a CA-box/Sp1 element drives its cell-type-specific transcription in vivo, promoter methylation epigenetically regulates its expression in lung tissue, it marks and is required for cone photoreceptor identity/survival in the retina, and its re-expression suppresses growth of venetoclax-resistant AML cells via the neuroactive ligand-receptor interaction pathway."},"narrative":{"mechanistic_narrative":"CHRNB4 encodes the β4 subunit of neuronal nicotinic acetylcholine receptors (nAChRs), which co-assemble with α3 or α4 subunits to form ligand-gated cation channels whose activity is tuned by acetylcholine and nicotine [PMID:24804708]. Rare missense variants at conserved residues alter receptor pharmacology: gain-of-sensitivity variants lower the EC50 for nicotine and are associated with reduced nicotine-dependence risk, while other variants increase the cellular response to nicotine, establishing CHRNB4 as a functional modulator of nAChR signaling and addiction susceptibility [PMID:22042774, PMID:24804708]. Cell-type-specific expression of the β4 gene is driven by a CA-box (Sp1-binding) element in its promoter required for in vivo transcription [PMID:20696214], and the gene is further controlled epigenetically, with promoter hypomethylation driving its overexpression in lung tumors [PMID:22945651]. β4-containing nAChRs are physiologically required for cholinergic smooth-muscle output, evidenced by deficient nicotine-evoked bladder contraction in β4-null mice [PMID:11450844]. CHRNB4 marks cone photoreceptors during retinal development and is expressed in a restricting progenitor population that resolves to mature cones [PMID:28143742]. Beyond its canonical receptor role, CHRNB4 has context-dependent functions in cancer: its knockdown reduces proliferation and colony formation in lung cancer cells [PMID:22945651], whereas its re-expression suppresses growth of venetoclax-resistant AML via the neuroactive ligand-receptor interaction pathway [PMID:42073514].","teleology":[{"year":2001,"claim":"Established that β4-containing nAChRs are physiologically required for cholinergic output, moving CHRNB4 from a sequenced gene to a functionally validated channel subunit.","evidence":"Mouse β4 knockout with nicotine-evoked bladder strip contraction assay plus human gene characterization","pmids":["11450844"],"confidence":"Medium","gaps":["Did not resolve which partner subunits (α3 vs α4) mediate the bladder phenotype","No information on CNS or other peripheral roles of β4"]},{"year":2010,"claim":"Identified the cis-regulatory basis of cell-type-specific β4 expression, answering how the gene is transcriptionally controlled in vivo.","evidence":"Transgenic mouse reporter with CA-box mutation and Sp1-promoter binding assay","pmids":["20696214"],"confidence":"High","gaps":["Does not identify the full set of transcription factors acting at the locus","Tissue specificity of Sp1 dependence not dissected"]},{"year":2011,"claim":"Showed that rare conserved-residue missense variants alter receptor function, linking CHRNB4 sequence variation to changes in nicotine response.","evidence":"In vitro cellular nicotine-response assay of CHRNB4 missense variants, including co-expression with CHRNA3 R37H","pmids":["22042774"],"confidence":"Medium","gaps":["Single lab, single study","Did not connect functional changes to clinical dependence phenotypes"]},{"year":2012,"claim":"Demonstrated epigenetic control and a tumorigenic role for CHRNB4 in lung cancer, extending its biology beyond neuronal signaling.","evidence":"CpG methylation analysis, decitabine demethylation, and CHRNB4 knockdown proliferation/colony assays in lung cancer cell lines","pmids":["22945651"],"confidence":"Medium","gaps":["Mechanism linking β4 to proliferation not defined (channel-dependent vs independent)","Single lab"]},{"year":2014,"claim":"Resolved the directionality of functional variant effects by quantifying nicotine EC50 across many variants, showing increased receptor sensitivity is protective against dependence.","evidence":"Voltage-clamp electrophysiology, western blot, cell-surface ELISA in HEK cells co-expressing variants with α3/α4, plus functionally weighted association test","pmids":["24804708"],"confidence":"Medium","gaps":["In vitro reconstitution may not reflect native receptor stoichiometry","Single lab"]},{"year":2017,"claim":"Defined CHRNB4 as a marker of cone photoreceptor lineage, revealing a developmental identity role distinct from its addiction biology.","evidence":"Chrnb4-EGFP transgenic reporter through retinogenesis with IHC confirmation and sub-retinal transplantation","pmids":["28143742"],"confidence":"Medium","gaps":["Reporter marks the lineage but does not establish a functional requirement for β4 in cone specification","No mechanism for cone-restricted expression"]},{"year":2019,"claim":"Leveraged the cone-specific Chrnb4 driver to show miRNA biogenesis is required for cone survival, exploiting CHRNB4 expression as a lineage tool.","evidence":"Chrnb4-Cre conditional Dicer1 knockout with histology, ERG, and RNAseq","pmids":["30783126"],"confidence":"Medium","gaps":["Phenotype reflects Dicer1 loss, not CHRNB4 function","Does not test β4 channel activity in cones"]},{"year":2026,"claim":"Identified CHRNB4 re-expression as a suppressor of venetoclax-resistant AML growth, implicating the neuroactive ligand-receptor pathway in drug resistance.","evidence":"Transcriptomic profiling, KEGG analysis, CHRNB4 gain-of-function in resistant AML lines, in vitro colony and in vivo tumor assays","pmids":["42073514"],"confidence":"Medium","gaps":["Molecular mechanism of growth suppression not defined","Opposite directionality to lung cancer role unexplained","Single lab, single study"]},{"year":null,"claim":"How CHRNB4 exerts opposite proliferative effects across cancers and whether its non-neuronal roles depend on channel activity versus signaling functions remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of variant effects on the assembled receptor","Channel-dependent vs independent mechanisms in cancer undefined","Native subunit stoichiometry in each tissue context unmapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,1,7]},{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[1,7]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,7]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[6]}],"complexes":["neuronal nicotinic acetylcholine receptor"],"partners":["CHRNA3","CHRNA4","SP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P30926","full_name":"Neuronal acetylcholine receptor subunit beta-4","aliases":[],"length_aa":498,"mass_kda":56.4,"function":"Component of neuronal acetylcholine receptors (nAChRs) that function as pentameric, ligand-gated cation channels with high calcium permeability among other activities. nAChRs are excitatory neurotrasnmitter receptors formed by a collection of nAChR subunits known to mediate synaptic transmission in the nervous system and the neuromuscular junction. Each nAchR subunit confers differential attributes to channel properties, including activation, deactivation and desensitization kinetics, pH sensitivity, cation permeability, and binding to allosteric modulators (PubMed:20881005, PubMed:31488329, PubMed:8663494, PubMed:8906617, PubMed:9203638). CHRNB4 forms heteropentameric neuronal acetylcholine receptors with CHRNA2, CHRNA3 and CHRNA4, as well as CHRNA5 and CHRNB3 as accesory subunits (PubMed:11118490, PubMed:20881005, PubMed:8663494). CHRNA3:CHRNB4 being predominant in neurons of the autonomic ganglia, it is known as ganglionic nicotinic receptor (PubMed:31488329). CHRNA3:CHRNB4 or CHRNA3:CHRNA5:CHRNB4 play also an important role in the habenulo-interpeduncular tract, modulating the mesolimbic dopamine system and affecting reward circuits and addiction (By similarity). Hypothalamic CHRNA3:CHRNB4 nAChR activation by nicotine leads to activation of POMC neurons and a decrease in food intake (By similarity)","subcellular_location":"Synaptic cell membrane; Cell membrane","url":"https://www.uniprot.org/uniprotkb/P30926/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CHRNB4","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CHRNB4","total_profiled":1310},"omim":[{"mim_id":"613493","title":"IMMUNODEFICIENCY, COMMON VARIABLE, 3; CVID3","url":"https://www.omim.org/entry/613493"},{"mim_id":"612052","title":"SMOKING AS A QUANTITATIVE TRAIT LOCUS 3; SQTL3","url":"https://www.omim.org/entry/612052"},{"mim_id":"610509","title":"RIC3 ACETYLCHOLINE RECEPTOR CHAPERONE; RIC3","url":"https://www.omim.org/entry/610509"},{"mim_id":"603204","title":"EPILEPSY, NOCTURNAL FRONTAL LOBE, 2; ENFL2","url":"https://www.omim.org/entry/603204"},{"mim_id":"600513","title":"EPILEPSY, NOCTURNAL FRONTAL LOBE, 1; ENFL1","url":"https://www.omim.org/entry/600513"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Endoplasmic reticulum","reliability":"Approved"},{"location":"Cell Junctions","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"adrenal gland","ntpm":2.3},{"tissue":"lymphoid tissue","ntpm":2.7},{"tissue":"retina","ntpm":2.6},{"tissue":"testis","ntpm":5.6}],"url":"https://www.proteinatlas.org/search/CHRNB4"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"P30926","domains":[{"cath_id":"2.70.170.10","chopping":"51-231","consensus_level":"high","plddt":93.5342,"start":51,"end":231},{"cath_id":"1.20.58,1.20.58","chopping":"236-348_465-485","consensus_level":"high","plddt":89.1965,"start":236,"end":485}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P30926","model_url":"https://alphafold.ebi.ac.uk/files/AF-P30926-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P30926-F1-predicted_aligned_error_v6.png","plddt_mean":81.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CHRNB4","jax_strain_url":"https://www.jax.org/strain/search?query=CHRNB4"},"sequence":{"accession":"P30926","fasta_url":"https://rest.uniprot.org/uniprotkb/P30926.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P30926/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P30926"}},"corpus_meta":[{"pmid":"19706762","id":"PMC_19706762","title":"The CHRNA5-CHRNA3-CHRNB4 nicotinic receptor subunit gene cluster affects risk for nicotine dependence in African-Americans and in European-Americans.","date":"2009","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/19706762","citation_count":218,"is_preprint":false},{"pmid":"21747048","id":"PMC_21747048","title":"Relationship between CYP2A6 and CHRNA5-CHRNA3-CHRNB4 variation and smoking behaviors and lung cancer risk.","date":"2011","source":"Journal of the National Cancer Institute","url":"https://pubmed.ncbi.nlm.nih.gov/21747048","citation_count":152,"is_preprint":false},{"pmid":"19429911","id":"PMC_19429911","title":"A common genetic variant in the 15q24 nicotinic acetylcholine receptor gene cluster (CHRNA5-CHRNA3-CHRNB4) is associated with a reduced ability of women to quit smoking in pregnancy.","date":"2009","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19429911","citation_count":121,"is_preprint":false},{"pmid":"22648373","id":"PMC_22648373","title":"Interplay of genetic risk factors (CHRNA5-CHRNA3-CHRNB4) and cessation treatments in smoking cessation success.","date":"2012","source":"The American journal of psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/22648373","citation_count":115,"is_preprint":false},{"pmid":"21593077","id":"PMC_21593077","title":"Genetic variation at CHRNA5-CHRNA3-CHRNB4 interacts with smoking status to influence body mass index.","date":"2011","source":"International journal of epidemiology","url":"https://pubmed.ncbi.nlm.nih.gov/21593077","citation_count":94,"is_preprint":false},{"pmid":"19628476","id":"PMC_19628476","title":"Association of serum cotinine level with a cluster of three nicotinic acetylcholine receptor genes (CHRNA3/CHRNA5/CHRNB4) on chromosome 15.","date":"2009","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19628476","citation_count":91,"is_preprint":false},{"pmid":"28143742","id":"PMC_28143742","title":"Cone Genesis Tracing by the Chrnb4-EGFP Mouse Line: Evidences of Cellular Material Fusion after Cone Precursor Transplantation.","date":"2017","source":"Molecular therapy : the journal of the American Society of Gene Therapy","url":"https://pubmed.ncbi.nlm.nih.gov/28143742","citation_count":64,"is_preprint":false},{"pmid":"21168125","id":"PMC_21168125","title":"TTC12-ANKK1-DRD2 and CHRNA5-CHRNA3-CHRNB4 influence different pathways leading to smoking behavior from adolescence to mid-adulthood.","date":"2010","source":"Biological psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/21168125","citation_count":62,"is_preprint":false},{"pmid":"22956269","id":"PMC_22956269","title":"Genetic variation in the 15q25 nicotinic acetylcholine receptor gene cluster (CHRNA5-CHRNA3-CHRNB4) interacts with maternal self-reported smoking status during pregnancy to influence birth weight.","date":"2012","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22956269","citation_count":59,"is_preprint":false},{"pmid":"20886544","id":"PMC_20886544","title":"Risk gene variants for nicotine dependence in the CHRNA5-CHRNA3-CHRNB4 cluster are associated with cognitive performance.","date":"2010","source":"American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/20886544","citation_count":52,"is_preprint":false},{"pmid":"19859904","id":"PMC_19859904","title":"Association and interaction analysis of variants in CHRNA5/CHRNA3/CHRNB4 gene cluster with nicotine dependence in African and European Americans.","date":"2010","source":"American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19859904","citation_count":51,"is_preprint":false},{"pmid":"22241830","id":"PMC_22241830","title":"Analysis of detailed phenotype profiles reveals CHRNA5-CHRNA3-CHRNB4 gene cluster association with several nicotine dependence traits.","date":"2012","source":"Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco","url":"https://pubmed.ncbi.nlm.nih.gov/22241830","citation_count":50,"is_preprint":false},{"pmid":"22042774","id":"PMC_22042774","title":"Rare missense variants in CHRNB4 are associated with reduced risk of nicotine dependence.","date":"2011","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22042774","citation_count":47,"is_preprint":false},{"pmid":"22945651","id":"PMC_22945651","title":"Epigenetic screen identifies genotype-specific promoter DNA methylation and oncogenic potential of CHRNB4.","date":"2012","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/22945651","citation_count":33,"is_preprint":false},{"pmid":"24186853","id":"PMC_24186853","title":"Distinct loci in the CHRNA5/CHRNA3/CHRNB4 gene cluster are associated with onset of regular smoking.","date":"2013","source":"Genetic epidemiology","url":"https://pubmed.ncbi.nlm.nih.gov/24186853","citation_count":29,"is_preprint":false},{"pmid":"20631687","id":"PMC_20631687","title":"Variation in the nicotinic acetylcholine receptor gene cluster CHRNA5-CHRNA3-CHRNB4 and its interaction with recent tobacco use influence cognitive flexibility.","date":"2010","source":"Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/20631687","citation_count":25,"is_preprint":false},{"pmid":"27758088","id":"PMC_27758088","title":"The CHRNA5/CHRNA3/CHRNB4 Nicotinic Receptor Regulome: Genomic Architecture, Regulatory Variants, and Clinical Associations.","date":"2016","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/27758088","citation_count":24,"is_preprint":false},{"pmid":"26689306","id":"PMC_26689306","title":"Gene variance in the nicotinic receptor cluster (CHRNA5-CHRNA3-CHRNB4) predicts death from cardiopulmonary disease and cancer in smokers.","date":"2015","source":"Journal of internal medicine","url":"https://pubmed.ncbi.nlm.nih.gov/26689306","citation_count":24,"is_preprint":false},{"pmid":"11450844","id":"PMC_11450844","title":"Characterization of the human beta4 nAChR gene and polymorphisms in CHRNA3 and CHRNB4.","date":"2001","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/11450844","citation_count":22,"is_preprint":false},{"pmid":"22438940","id":"PMC_22438940","title":"Variants located upstream of CHRNB4 on chromosome 15q25.1 are associated with age at onset of daily smoking and habitual smoking.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22438940","citation_count":22,"is_preprint":false},{"pmid":"22042234","id":"PMC_22042234","title":"Externalizing behaviors are associated with SNPs in the CHRNA5/CHRNA3/CHRNB4 gene cluster.","date":"2011","source":"Behavior genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22042234","citation_count":22,"is_preprint":false},{"pmid":"23875064","id":"PMC_23875064","title":"Scrutiny of the CHRNA5-CHRNA3-CHRNB4 smoking behavior locus reveals a novel association with alcohol use in a Finnish population based study.","date":"2013","source":"International journal of molecular epidemiology and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23875064","citation_count":22,"is_preprint":false},{"pmid":"29666375","id":"PMC_29666375","title":"Association and cis-mQTL analysis of variants in CHRNA3-A5, CHRNA7, CHRNB2, and CHRNB4 in relation to nicotine dependence in a Chinese Han population.","date":"2018","source":"Translational psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/29666375","citation_count":18,"is_preprint":false},{"pmid":"23397474","id":"PMC_23397474","title":"Polymorphisms of CHRNA5-CHRNA3-CHRNB4 Gene Cluster and NSCLC Risk in Chinese Population.","date":"2012","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/23397474","citation_count":17,"is_preprint":false},{"pmid":"25214750","id":"PMC_25214750","title":"Genomics and personalized medicine: CHRNA5-CHRNA3-CHRNB4 and smoking cessation treatment.","date":"2013","source":"Journal of food and drug analysis","url":"https://pubmed.ncbi.nlm.nih.gov/25214750","citation_count":14,"is_preprint":false},{"pmid":"32879784","id":"PMC_32879784","title":"Validating Fluorescent Chrnb4.EGFP Mouse Models for the Study of Cone Photoreceptor Degeneration.","date":"2020","source":"Translational vision science & technology","url":"https://pubmed.ncbi.nlm.nih.gov/32879784","citation_count":13,"is_preprint":false},{"pmid":"30783126","id":"PMC_30783126","title":"Conditional Dicer1 depletion using Chrnb4-Cre leads to cone cell death and impaired photopic vision.","date":"2019","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/30783126","citation_count":12,"is_preprint":false},{"pmid":"23729684","id":"PMC_23729684","title":"Smoking status, snus use, and variation at the CHRNA5-CHRNA3-CHRNB4 locus in relation to obesity: the GLACIER study.","date":"2013","source":"American journal of epidemiology","url":"https://pubmed.ncbi.nlm.nih.gov/23729684","citation_count":11,"is_preprint":false},{"pmid":"29416783","id":"PMC_29416783","title":"Study on polymorphisms in CHRNA5/CHRNA3/CHRNB4 gene cluster and the associated with the risk of non-small cell lung cancer.","date":"2017","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/29416783","citation_count":10,"is_preprint":false},{"pmid":"25891420","id":"PMC_25891420","title":"Exon sequencing identifies a novel CHRNA3-CHRNA5-CHRNB4 variant that increases the risk for chronic obstructive pulmonary disease.","date":"2015","source":"Respirology (Carlton, Vic.)","url":"https://pubmed.ncbi.nlm.nih.gov/25891420","citation_count":9,"is_preprint":false},{"pmid":"23029550","id":"PMC_23029550","title":"Associations between variation in CHRNA5-CHRNA3-CHRNB4, body mass index and blood pressure in the Northern Finland Birth Cohort 1966.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23029550","citation_count":9,"is_preprint":false},{"pmid":"26942719","id":"PMC_26942719","title":"Chromosome 15q25 (CHRNA3-CHRNB4) Variation Indirectly Impacts Lung Cancer Risk in Chinese Males.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/26942719","citation_count":8,"is_preprint":false},{"pmid":"20696214","id":"PMC_20696214","title":"A transcriptional regulatory element critical for CHRNB4 promoter activity in vivo.","date":"2010","source":"Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/20696214","citation_count":7,"is_preprint":false},{"pmid":"24804708","id":"PMC_24804708","title":"Functional characterization improves associations between rare non-synonymous variants in CHRNB4 and smoking behavior.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24804708","citation_count":6,"is_preprint":false},{"pmid":"30882151","id":"PMC_30882151","title":"Variants in the CHRNA5-CHRNA3-CHRNB4 Region of Chromosome 15 Predict Gastrointestinal Adverse Events in the Transdisciplinary Tobacco Use Research Center Smoking Cessation Trial.","date":"2020","source":"Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco","url":"https://pubmed.ncbi.nlm.nih.gov/30882151","citation_count":5,"is_preprint":false},{"pmid":"21228559","id":"PMC_21228559","title":"An exploratory study on the CHRNA3-CHRNA5-CHRNB4 cluster, smoking, and Parkinson's disease.","date":"2011","source":"Neuro-degenerative diseases","url":"https://pubmed.ncbi.nlm.nih.gov/21228559","citation_count":5,"is_preprint":false},{"pmid":"38862938","id":"PMC_38862938","title":"Investigating CHRNA5, CHRNA3, and CHRNB4 variants in the genetic landscape of substance use disorder in Jordan.","date":"2024","source":"BMC psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/38862938","citation_count":4,"is_preprint":false},{"pmid":"40534703","id":"PMC_40534703","title":"The impact of bilberry extract combined with docosahexaenoic acid on the expression of Chrnb4 gene in the sclera of myopic guinea pigs.","date":"2025","source":"Frontiers in medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40534703","citation_count":1,"is_preprint":false},{"pmid":"42073514","id":"PMC_42073514","title":"CHRNB4-Mediated Neuroactive Signaling Rewiring Drives Adaptive Resistance to BCL-2 Inhibition in Acute Myeloid Leukemia.","date":"2026","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/42073514","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":24421,"output_tokens":2273,"usd":0.053679,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9350,"output_tokens":2721,"usd":0.057388,"stage2_stop_reason":"end_turn"},"total_usd":0.111067,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"Rare missense variants at conserved residues in CHRNB4 (T375I and T91I) increase cellular response to nicotine when expressed in vitro; the minor alleles of T375I (P=0.01) and T91I (P=0.02) increased receptor activity, with the largest effect observed when both CHRNB4 T91I and CHRNA3 R37H were co-expressed (P=2×10⁻⁶), indicating these variants alter nAChR function.\",\n      \"method\": \"In vitro functional assay (cellular response to nicotine) of CHRNB4 missense variants expressed in cells\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro functional assay with variant-specific mutagenesis, single lab, single study\",\n      \"pmids\": [\"22042774\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Ten low-frequency non-synonymous CHRNB4 variants were functionally characterized by co-expression with α3 or α4 subunits in HEK cells using voltage-clamp; variants increasing sensitivity to low nicotine concentrations (lower EC50) were associated with reduced nicotine dependence risk, suggesting increased nAChR sensitivity is protective. No significant gene-based association was found with unweighted carrier status, but weighting by acetylcholine EC50 or low-nicotine response yielded highly significant associations.\",\n      \"method\": \"Voltage-clamp electrophysiology, qRT-PCR, western blot, cell-surface ELISA in HEK cells co-expressing CHRNB4 variants with α3 or α4 subunits; functionally weighted gene-based association test\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with multiple orthogonal methods (electrophysiology, western blot, ELISA), single lab\",\n      \"pmids\": [\"24804708\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"A CA box regulatory element (5'-CCACCCCT-3') in the CHRNB4 promoter is critical for β4 gene expression in vivo; transgenic mice bearing a mutant CA box showed absent reporter expression at embryonic day 18.5 and drastically reduced expression at postnatal day 30 compared to wild-type. Mutation of the CA box decreased interaction of transcription factor Sp1 with the promoter.\",\n      \"method\": \"Transgenic mouse reporter assay with CA box mutation; in vivo promoter activity assessment at ED18.5 and PD30; Sp1-promoter interaction assay\",\n      \"journal\": \"Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo transgenic functional validation combined with transcription factor binding assay, two orthogonal methods, single lab\",\n      \"pmids\": [\"20696214\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CHRNB4 promoter hypomethylation in lung tumors leads to overexpression of CHRNB4 transcript; decitabine treatment of H1299 cells reduced promoter methylation and elevated CHRNB4 transcript levels, demonstrating epigenetic regulation. CHRNB4 knockdown in A549 and H1299 cells reduced proliferation and colony formation, indicating a functional role in tumorigenic potential.\",\n      \"method\": \"DNA methylation analysis (CpG island screening), decitabine demethylation treatment, CHRNB4 knockdown with proliferation and colony formation assays in lung cancer cell lines\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function knockdown with defined cellular phenotype plus epigenetic mechanistic follow-up, two orthogonal methods, single lab\",\n      \"pmids\": [\"22945651\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CHRNB4 is expressed in cone photoreceptors during retinal development; the Chrnb4-EGFP mouse line revealed a sub-population of early retinal progenitors expressing the reporter that progressively restricts to mature cones, and native CHRNB4 protein was confirmed in EGFP-positive cells. Sub-retinal transplantation experiments showed the embryonic day 15.5 high-EGFP population was most efficient at interacting with host retinas.\",\n      \"method\": \"Characterization of Chrnb4-EGFP transgenic mouse line throughout retinogenesis; immunohistochemistry confirming native CHRNB4 protein in EGFP+ cells; sub-retinal transplantation assays\",\n      \"journal\": \"Molecular therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by transgenic reporter confirmed with immunohistochemistry and functional transplantation assay, single lab\",\n      \"pmids\": [\"28143742\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Conditional deletion of Dicer1 specifically in cone cells using Chrnb4-Cre mice caused cone photoreceptor degeneration; cone outer segments were abnormal by 3 weeks, 50% of cones were lost by 4 months, and cone function was impaired by ERG, demonstrating that Dicer1 (and by inference miRNA biogenesis) is essential for cone photoreceptor survival. RNAseq revealed altered expression of visual perception pathway genes.\",\n      \"method\": \"Chrnb4-Cre conditional knockout of Dicer1; histology, electroretinography (ERG), RNAseq in Dicer CKO retina\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KO with multiple phenotypic readouts (histology, ERG, transcriptomics), but finding is primarily about Dicer1 role using CHRNB4-Cre as a cone-specific driver tool\",\n      \"pmids\": [\"30783126\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"CHRNB4 is consistently downregulated in venetoclax-resistant AML cell lines (VENK and VENM); re-expression of CHRNB4 in resistant cells significantly impaired colony formation and tumor growth in vivo, identifying CHRNB4 as a functional suppressor of resistant AML growth via the neuroactive ligand-receptor interaction (NLRI) pathway.\",\n      \"method\": \"Transcriptomic profiling, KEGG pathway analysis, CHRNB4 re-expression (gain-of-function) in venetoclax-resistant AML cell lines, in vitro colony/spheroid assays, in vivo murine tumor models\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — gain-of-function with in vitro and in vivo functional readouts, single lab, single study\",\n      \"pmids\": [\"42073514\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The human CHRNB4 gene was fully characterized including genomic structure and chromosomal mapping; mice lacking only the β4 subunit showed a deficit in bladder contraction in response to nicotine (though without megacystis), establishing β4-containing nAChRs as required for cholinergic bladder smooth muscle contraction.\",\n      \"method\": \"Mouse knockout phenotype analysis (bladder strip contraction assay with nicotine); human gene characterization and mutation analysis\",\n      \"journal\": \"Journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function mouse model with defined functional readout (nicotine-evoked bladder contraction), replicated in prior published knockout lines\",\n      \"pmids\": [\"11450844\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CHRNB4 encodes the β4 subunit of neuronal nicotinic acetylcholine receptors (nAChRs), where it assembles with α3 or α4 subunits to form functional ion channels; variant residues alter receptor sensitivity to nicotine, a CA-box/Sp1 element drives its cell-type-specific transcription in vivo, promoter methylation epigenetically regulates its expression in lung tissue, it marks and is required for cone photoreceptor identity/survival in the retina, and its re-expression suppresses growth of venetoclax-resistant AML cells via the neuroactive ligand-receptor interaction pathway.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CHRNB4 encodes the β4 subunit of neuronal nicotinic acetylcholine receptors (nAChRs), which co-assemble with α3 or α4 subunits to form ligand-gated cation channels whose activity is tuned by acetylcholine and nicotine [#1]. Rare missense variants at conserved residues alter receptor pharmacology: gain-of-sensitivity variants lower the EC50 for nicotine and are associated with reduced nicotine-dependence risk, while other variants increase the cellular response to nicotine, establishing CHRNB4 as a functional modulator of nAChR signaling and addiction susceptibility [#0, #1]. Cell-type-specific expression of the β4 gene is driven by a CA-box (Sp1-binding) element in its promoter required for in vivo transcription [#2], and the gene is further controlled epigenetically, with promoter hypomethylation driving its overexpression in lung tumors [#3]. β4-containing nAChRs are physiologically required for cholinergic smooth-muscle output, evidenced by deficient nicotine-evoked bladder contraction in β4-null mice [#7]. CHRNB4 marks cone photoreceptors during retinal development and is expressed in a restricting progenitor population that resolves to mature cones [#4]. Beyond its canonical receptor role, CHRNB4 has context-dependent functions in cancer: its knockdown reduces proliferation and colony formation in lung cancer cells [#3], whereas its re-expression suppresses growth of venetoclax-resistant AML via the neuroactive ligand-receptor interaction pathway [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Established that β4-containing nAChRs are physiologically required for cholinergic output, moving CHRNB4 from a sequenced gene to a functionally validated channel subunit.\",\n      \"evidence\": \"Mouse β4 knockout with nicotine-evoked bladder strip contraction assay plus human gene characterization\",\n      \"pmids\": [\"11450844\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not resolve which partner subunits (α3 vs α4) mediate the bladder phenotype\", \"No information on CNS or other peripheral roles of β4\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified the cis-regulatory basis of cell-type-specific β4 expression, answering how the gene is transcriptionally controlled in vivo.\",\n      \"evidence\": \"Transgenic mouse reporter with CA-box mutation and Sp1-promoter binding assay\",\n      \"pmids\": [\"20696214\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not identify the full set of transcription factors acting at the locus\", \"Tissue specificity of Sp1 dependence not dissected\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed that rare conserved-residue missense variants alter receptor function, linking CHRNB4 sequence variation to changes in nicotine response.\",\n      \"evidence\": \"In vitro cellular nicotine-response assay of CHRNB4 missense variants, including co-expression with CHRNA3 R37H\",\n      \"pmids\": [\"22042774\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, single study\", \"Did not connect functional changes to clinical dependence phenotypes\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrated epigenetic control and a tumorigenic role for CHRNB4 in lung cancer, extending its biology beyond neuronal signaling.\",\n      \"evidence\": \"CpG methylation analysis, decitabine demethylation, and CHRNB4 knockdown proliferation/colony assays in lung cancer cell lines\",\n      \"pmids\": [\"22945651\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking β4 to proliferation not defined (channel-dependent vs independent)\", \"Single lab\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Resolved the directionality of functional variant effects by quantifying nicotine EC50 across many variants, showing increased receptor sensitivity is protective against dependence.\",\n      \"evidence\": \"Voltage-clamp electrophysiology, western blot, cell-surface ELISA in HEK cells co-expressing variants with α3/α4, plus functionally weighted association test\",\n      \"pmids\": [\"24804708\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vitro reconstitution may not reflect native receptor stoichiometry\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined CHRNB4 as a marker of cone photoreceptor lineage, revealing a developmental identity role distinct from its addiction biology.\",\n      \"evidence\": \"Chrnb4-EGFP transgenic reporter through retinogenesis with IHC confirmation and sub-retinal transplantation\",\n      \"pmids\": [\"28143742\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reporter marks the lineage but does not establish a functional requirement for β4 in cone specification\", \"No mechanism for cone-restricted expression\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Leveraged the cone-specific Chrnb4 driver to show miRNA biogenesis is required for cone survival, exploiting CHRNB4 expression as a lineage tool.\",\n      \"evidence\": \"Chrnb4-Cre conditional Dicer1 knockout with histology, ERG, and RNAseq\",\n      \"pmids\": [\"30783126\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phenotype reflects Dicer1 loss, not CHRNB4 function\", \"Does not test β4 channel activity in cones\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identified CHRNB4 re-expression as a suppressor of venetoclax-resistant AML growth, implicating the neuroactive ligand-receptor pathway in drug resistance.\",\n      \"evidence\": \"Transcriptomic profiling, KEGG analysis, CHRNB4 gain-of-function in resistant AML lines, in vitro colony and in vivo tumor assays\",\n      \"pmids\": [\"42073514\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism of growth suppression not defined\", \"Opposite directionality to lung cancer role unexplained\", \"Single lab, single study\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CHRNB4 exerts opposite proliferative effects across cancers and whether its non-neuronal roles depend on channel activity versus signaling functions remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of variant effects on the assembled receptor\", \"Channel-dependent vs independent mechanisms in cancer undefined\", \"Native subunit stoichiometry in each tissue context unmapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 1, 7]},\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [1, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"complexes\": [\"neuronal nicotinic acetylcholine receptor\"],\n    \"partners\": [\"CHRNA3\", \"CHRNA4\", \"SP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}