Affinage

CHRNB4

Neuronal acetylcholine receptor subunit beta-4 · UniProt P30926

Length
498 aa
Mass
56.4 kDa
Annotated
2026-06-09
39 papers in source corpus 8 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

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).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2001 Medium

    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

    PMID:11450844

    Open questions at the time
    • Did not resolve which partner subunits (α3 vs α4) mediate the bladder phenotype
    • No information on CNS or other peripheral roles of β4
  2. 2010 High

    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

    PMID:20696214

    Open questions at the time
    • Does not identify the full set of transcription factors acting at the locus
    • Tissue specificity of Sp1 dependence not dissected
  3. 2011 Medium

    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

    PMID:22042774

    Open questions at the time
    • Single lab, single study
    • Did not connect functional changes to clinical dependence phenotypes
  4. 2012 Medium

    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

    PMID:22945651

    Open questions at the time
    • Mechanism linking β4 to proliferation not defined (channel-dependent vs independent)
    • Single lab
  5. 2014 Medium

    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

    PMID:24804708

    Open questions at the time
    • In vitro reconstitution may not reflect native receptor stoichiometry
    • Single lab
  6. 2017 Medium

    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

    PMID:28143742

    Open questions at the time
    • Reporter marks the lineage but does not establish a functional requirement for β4 in cone specification
    • No mechanism for cone-restricted expression
  7. 2019 Medium

    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

    PMID:30783126

    Open questions at the time
    • Phenotype reflects Dicer1 loss, not CHRNB4 function
    • Does not test β4 channel activity in cones
  8. 2026 Medium

    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

    PMID:42073514

    Open questions at the time
    • Molecular mechanism of growth suppression not defined
    • Opposite directionality to lung cancer role unexplained
    • Single lab, single study

Open questions

Synthesis pass · forward-looking unresolved questions
  • How CHRNB4 exerts opposite proliferative effects across cancers and whether its non-neuronal roles depend on channel activity versus signaling functions remains unresolved.
  • 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

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060089 molecular transducer activity 3 GO:0005215 transporter activity 2
Localization
GO:0005886 plasma membrane 2
Pathway
R-HSA-112316 Neuronal System 2 R-HSA-162582 Signal Transduction 1
Partners
CHRNA3CHRNA4SP1
Complex memberships
neuronal nicotinic acetylcholine receptor

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2011 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. In vitro functional assay (cellular response to nicotine) of CHRNB4 missense variants expressed in cells Human molecular genetics Medium 22042774
2014 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. 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 PloS one Medium 24804708
2010 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. Transgenic mouse reporter assay with CA box mutation; in vivo promoter activity assessment at ED18.5 and PD30; Sp1-promoter interaction assay Neuroscience High 20696214
2012 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. DNA methylation analysis (CpG island screening), decitabine demethylation treatment, CHRNB4 knockdown with proliferation and colony formation assays in lung cancer cell lines Oncogene Medium 22945651
2017 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. Characterization of Chrnb4-EGFP transgenic mouse line throughout retinogenesis; immunohistochemistry confirming native CHRNB4 protein in EGFP+ cells; sub-retinal transplantation assays Molecular therapy Medium 28143742
2019 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. Chrnb4-Cre conditional knockout of Dicer1; histology, electroretinography (ERG), RNAseq in Dicer CKO retina Scientific reports Medium 30783126
2026 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. 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 Cancers Medium 42073514
2001 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. Mouse knockout phenotype analysis (bladder strip contraction assay with nicotine); human gene characterization and mutation analysis Journal of human genetics Medium 11450844

Source papers

Stage 0 corpus · 39 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2009 The CHRNA5-CHRNA3-CHRNB4 nicotinic receptor subunit gene cluster affects risk for nicotine dependence in African-Americans and in European-Americans. Cancer research 218 19706762
2011 Relationship between CYP2A6 and CHRNA5-CHRNA3-CHRNB4 variation and smoking behaviors and lung cancer risk. Journal of the National Cancer Institute 152 21747048
2009 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. Human molecular genetics 121 19429911
2012 Interplay of genetic risk factors (CHRNA5-CHRNA3-CHRNB4) and cessation treatments in smoking cessation success. The American journal of psychiatry 115 22648373
2011 Genetic variation at CHRNA5-CHRNA3-CHRNB4 interacts with smoking status to influence body mass index. International journal of epidemiology 94 21593077
2009 Association of serum cotinine level with a cluster of three nicotinic acetylcholine receptor genes (CHRNA3/CHRNA5/CHRNB4) on chromosome 15. Human molecular genetics 91 19628476
2017 Cone Genesis Tracing by the Chrnb4-EGFP Mouse Line: Evidences of Cellular Material Fusion after Cone Precursor Transplantation. Molecular therapy : the journal of the American Society of Gene Therapy 64 28143742
2010 TTC12-ANKK1-DRD2 and CHRNA5-CHRNA3-CHRNB4 influence different pathways leading to smoking behavior from adolescence to mid-adulthood. Biological psychiatry 62 21168125
2012 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. Human molecular genetics 59 22956269
2010 Risk gene variants for nicotine dependence in the CHRNA5-CHRNA3-CHRNB4 cluster are associated with cognitive performance. American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics 52 20886544
2010 Association and interaction analysis of variants in CHRNA5/CHRNA3/CHRNB4 gene cluster with nicotine dependence in African and European Americans. American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics 51 19859904
2012 Analysis of detailed phenotype profiles reveals CHRNA5-CHRNA3-CHRNB4 gene cluster association with several nicotine dependence traits. Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco 50 22241830
2011 Rare missense variants in CHRNB4 are associated with reduced risk of nicotine dependence. Human molecular genetics 47 22042774
2012 Epigenetic screen identifies genotype-specific promoter DNA methylation and oncogenic potential of CHRNB4. Oncogene 33 22945651
2013 Distinct loci in the CHRNA5/CHRNA3/CHRNB4 gene cluster are associated with onset of regular smoking. Genetic epidemiology 29 24186853
2010 Variation in the nicotinic acetylcholine receptor gene cluster CHRNA5-CHRNA3-CHRNB4 and its interaction with recent tobacco use influence cognitive flexibility. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 25 20631687
2016 The CHRNA5/CHRNA3/CHRNB4 Nicotinic Receptor Regulome: Genomic Architecture, Regulatory Variants, and Clinical Associations. Human mutation 24 27758088
2015 Gene variance in the nicotinic receptor cluster (CHRNA5-CHRNA3-CHRNB4) predicts death from cardiopulmonary disease and cancer in smokers. Journal of internal medicine 24 26689306
2013 Scrutiny of the CHRNA5-CHRNA3-CHRNB4 smoking behavior locus reveals a novel association with alcohol use in a Finnish population based study. International journal of molecular epidemiology and genetics 22 23875064
2012 Variants located upstream of CHRNB4 on chromosome 15q25.1 are associated with age at onset of daily smoking and habitual smoking. PloS one 22 22438940
2011 Externalizing behaviors are associated with SNPs in the CHRNA5/CHRNA3/CHRNB4 gene cluster. Behavior genetics 22 22042234
2001 Characterization of the human beta4 nAChR gene and polymorphisms in CHRNA3 and CHRNB4. Journal of human genetics 22 11450844
2018 Association and cis-mQTL analysis of variants in CHRNA3-A5, CHRNA7, CHRNB2, and CHRNB4 in relation to nicotine dependence in a Chinese Han population. Translational psychiatry 18 29666375
2012 Polymorphisms of CHRNA5-CHRNA3-CHRNB4 Gene Cluster and NSCLC Risk in Chinese Population. Translational oncology 17 23397474
2013 Genomics and personalized medicine: CHRNA5-CHRNA3-CHRNB4 and smoking cessation treatment. Journal of food and drug analysis 14 25214750
2020 Validating Fluorescent Chrnb4.EGFP Mouse Models for the Study of Cone Photoreceptor Degeneration. Translational vision science & technology 13 32879784
2019 Conditional Dicer1 depletion using Chrnb4-Cre leads to cone cell death and impaired photopic vision. Scientific reports 12 30783126
2013 Smoking status, snus use, and variation at the CHRNA5-CHRNA3-CHRNB4 locus in relation to obesity: the GLACIER study. American journal of epidemiology 11 23729684
2017 Study on polymorphisms in CHRNA5/CHRNA3/CHRNB4 gene cluster and the associated with the risk of non-small cell lung cancer. Oncotarget 10 29416783
2015 Exon sequencing identifies a novel CHRNA3-CHRNA5-CHRNB4 variant that increases the risk for chronic obstructive pulmonary disease. Respirology (Carlton, Vic.) 9 25891420
2012 Associations between variation in CHRNA5-CHRNA3-CHRNB4, body mass index and blood pressure in the Northern Finland Birth Cohort 1966. PloS one 9 23029550
2016 Chromosome 15q25 (CHRNA3-CHRNB4) Variation Indirectly Impacts Lung Cancer Risk in Chinese Males. PloS one 8 26942719
2010 A transcriptional regulatory element critical for CHRNB4 promoter activity in vivo. Neuroscience 7 20696214
2014 Functional characterization improves associations between rare non-synonymous variants in CHRNB4 and smoking behavior. PloS one 6 24804708
2020 Variants in the CHRNA5-CHRNA3-CHRNB4 Region of Chromosome 15 Predict Gastrointestinal Adverse Events in the Transdisciplinary Tobacco Use Research Center Smoking Cessation Trial. Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco 5 30882151
2011 An exploratory study on the CHRNA3-CHRNA5-CHRNB4 cluster, smoking, and Parkinson's disease. Neuro-degenerative diseases 5 21228559
2024 Investigating CHRNA5, CHRNA3, and CHRNB4 variants in the genetic landscape of substance use disorder in Jordan. BMC psychiatry 4 38862938
2025 The impact of bilberry extract combined with docosahexaenoic acid on the expression of Chrnb4 gene in the sclera of myopic guinea pigs. Frontiers in medicine 1 40534703
2026 CHRNB4-Mediated Neuroactive Signaling Rewiring Drives Adaptive Resistance to BCL-2 Inhibition in Acute Myeloid Leukemia. Cancers 0 42073514

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