Affinage

CHRNA1

Acetylcholine receptor subunit alpha · UniProt P02708

Length
457 aa
Mass
51.8 kDa
Annotated
2026-06-09
27 papers in source corpus 10 papers cited in narrative 10 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

CHRNA1 encodes the α1-subunit of the muscle nicotinic acetylcholine receptor, a ligand-gated cation channel whose abundance must be tightly controlled at the levels of transcription, alternative splicing, and mRNA localization to build and maintain the neuromuscular junction (PMID:18806275, PMID:22884571). Production of functional α-subunit depends on skipping of the nonfunctional in-frame exon P3A, which is enforced by a hierarchy of RNA-binding proteins acting on an intronic splicing silencer and adjacent polypyrimidine tract at the 3' end of intron 3: hnRNP H binds the silencer to drive P3A skipping (PMID:18806275), PTB independently suppresses P3A inclusion (PMID:19147685), and hnRNP L promotes PTB binding through its proline-rich region (thereby blocking U2AF65/U1 snRNP-dependent exon definition), while hnRNP LL antagonizes this suppression to favor P3A inclusion (PMID:24121633). Mutations that disrupt these elements—the intronic IVS3-8G>A silencer mutation that abolishes hnRNP H binding (PMID:18806275), a P3A mutation creating a de novo hnRNP LL site that displaces hnRNP L (PMID:24121633), and the c.257G>A (p.Arg86His) variant (PMID:36634413)—force exclusive P3A inclusion and produce a nonfunctional α-subunit, causing acetylcholine receptor deficiency congenital myasthenic syndrome (PMID:18806275, PMID:36634413). At the synapse, agrin stimulation recruits Chrna1 mRNA to the assembled receptor complex via Staufen1-mediated localization, which is required for AChR clustering (PMID:22884571). CHRNA1 expression is also regulated in non-muscle contexts: IRF8 and AIRE control its thymic epithelial expression for self-tolerance (PMID:17687331), and in sweat glands PAI1 (SERPINE1) negatively regulates CHRNA1, whose cholinergic ion-channel activity drives sweat secretion and primary focal hyperhidrosis through downstream AQP5, CACNA1C, and neurotrophic factor release (PMID:33476802, PMID:35393764, PMID:37542348).

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2007 High

    Established that CHRNA1 transcription is actively controlled outside muscle—in thymic epithelium—where IRF8 and AIRE set its expression level, explaining a route by which receptor self-tolerance is enforced.

    Evidence Promoter resequencing, in vitro promoter activity and transactivation assays in human thymic epithelial cells, ex vivo mRNA quantification

    PMID:17687331

    Open questions at the time
    • Does not address muscle/NMJ transcriptional control
    • Mechanism by which thymic CHRNA1 levels shape tolerance not directly demonstrated
  2. 2008 High

    Answered how the nonfunctional P3A exon is normally excluded by identifying hnRNP H binding to an intronic splicing silencer, and showed a CMS mutation that cripples this binding, directly linking splicing control to disease.

    Evidence ISS-binding and competition assays, hnRNP H siRNA knockdown, minigene reporter, patient mutation analysis

    PMID:18806275

    Open questions at the time
    • Other silencer-binding factors not yet defined
    • Did not establish how multiple regulators are coordinated
  3. 2009 Medium

    Identified PTB as a second, hnRNP H-independent suppressor of P3A inclusion and showed pharmacological induction of PTB can correct aberrant splicing, opening a therapeutic strategy.

    Evidence PTB binding and minigene reporter assays, promoter deletion, 960-compound screen, tannic acid rescue of IVS3-8G>A splicing

    PMID:19147685

    Open questions at the time
    • Single-lab compound screen without in vivo efficacy
    • How PTB and hnRNP H functionally intersect not resolved here
  4. 2013 High

    Resolved the regulatory hierarchy by showing hnRNP L promotes PTB binding via its proline-rich region to block exon definition while hnRNP LL antagonizes it, and a P3A mutation creating a de novo hnRNP LL site flips suppression to enhancement.

    Evidence RNA pulldown, hnRNP L–PTB Co-IP, UV cross-linking, domain deletion, U2AF65/U1 snRNP association assays, minigene reporter

    PMID:24121633

    Open questions at the time
    • Stoichiometry and dynamics of the multi-protein complex on the RNA not quantified
    • Tissue-specific abundance of hnRNP L vs LL not addressed
  5. 2012 Medium

    Showed that proper AChR assembly at the synapse depends on subcellular mRNA targeting, identifying Staufen1-mediated localization of Chrna1 mRNA as required for agrin-induced receptor clustering.

    Evidence Affinity/ultracentrifugation RT-PCR of AChR-associated RNA, Stau1 RIP, Stau1 RNAi with AChR clustering readout in C2C12 myotubes

    PMID:22884571

    Open questions at the time
    • Direct vs indirect Stau1–Chrna1 mRNA contact not distinguished
    • In vivo NMJ relevance not tested
  6. 2021 Medium

    Extended CHRNA1 biology to sweat glands, demonstrating that its upregulation drives hyperhidrosis through secretory and neurotrophic effector pathways (AQP5, CACNA1C, BDNF, NRG-1).

    Evidence Expression profiling, CHRNA1 siRNA knockdown, electron microscopy of secretory granules, ELISA, immunohistochemistry in PFH patients and pilocarpine mouse model

    PMID:33476802

    Open questions at the time
    • Causal ordering among downstream effectors not established
    • Cell-type source of altered acetylcholine unclear
  7. 2022 Medium

    Distinguished CHRNA1's channel function from its expression by showing the antagonist cisatracurium relieves hyperhidrosis by blocking ion conduction, with genetic epistasis confirming on-target action.

    Evidence HEK293 heterologous expression with electrophysiology, cisatracurium block, OE/KD epistasis, pilocarpine mouse model

    PMID:35393764

    Open questions at the time
    • Single-lab pharmacology
    • Receptor subunit composition in sweat gland context not defined
  8. 2022 Medium

    Provided in vivo evidence that elevated CHRNA1 is itself pathogenic in muscle aging, driving denervation and atrophy consistent with sarcopenia.

    Evidence AAV9-CHRNA1 overexpression in mouse hindlimb with innervation, mass index, fiber CSA, CMAP, and contractility readouts

    PMID:35809807

    Open questions at the time
    • Mechanism linking overexpression to synaptic elimination not defined
    • Single gain-of-function strategy without loss-of-function confirmation
  9. 2023 Medium

    Placed PAI1 (SERPINE1) upstream of CHRNA1 as a negative regulator of sweat gland secretion, with reciprocal genetic and pharmacological rescue establishing the regulatory direction.

    Evidence Serpine1 KO and Tg mice, AAV-Chrna1 and cisatracurium rescue, ELISA and expression assays in pilocarpine model

    PMID:37542348

    Open questions at the time
    • Whether PAI1 regulates CHRNA1 transcriptionally or post-transcriptionally not resolved
    • Direct vs indirect regulatory link unclear
  10. 2022 Medium

    Confirmed in a multi-kinship patient cohort that a coding CHRNA1 variant causes disease through pathological P3A inclusion, validating the splicing mechanism as a clinical cause of CMS with a distinctive weakness pattern.

    Evidence Whole-exome sequencing, mRNA analysis of P3A inclusion, clinical phenotyping of 13 patients from 9 kinships

    PMID:36634413

    Open questions at the time
    • Functional consequence inferred from prior P3A biology rather than directly assayed here
    • Genotype–phenotype determinants of facial/distal predominance unexplained

Open questions

Synthesis pass · forward-looking unresolved questions
  • How CHRNA1 expression and P3A splicing are coordinately tuned across muscle aging, thymus, and sweat gland contexts, and whether the splicing regulatory network is pharmacologically tractable in vivo, remains unresolved.
  • No in vivo validation of splice-modulation therapy
  • Connection between transcriptional regulators (IRF8/AIRE/PAI1) and splicing machinery untested
  • Structural model of the regulatory RNP not available

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 1 GO:0005215 transporter activity 1 GO:0060089 molecular transducer activity 1
Localization
GO:0005886 plasma membrane 2
Pathway
R-HSA-1643685 Disease 2 R-HSA-8953854 Metabolism of RNA 2 R-HSA-112316 Neuronal System 1
Partners
HNRNPH1HNRNPLHNRNPLLPTBP1STAU1
Complex memberships
muscle nicotinic acetylcholine receptor

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2007 IRF8 binds the CHRNA1 promoter in thymic epithelial cells; a bi-allelic promoter variant prevents IRF8 binding and abrogates CHRNA1 promoter activity in vitro. AIRE also transactivates CHRNA1 in medullary thymic epithelial cells, and together IRF8 and AIRE regulate quantitative thymic expression of CHRNA1. Promoter resequencing, in vitro promoter activity assays in thymic epithelial cells, transactivation assay, ex vivo mRNA quantification in human medullary thymic epithelial cells Nature High 17687331
2008 hnRNP H binds an intronic splicing silencer (ISS) at the 3' end of CHRNA1 intron 3 and promotes skipping of the downstream nonfunctional exon P3A. A congenital myasthenic syndrome mutation (IVS3-8G>A) disrupts this ISS and reduces hnRNP H binding affinity ~100-fold, causing exclusive inclusion of P3A and loss of functional acetylcholine receptor α-subunit. RNA-binding assay (ISS-binding), siRNA knockdown of hnRNP H, minigene splicing reporter, affinity/competition binding assays, patient mutation analysis Human molecular genetics High 18806275
2009 Polypyrimidine tract binding protein (PTB) binds near the 3' end of CHRNA1 intron 3 and induces skipping of exon P3A. Tannic acid increases PTB expression in a dose-dependent manner and ameliorates aberrant P3A inclusion caused by the IVS3-8G>A mutation without altering hnRNP H expression. PTB binding assay, minigene splicing reporter, PTB promoter deletion assay, chemical compound screen (960 compounds), qPCR/Western blot for PTB expression Human molecular genetics Medium 19147685
2013 hnRNP L and hnRNP LL antagonistically regulate PTB-mediated splicing suppression of CHRNA1 exon P3A. hnRNP L interacts with PTB via its proline-rich region and promotes PTB binding to the polypyrimidine tract upstream of P3A, inhibiting U2AF65 and U1 snRNP association and blocking exon P3A definition. A CMS mutation in exon P3A creates a de novo hnRNP LL binding site and displaces hnRNP L, switching splicing from suppression to enhancement of P3A inclusion. RNA pulldown, Co-IP (hnRNP L–PTB interaction), siRNA knockdown, minigene splicing reporter, UV cross-linking assay, domain deletion (proline-rich region), U2AF65/U1 snRNP association assay Scientific reports High 24121633
2012 Agrin stimulation induces association of Chrna1 mRNA with the assembled nicotinic AChR protein complex in C2C12 myotubes. Staufen1 (Stau1) interacts with Chrna1 mRNA, and RNAi-mediated knockdown of Stau1 results in defective AChR clustering, indicating mRNA localization contributes to NMJ postsynaptic specialization. RT-PCR of AChR-associated RNA (affinity column and ultracentrifugation), RIP (Stau1–Chrna1 mRNA interaction), RNAi knockdown of Stau1 with AChR clustering readout FEBS letters Medium 22884571
2022 AAV9-mediated overexpression of CHRNA1 in mouse hindlimb muscle decreases the percentage of muscle innervation and causes skeletal muscle atrophy (reduced gastrocnemius mass index, muscle fiber cross-sectional area, compound muscle action potential, and contractility), establishing that elevated CHRNA1 drives sarcopenia through neuromuscular synaptic elimination. AAV9-CHRNA1 local injection into hindlimb muscles, muscle innervation analysis, gastrocnemius mass index, fiber cross-sectional area measurement, compound muscle action potential recording, muscle contractility assay Experimental gerontology Medium 35809807
2021 CHRNA1 is upregulated in sweat glands of primary focal hyperhidrosis (PFH) patients and mouse models. siRNA-mediated silencing of CHRNA1 decreases sweat secretion, reduces sweat secretory granule number, lowers serum acetylcholine, reduces AQP5 and CACNA1C expression in sweat glands, and attenuates BDNF and NRG-1 release from sympathetic ganglia axons. Western blot and qRT-PCR (expression), siRNA knockdown, transmission electron microscopy (secretory granules), ELISA (acetylcholine), immunohistochemistry and Western blot (AQP5, CACNA1C, BDNF, NRG-1), pilocarpine-induced mouse model Molecular and cellular neurosciences Medium 33476802
2022 Cisatracurium (a CHRNA1 antagonist) blocks the ion channel function of CHRNA1 without altering its gene or protein expression level, alleviating hyperhidrosis in mice. This was confirmed by showing that CHRNA1 overexpression abolishes cisatracurium's effect, while CHRNA1 knockdown does not allow additional cisatracurium effect. HEK293 overexpression of Chrna1 with cisatracurium treatment, electrophysiology/ion channel block assay, siRNA knockdown, pilocarpine mouse model, Western blot for Chrna1 expression, sweat secretion measurement Annals of clinical and translational neurology Medium 35393764
2023 PAI1 (encoded by SERPINE1) negatively regulates CHRNA1 expression. Serpine1 knockout increases Chrna1 expression and hyperhidrosis markers; Serpine1 transgenic overexpression decreases them. AAV-mediated Chrna1 overexpression in Serpine1-Tg mice rescues hyperhidrosis, and cisatracurium (CHRNA1 antagonist) rescues the enhanced hyperhidrosis in Serpine1 KO mice, placing PAI1 upstream of CHRNA1 in the regulation of sweat gland secretion. Serpine1 KO and Tg mouse models, AAV-Chrna1 rescue, cisatracurium pharmacological rescue, ELISA (acetylcholine), RT-PCR and Western blot (CACNA1C, AQP5), pilocarpine hyperhidrosis model Orphanet journal of rare diseases Medium 37542348
2022 The CHRNA1 variant c.257G>A (p.Arg86His) results in pathological inclusion of the alternatively-spliced exon P3A, leading to expression of a non-functional acetylcholine receptor α-subunit and causing acetylcholine receptor deficiency syndrome (congenital myasthenic syndrome) with a distinctive phenotype of predominant facial and distal weakness. Whole-exome sequencing, molecular characterization of P3A exon inclusion by mRNA analysis, clinical phenotype assessment of 13 patients from 9 kinships Neuromuscular disorders : NMD Medium 36634413

Source papers

Stage 0 corpus · 27 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2007 An IRF8-binding promoter variant and AIRE control CHRNA1 promiscuous expression in thymus. Nature 148 17687331
2008 Smokers with the CHRNA lung cancer-associated variants are exposed to higher levels of nicotine equivalents and a carcinogenic tobacco-specific nitrosamine. Cancer research 124 19010884
2008 Mutation analysis of CHRNA1, CHRNB1, CHRND, and RAPSN genes in multiple pterygium syndrome/fetal akinesia patients. American journal of human genetics 81 18179903
1994 Involvement of human muscle acetylcholine receptor alpha-subunit gene (CHRNA) in susceptibility to myasthenia gravis. Proceedings of the National Academy of Sciences of the United States of America 64 7910962
2008 hnRNP H enhances skipping of a nonfunctional exon P3A in CHRNA1 and a mutation disrupting its binding causes congenital myasthenic syndrome. Human molecular genetics 52 18806275
2013 HnRNP L and hnRNP LL antagonistically modulate PTB-mediated splicing suppression of CHRNA1 pre-mRNA. Scientific reports 39 24121633
2009 Tannic acid facilitates expression of the polypyrimidine tract binding protein and alleviates deleterious inclusion of CHRNA1 exon P3A due to an hnRNP H-disrupting mutation in congenital myasthenic syndrome. Human molecular genetics 29 19147685
1996 Human muscle acetylcholine receptor alpha-subunit gene (CHRNA1) association with autoimmune myasthenia gravis in black, mixed-ancestry and Caucasian subjects. Journal of autoimmunity 26 8738961
1997 Association of the AChRalpha-subunit gene (CHRNA), DQA1*0101, and the DR3 haplotype in myasthenia gravis. Evidence for a three-gene disease model in a subgroup of patients. Journal of autoimmunity 23 9237805
2017 Genes Involved in Neurodevelopment, Neuroplasticity, and Bipolar Disorder: CACNA1C, CHRNA1, and MAPK1. Neuropsychobiology 19 28494468
2014 Role of SLCO1B1, ABCB1, and CHRNA1 gene polymorphisms on the efficacy of rocuronium in Chinese patients. Journal of clinical pharmacology 16 25279974
2010 Identification of previously unreported mutations in CHRNA1, CHRNE and RAPSN genes in three unrelated Italian patients with congenital myasthenic syndromes. Journal of neurology 14 20157724
2013 High expression of CHRNA1 is associated with reduced survival in early stage lung adenocarcinoma after complete resection. Annals of surgical oncology 12 23775407
2022 CHRNA1 induces sarcopenia through neuromuscular synaptic elimination. Experimental gerontology 11 35809807
2021 CHRNA1 promotes the pathogenesis of primary focal hyperhidrosis. Molecular and cellular neurosciences 11 33476802
2012 Agrin induces association of Chrna1 mRNA and nicotinic acetylcholine receptor in C2C12 myotubes. FEBS letters 11 22884571
2012 Association study of nicotinic acetylcholine receptor genes identifies a novel lung cancer susceptibility locus near CHRNA1 in African-Americans. Oncotarget 9 23232035
2022 Epidemiological evidence for associations between variants in CHRNA genes and risk of lung cancer and chronic obstructive pulmonary disease. Frontiers in oncology 8 36276121
2022 A novel phenotype of AChR-deficiency syndrome with predominant facial and distal weakness resulting from the inclusion of an evolutionary alternatively-spliced exon in CHRNA1. Neuromuscular disorders : NMD 6 36634413
2022 Antagonist of Chrna1 prevents the pathogenesis of primary focal hyperhidrosis. Annals of clinical and translational neurology 5 35393764
2013 Clinical phenotype and the lack of mutations in the CHRNG, CHRND, and CHRNA1 genes in two Indian families with Escobar syndrome. Clinical dysmorphology 5 23448903
2007 Analysis and mapping of CACNB4, CHRNA1, KCNJ3, SCN2A and SPG4, physiological candidate genes for porcine congenital progressive ataxia and spastic paresis. Journal of animal breeding and genetics = Zeitschrift fur Tierzuchtung und Zuchtungsbiologie 5 17868079
2023 PAI1 inhibits the pathogenesis of primary focal hyperhidrosis by targeting CHRNA1. Orphanet journal of rare diseases 4 37542348
2022 Case Report: Novel compound heterozygous variants in CHRNA1 gene leading to lethal multiple pterygium syndrome: A case report. Frontiers in genetics 3 36092864
2025 Causal Variants in CHRNA1 and CHRNB1 Genes for Anti-acetylcholine Receptor Antibody Positive Myasthenia Gravis: Evidence from Bayesian Fine-Mapping and Genetic Association Study. Molecular neurobiology 2 40279038
2025 PAI1 regulating CHRNA1 contributes to primary focal hyperhidrosis: Clinical and experimental studies. Molecular therapy. Nucleic acids 1 40503176
2025 Circular RNA circAtxn10 regulates skeletal muscle cell differentiation by targeting miR-143-3p and Chrna1. The Korean journal of physiology & pharmacology : official journal of the Korean Physiological Society and the Korean Society of Pharmacology 1 40701844

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