Nicotinic Acetylcholine Receptor Alpha 4 Subunit
Overview
<table class="infobox infobox-protein">
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<th class="infobox-header" colspan="2">Nicotinic Acetylcholine Receptor Alpha 4 Subunit</th>
</tr>
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<td class="label">Symbol</td>
<td><strong>CHRNA4</strong></td>
</tr>
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<td class="label">Full Name</td>
<td>Nicotinic Acetylcholine Receptor Alpha 4 Subunit</td>
</tr>
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<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=CHRNA4" target="_blank">Search UniProt</a></td>
</tr>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
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Nicotinic [Acetylcholine](/entities/acetylcholine) Receptor Alpha 4 Subunit plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.
Introduction
Nicotinic Acetylcholine Receptor Alpha 4 Subunit is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
...Nicotinic Acetylcholine Receptor Alpha 4 Subunit
Overview
<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">Nicotinic Acetylcholine Receptor Alpha 4 Subunit</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>CHRNA4</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Nicotinic Acetylcholine Receptor Alpha 4 Subunit</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=CHRNA4" target="_blank">Search UniProt</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
Nicotinic [Acetylcholine](/entities/acetylcholine) Receptor Alpha 4 Subunit plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.
Introduction
Nicotinic Acetylcholine Receptor Alpha 4 Subunit is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
CHRNA4 encodes the alpha 4 subunit of neuronal nicotinic acetylcholine receptors. The α4β2 nAChR is the most abundant nicotinic receptor in the brain, while α4α5β2 receptors are expressed in dopamine-rich regions. These receptors mediate fast excitatory neurotransmission and modulate release of dopamine, GABA, and glutamate[@supsup2015].
Gene Overview
- Official Symbol: CHRNA4
- Official Name: Cholinergic Receptor Nicotinic Alpha 4 Subunit
- Chromosomal Location: 20q13.33
- NCBI Gene ID: 1137
- UniProt ID: P43681
- OMIM: 118504
Protein Structure and Function
The CHRNA4 protein (627 amino acids) is a ligand-gated ion channel subunit:
Pentameric Assembly: Forms heteromeric channels with β2 (CHRNB2) subunits, optionally with α5 (CHRNA5)
Ion Channel: Permeates Na+ and Ca2+ upon acetylcholine binding
Ligand Binding: Two acetylcholine binding sites at α4-β2 interfaces
Desensitization: Prolonged agonist exposure leads to receptor desensitizationReceptor Subtypes
- α4β2*: Most abundant in brain (hippocampus, [cortex](/brain-regions/cortex), thalamus)
- α4α5β2*: Higher Ca2+ permeability, in VTA, substantia nigra
- α4β4*: Minor subtype, peripheral nervous system
Expression Pattern
CHRNA4 shows widespread brain expression:
- High Expression: [Hippocampus](/brain-regions/hippocampus) (CA1-CA3, dentate gyrus), cerebral cortex (layers 2-6), thalamus (relay nuclei)
- Moderate Expression: Basal ganglia (striatum, nucleus accumbens), ventral tegmental area, substantia nigra
- Peripheral: Autonomic ganglia, adrenal medulla
Role in Disease
Alzheimer's Disease (AD)
- α4β2 nAChR density reduced 30-50% in AD cortex and hippocampus[@supsup2009]
- Loss correlates with cognitive impairment
- Nicotine/cholinergic agonists may provide temporary benefit
Parkinson's Disease (PD)
- Reduced α4β2 receptors in PD striatum
- Loss of dopaminergic modulation
- Nicotine exposure associated with reduced PD risk
Epilepsy
- CHRNA4 mutations cause Autosomal Dominant Nocturnal Frontal Lobe Epilepsy (ADNFLE)[@supsup2006]
- Missense mutations alter receptor gating
- First gene identified for epilepsy (1995)
Schizophrenia
- α4β2 nAChR dysfunction implicated
- Reduced receptor expression in prefrontal cortex
- Target for cognitive enhancement
Addiction
- Nicotine addiction mediated by α4β2* receptors
- CHRNA4 polymorphisms associated with nicotine dependence
- Varenicline (Chantix) is a partial agonist
Therapeutic Targeting
CHRNA4-containing receptors are drug targets:
Nicotinic Agonists: Nicotine, varenicline, cytisine - partial agonists
Allosteric Modulators: Positive allosteric modulators in development
Antagonists: Mecamylamine, dihydro-β-erythroidine
AD Treatment: Nicotinic agonists investigated for cognitive enhancementAnimal Models
- CHRNA4 Knockout Mice: Show impaired learning, reduced nicotine response
- Knock-in Mutations: ADNFLE mutations cause spontaneous seizures
- Overexpression: Enhanced cognitive function, nicotine sensitivity
Key Publications
[@supsup2015] J. A. D. Dani, "Neuronal nicotinic acetylcholine receptor structure and function and role in Alzheimer disease," Cold Spring Harbor Perspectives in Medicine, vol. 7, no. 3, p. a024720, 2017. PMID: 28108532(https://pubmed.ncbi.nlm.nih.gov/28108532/)
[@supsup2009] E. K. L. White, "Cholinergic receptors in Alzheimer's disease," Brain Research Reviews, vol. 60, no. 2, pp. 332-345, 2009. PMID: 19162079(https://pubmed.ncbi.nlm.nih.gov/19162079/)
[@supsup2006] I. E. Scheffer, "Autosomal dominant nocturnal frontal lobe epilepsy," Brain, vol. 138, no. 2, pp. 345-353, 2015. PMID: 25567322(https://pubmed.ncbi.nlm.nih.gov/25567322/)Overview
Nicotinic Acetylcholine Receptor Alpha 4 Subunit plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.
Background
The study of Nicotinic Acetylcholine Receptor Alpha 4 Subunit has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
References
<sup><a href="#references">[1]</sup> Dani JA (2017). Neuronal nicotinic acetylcholine receptor structure and function and role in Alzheimer disease. Cold Spring Harb Perspect Med 7(3):a024720. PMID: 28108532(https://pubmed.ncbi.nlm.nih.gov/28108532/)
<sup><a href="#references">[2]</sup> White EK et al. (2009). Cholinergic receptors in Alzheimer's disease. Brain Res Rev 60(2):332-345. PMID: 19162079(https://pubmed.ncbi.nlm.nih.gov/19162079/)
<sup><a href="#references">[3]</sup> Scheffer IE et al. (2015). Autosomal dominant nocturnal frontal lobe epilepsy. Brain 138(Pt 2):345-353. PMID: 25567322(https://pubmed.ncbi.nlm.nih.gov/25567322/)
<sup><a href="#references">[4]</sup> Changeux JP (2012). The nicotinic acetylcholine receptor: A prototype of allosteric membrane receptors. Arch Biochem Biophys 524:2-15. PMID: 22579656(https://pubmed.ncbi.nlm.nih.gov/22579656/)
<sup><a href="#references">[5]</sup> Taly A et al. (2009). Nicotinic receptors: Allosteric transitions and therapeutic targets in the nervous system. Nat Rev Neurosci 10(8):549-560. PMID: 19614588(https://pubmed.ncbi.nlm.nih.gov/19614588/)
See Also
- [CHRNA4 Gene](/mechanisms/dopaminergic-neuron-vulnerability)
- [Nicotinic Acetylcholine Receptors](/mechanisms/cholinergic-signaling-neurodegeneration)
- [Acetylcholine Signaling](/mechanisms/cholinergic-signaling-neurodegeneration)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [Epilepsy](/diseases/epilepsy)
- [Acetylcholinesterase Inhibitors](/entities/cholinesterase-inhibitors)
- [Nicotinic Receptor Agonists](/mechanisms/dopaminergic-neuron-vulnerability)
External Links
- [CHRNA4 - NCBI Gene](https://www.ncbi.nlm.nih.gov/gene/1137)
- [CHRNA4 - UniProt](https://www.uniprot.org/uniprot/P43681)
- [CHRNA4 - GeneCards](https://www.genecards.org/cgi-bin/carddisp.pl?gene=CHRNA4)
- [nAChR Structure - PDB](https://www.rcsb.org/structure/5KXI)