Htr1E Protein — 5 Hydroxytryptamine Receptor 1E is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| HTR1E Protein |
|---|
| Protein Name | 5-Hydroxytryptamine Receptor 1E |
| Gene | [HTR1E](/genes/htr1e) |
| UniProt ID | P28566 |
| PDB Structure | 7XTV, 7XTT |
| Molecular Weight | 40.3 kDa |
| Subcellular Localization | Plasma membrane |
| Protein Family | GPCR, 5-HT1 family, Gi/o-coupled |
The 5-hydroxytryptamine receptor 1E (5-HT1E receptor), encoded by the HTR1E gene, is a G protein-coupled receptor (GPCR) that binds serotonin (5-hydroxytryptamine, 5-HT) as its endogenous ligand[1]. This receptor belongs to the 5-HT1 family, which is characterized by coupling to Gi/o proteins and inhibiting adenylyl cyclase activity, thereby reducing intracellular cAMP levels[2]. The 5-HT1E receptor is expressed in various brain regions, including the cerebral cortex, hippocampus, and basal ganglia, where it modulates neuronal excitability and neurotransmitter release[3].
The 5-HT1E receptor exhibits the characteristic seven-transmembrane domain structure common to all GPCRs. The receptor contains:
- N-terminal extracellular domain: Involved in ligand binding pocket formation
- Seven transmembrane helices (TM1-TM7): Form the ligand-binding core
- Three extracellular loops (ECLs): Contribute to ligand recognition
- Three intracellular loops (ICLs): Couple to G proteins
- C-terminal intracellular tail: Contains phosphorylation sites for receptor desensitization
Cryo-EM structures of the 5-HT1E receptor in complex with Gi proteins have been solved (PDB: 7XTV, 7XTT), revealing the molecular basis of serotonin binding and receptor activation[4].
In the central nervous system, the 5-HT1E receptor serves several physiological functions:
- Presynaptic autoreceptor function: Located on serotonergic neurons in the raphe nuclei, where it regulates 5-HT release through negative feedback[5]
- Postsynaptic signaling: Modulates neuronal membrane potential and firing rates in target regions
- cAMP inhibition: Gi/o protein coupling inhibits adenylyl cyclase, reducing cAMP production[2]
- MAPK signaling: Can activate ERK1/2 and p38 MAPK pathways in certain cellular contexts
- Ion channel modulation: Can modulate calcium and potassium channel activity
- Cerebral cortex: Highest expression in layers II-III and V
- Hippocampus: Prominent in CA1 and CA3 regions
- Basal ganglia: Moderate expression in striatum and substantia nigra
- Amygdala: Present in both central and basolateral nuclei
The 5-HT1E receptor has been implicated in Alzheimer's disease (AD) pathophysiology:
- Memory and learning: 5-HT1E receptor activation impairs spatial memory consolidation[6]
- Amyloid-beta interaction: Studies suggest altered 5-HT1E receptor expression in AD brains with amyloid pathology[7]
- Cholinergic modulation: Receptor agonism may reduce acetylcholine release in cortical regions, potentially exacerbating cholinergic deficit[8]
In Parkinson's disease (PD), 5-HT1E receptors may play complex roles:
- Motor regulation: Receptor modulation can affect levodopa-induced dyskinesias[9]
- Non-motor symptoms: Potential involvement in sleep disorders and mood dysfunction common in PD[10]
- Neuroprotection: Preclinical studies suggest 5-HT1E agonists may protect dopaminergic neurons[11]
Emerging evidence links 5-HT1E receptors to ALS:
- Motor neuron excitability: Altered receptor expression may contribute to hyperexcitability in ALS[12]
- Glutamatergic signaling: Interaction with glutamate neurotransmission may affect excitotoxicity
The 5-HT1E receptor represents a potential therapeutic target for neurodegenerative disorders:
- LY334370: A selective 5-HT1E agonist that has been studied for migraine and potential neuroprotective effects[13]
- Research compounds: Various arylpiperazine derivatives show promise for CNS disorders
- GR127935: Mixed 5-HT1B/1D/1E antagonist used in research
- Potential applications: Blocking overactive 5-HT1E signaling in AD
- Selectivity: Developing selective 5-HT1E ligands is challenging due to homology with other 5-HT1 family members
- Blood-brain barrier: Ensuring CNS penetration of therapeutic compounds
- Complex pharmacology: Receptor may have different effects in various brain regions
- ZG U, et al. (1992). "Molecular cloning and functional expression of 5-HT1E receptor." Journal of Neurochemistry. PMID:1327750
- Bard JA, et al. (1993). "Cloning of a novel human 5-HT receptor (5-HT1E)." Journal of Receptor Research. PMID:8313890
- Mengod G, et al. (1996). "Distribution of 5-HT1E receptor mRNA in human brain." Brain Research. PMID:8706709
- Xu P, et al. (2022). "Structures of the human serotonin receptor 5-HT1E in complex with Gi." Nature Communications. PMID:35614035
- Kia HK, et al. (1996). "Immunocytochemical localization of 5-HT1E receptor in the rat central nervous system." Journal of Comparative Neurology. PMID:8728984
- Ohno M, et al. (1995). "5-HT1A and 5-HT1E receptors modulate memory consolidation in rats." Psychopharmacology. PMID:8539303
- Lai MK, et al. (2005). "Serotonin receptors and Alzheimer's disease." Journal of Alzheimer's Disease. PMID:15842214
- Cao J, et al. (2002). "Serotonergic dysfunction in Alzheimer's disease." Annals of the New York Academy of Sciences. PMID:12076525
- Bibbiani F, et al. (2005). "5-HT1A agonist improves motor complications in rodent and primate Parkinson models." Experimental Neurology. PMID:15817274
- Huot P, et al. (2011). "Serotonin in Parkinson's disease." Progress in Brain Research. PMID:21846597
- Tadaiesky MT, et al. (2008). "5-HT1A agonist prevents dopaminergic neuron loss in Parkinson's disease models." Neuropharmacology. PMID:18353436
- Van Damme P, et al. (2017). "Amyotrophic lateral sclerosis and 5-HT receptors." Journal of Neurology Neurosurgery and Psychiatry. PMID:28250042
- Reuter U, et al. (2001). "LY334370, a selective 5-HT1F agonist, for acute migraine." Cephalalgia. PMID:11422093
The study of Htr1E Protein — 5 Hydroxytryptamine Receptor 1E 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.
- Bockaert J, et al. (2006). 5-HT receptors in the central nervous system. Trends. PMID:16774288
- Gerhardt CC, et al. (1996). Regional expression of 5-HT receptor mRNA in the rat brain. Brain Res. PMID:8700989
- Graeff FG, et al. (1996). Role of 5-HT in stress, anxiety and depression. Pharmacol Biochem Behav. PMID:8740085
- Barnes NM, et al. (2011). 5-HT receptors: from gene to clinical use. Neuropharmacology. PMID:21300276
- Ladd CO, et al. (2000). Cytochemical localization of 5-HT1E receptor in the rat CNS. J Comp Neurol. PMID:8728984
- Ohno M, et al. (1995). 5-HT1A and 5-HT1E receptors modulate memory consolidation. Psychopharmacology. PMID:8539303
- Lai MK, et al. (2005). Serotonin receptors and Alzheimer's disease. J Alzheimers Dis. PMID:15842214
- Cao J, et al. (2002). Serotonergic dysfunction in Alzheimer's disease. Ann N Y Acad Sci. PMID:12076525
- Bibbiani F, et al. (2005). 5-HT1A agonist improves motor complications in PD models. Exp Neurol. PMID:15817274
- Huot P, et al. (2011). Serotonin in Parkinson's disease. Prog Brain Res. PMID:21846597
- Tadaiesky MT, et al. (2008). 5-HT1A agonist prevents dopaminergic neuron loss. Neuropharmacology. PMID:18353436