KCNE3 (Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 3)

KCNE3 (Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 3)

<table class="infobox infobox-gene">
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<th class="infobox-header" colspan="2">kcne3</th>
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<td class="label">Symbol</td>
<td><strong>KCNE3</strong></td>
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<td class="label">Full Name</td>
<td>kcne3</td>
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<td class="label">Type</td>
<td>Gene</td>
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<td class="label">NCBI</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/?term=KCNE3" target="_blank">Search NCBI</a></td>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">8 edges</a></td>
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Overview

KCNE3 (Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 3)

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">kcne3</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>KCNE3</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>kcne3</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Gene</td>
</tr>
<tr>
<td class="label">NCBI</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/?term=KCNE3" target="_blank">Search NCBI</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">8 edges</a></td>
</tr>
</table>

Overview

KCNE3 (Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 3), also known as MiRP2 (MinK-Related Peptide 2), is a critical regulatory subunit that modulates the function of various voltage-gated potassium (Kv) channels. The KCNE gene family consists of five members (KCNE1-5) that encode small single-pass membrane proteins which associate with Kv channel alpha subunits to form functional channel complexes with distinct biophysical properties. KCNE3 is unique among the KCNE family in its ability to convert certain Kv channels into channels with novel properties, including calcium-activated-like behavior in some contexts. The gene is located on chromosome 11p15.5 (NCBI Gene ID: 10088, OMIM: 607333, UniProt: Q9NP86) and encodes a protein of 179 amino acids with the characteristic KCNE protein structure. KCNE3 is expressed in both cardiac and neuronal tissues, where it plays crucial roles in regulating excitability. In the heart, KCNE3 modulates cardiac repolarization and is implicated in arrhythmia susceptibility. In the brain, KCNE3 regulates neuronal potassium channels that control firing patterns and contribute to synaptic function. Emerging evidence suggests KCNE3 dysfunction may contribute to neurodegenerative processes in Alzheimer's disease and Parkinson's disease. This comprehensive review covers KCNE3 gene structure, protein function, expression patterns, disease associations, and therapeutic implications. [@hille2001][@abbott2018]

Gene Structure and Expression

Genomic Organization

The KCNE3 gene is located on chromosome 11p15.5 in the imprinted region containing multiple KCNE family members. The gene spans approximately 6 kb of genomic DNA and consists of 3 exons encoding a protein of 179 amino acids with a molecular weight of approximately 19 kDa. The genomic organization is similar to other KCNE genes, with the coding sequence contained within a compact genomic region. The promoter region contains elements that drive tissue-specific expression in heart, skeletal muscle, and brain. The gene shows relatively high conservation across mammalian species, with particularly conserved regions in the transmembrane domain and C-terminal cytoplasmic domain that mediate channel interactions. Alternative splicing of KCNE3 has been reported, generating multiple transcript variants with potentially different functional properties, though the significance of these variants is not fully characterized. The chromosomal location of KCNE3 in the 11p15.5 imprinted region has raised the possibility of imprinting effects on expression, though this remains an area of investigation. Understanding the genomic organization of KCNE3 provides insight into its regulation and disease associations. @abbott2018

Tissue Distribution

KCNE3 exhibits a distinctive tissue expression pattern with high levels in heart, skeletal muscle, and various brain regions. In the heart, KCNE3 is expressed in atrial and ventricular myocytes, where it modulates potassium channel function and contributes to cardiac repolarization. The expression pattern in the heart overlaps with the distribution of certain Kv channel alpha subunits that KCNE3 can modulate. In skeletal muscle, KCNE3 is expressed in muscle fibers, where it contributes to muscle excitability and contractile properties. In the brain, KCNE3 shows region-specific and cell-type-specific expression. The hippocampus expresses KCNE3 in CA1-CA3 pyramidal neurons and dentate gyrus granule cells, regions important for learning and memory. The cerebral cortex shows KCNE3 expression in pyramidal neurons across layers. The cerebellum expresses KCNE3 in Purkinje cells and other neuronal types. KCNE3 is also expressed in some glial cells, including astrocytes, where it may contribute to glial function. The widespread but specific expression pattern of KCNE3 reflects its diverse functional roles in different tissues and cell types. @kawasaki2019

Protein Structure and Function

Domain Architecture

KCNE3 shares the characteristic structure of KCNE family proteins, consisting of a small single-pass membrane protein with distinct functional domains. The N-terminal extracellular domain (approximately 1-50 amino acids) is relatively short and contains potential N-linked glycosylation sites that may affect protein folding and trafficking. The single transmembrane domain (approximately 51-73 amino acids) consists of an α-helical segment that anchors the protein in the cell membrane. The C-terminal cytoplasmic domain (approximately 74-179 amino acids) is the largest region and contains motifs that mediate interactions with Kv channel alpha subunits. This C-terminal region contains multiple phosphorylation sites that can modulate KCNE3 function and its interactions with channel partners. The overall architecture allows KCNE3 to associate with Kv channel alpha subunits while retaining the ability to modulate their gating properties. The transmembrane domain positions the protein correctly in the membrane, while the cytoplasmic domain extends into the intracellular space where it can interact with channel domains that control gating. The structural features of KCNE3 are conserved across the KCNE family, but sequence variations in the C-terminal domain determine the specific channel interactions and modulation properties of each KCNE member. @hille2001

Channel Modulation

KCNE3 modulates the function of multiple Kv channel alpha subunits, producing complexes with unique biophysical properties. The primary channel partners of KCNE3 include:

Kv1.x family: KCNE3 can co-assemble with Kv1.1, Kv1.2, and Kv1.3 subunits to modulate their gating kinetics. When combined with Kv1.x channels, KCNE3 typically slows activation and modifies voltage dependence.

Kv3.x family: KCNE3 modulates Kv3.1 and Kv3.2 channels, which are important for fast-spiking neurons. This modulation affects the firing properties of fast-spiking interneurons.

KCNQ (Kv7) family: KCNE3 interacts with KCNQ1 (Kv7.1) in some tissues, though this interaction is less prominent than with other KCNE family members.

The functional effects of KCNE3 binding include:

• Altered gating kinetics: Changed activation and inactivation rates
• Shifted voltage dependence: Modified voltage sensitivity of channel activation
• Changed pharmacology: Altered sensitivity to channel blockers and activators
• Modified unitary conductance: In some cases, changes in single channel properties

Role in Neuronal Function

Neuronal Excitability

KCNE3 plays important roles in regulating neuronal excitability through its modulation of Kv channels. In neurons, KCNE3-containing channels contribute to several aspects of electrical signaling:

Membrane Repolarization: Following action potential generation, KCNE3-modulated Kv channels contribute to repolarization, influencing the shape and duration of the action potential. This affects the refractory period and the ability of neurons to fire at high frequencies.

Resting Membrane Potential: The conductances regulated by KCNE3 contribute to setting the resting membrane potential and input resistance, which affect the integration of synaptic inputs.

Firing Pattern Regulation: KCNE3 modulates the firing patterns of different neuronal types. In fast-spiking neurons, KCNE3 influences the ability to sustain high-frequency firing.

Synaptic Integration: Dendritic Kv channels modulated by KCNE3 affect the temporal integration of excitatory and inhibitory synaptic inputs.

The specific effects of KCNE3 on neuronal excitability depend on the complement of Kv channels expressed in each neuronal type and the specific channel partners with which KCNE3 associates. @angulo2004

Synaptic Function

Beyond direct effects on neuronal excitability, KCNE3 influences synaptic function through several mechanisms. Kv channels regulated by KCNE3 affect presynaptic neurotransmitter release by modulating action potential duration in presynaptic terminals. Reduced action potential duration decreases calcium influx and reduces neurotransmitter release probability. At postsynaptic sites, KCNE3-modulated channels affect the integration of synaptic potentials and the induction of synaptic plasticity. The effects on firing patterns influence the patterns of activity that drive long-term potentiation and depression. Additionally, KCNE3 is expressed in some glial cells, where it may influence glial contributions to synaptic function, including potassium buffering and neurotransmitter clearance. These synaptic functions of KCNE3 have implications for learning, memory, and neurological function. @yang2019

Role in Neurodegenerative Diseases

Alzheimer's Disease

KCNE3 dysfunction is implicated in Alzheimer's disease (AD) through multiple mechanisms. Potassium channel dysfunction is a consistent finding in AD, with alterations in multiple potassium channel types contributing to the hyperexcitability observed in AD models and patients.

Channel dysfunction: Studies of AD brain tissue and cellular models reveal altered KCNE3 expression in regions vulnerable to neurodegeneration, including the hippocampus and cortex. These changes correlate with:

• Reduced Kv channel function
• Increased neuronal excitability
• Disrupted synaptic plasticity
• Enhanced susceptibility to excitotoxicity

Therapeutic implications: KCNE3 and associated Kv channels represent potential therapeutic targets for AD. Strategies include:

• KCNQ activators to enhance M-current
• Modulators of KCNE3 expression
• Gene therapy approaches

Parkinson's Disease

KCNE3 involvement in Parkinson's disease (PD) is an emerging area of research. Dopaminergic neurons in the substantia nigra pars compacta, which degenerate in PD, express KCNE3 and associated Kv channels.

Dopaminergic neuron function: KCNE3 modulates Kv channel function in dopaminergic neurons, affecting their firing patterns and survival. Altered KCNE3 function may contribute to:

• Abnormal firing patterns in PD model systems
• Increased vulnerability of dopaminergic neurons
• Dysregulated dopamine release

Other Neurological Disorders

Epilepsy: KCNE3 variants have been associated with epilepsy susceptibility. KCNE3 modulates neuronal excitability, and dysfunction may contribute to seizure generation.

Stroke and excitotoxicity: Following ischemic injury, KCNE3 expression and function are altered, affecting neuronal survival and recovery.

Neuropathic pain: KCNE3 in sensory neurons contributes to pain signaling, and altered expression is observed in models of neuropathic pain. @song2019

Therapeutic Implications

Drug Development

KCNE3 and its partner channels represent attractive therapeutic targets for multiple conditions. In neurodegenerative diseases like AD and PD, strategies that enhance KCNE3-mediated Kv channel function could reduce hyperexcitability and provide neuroprotection. However, the challenge is achieving this without affecting cardiac function, given KCNE3's role in the heart.

In cardiac disease, KCNE3 variants are associated with arrhythmia susceptibility. Understanding KCNE3 function may inform antiarrhythmic therapy development.

Biomarker Potential

KCNE3 expression in peripheral tissues may serve as a biomarker for neuronal Kv channel function:

• Lymphocyte KCNE3 expression as proxy for neuronal changes
• Genetic variants as risk markers for neurodegeneration

Research Directions

Unanswered Questions

Significant questions remain about KCNE3 function. The precise mechanisms by which KCNE3 modulates different channel types require further investigation. The role of KCNE3 in specific neurodegenerative diseases needs more rigorous testing. Better tools for studying KCNE3 would facilitate progress.

Emerging Research

New approaches are enabling progress on KCNE3 research. Structural studies are revealing the molecular basis of KCNE3-channel interactions. Human genetics is identifying additional disease-associated variants. These approaches promise to advance understanding of KCNE3 biology and disease relevance.

See Also

• [Potassium Channels](/mechanisms/potassium-channels-neurodegeneration)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Neuronal Excitability](/mechanisms/neuronal-excitability)
• [Synaptic Plasticity](/mechanisms/synaptic-plasticity)

External Links

• [NCBI Gene: KCNE3](https://www.ncbi.nlm.nih.gov/gene/10088)
• [OMIM: 607333](https://omim.org/entry/607333)
• [UniProt: Q9NP86](https://www.uniprot.org/uniprot/Q9NP86)
• [Ensembl: ENSG00000166320](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000166320)
• [Allen Brain Atlas: KCNE3](https://human.brain-map.org/microarray/search/show?search_term=KCNE3)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving kcne3 discovered through SciDEX knowledge graph analysis: