KCNJ4 — Potassium Inwardly Rectifying Channel Subfamily J Member 4

KCNJ4 — Potassium Inwardly Rectifying Channel Subfamily J Member 4

Introduction

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">KCNJ4 — Potassium Inwardly Rectifying Channel Subfamily J Member 4</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td>KCNJ4</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Potassium Inwardly Rectifying Channel Subfamily J Member 4</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>22q13.1</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>3765</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>600494</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000102195</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P48745</td>
</tr>
<tr>
<td class="label">Strategy</td>
<td>Drug/Approach</td>
</tr>
<tr>
<td class="label">Agonist</td>
<td>PDP (pyridine derivative)</td>
</tr>
<tr>
<td class="label">Antagonist</td>
<td>Terfenadine</td>
</tr>
<tr>
<td class="label">Gene therapy</td>
<td>AAV-Kir2.3</td>
</tr>
<tr>
<td class="label">Modulator</td>
<td>PIP2 analogs</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

KCNJ4 — Potassium Inwardly Rectifying Channel Subfamily J Member 4

Introduction

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">KCNJ4 — Potassium Inwardly Rectifying Channel Subfamily J Member 4</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td>KCNJ4</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Potassium Inwardly Rectifying Channel Subfamily J Member 4</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>22q13.1</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>3765</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>600494</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000102195</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P48745</td>
</tr>
<tr>
<td class="label">Strategy</td>
<td>Drug/Approach</td>
</tr>
<tr>
<td class="label">Agonist</td>
<td>PDP (pyridine derivative)</td>
</tr>
<tr>
<td class="label">Antagonist</td>
<td>Terfenadine</td>
</tr>
<tr>
<td class="label">Gene therapy</td>
<td>AAV-Kir2.3</td>
</tr>
<tr>
<td class="label">Modulator</td>
<td>PIP2 analogs</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

Kcnj4 — Potassium Inwardly Rectifying Channel Subfamily J Member 4 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

KCNJ4 (also known as Kir2.3) encodes an inward rectifier potassium channel that plays crucial roles in neuronal excitability, cardiac rhythm, and cellular homeostasis. These channels allow potassium ions to flow more easily into the cell than out, helping maintain the resting membrane potential. [@lignani2020]

Gene Information

Normal Function

Kir2.3 channels contribute to:

• Resting membrane potential: Maintains negative resting potential in [neurons](/entities/neurons) and cardiomyocytes
• Neuronal excitability: Regulates action potential threshold and firing patterns
• Potassium homeostasis: Controls intracellular K+ levels
• Cardiac physiology: Influences cardiac repolarization

Molecular Mechanisms

Channel Structure

• Two transmembrane domains: Form the channel pore
• P-loop region: Selectivity filter determining K+ specificity
• N-terminal and C-terminal cytoplasmic domains: Regulate channel gating and trafficking

Gating Mechanism

• Gating kinetics: Kir2.3 channels exhibit strong inward rectification
• Phosphorylation regulation: PKA-mediated phosphorylation increases channel activity
• PIP2 interaction: Phosphatidylinositol 4,5-bisphosphate (PIP2) is required for channel function
• Intracellular Mg²⁺ and polyamines: Block outward current at depolarized potentials

Protein Interactions

• Filamin A: Associates with Kir2.3 for proper membrane localization
• MAGUK proteins: Scaffold proteins organize channel complexes
• Sodium channels: Functional coupling with Nav channels in neurons

Disease Associations

Parkinson's Disease

• Role: Altered Kir channel function in dopaminergic neurons
• Mechanism: May affect neuronal survival and excitability
• Research: KCNJ4 variants studied in PD susceptibility
• Evidence: Post-mortem studies show altered K+ channel expression in substantia nigra

Alzheimer's Disease

• Role: Potassium channel dysfunction in hippocampal neurons
• Mechanism: May contribute to hyperexcitability and network dysfunction
• Therapeutic potential: Kir channel modulators may restore neuronal homeostasis

Cardiac Arrhythmias

• Role: Loss-of-function mutations associated with atrial fibrillation
• Mechanism: Altered cardiac repolarization
• Treatment: Class III antiarrhythmics target related channels

Neurodevelopmental Disorders

• Role: KCNJ4 mutations identified in patients with intellectual disability
• Mechanism: Disrupted neuronal excitability during development
• References: Multiple case reports link KCNJ4 variants to neurological phenotypes

Expression Pattern

High expression in:

• Brain ([cortex](/brain-regions/cortex), hippocampus, basal ganglia)
• Heart
• Skeletal muscle
• Various peripheral tissues

Brain Regional Distribution

• Cerebral cortex: Layer 5 pyramidal neurons
• [Hippocampus](/brain-regions/hippocampus): CA1-CA3 regions, dentate gyrus
• Basal ganglia: Striatum, globus pallidus
• Thalamus: Relay neurons

Therapeutic Targeting

Drug Development Challenges

Animal Models

Knockout Mice

• Phenotype: Show cardiac abnormalities and altered neuronal excitability
• Use: Studying channel function in vivo
• Limitations: Developmental compensation may mask phenotypes

Transgenic Models

• Overexpression: Used to study gain-of-function effects
• Conditional knockout: Allows tissue-specific deletion

Research Directions

Key Publications

See Also

• [Potassium Channels in Neurodegeneration](/mechanisms/potassium-channel-dysfunction)
• [Neuronal Excitability](/mechanisms/synaptic-dysfunction-pathway)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Dopaminergic Neurons](/cell-types/substantia-nigra-pars-compacta)
• [Ion Channel Therapies](/therapeutics/ion-channel-modulators)

External Links

• [NCBI Gene: KCNJ4](https://www.ncbi.nlm.nih.gov/gene/3765)
• [UniProt: KCNJ4](https://www.uniprot.org/uniprot/P48745)
• [HGNC: KCNJ4](https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:6264)
• [GeneCards: KCNJ4](https://www.genecards.org/cgi-bin/carddisp.pl?gene=KCNJ4)
• [Human Protein Atlas: KCNJ4](https://www.proteinatlas.org/ENSG00000102195-KCNJ4)

Background

The study of Kcnj4 — Potassium Inwardly Rectifying Channel Subfamily J Member 4 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.

Molecular Mechanisms

KCNJ4 (Potassium Inwardly Rectifying Channel Subfamily J Member 4), also known as Kir2.3, is an inward rectifier potassium channel:

• Channel structure: Tetrameric assembly of Kir2.3 subunits
• Inward rectification: Conducts inward current more efficiently than outward
• Regulation: Modulated by phosphatidylinositol 4,5-bisphosphate (PIP2)
• Localization: Brain, particularly cortex and hippocampus

• Resting membrane potential: Maintains negative resting potential
• Neuronal excitability: Modulates firing patterns
• Potassium homeostasis: Regulates intracellular K+ levels

Role in Neurodegeneration

• Alzheimer's disease: Altered Kir channel function affects neuronal viability
• Parkinson's disease: Dysregulation of K+ channels in dopaminergic neurons
• Stroke: Ischemia affects Kir channel activity

References