GO:1905033 positive regulation of membrane repolarization during cardiac muscle cell action potential: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1905033 describes any process that activates or increases the frequency, rate or extent of membrane repolarization during a cardiac muscle cell action potential.
• Repolarization is driven by the coordinated activity of potassium currents, including IKr (hERG), IKs, Ito, and IK1, which restore the resting membrane potential after depolarization.
• The hERG channel (KCNH2) carries IKr and exhibits unusual gating properties, including slow activation and rapid inactivation, that are critical for normal repolarization.
• PRMT1-mediated modulation of the IKs channel-PIP2 interaction is a key regulatory mechanism controlling cardiac repolarization.
• Disruption of repolarization underlies arrhythmias, including long QT syndrome and drug-induced torsades de pointes, making this GO term highly relevant to cardiac safety pharmacology.
• CRISPR-based knockout, point-mutation, and knock-in models enable precise dissection of genes that positively regulate cardiac repolarization.
Description
GO:1905033, positive regulation of membrane repolarization during cardiac muscle cell action potential, is a biological process term that captures any mechanism that activates or increases the frequency, rate, or extent of membrane repolarization during a cardiac action potential. Repolarization is the phase of the cardiac action potential in which the cell returns to its resting negative membrane potential after depolarization, and it is essential for maintaining normal heart rhythm and preventing arrhythmias. This process is governed by a delicate balance of ion channel activities, particularly potassium currents such as IKr, IKs, and Ito, which collectively shape the action potential duration. Researchers study GO:1905033 because defects in repolarization are directly linked to life-threatening cardiac arrhythmias, including long QT syndrome and drug-induced torsades de pointes. The hERG channel, which carries the rapid delayed rectifier potassium current IKr, is a prime example of a protein whose dysfunction prolongs repolarization and increases arrhythmia risk. Understanding the positive regulation of repolarization also has broad implications for cardiac safety pharmacology, as many drugs inadvertently block hERG and delay repolarization. This article synthesizes authoritative QuickGO data and verified PubMed literature to provide a research-grade overview of GO:1905033, covering its definition, molecular mechanisms, key genes, disease relevance, and experimental models. It is designed for researchers seeking to investigate repolarization biology using CRISPR-based approaches and advanced screening technologies.
positive regulation of membrane repolarization during cardiac muscle cell action potential At A Glance
| GO ID | GO:1905033 |
|---|---|
| GO term | positive regulation of membrane repolarization during cardiac muscle cell action potential |
| Ontology | biological_process |
| Synonym | activation of membrane repolarization during cardiac muscle cell action potential; up regulation of membrane repolarization during cardiac muscle cell action potential; up-regulation of membrane repolarization during cardiac muscle cell action potential; upregulation of membrane repolarization during cardiac muscle cell action potential |
| Major function | Enhances the rate and extent of membrane repolarization in cardiac muscle cells, thereby controlling action potential duration and preventing arrhythmias. |
| Key currents involved | IKr (hERG), IKs, Ito, IK1 |
| Regulatory example | PRMT1 modulates IKs channel-PIP2 interaction to control repolarization |
| Disease relevance | Long QT syndrome, drug-induced arrhythmias, cardiac hypertrophy |
What Is GO:1905033?
GO:1905033 is defined as any process that activates or increases the frequency, rate or extent of membrane repolarization during cardiac muscle cell action potential. In simpler terms, it encompasses all molecular events that accelerate or enhance the return of a cardiac muscle cell's membrane potential to its resting negative state after an action potential. This includes the opening of potassium channels, the modulation of channel kinetics, and regulatory signaling that boosts repolarizing currents.
Why Is positive regulation of membrane repolarization during cardiac muscle cell action potential Important in Cell Biology?
GO:1905033 is critically important because repolarization is the final phase of the cardiac action potential, and its positive regulation determines action potential duration, refractory period, and susceptibility to arrhythmias. Impaired repolarization, often due to loss-of-function mutations in potassium channels or drug-induced hERG block, can lead to early afterdepolarizations and torsades de pointes. Conversely, excessive repolarization shortening can predispose to reentrant arrhythmias. Thus, understanding the positive regulation of repolarization is essential for cardiac electrophysiology, drug safety assessment, and the development of antiarrhythmic therapies.
• Controls action potential duration and refractory period, which are determinants of normal heart rhythm.
• Dysregulation causes long QT syndrome and drug-induced torsades de pointes.
• hERG (KCNH2) channel block is a major safety liability in drug development, making repolarization assays critical.
• PRMT1-mediated regulation of IKs-PIP2 interaction represents a novel therapeutic target for repolarization disorders.
• Repolarization abnormalities are observed in cardiac hypertrophy and heart failure.
• Positive regulation of repolarization is essential for proper excitation-contraction coupling and mechanical function.
• CRISPR models of repolarization genes enable precise mechanistic studies and drug screening.
• Understanding species-specific differences in repolarizing currents is important for translational research.
• Repolarization reserve is a concept that explains inter-individual variability in arrhythmia susceptibility.
• Modulation of repolarization by signaling pathways (e.g., MAPK, PI3K) links cardiac stress to arrhythmogenesis.
What Happens During positive regulation of membrane repolarization during cardiac muscle cell action potential?
Phase 1: Early Repolarization and Ito
In simple terms: The first step in repolarization is a quick, partial return of the cell's voltage, driven by potassium ions leaving the cell.
Early repolarization (phase 1) is mediated by the transient outward potassium current (Ito), which flows through channels such as Kv4.3 and Kv1.4. Ito contributes to the notch of the action potential and sets the plateau potential. In canine ventricular myocytes, Ito plays a role in regulating mechanical properties, and its modulation affects the force of contraction. Positive regulation of repolarization can involve enhancement of Ito, which shortens the action potential duration and reduces calcium influx, thereby affecting contractility.
Phase 2: Plateau and the Balance of Calcium and Potassium Currents
In simple terms: During the plateau, calcium ions entering the cell are balanced by potassium ions leaving, keeping the voltage stable for a while.
The plateau phase (phase 2) results from a fine balance between inward L-type calcium current (ICaL) and outward potassium currents, particularly IKr and IKs. The L-type calcium channel (Cav1.2) undergoes calcium-induced calcium release, which can remodel its own signaling pathway. Positive regulation of repolarization during this phase typically involves increasing outward potassium currents or reducing inward calcium current, which accelerates the transition to phase 3. For example, PRMT1 modulates the IKs channel-PIP2 interaction, enhancing IKs and promoting repolarization.
Phase 3: Rapid Repolarization and IKr/IKs
In simple terms: The cell rapidly returns to its resting voltage as potassium ions rush out through specific channels.
Phase 3 repolarization is driven primarily by IKr (hERG) and IKs (Kv7.1/KCNE1). The hERG channel has unique gating properties, including slow activation and rapid inactivation, which are critical for its role in repolarization. Studies of HERG channels stably expressed in HEK 293 cells at physiological temperature have characterized these properties in detail. Positive regulation of repolarization can occur through increased IKr or IKs activity, or through modulation of channel trafficking and PIP2 interactions. Altered gating of HERG by divalent cations such as cobalt and lanthanum has also been described, highlighting the sensitivity of these channels to environmental factors.
Phase 4: Resting Potential and IK1
In simple terms: After repolarization, the cell stays at its resting voltage thanks to potassium channels that remain open.
The resting membrane potential (phase 4) is maintained by the inward rectifier potassium current (IK1), which flows through Kir2.x channels. IK1 ensures stable resting potential and contributes to the final phase of repolarization. Positive regulation of repolarization may involve enhancement of IK1, which stabilizes the resting state and prevents spontaneous depolarizations. Although IK1 is not a major driver of phase 3, its proper function is essential for the overall repolarization process and for preventing arrhythmias.
Regulation by Signaling Pathways
In simple terms: Signals inside the cell can speed up or slow down repolarization by modifying ion channels.
Repolarization is dynamically regulated by intracellular signaling pathways. For instance, PRMT1 (protein arginine methyltransferase 1) modulates the interaction between IKs channels and PIP2, thereby controlling repolarization. Additionally, MAP kinases and PI3-kinase regulate potassium channels during eccentric cardiac hypertrophy, linking hypertrophic signaling to repolarization changes. Calcium-induced calcium release via RyR2 can also influence repolarization by affecting calcium-sensitive currents and gap junction communication. These pathways represent potential targets for therapeutic modulation of repolarization.
Key Genes Involved in GO:1905033 positive regulation of membrane repolarization during cardiac muscle cell action potential
The following genes and proteins are central to the positive regulation of membrane repolarization during cardiac muscle cell action potential, based on verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| KCNH2 (hERG) | Alpha subunit of the rapid delayed rectifier potassium channel (IKr) | Mutations cause long QT syndrome; primary target for drug safety screening |
| KCNQ1 | Alpha subunit of the slow delayed rectifier potassium channel (IKs) | Mutations cause long QT syndrome; regulated by PIP2 and PRMT1 |
| KCNE1 | Beta subunit of IKs channel | Modulates IKs gating and function; mutations linked to arrhythmias |
| KCNE2 | Beta subunit that associates with hERG | Modulates IKr; mutations associated with long QT syndrome |
| KCND3 (Kv4.3) | Alpha subunit of the transient outward potassium channel (Ito) | Contributes to early repolarization; role in cardiac hypertrophy |
| KCNA4 (Kv1.4) | Alpha subunit of Ito in some species | Contributes to phase 1 repolarization |
| KCNJ2 (Kir2.1) | Alpha subunit of the inward rectifier potassium channel (IK1) | Maintains resting potential; mutations cause Andersen-Tawil syndrome |
| CACNA1C (Cav1.2) | Alpha subunit of L-type calcium channel | Inward current during plateau; calcium-induced calcium release |
| RYR2 | Ryanodine receptor 2, mediates calcium release from sarcoplasmic reticulum | Regulates calcium-dependent signaling and repolarization |
| PRMT1 | Protein arginine methyltransferase 1 | Modulates IKs-PIP2 interaction, controlling repolarization |
| MAPK1/3 (ERK1/2) | Mitogen-activated protein kinases | Regulate potassium channels during cardiac hypertrophy |
| PIK3CA/PIK3CB | PI3-kinase subunits | Regulate potassium channels during hypertrophy |
| GJA1 (Cx43) | Connexin 43, gap junction protein | Regulated by RyR2-mediated calcium signaling; affects electrical coupling |
| ATP1A1 | Na+/K+-ATPase alpha subunit | Maintains ion gradients essential for repolarization |
| SCN5A | Voltage-gated sodium channel alpha subunit | Depolarization phase; mutations cause Brugada syndrome and long QT |
| CALM1 | Calmodulin 1 | Calcium sensor that modulates ion channels including hERG |
| AKAP9 | A-kinase anchoring protein 9 | Scaffolds signaling complexes that regulate repolarization channels |
| SLC8A1 (NCX1) | Sodium-calcium exchanger | Influences calcium handling and repolarization |
How Is positive regulation of membrane repolarization during cardiac muscle cell action potential Regulated?
The positive regulation of membrane repolarization is itself regulated by multiple signaling mechanisms. PRMT1-mediated methylation modulates the interaction between IKs channels and PIP2, thereby enhancing IKs and promoting repolarization. MAP kinases and PI3-kinase pathways regulate potassium channel expression and function during eccentric cardiac hypertrophy, which can alter repolarization. Calcium-induced calcium release via RyR2 influences calcium-dependent signaling that affects repolarization and gap junction function. Additionally, electrical stimulation promotes maturation of cardiomyocytes derived from human embryonic stem cells, which involves changes in repolarization currents. These regulatory layers ensure that repolarization is adaptable to physiological demands but also render it vulnerable to pathological disruption.
positive regulation of membrane repolarization during cardiac muscle cell action potential and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| KCNH2 | Long QT syndrome type 2; drug-induced arrhythmia | Knockout or point-mutation knock-in in hiPSC-derived cardiomyocytes |
| KCNQ1 | Long QT syndrome type 1; atrial fibrillation | Knockout or overexpression in cardiomyocytes |
| PRMT1 | Repolarization regulation; potential arrhythmia modifier | Knockout or point-mutation in cardiac cell lines |
| RYR2 | Catecholaminergic polymorphic ventricular tachycardia; calcium handling disorders | Knock-in of disease mutations in hiPSC-cardiomyocytes |
| MAPK1/3 | Cardiac hypertrophy; electrical remodeling | Knockout or overexpression in hypertrophic models |
Long QT Syndrome and Drug-Induced Arrhythmias
Long QT syndrome (LQTS) is a cardiac disorder characterized by prolonged repolarization, which increases the risk of torsades de pointes and sudden cardiac death. Mutations in KCNH2 (hERG) and KCNQ1, which carry IKr and IKs respectively, are common causes of LQTS. Additionally, many pharmacological agents block hERG channels, inadvertently delaying repolarization and causing drug-induced LQTS. Positive regulation of repolarization is therefore a protective mechanism, and understanding how to enhance it could lead to therapies for LQTS.
Cardiac Hypertrophy and Heart Failure
Cardiac hypertrophy is associated with electrical remodeling, including changes in potassium channel expression that can prolong repolarization and increase arrhythmia risk. In eccentric cardiac hypertrophy, MAP kinases and PI3-kinase regulate potassium channels, affecting repolarization. The transient outward current Ito is also altered in hypertrophy, contributing to action potential prolongation. These changes highlight the importance of positive regulation of repolarization in maintaining electrical stability during cardiac stress.
Calcium Handling Disorders and Arrhythmogenesis
RyR2-mediated calcium release regulates multiple downstream effectors, including connexin 43 hemichannels, which can influence repolarization and electrical coupling. Dysregulation of calcium-induced calcium release can lead to delayed afterdepolarizations and arrhythmias. Thus, positive regulation of repolarization intersects with calcium signaling pathways, and their dysfunction contributes to arrhythmogenesis.
From positive regulation of membrane repolarization during cardiac muscle cell action potential-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of KCNH2 abolish IKr and prolong repolarization? | CRISPR knockout of KCNH2 in hiPSC-derived cardiomyocytes |
| Does a specific point mutation in KCNQ1 alter IKs gating? | Point-mutation knock-in in HEK293 or cardiomyocytes |
| Can overexpression of PRMT1 enhance repolarization? | Overexpression of PRMT1 in cardiac cell lines |
| How does RyR2-mediated calcium release affect repolarization? | Knockout or knock-in of RyR2 in cardiomyocytes |
| What is the role of Ito in mechanical properties? | Knockout of KCND3 in canine ventricular myocytes |
| Does electrical stimulation mature repolarization currents? | Overexpression or optogenetic stimulation in hESC-derived cardiomyocytes |
How to Study the positive regulation of membrane repolarization during cardiac muscle cell action potential Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Patch-clamp electrophysiology | Ion currents and action potential duration | Assessing effects of gene knockout or drugs on repolarization |
| Calcium imaging | Intracellular calcium transients | Linking repolarization to calcium handling |
| RNA sequencing | Gene expression profiles | Identifying transcriptional changes in ion channels |
| CRISPR screening | Functional impact of gene perturbations | Discovering novel regulators of repolarization |
| Voltage-sensitive dyes | Membrane potential changes | High-throughput screening of repolarization modulators |
| Western blotting | Protein expression and phosphorylation | Validating signaling pathways affecting repolarization |
| Immunofluorescence | Subcellular localization of channels | Studying trafficking and membrane expression |
| qRT-PCR | mRNA levels of ion channels | Quantifying gene expression changes |
Patch-Clamp Electrophysiology
Patch-clamp electrophysiology is the gold standard for measuring ion currents that underlie repolarization, such as IKr, IKs, and Ito. It allows direct assessment of action potential duration and the effects of genetic manipulations or drugs. This method is essential for validating CRISPR models of repolarization genes.
Calcium Imaging and Fluorescent Indicators
Calcium imaging using fluorescent dyes or genetically encoded indicators measures intracellular calcium transients, which are tightly linked to repolarization and excitation-contraction coupling. It can reveal how modulation of repolarization affects calcium handling.
RNA Sequencing and Transcriptomics
RNA sequencing quantifies expression levels of ion channel genes and regulatory factors, providing insights into transcriptional changes that affect repolarization. It is useful for studying hypertrophy-induced electrical remodeling.
CRISPR Screening and Functional Genomics
CRISPR library screening enables unbiased identification of genes that positively or negatively regulate repolarization. Combined with high-throughput electrophysiology or voltage-sensitive dyes, it can uncover novel regulators of GO:1905033.
How CRISPR Can Be Used to Study GO:1905033 positive regulation of membrane repolarization during cardiac muscle cell action potential
Knockout
CRISPR knockout of genes such as KCNH2, KCNQ1, or PRMT1 in cardiomyocytes or cell lines can abolish specific repolarizing currents, leading to prolonged action potential duration. These models are invaluable for establishing causal roles in GO:1905033 and for testing compensatory mechanisms.
Point Mutation
Point mutations identified in patients with long QT syndrome can be introduced into endogenous loci using CRISPR base editing or homology-directed repair. Such models replicate disease-specific gating defects and allow precise assessment of repolarization abnormalities.
Knock-in
Knock-in of reporter tags or disease alleles enables tracking of channel trafficking, function, and regulation. For example, tagging KCNH2 with fluorescent proteins allows live-cell imaging of hERG trafficking and its modulation by signaling pathways.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression can increase expression of genes that positively regulate repolarization, such as PRMT1 or KCNQ1. These models help test whether enhancing a specific gene accelerates repolarization and protects against arrhythmias.
How EDITGENE Supports positive regulation of membrane repolarization during cardiac muscle cell action potential Research
Researchers studying positive regulation of membrane repolarization during cardiac muscle cell action potential-related genes often need to determine whether a candidate gene is causally involved in repolarization or merely correlated with it. CRISPR-based models provide the gold standard for establishing causality, and EDITGENE offers a comprehensive suite of services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for positive regulation of membrane repolarization during cardiac muscle cell action potential research.
Frequently Asked Questions About positive regulation of membrane repolarization during cardiac muscle cell action potential
What is GO:1905033?
GO:1905033 is a Gene Ontology biological process term defined as any process that activates or increases the frequency, rate or extent of membrane repolarization during cardiac muscle cell action potential.
What genes are involved in positive regulation of membrane repolarization during cardiac muscle cell action potential?
Key genes include KCNH2 (hERG), KCNQ1, KCNE1, KCND3, KCNJ2, PRMT1, and RYR2, among others.
How does hERG contribute to cardiac repolarization?
hERG (KCNH2) carries the rapid delayed rectifier potassium current IKr, which is critical for phase 3 repolarization; its unique gating properties have been characterized in detail.
What diseases are linked to abnormal repolarization?
Long QT syndrome, drug-induced torsades de pointes, cardiac hypertrophy, and heart failure are associated with repolarization abnormalities.
How can CRISPR be used to study repolarization?
CRISPR knockout, point mutation, knock-in, and overexpression models allow precise manipulation of repolarization genes in cardiomyocytes and cell lines.
What is the role of PRMT1 in repolarization?
PRMT1 modulates the interaction between IKs channels and PIP2, thereby controlling cardiac repolarization.
What methods measure membrane repolarization?
Patch-clamp electrophysiology, voltage-sensitive dyes, and calcium imaging are commonly used to assess repolarization.
Why is repolarization important for drug safety?
Many drugs block hERG and delay repolarization, increasing arrhythmia risk; therefore, repolarization assays are essential in drug development.
What is the transient outward current (Ito)?
Ito is a potassium current that mediates early repolarization (phase 1) and influences action potential duration and contractility.
How does calcium signaling affect repolarization?
Calcium release via RyR2 regulates calcium-dependent signaling that can influence repolarization and gap junction function.
Conclusion
GO:1905033, positive regulation of membrane repolarization during cardiac muscle cell action potential, is a fundamental biological process that ensures proper cardiac electrical activity. Its dysregulation leads to arrhythmias, making it a key area of research in cardiac electrophysiology and drug safety. Advances in CRISPR-based models and high-throughput screening are accelerating the discovery of novel regulators and therapeutic targets. EDITGENE provides comprehensive services to support these investigations, from knockout and point-mutation models to library screening and bioinformatics.
References
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- 2. Lissoni A et al.. 2021. RyR2 regulates Cx43 hemichannel intracellular Ca2+-dependent activation in cardiomyocytes.. Cardiovasc Res 117(1):123-136 PMID: 31841141
- 3. Richard S et al.. 2006. 'Ca(2+)-induced Ca(2+) entry' or how the L-type Ca(2+) channel remodels its own signalling pathway in cardiac cells.. Prog Biophys Mol Biol 90(1-3):118-35 PMID: 15987656
- 4. Chan YC et al.. 2013. Electrical stimulation promotes maturation of cardiomyocytes derived from human embryonic stem cells.. J Cardiovasc Transl Res 6(6):989-99 PMID: 24081385
- 5. Dong M et al.. 2010. Role of the transient outward current in regulating mechanical properties of canine ventricular myocytes.. J Cardiovasc Electrophysiol 21(6):697-703 PMID: 20132386
- 6. Teos LY et al.. 2008. Basal and IGF-I-dependent regulation of potassium channels by MAP kinases and PI3-kinase during eccentric cardiac hypertrophy.. Am J Physiol Heart Circ Physiol 295(5):H1834-45 PMID: 18757484
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- 8. Zhou Z et al.. 1998. Properties of HERG channels stably expressed in HEK 293 cells studied at physiological temperature.. Biophys J 74(1):230-41 PMID: 9449325
