GO:1905025 negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential: Cardiac Repolarization Control, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1905025 describes any process that stops, prevents, or reduces the frequency, rate, or extent of membrane repolarization during the ventricular cardiac muscle cell action potential.
• Ventricular repolarization is shaped by a balance between inward depolarizing currents and outward repolarizing potassium currents, including IKs, IKr, Ito, and IK1 [1,4,5,7].
• Negative regulation of repolarization can be studied by single-cell voltage clamp, which directly measures action potential duration and current contributions in ventricular myocytes.
• Key molecular players include KCNQ1/KCNE1 (IKs), KCNH2 (IKr), KCND2/KCND3 (Ito), KCNJ2 (IK1), and the transcription factor IRX5, which establishes the ventricular repolarization gradient [4,6,7,8].
• Dysregulation of repolarization underlies arrhythmia risk, and cardiotoxic agents such as lindane or cobalt/lanthanum can alter HERG and other potassium channel gating [2,8].
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models enable causal testing of repolarization genes in ventricular cardiomyocytes [3,6,7].
Description
GO:1905025, negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential, is a biological process term that captures any mechanism that slows, prevents, or reduces the repolarization phase of the ventricular action potential. Repolarization is the return of the cardiomyocyte membrane potential to its resting negative value after depolarization, and its timing determines the QT interval on the electrocardiogram. Because ventricular action potential duration must be tightly controlled for coordinated contraction and relaxation, negative regulation of repolarization is central to cardiac electrophysiology and arrhythmia susceptibility [1,4]. Researchers study this process to understand how ion channel conductances, calcium handling, and transcriptional programs set repolarization reserve in the ventricle [4,5,6]. The term is also relevant to drug safety, since many pharmacological agents and toxins can inhibit repolarizing currents and prolong the action potential [2,8]. This article summarizes the ontology definition, molecular components, key genes, disease links, and experimental models used to investigate GO:1905025.
negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential At A Glance
| GO ID | GO:1905025 |
|---|---|
| GO term | negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential |
| Ontology | biological_process |
| Synonym | negative regulation of ventricular repolarization; inhibition of electrocardiogram T wave; downregulation of membrane repolarization during ventricular cardiac muscle cell action potential |
| Major function | Slowing or reducing the repolarization phase of the ventricular action potential, thereby prolonging action potential duration and influencing the T wave. |
| Key currents involved | IKs (KCNQ1/KCNE1), IKr (KCNH2), Ito (KCND2/KCND3), IK1 (KCNJ2) [4,5,7,8]. |
| Regulatory transcription factor | IRX5 establishes the mouse cardiac ventricular repolarization gradient. |
| Experimental readout | Action potential duration and repolarizing current amplitudes measured by single-cell voltage clamp. |
| Disease relevance | Arrhythmia risk and drug-induced QT prolongation linked to altered repolarization [2,8]. |
What Is GO:1905025?
In our own words, GO:1905025 refers to any biological process that negatively regulates, i.e., decreases the frequency, rate, or extent of, membrane repolarization specifically during the action potential of ventricular cardiac muscle cells. It is a subprocess of regulation of ventricular cardiac muscle cell action potential and is synonymous with negative regulation of ventricular repolarization or inhibition of the electrocardiogram T wave. The term excludes repolarization in atrial or nodal cells and focuses on the ventricular myocyte context where delayed rectifier and inward rectifier potassium currents dominate the repolarization phase [1,4,7].
Why Is negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential Important in Cell Biology?
GO:1905025 is important because the duration of the ventricular action potential is a primary determinant of the QT interval and a critical safety parameter in drug development. Negative regulation of repolarization can be adaptive or pathological; excessive slowing of repolarization increases the risk of early afterdepolarizations and torsades de pointes, while insufficient negative regulation can shorten the action potential and predispose to reentrant arrhythmias [1,8]. Understanding the molecular players that negatively regulate repolarization, such as delayed rectifier potassium channels and their transcriptional regulators, is therefore essential for cardiac physiology, pharmacology, and precision medicine [4,6,7].
• Defines a key electrophysiological process that controls ventricular action potential duration and the ECG T wave.
• Provides a framework for studying drug-induced QT prolongation and proarrhythmic risk [2,8].
• Links ion channel function (IKs, IKr, Ito, IK1) to cellular repolarization reserve [4,5,7].
• Highlights transcriptional control of repolarization gradients by factors such as IRX5.
• Supports research on inherited and acquired arrhythmia syndromes [1,6].
• Enables mechanistic interpretation of cardiotoxicity from environmental or pharmacological agents [2,8].
• Guides CRISPR-based causal testing of candidate repolarization genes [3,7].
• Informs the development of safer drugs with minimal repolarization delay [1,8].
What Happens During negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential?
Phase 2 plateau and the balance of inward and outward currents
In simple terms: During the plateau of the ventricular action potential, calcium coming in is balanced by potassium going out, and anything that reduces the potassium going out slows repolarization.
The ventricular action potential plateau is maintained by a fine balance between inward L-type calcium current and outward potassium currents. Negative regulation of repolarization occurs when outward repolarizing currents are reduced or inward currents are enhanced, prolonging the plateau. Single-cell voltage clamp studies have been instrumental in quantifying these current contributions and showing how changes in individual conductances alter action potential duration.
Delayed rectifier potassium currents IKs and IKr
In simple terms: Two slow potassium currents, IKs and IKr, are the main brakes that end the plateau; reducing them delays repolarization.
The slowly activating delayed rectifier current IKs, carried by KCNQ1/KCNE1 channels, and the rapidly activating IKr, carried by KCNH2 (HERG) channels, are major determinants of repolarization [4,8]. Quantitative analysis in rabbit ventricular myocytes has shown that IKs is strongly regulated by intracellular calcium, linking calcium handling to repolarization timing. Pharmacological inhibition or altered gating of HERG by agents such as cobalt and lanthanum reduces IKr and negatively regulates repolarization.
Transient outward current Ito and early repolarization
In simple terms: The transient outward current Ito shapes the early part of repolarization and can influence the whole action potential duration.
Ito, carried by KCND2/KCND3 channels, contributes to phase 1 repolarization and modulates the plateau level. In canine ventricular myocytes, the transient outward current has been shown to regulate mechanical properties, indicating that early repolarization currents can feed back on excitation-contraction coupling. Negative regulation of repolarization can therefore involve changes in Ito density or kinetics that indirectly prolong the action potential.
Inward rectifier current IK1 and terminal repolarization
In simple terms: The inward rectifier current IK1 helps set the resting potential and the final phase of repolarization; reducing it can destabilize the membrane potential.
IK1, carried by Kir2.1 (KCNJ2), is critical for maintaining the resting membrane potential and for terminal repolarization. Functional studies using Kir2.1 overexpression and dominant-negative suppression demonstrated that altering IK1 strongly affects action potential duration and excitability. Thus, negative regulation of repolarization can also arise from modulation of IK1, particularly in the final repolarization phase.
Transcriptional control of repolarization gradients
In simple terms: The heart wall has a gradient of repolarization timing, and transcription factors like IRX5 set this gradient by controlling ion channel genes.
The homeodomain transcription factor Irx5 establishes the mouse cardiac ventricular repolarization gradient by regulating the expression of potassium channel genes such as KCND2. This transcriptional control creates regional differences in action potential duration across the ventricular wall, which is essential for normal mechanical function. Disruption of such transcriptional programs can negatively regulate repolarization in a chamber-specific manner.
Calcium-dependent regulation of repolarizing currents
In simple terms: Calcium inside the cell can change how strongly repolarizing potassium currents work, linking calcium signaling to repolarization speed.
Intracellular calcium regulates several repolarizing currents. For example, RyR2-mediated calcium release activates Cx43 hemichannels in cardiomyocytes, which can influence membrane potential and repolarization. Additionally, IKs is calcium-dependent, as shown in rabbit ventricular myocytes. These calcium-dependent mechanisms provide a means by which calcium handling abnormalities can negatively regulate repolarization.
Key Genes Involved in GO:1905025 negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential
The following genes and proteins are central to the negative regulation of ventricular repolarization, based on functional studies in cardiomyocytes and animal models.
| Gene | Major Role | Research Relevance |
|---|---|---|
| KCNQ1 | Pore-forming subunit of IKs | Loss-of-function reduces IKs and delays repolarization. |
| KCNE1 | Beta subunit of IKs | Modulates IKs kinetics and calcium sensitivity. |
| KCNH2 | Pore-forming subunit of IKr (HERG) | Inhibition or gating changes reduce IKr and prolong action potential. |
| KCND2 | Pore-forming subunit of Ito | Contributes to early repolarization and is regulated by IRX5 [5,6]. |
| KCND3 | Pore-forming subunit of Ito | Modulates transient outward current density. |
| KCNJ2 | Pore-forming subunit of IK1 (Kir2.1) | Overexpression or suppression alters action potential duration. |
| IRX5 | Transcription factor | Establishes ventricular repolarization gradient. |
| RYR2 | Sarcoplasmic reticulum calcium release channel | Regulates calcium-dependent activation of Cx43 hemichannels. |
| GJA1 | Connexin 43 hemichannel | Calcium-dependent activation affects membrane potential. |
| CACNA1C | L-type calcium channel | Inward current that opposes repolarization. |
| SCN5A | Voltage-gated sodium channel | Depolarizing current that influences action potential duration. |
| ATP2A2 | SERCA2 calcium pump | Calcium handling affects repolarization indirectly. |
| CALM1 | Calmodulin | Calcium sensor modulating ion channels. |
| KCNE2 | Beta subunit for IKr | Modifies HERG current properties. |
| KCNE3 | Beta subunit for IKs | Modulates IKs. |
| KCNJ12 | Kir2.2 subunit | Contributes to IK1 in some species. |
| KCNJ4 | Kir2.3 subunit | Contributes to IK1. |
| KCNIP2 | Ito auxiliary subunit | Regulates Ito expression and kinetics. |
How Is negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential Regulated?
The process of negative regulation of ventricular repolarization is itself regulated at multiple levels. Transcriptional control by IRX5 sets regional differences in potassium channel expression. Calcium-dependent signaling modulates IKs and Cx43 hemichannel activity [3,4]. Pharmacological agents and toxins can acutely inhibit repolarizing currents, as shown for HERG with cobalt and lanthanum. Additionally, the balance between sympathetic stimulation and other neurohumoral factors can alter repolarization reserve, although specific pathways are beyond the scope of the cited literature.
negative regulation of membrane repolarization during ventricular 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 in hiPSC-cardiomyocytes. |
| KCNQ1 | Long QT syndrome type 1, IKs dysfunction | Knock-in of patient variants in ventricular myocytes. |
| KCNJ2 | Andersen-Tawil syndrome, short QT | Overexpression or dominant-negative suppression. |
| IRX5 | Ventricular repolarization gradient disorders | Knockout mouse model. |
| RYR2 | Catecholaminergic polymorphic ventricular tachycardia | Knock-in of CPVT mutations. |
Arrhythmia and QT prolongation
Excessive negative regulation of ventricular repolarization prolongs the action potential and QT interval, increasing the risk of early afterdepolarizations and torsades de pointes [1,8]. Inherited or acquired loss of function of repolarizing currents, such as IKr or IKs, is a well-known mechanism [4,8].
Drug-induced cardiotoxicity
Many drugs and environmental toxins inhibit HERG or other potassium channels, reducing repolarizing currents and causing acquired long QT syndrome [2,8]. The cardiotoxicity of lindane has been linked to effects on cardiac ion channels, and cobalt/lanthanum alter HERG gating.
Cardiac developmental and regional disorders
Disruption of the IRX5-dependent repolarization gradient can lead to abnormal regional heterogeneity of action potential duration, which may predispose to arrhythmias. Such gradients are important for normal excitation-contraction coupling and are altered in heart failure models.
From negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of KCNH2 reduce IKr and prolong action potential? | CRISPR knockout in hiPSC-derived ventricular cardiomyocytes. |
| How does a specific KCNQ1 variant affect IKs? | Point mutation knock-in in cardiomyocytes. |
| What is the role of IRX5 in repolarization gradient? | IRX5 knockout mouse. |
| Can overexpression of Kir2.1 shorten action potential? | Overexpression of KCNJ2 in ventricular myocytes. |
| Does RyR2-mediated calcium release affect hemichannel activation? | Knock-in or knockout of RYR2 in cardiomyocytes. |
| How does Ito density regulate mechanical properties? | Overexpression or knockout of KCND2 in canine myocytes. |
How to Study the negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Patch clamp | Action potential duration and ionic currents | Assess negative regulation of repolarization. |
| Calcium imaging | Intracellular calcium transients | Link calcium handling to repolarization [3,4]. |
| qRT-PCR | mRNA expression of ion channels | Quantify KCNQ1, KCNH2, KCND2, IRX5. |
| Western blot | Protein levels of channels | Validate knockout or overexpression. |
| Microelectrode array | Extracellular field potentials | High-throughput drug screening. |
| RNA-seq | Global transcriptome | Identify repolarization gene networks. |
| Optogenetics | Membrane potential control | Light-induced repolarization studies. |
| CRISPR screening | Gene function at scale | Discover novel repolarization regulators. |
Single-cell voltage clamp
Voltage clamp directly measures ionic currents and action potentials in isolated ventricular myocytes, allowing quantification of repolarizing currents such as IKs, IKr, Ito, and IK1 [1,4,5,7].
Calcium imaging and optogenetics
Calcium imaging reveals intracellular calcium transients that modulate repolarizing currents and hemichannel activity [3,4]. Optogenetic tools can be used to control membrane potential, although specific studies are not cited here.
Transcriptional profiling and qPCR
Quantitative PCR and RNA-seq can measure expression levels of potassium channel genes and transcription factors like IRX5 that set repolarization gradients.
Pharmacological screening
Automated patch clamp or microelectrode array platforms can screen compounds for effects on repolarization, using known inhibitors such as cobalt or lanthanum as controls.
How CRISPR Can Be Used to Study GO:1905025 negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential
Knockout
CRISPR knockout of KCNH2, KCNQ1, or KCNJ2 in hiPSC-derived cardiomyocytes can eliminate specific repolarizing currents and reveal their contribution to action potential duration [7,8].
Point Mutation
Introducing patient-specific point mutations in KCNQ1 or KCNH2 via CRISPR base editing or HDR allows study of variant effects on IKs or IKr gating and repolarization [4,8].
Knock-in
Knock-in of fluorescent tags or reporter genes into endogenous loci such as KCND2 enables live tracking of channel expression and localization in ventricular myocytes [5,6].
Overexpression
CRISPR activation or lentiviral overexpression of KCNJ2 or other channels can increase repolarizing current density and test whether enhanced repolarization shortens action potential.
How EDITGENE Supports negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential Research
Researchers studying negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential-related genes often need to determine whether a candidate gene is causally involved in setting action potential duration or repolarization reserve. EDITGENE provides CRISPR-based cell model services to enable such causal experiments in relevant cardiac cell types.
Contact EDITGENE today to design your custom CRISPR model for negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential research.
Frequently Asked Questions About negative regulation of membrane repolarization during ventricular cardiac muscle cell action potential
What is GO:1905025?
GO:1905025 is a Gene Ontology biological process term for any process that stops, prevents, or reduces the frequency, rate, or extent of membrane repolarization during ventricular cardiac muscle cell action potential.
What genes are involved in negative regulation of ventricular repolarization?
Key genes include KCNQ1, KCNE1, KCNH2, KCND2, KCND3, KCNJ2, and the transcription factor IRX5 [4,5,6,7,8].
How is ventricular repolarization measured?
Single-cell voltage clamp is the gold standard for measuring action potential duration and repolarizing currents in ventricular myocytes.
What diseases are linked to abnormal ventricular repolarization?
Long QT syndrome, drug-induced arrhythmia, and other cardiac rhythm disorders are linked to altered repolarization [2,8].
What is the role of IKs in repolarization?
IKs, carried by KCNQ1/KCNE1, is a slowly activating delayed rectifier current that contributes to repolarization and is calcium-dependent.
How does IRX5 affect repolarization?
IRX5 is a transcription factor that establishes the mouse cardiac ventricular repolarization gradient by regulating potassium channel expression.
Can CRISPR be used to study repolarization genes?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models allow causal testing of genes in cardiomyocytes [3,7].
What is the difference between IKr and IKs?
IKr is the rapidly activating delayed rectifier current carried by HERG (KCNH2), while IKs is the slowly activating current carried by KCNQ1/KCNE1 [4,8].
What is the clinical significance of the T wave?
The T wave on the electrocardiogram reflects ventricular repolarization, and its prolongation indicates delayed repolarization and arrhythmia risk.
How does calcium influence repolarization?
Intracellular calcium regulates IKs and can activate Cx43 hemichannels, thereby modulating repolarization [3,4].
Conclusion
GO:1905025 provides a precise ontology framework for studying how ventricular repolarization is slowed or reduced, a process with direct implications for cardiac arrhythmia and drug safety [1,8]. The integration of ion channel physiology, transcriptional control, and calcium signaling defines the molecular landscape of this process [4,6,7]. CRISPR-based cell models are powerful tools to dissect causal roles of individual genes and to screen for novel regulators of repolarization [3,7]. Continued research using these approaches will improve our understanding of repolarization reserve and guide safer therapeutic development.
References
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- 2. Sauviat MP et al.. 2002. [Cardiotoxicity of lindane, a gamma isomer of hexachlorocyclohexane].. J Soc Biol 196(4):339-48 PMID: 12645305
- 3. Lissoni A et al.. 2021. RyR2 regulates Cx43 hemichannel intracellular Ca2+-dependent activation in cardiomyocytes.. Cardiovasc Res 117(1):123-136 PMID: 31841141
- 4. Bartos DC et al.. 2017. Quantitative analysis of the Ca(2+) -dependent regulation of delayed rectifier K(+) current I(Ks) in rabbit ventricular myocytes.. J Physiol 595(7):2253-2268 PMID: 28008618
- 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. Costantini DL et al.. 2005. The homeodomain transcription factor Irx5 establishes the mouse cardiac ventricular repolarization gradient.. Cell 123(2):347-58 PMID: 16239150
- 7. Miake J et al.. 2003. Functional role of inward rectifier current in heart probed by Kir2.1 overexpression and dominant-negative suppression.. J Clin Invest 111(10):1529-36 PMID: 12750402
- 8. Sanchez-Chapula JA et al.. 2000. Altered gating of HERG potassium channels by cobalt and lanthanum.. Pflugers Arch 440(2):264-74 PMID: 10898527
