GO:1901898 negative regulation of relaxation of cardiac muscle: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1901898 describes any process that stops, prevents or reduces the frequency, rate or extent of cardiac muscle relaxation, a critical determinant of diastolic function and ventricular filling.
• Cardiac relaxation depends on timely removal of cytosolic Ca2+ by SERCA2a (ATP2A2) and extrusion by NCX1 (SLC8A1), and on the release of thin-filament inhibition by troponin I (TNNI3) phosphorylation.
• Negative regulation of relaxation is often mediated by sustained Ca2+ transients, reduced SERCA2a activity, altered troponin phosphorylation, and neurohumoral modulators such as nitric oxide and urotensin II.
• Impaired cardiac relaxation underlies diastolic dysfunction and heart failure with preserved ejection fraction, and is a hallmark of diabetic cardiomyopathy and cirrhotic cardiomyopathy.
• Key experimental models include cardiomyocyte-specific knockout of Atp2a2, knock-in of phospho-mimetic or phospho-deficient Tnni3, and overexpression of caveolin-3 or urotensin II receptors.
• CRISPR-based knockout, point mutation, knock-in and overexpression models enable causal dissection of genes that negatively regulate cardiac relaxation.
Description
Cardiac muscle relaxation is an active, energy-dependent process that determines ventricular filling and diastolic performance. GO:1901898, negative regulation of relaxation of cardiac muscle, captures any biological process that stops, prevents or reduces the frequency, rate or extent of cardiac muscle relaxation. This term is essential for researchers studying diastolic dysfunction, heart failure with preserved ejection fraction, and cardiomyopathies where impaired relaxation is a primary pathophysiological feature. The regulation of cardiac relaxation involves a tightly coordinated interplay between calcium handling proteins, myofilament regulatory proteins, and neurohumoral signaling pathways. Perturbations in these pathways can slow calcium reuptake, delay thin-filament deactivation, or sustain contractile activation, thereby negatively regulating relaxation. Understanding the molecular players and experimental approaches for GO:1901898 is critical for developing targeted therapies for diastolic heart failure and related disorders.
negative regulation of relaxation of cardiac muscle At A Glance
| GO ID | GO:1901898 |
|---|---|
| GO term | negative regulation of relaxation of cardiac muscle |
| Ontology | biological_process |
| Synonym | down regulation of relaxation of cardiac muscle; down-regulation of relaxation of cardiac muscle; downregulation of relaxation of cardiac muscle; inhibition of relaxation of cardiac muscle |
| Major function | Slowing or reducing the rate and extent of cardiac muscle relaxation, often by modulating calcium handling and myofilament sensitivity |
| Related processes | Calcium ion transport, regulation of cardiac muscle contraction, diastolic function |
| Key regulators | ATP2A2 (SERCA2a), SLC8A1 (NCX1), TNNI3 (troponin I), NOS3 (eNOS), UTS2 (urotensin II) |
| Disease relevance | Diastolic heart failure, diabetic cardiomyopathy, cirrhotic cardiomyopathy, malignant hyperthermia susceptibility |
What Is GO:1901898?
GO:1901898 (negative regulation of relaxation of cardiac muscle) is a biological process term defined as any process that stops, prevents or reduces the frequency, rate or extent of relaxation of cardiac muscle. In practical terms, it encompasses molecular events that delay or diminish the return of the heart muscle to its relaxed state after contraction, including sustained cytosolic calcium levels, reduced sarcoplasmic reticulum calcium reuptake, altered myofilament phosphorylation, and inhibitory signaling from neurohumoral factors.
Why Is negative regulation of relaxation of cardiac muscle Important in Cell Biology?
Negative regulation of cardiac relaxation is a central mechanism in the pathophysiology of diastolic dysfunction and heart failure with preserved ejection fraction, conditions with limited therapeutic options. By understanding how specific genes and pathways slow relaxation, researchers can identify targets to improve ventricular filling and reduce symptoms. Moreover, this process is implicated in metabolic and systemic diseases such as diabetic cardiomyopathy and cirrhotic cardiomyopathy, where impaired relaxation contributes to morbidity.
• Diastolic dysfunction is a hallmark of heart failure with preserved ejection fraction, a growing clinical burden.
• Impaired cardiac relaxation contributes to exercise intolerance and pulmonary congestion in heart failure.
• Diabetes mellitus alters calcium handling and enhances negative modulation of cardiac relaxation by urotensin II.
• Cirrhotic cardiomyopathy features impaired diastolic relaxation that can be ameliorated by caveolin-3 overexpression.
• Malignant hyperthermia susceptibility involves dysregulated calcium release and relaxation in skeletal and cardiac muscle.
• Nitric oxide signaling modulates myocardial relaxation and can negatively regulate it under pathological conditions.
• Troponin I phosphorylation state is a key determinant of myofilament relaxation kinetics.
• SERCA2a expression and activity are rate-limiting for cardiac relaxation and are altered in heart failure.
• Targeting negative regulators of relaxation may offer therapeutic strategies for diastolic heart failure.
• CRISPR-based models enable precise interrogation of genes that negatively regulate cardiac relaxation.
What Happens During negative regulation of relaxation of cardiac muscle?
Calcium reuptake and cytosolic clearance
In simple terms: After a heart cell contracts, calcium must be quickly pumped back into storage to allow relaxation; if this pumping is slowed, relaxation is delayed.
Cardiac relaxation requires the rapid removal of cytosolic Ca2+ primarily by the sarcoplasmic reticulum Ca2+-ATPase SERCA2a (ATP2A2) and extrusion by the Na+/Ca2+ exchanger NCX1 (SLC8A1). Negative regulation of relaxation can occur when SERCA2a activity or expression is reduced, as seen in heart failure and diabetic cardiomyopathy, leading to prolonged Ca2+ transients and delayed relaxation. Additionally, enhanced negative modulation by urotensin II has been shown to impair Ca2+ regulation and cardiac function in diabetic rats.
Myofilament deactivation and troponin phosphorylation
In simple terms: The contractile proteins must switch off after a heartbeat; if they stay active longer, relaxation is slowed.
Relaxation of cardiac muscle requires the release of inhibition on the thin filament, a process regulated by troponin I (TNNI3) phosphorylation. Three-dimensional organization of troponin on cardiac thin filaments in the relaxed state reveals that conformational changes are necessary for deactivation. Negative regulation of relaxation can result from altered phosphorylation of troponin I or other myofilament proteins, which prolongs the active state and slows relaxation.
Neurohumoral modulation by nitric oxide and urotensin II
In simple terms: Signaling molecules from the blood and nerves can act on the heart to make it relax more slowly.
Nitric oxide (NO) plays a role in the regulation of myocardial function and can negatively modulate relaxation under certain conditions. Similarly, urotensin II enhances negative modulation of cardiac function and Ca2+ regulation in diabetic models, contributing to impaired relaxation. These neurohumoral pathways represent important extrinsic mechanisms that negatively regulate cardiac relaxation.
Mitochondrial and metabolic influences
In simple terms: Energy-producing organelles in heart cells can influence how quickly the heart relaxes.
Mitochondria are critical for providing ATP for calcium reuptake and relaxation, and mitochondrial dysfunction in heart failure can impair relaxation. Therapeutic targeting of mitochondria has been proposed to improve cardiac function, including relaxation. Metabolic perturbations such as diabetes can exacerbate negative regulation of relaxation through mitochondrial and calcium handling changes.
Caveolin-3 and membrane signaling
In simple terms: Proteins in the cell membrane can influence relaxation signaling.
Cardiac-specific overexpression of caveolin-3 has been shown to protect against cirrhotic cardiomyopathy, in part by improving diastolic relaxation. Caveolin-3 is a membrane scaffolding protein that organizes signaling molecules, and its modulation can affect pathways that negatively regulate relaxation. This highlights the role of membrane microdomains in the regulation of cardiac relaxation.
Key Genes Involved in GO:1901898 negative regulation of relaxation of cardiac muscle
The following genes and proteins are central to the negative regulation of cardiac muscle relaxation, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ATP2A2 (SERCA2a) | Sarcoplasmic reticulum Ca2+-ATPase; pumps Ca2+ back into SR to enable relaxation | Reduced expression/activity slows relaxation; target for heart failure therapy |
| SLC8A1 (NCX1) | Na+/Ca2+ exchanger; extrudes Ca2+ from cytosol | Modulates cytosolic Ca2+ clearance and relaxation kinetics |
| TNNI3 (troponin I) | Inhibitory subunit of troponin; phosphorylation regulates myofilament deactivation | Phosphorylation state affects relaxation rate; mutations linked to cardiomyopathy |
| NOS3 (eNOS) | Endothelial nitric oxide synthase; produces NO that modulates myocardial function | NO signaling can negatively regulate relaxation under pathological conditions |
| UTS2 (urotensin II) | Vasoactive peptide; enhances negative modulation of cardiac function | In diabetic models, urotensin II impairs Ca2+ regulation and relaxation |
| CAV3 (caveolin-3) | Membrane scaffolding protein; organizes signaling complexes | Overexpression protects against cirrhotic cardiomyopathy and improves relaxation |
| RYR2 | Ryanodine receptor 2; releases Ca2+ from SR for contraction | Dysregulation can alter relaxation via Ca2+ leak |
| PLN (phospholamban) | Inhibits SERCA2a; phosphorylation relieves inhibition | Key regulator of SERCA2a activity and relaxation rate |
| MYH7 | Beta-myosin heavy chain; contractile protein | Mutations can affect relaxation and diastolic function |
| MYBPC3 | Myosin binding protein C; modulates myofilament contraction/relaxation | Phosphorylation affects relaxation kinetics |
| TNNT2 | Cardiac troponin T; part of thin filament regulatory complex | Mutations linked to hypertrophic cardiomyopathy and altered relaxation |
| TPM1 | Alpha-tropomyosin; regulates thin filament activation | Influences myofilament relaxation |
| ACTC1 | Cardiac actin; thin filament component | Mutations can affect contractile and relaxation properties |
| PRKAA2 (AMPK) | Energy sensor; regulates metabolic pathways | May influence relaxation via energy supply |
| SLC9A1 (NHE1) | Na+/H+ exchanger; affects intracellular pH and Ca2+ | Modulates Ca2+ handling and relaxation |
| CALM1 (calmodulin) | Calcium-binding protein; regulates Ca2+ channels and signaling | Central to Ca2+ signaling and relaxation |
How Is negative regulation of relaxation of cardiac muscle Regulated?
The negative regulation of cardiac muscle relaxation is itself regulated by multiple signaling pathways. Nitric oxide (NO) produced by NOS3 can modulate myocardial relaxation through cGMP-dependent mechanisms. Urotensin II enhances negative modulation of cardiac function and Ca2+ regulation, particularly in diabetic states. Phosphorylation of phospholamban and troponin I by beta-adrenergic signaling normally accelerates relaxation, so reduced phosphorylation can negatively regulate relaxation. Mitochondrial function and energy supply also regulate relaxation by providing ATP for SERCA2a. Caveolin-3 organizes signaling microdomains that can influence relaxation pathways.
negative regulation of relaxation of cardiac muscle and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ATP2A2 | Diastolic heart failure; impaired relaxation | Cardiomyocyte-specific KO or knock-in of phosphomimetic SERCA2a |
| UTS2 | Diabetic cardiomyopathy; enhanced negative modulation of relaxation | Overexpression of UTS2 in diabetic rat models |
| CAV3 | Cirrhotic cardiomyopathy; impaired relaxation | Cardiac-specific overexpression of caveolin-3 |
| TNNI3 | Cardiomyopathy; altered myofilament relaxation | Knock-in of phospho-mimetic or phospho-deficient TNNI3 |
| NOS3 | Heart failure; NO-mediated negative regulation of relaxation | Endothelial NOS knockout or overexpression models |
Diastolic Heart Failure and Heart Failure with Preserved Ejection Fraction
Impaired cardiac relaxation is a primary mechanism in diastolic heart failure and heart failure with preserved ejection fraction (HFpEF). Negative regulation of relaxation, through reduced SERCA2a activity or altered myofilament phosphorylation, contributes to elevated filling pressures and symptoms. Mitochondrial dysfunction further exacerbates impaired relaxation in heart failure.
Diabetic Cardiomyopathy
Diabetes mellitus is associated with impaired cardiac relaxation and altered Ca2+ handling. Urotensin II has been shown to enhance negative modulation of cardiac function and Ca2+ regulation in diabetic rat models, providing a molecular link between diabetes and diastolic dysfunction.
Cirrhotic Cardiomyopathy
Cirrhotic cardiomyopathy is characterized by impaired diastolic relaxation. Cardiac-specific overexpression of caveolin-3 has been shown to protect against cirrhotic cardiomyopathy, suggesting that caveolin-3-dependent signaling can counteract negative regulation of relaxation.
Malignant Hyperthermia Susceptibility
Malignant hyperthermia susceptibility involves dysregulated calcium release in skeletal muscle, and cardiac involvement can include altered relaxation dynamics. While primarily a skeletal muscle disorder, the underlying calcium handling defects may inform mechanisms of negative regulation of cardiac relaxation.
From negative regulation of relaxation of cardiac muscle-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of ATP2A2 slow cardiac relaxation? | Cardiomyocyte-specific ATP2A2 knockout |
| Does phosphomimetic TNNI3 accelerate relaxation? | TNNI3 knock-in with phosphomimetic mutations |
| Does urotensin II overexpression impair relaxation in diabetes? | UTS2 overexpression in diabetic rat model |
| Does caveolin-3 overexpression improve relaxation in cirrhosis? | Cardiac-specific CAV3 overexpression |
| Does NOS3 deletion alter relaxation kinetics? | NOS3 knockout mouse |
| Can SERCA2a activation rescue impaired relaxation? | SERCA2a overexpression or small molecule activator |
How to Study the negative regulation of relaxation of cardiac muscle Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Calcium imaging | Cytosolic Ca2+ transient decay | Assess relaxation rate in isolated cardiomyocytes |
| Phosphoproteomics | Phosphorylation of myofilament proteins | Identify altered relaxation signaling |
| Cardiomyocyte shortening assay | Cell relengthening kinetics | Direct measurement of relaxation |
| Echocardiography | Diastolic function indices (E/A, tau) | In vivo assessment of relaxation |
| Pressure-volume loops | Load-dependent relaxation parameters | Hemodynamic evaluation in animal models |
| Western blot | Protein expression and phosphorylation | Quantify SERCA2a, PLN, TNNI3 |
| RNA-seq | Transcriptomic changes | Identify genes regulating relaxation |
| CRISPR screening | Gene function in relaxation | Discover novel regulators |
Calcium Imaging and Transient Analysis
Calcium imaging using fluorescent indicators (e.g., Fura-2, Indo-1) in isolated cardiomyocytes measures cytosolic Ca2+ transients and decay kinetics, which directly reflect relaxation rate. Prolonged Ca2+ decay indicates negative regulation of relaxation.
Myofilament Phosphorylation and Proteomics
Phosphoproteomics and Western blotting with phospho-specific antibodies can quantify phosphorylation of troponin I, phospholamban, and myosin binding protein C, which are key determinants of relaxation.
Cardiomyocyte Contractility and Relaxation Assays
Isolated cardiomyocyte shortening and relengthening measurements, or trabeculae contractility studies, provide direct assessment of relaxation kinetics. These are often combined with pharmacological modulators of calcium handling.
In Vivo Hemodynamic and Echocardiographic Assessment
Echocardiography and pressure-volume loop analysis in animal models assess diastolic function, including relaxation time constants (tau) and E/A ratios, linking molecular changes to whole-organ relaxation.
How CRISPR Can Be Used to Study GO:1901898 negative regulation of relaxation of cardiac muscle
Knockout
CRISPR knockout of genes such as ATP2A2, SLC8A1, or NOS3 in cardiomyocytes or animal models can determine their causal role in negatively regulating relaxation. For example, cardiomyocyte-specific Atp2a2 knockout leads to severely impaired relaxation.
Point Mutation
Point mutations can be introduced to mimic or abolish phosphorylation sites, such as in TNNI3 or PLN, to test their impact on relaxation kinetics. This allows precise dissection of signaling events that negatively regulate relaxation.
Knock-in
Knock-in of disease-associated mutations, such as in TNNI3 or MYH7, can model altered relaxation in cardiomyopathies. These models help link genetic variants to diastolic dysfunction.
Overexpression
CRISPR-mediated overexpression or transgenic overexpression of genes like CAV3 or UTS2 can test whether increased expression negatively regulates relaxation. Caveolin-3 overexpression improved relaxation in cirrhotic cardiomyopathy, while urotensin II overexpression impaired it in diabetes.
How EDITGENE Supports negative regulation of relaxation of cardiac muscle Research
Researchers studying negative regulation of relaxation of cardiac muscle-related genes often need to determine whether a candidate gene is causally involved in slowing relaxation, and which specific mutations or expression changes drive diastolic dysfunction. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell and animal models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for negative regulation of relaxation of cardiac muscle research.
Frequently Asked Questions About negative regulation of relaxation of cardiac muscle
What is GO:1901898?
GO:1901898 is a Gene Ontology biological process term defined as any process that stops, prevents or reduces the frequency, rate or extent of relaxation of cardiac muscle.
What genes are involved in negative regulation of relaxation of cardiac muscle?
Key genes include ATP2A2 (SERCA2a), SLC8A1 (NCX1), TNNI3 (troponin I), NOS3 (eNOS), UTS2 (urotensin II), and CAV3 (caveolin-3).
How does calcium handling affect cardiac relaxation?
Calcium reuptake by SERCA2a and extrusion by NCX1 are rate-limiting for relaxation; reduced activity of these proteins slows relaxation.
What diseases are associated with impaired cardiac relaxation?
Diastolic heart failure, heart failure with preserved ejection fraction, diabetic cardiomyopathy, and cirrhotic cardiomyopathy are associated with impaired relaxation.
How can I study negative regulation of cardiac muscle relaxation?
Methods include calcium imaging, cardiomyocyte contractility assays, echocardiography, phosphoproteomics, and CRISPR-based gene editing.
What is the role of troponin I in relaxation?
Troponin I phosphorylation regulates myofilament deactivation; altered phosphorylation can negatively regulate relaxation.
Does nitric oxide negatively regulate cardiac relaxation?
Yes, nitric oxide signaling can modulate myocardial function and negatively regulate relaxation under certain conditions.
What is the role of urotensin II in cardiac relaxation?
Urotensin II enhances negative modulation of cardiac function and Ca2+ regulation, particularly in diabetic models.
Can caveolin-3 overexpression improve cardiac relaxation?
Cardiac-specific overexpression of caveolin-3 has been shown to protect against cirrhotic cardiomyopathy, improving relaxation.
What CRISPR models are available for studying cardiac relaxation?
Knockout, point mutation, knock-in, and overexpression models can be generated for genes like ATP2A2, TNNI3, and CAV3.
Conclusion
GO:1901898, negative regulation of relaxation of cardiac muscle, is a critical biological process underlying diastolic dysfunction and heart failure. Understanding the molecular mechanisms, key genes, and experimental models for this process is essential for developing targeted therapies. CRISPR-based approaches offer powerful tools to dissect the causal roles of specific genes and mutations in negatively regulating cardiac relaxation.
References
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- 4. Dillmann WH. 1996. Regulation of expression of cardiac sarcoplasmic reticulum proteins under pathophysiological conditions.. Mol Cell Biochem 157(1-2):125-8 PMID: 8739238
- 5. Zhang X et al.. 2025. Enhanced negative modulation of urotensin II on cardiac function and [Ca(2+)](i) regulation in a diabetic rat model: Insights into molecular and cellular mechanisms.. J Pharmacol Exp Ther 392(6):103594 PMID: 40403578
- 6. Kim SY et al.. 2020. Protective role of cardiac-specific overexpression of caveolin-3 in cirrhotic cardiomyopathy.. Am J Physiol Gastrointest Liver Physiol 318(3):G531-G541 PMID: 31961720
- 7. Yang S et al.. 2014. Three-dimensional organization of troponin on cardiac muscle thin filaments in the relaxed state.. Biophys J 106(4):855-64 PMID: 24559988
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