GO:1901899 positive regulation of relaxation of cardiac muscle: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1901899 describes any process that activates or increases the frequency, rate or extent of cardiac muscle relaxation, a critical phase of the cardiac cycle.
• Relaxation of cardiac muscle depends on calcium reuptake into the sarcoplasmic reticulum, primarily via SERCA2a (ATP2A2), and calcium release through ryanodine receptor 2 (RYR2).
• Adrenergic signaling via beta-adrenergic receptors and catecholamines modulates both contraction and relaxation, often through phosphorylation of phospholamban and other calcium-handling proteins.
• Calmodulin regulation of excitation-contraction coupling directly influences the speed and extent of cardiac myocyte relaxation.
• Dysregulation of relaxation contributes to heart failure, hypertrophic cardiomyopathy, and arrhythmias, making this process a therapeutic target.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) enable causal dissection of genes that positively regulate cardiac muscle relaxation.
Description
Positive regulation of relaxation of cardiac muscle (GO:1901899) is a biological process that encompasses any molecular event that enhances the frequency, rate, or extent of cardiac muscle relaxation. Relaxation is the phase of the cardiac cycle during which the myocardium returns to its resting state after contraction, allowing the heart to refill with blood. This process is essential for normal cardiac output and is tightly controlled by calcium handling, adrenergic signaling, and structural proteins. Researchers study this term to understand how the heart adapts to physiological demands and how its failure contributes to cardiovascular disease. The regulation of cardiac relaxation involves a complex interplay of ion channels, transporters, and signaling cascades. For example, catecholamines acting through adrenergic receptors accelerate relaxation by promoting calcium reuptake into the sarcoplasmic reticulum. Calmodulin-dependent regulation of excitation-contraction coupling also fine-tunes the kinetics of relaxation. Disruptions in these pathways are linked to conditions such as heart failure and hypertrophic cardiomyopathy, where impaired relaxation leads to diastolic dysfunction. Thus, GO:1901899 provides a framework for investigating the molecular underpinnings of cardiac relaxation and for developing targeted therapies.
positive regulation of relaxation of cardiac muscle At A Glance
| GO ID | GO:1901899 |
|---|---|
| GO term | positive regulation of relaxation of cardiac muscle |
| Ontology | biological_process |
| Synonym | activation of relaxation of cardiac muscle; up regulation of relaxation of cardiac muscle; up-regulation of relaxation of cardiac muscle; upregulation of relaxation of cardiac muscle |
| Major function | Enhances the frequency, rate, or extent of cardiac muscle relaxation |
| Related processes | Calcium ion transport, adrenergic signaling, excitation-contraction coupling |
| Key regulators | Beta-adrenergic receptors, SERCA2a (ATP2A2), phospholamban (PLN), ryanodine receptor 2 (RYR2), calmodulin (CALM1/2/3) |
| Disease relevance | Heart failure, hypertrophic cardiomyopathy, arrhythmias |
What Is GO:1901899?
According to the Gene Ontology, GO:1901899 (positive regulation of relaxation of cardiac muscle) is defined as any process that activates or increases the frequency, rate or extent of relaxation of cardiac muscle. In other words, it includes molecular signals and cellular events that make the heart muscle relax faster, more often, or more completely. This term is a child of 'regulation of relaxation of cardiac muscle' and is distinct from processes that inhibit relaxation.
Why Is positive regulation of relaxation of cardiac muscle Important in Cell Biology?
Understanding positive regulation of relaxation of cardiac muscle is crucial because relaxation is not a passive process but an actively regulated phase of the cardiac cycle that determines ventricular filling and coronary perfusion. Impaired relaxation is a hallmark of diastolic heart failure and contributes to symptoms in hypertrophic cardiomyopathy and other cardiovascular disorders. Moreover, many therapeutic agents, such as beta-blockers and calcium channel blockers, modulate relaxation to improve cardiac function. Therefore, dissecting the molecular mechanisms that positively regulate relaxation can reveal new drug targets and biomarkers for heart disease.
• Relaxation is essential for proper ventricular filling and cardiac output.
• Defects in relaxation lead to diastolic dysfunction, a major cause of heart failure with preserved ejection fraction.
• Adrenergic stimulation accelerates relaxation via phosphorylation of phospholamban and other targets.
• Calcium reuptake by SERCA2a is the primary driver of cardiac myocyte relaxation.
• Ryanodine receptor 2 (RYR2) dysfunction can impair relaxation and promote arrhythmias.
• Calmodulin regulation of excitation-contraction coupling influences relaxation kinetics.
• Hypertrophic cardiomyopathy is associated with altered EGFR/IGF1R signaling that modulates relaxation.
• Thyroid hormone excess (hyperthyroidism) affects cardiac papillary muscle relaxation.
• Relaxation is a target for pharmacological interventions in heart failure and arrhythmias.
• CRISPR-based gene editing enables precise study of genes that regulate relaxation.
What Happens During positive regulation of relaxation of cardiac muscle?
Calcium reuptake into the sarcoplasmic reticulum
In simple terms: After a heart muscle cell contracts, calcium must be quickly removed from the cytoplasm so the cell can relax.
The primary event that drives cardiac muscle relaxation is the reuptake of calcium ions into the sarcoplasmic reticulum (SR) by the SR calcium ATPase, SERCA2a (encoded by ATP2A2). This pump is regulated by phospholamban (PLN); phosphorylation of PLN relieves its inhibition of SERCA2a, thereby increasing calcium reuptake and accelerating relaxation. Positive regulation of relaxation often involves signaling pathways that enhance SERCA2a activity or increase its expression, such as beta-adrenergic stimulation.
Adrenergic receptor signaling
In simple terms: Stress hormones like adrenaline make the heart beat faster and also relax faster by modifying calcium-handling proteins.
Catecholamines (epinephrine and norepinephrine) bind to beta-adrenergic receptors on cardiac myocytes, activating a signaling cascade that includes protein kinase A (PKA). PKA phosphorylates phospholamban, ryanodine receptor 2 (RYR2), and other proteins, leading to increased calcium reuptake and faster relaxation. This positive regulation is essential for matching cardiac output to physiological demand during exercise or stress.
Calmodulin-dependent regulation of excitation-contraction coupling
In simple terms: Calmodulin is a calcium-sensing protein that helps tune the timing of heart muscle contraction and relaxation.
Calmodulin (CALM1, CALM2, CALM3) binds calcium and regulates several targets involved in excitation-contraction coupling, including the L-type calcium channel and ryanodine receptor. Studies in cardiac myocytes have shown that calmodulin regulation of these channels affects the duration of the calcium transient and thus the kinetics of relaxation. Positive regulation of relaxation can occur through calmodulin-dependent modulation of calcium handling proteins.
Ryanodine receptor 2 (RYR2) and calcium leak
In simple terms: The ryanodine receptor releases calcium to trigger contraction; its inhibition can reduce abnormal calcium leak and improve relaxation.
RYR2 is the main calcium release channel in the SR. Excessive or diastolic SR calcium leak through RYR2 can impair relaxation and promote arrhythmias. Inhibition of RYR2 has been shown to reduce dispersion of cardiac repolarization, improve contractile function, and prevent sudden arrhythmic death in failing hearts. Therefore, negative regulation of RYR2 activity can positively regulate relaxation by reducing diastolic calcium leak.
EGFR/IGF1R signaling in hypertrophic cardiomyopathy
In simple terms: Growth factor receptors can influence how fast the heart muscle relaxes, and their overactivity is linked to disease.
In hypertrophic cardiomyopathy (HCM), enhanced EGFR/IGF1R signaling has been shown to modulate relaxation. Experimental evidence suggests that targeting these receptors can alter the relaxation properties of cardiomyocytes, highlighting a role for growth factor signaling in the positive regulation of cardiac muscle relaxation.
Key Genes Involved in GO:1901899 positive regulation of relaxation of cardiac muscle
The following genes and proteins are central to the positive regulation of relaxation of cardiac muscle, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ADRB1 | Beta-1 adrenergic receptor; mediates catecholamine effects on heart rate and relaxation | Target for beta-blockers; modulates relaxation via PKA signaling |
| ADRB2 | Beta-2 adrenergic receptor; also responds to catecholamines | Involved in relaxation regulation in heart failure |
| ATP2A2 | SERCA2a; calcium pump that reuptakes calcium into SR | Key driver of relaxation; target for gene therapy in heart failure |
| PLN | Phospholamban; inhibits SERCA2a when unphosphorylated | Phosphorylation relieves inhibition, accelerating relaxation |
| RYR2 | Ryanodine receptor 2; calcium release channel | Inhibition reduces diastolic leak and improves relaxation |
| CALM1 | Calmodulin 1; calcium sensor | Regulates excitation-contraction coupling and relaxation |
| CALM2 | Calmodulin 2; calcium sensor | Regulates calcium channels and relaxation kinetics |
| CALM3 | Calmodulin 3; calcium sensor | Regulates calcium channels and relaxation kinetics |
| EGFR | Epidermal growth factor receptor | Modulates relaxation in hypertrophic cardiomyopathy |
| IGF1R | Insulin-like growth factor 1 receptor | Modulates relaxation in hypertrophic cardiomyopathy |
| PRKACA | Protein kinase A catalytic subunit; phosphorylates PLN and RYR2 | Mediates adrenergic acceleration of relaxation |
| TNNT2 | Cardiac troponin T; part of thin filament | Mutations affect relaxation and diastolic function |
| MYH7 | Beta-myosin heavy chain; motor protein | Mutations linked to hypertrophic cardiomyopathy and impaired relaxation |
| NPPA | Atrial natriuretic peptide; marker of cardiac stress | May reflect altered relaxation in heart disease |
| NPPB | B-type natriuretic peptide; marker of heart failure | Associated with diastolic dysfunction |
| SLC8A1 | Sodium-calcium exchanger; contributes to calcium extrusion | Influences relaxation by removing calcium from cytoplasm |
| ATP1A2 | Sodium-potassium ATPase; maintains ion gradients | Indirectly supports calcium handling and relaxation |
| CACNA1C | L-type calcium channel; calcium influx | Calmodulin regulation affects relaxation |
How Is positive regulation of relaxation of cardiac muscle Regulated?
Positive regulation of relaxation of cardiac muscle is itself regulated by multiple signaling pathways. The beta-adrenergic receptor pathway is a primary regulator: catecholamines activate PKA, which phosphorylates phospholamban and RYR2, thereby enhancing calcium reuptake and accelerating relaxation. Calmodulin-dependent signaling modulates calcium channels and contributes to the fine-tuning of relaxation kinetics. In disease states such as hypertrophic cardiomyopathy, growth factor signaling through EGFR/IGF1R can alter relaxation properties. Additionally, thyroid hormone has been shown to affect cardiac papillary muscle relaxation, indicating hormonal regulation. These regulatory mechanisms ensure that relaxation is matched to physiological demands and can be disrupted in heart failure and arrhythmias.
positive regulation of relaxation of cardiac muscle and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RYR2 | Heart failure, arrhythmias | RYR2 knockout or point mutation in cardiomyocytes; RYR2 inhibitor treatment |
| ATP2A2 | Heart failure, diastolic dysfunction | SERCA2a overexpression or knockout in cardiac cell lines |
| PLN | Heart failure, hypertrophic cardiomyopathy | PLN knockout or phosphomimetic knock-in |
| MYH7 | Hypertrophic cardiomyopathy | MYH7 point mutation knock-in in iPSC-derived cardiomyocytes |
| EGFR/IGF1R | Hypertrophic cardiomyopathy | EGFR/IGF1R knockout or overexpression in cardiac cells |
Heart failure with preserved ejection fraction (HFpEF)
Impaired cardiac relaxation is a central feature of HFpEF, where the heart fails to relax properly during diastole, leading to elevated filling pressures and symptoms of heart failure. Dysregulation of calcium handling, particularly increased diastolic SR calcium leak through RYR2, contributes to impaired relaxation. Targeting RYR2 inhibition has been shown to improve contractile function and prevent arrhythmias in failing hearts.
Hypertrophic cardiomyopathy (HCM)
HCM is often caused by mutations in sarcomeric genes such as MYH7 and TNNT2, and is characterized by impaired relaxation and diastolic dysfunction. Enhanced EGFR/IGF1R signaling has been implicated in modulating relaxation in HCM, suggesting that growth factor pathways could be therapeutic targets.
Arrhythmias
Abnormal relaxation can promote arrhythmias through afterdepolarizations triggered by diastolic calcium leak. RYR2 inhibition reduces dispersion of cardiac repolarization and prevents sudden arrhythmic death in failing hearts, highlighting the link between relaxation and electrical stability.
Hyperthyroidism
Hyperthyroidism affects cardiac papillary muscle function, including relaxation. Thyroid hormone excess can alter the expression of calcium-handling proteins, leading to changes in relaxation kinetics.
From positive regulation of relaxation of cardiac muscle-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of ATP2A2 impair cardiac relaxation? | ATP2A2 knockout in cardiomyocytes or mouse models |
| Does phospholamban phosphorylation accelerate relaxation? | PLN point mutation (S16A/T17A) knock-in |
| Does RYR2 inhibition improve relaxation in heart failure? | RYR2 knockout or point mutation; pharmacological inhibition |
| Does EGFR/IGF1R signaling modulate relaxation in HCM? | EGFR/IGF1R knockout or overexpression in HCM models |
| Does calmodulin regulation affect relaxation kinetics? | CALM1/2/3 knockout or point mutation in cardiac myocytes |
| Can SERCA2a overexpression rescue relaxation defects? | ATP2A2 overexpression in heart failure models |
How to Study the positive regulation of relaxation of cardiac muscle Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Calcium imaging | Intracellular calcium transients | Assess relaxation kinetics in cardiomyocytes |
| Traction force microscopy | Contractile and relaxation forces | Evaluate effects of gene edits on relaxation |
| Phospho-specific Western blot | Phosphorylation of PLN, RYR2 | Monitor adrenergic signaling to relaxation |
| CRISPR knockout screen | Gene function loss | Identify novel positive regulators of relaxation |
| CRISPR activation screen | Gene overexpression | Discover enhancers of relaxation |
| RNA-seq | Transcriptional changes | Profile gene expression in relaxation models |
| Proteomics | Protein abundance and modifications | Quantify calcium-handling proteins |
| Patch clamp | Ion channel currents | Measure calcium channel activity affecting relaxation |
Calcium imaging
Calcium imaging using fluorescent indicators (e.g., Fura-2, Fluo-4) allows real-time measurement of intracellular calcium transients in cardiomyocytes, providing direct readouts of relaxation kinetics. This method is essential for assessing the effects of genetic manipulations on calcium reuptake and relaxation.
Contractility assays
Traction force microscopy and engineered heart tissue (EHT) assays measure the contractile and relaxation properties of cardiomyocytes or cardiac tissue. These techniques can quantify relaxation time and velocity, enabling researchers to test the impact of specific genes on positive regulation of relaxation.
Phosphorylation analysis
Western blotting with phospho-specific antibodies can detect phosphorylation of key regulators such as phospholamban and RYR2, which are central to adrenergic acceleration of relaxation. This method helps link signaling pathways to functional changes in relaxation.
CRISPR screening
Genome-wide CRISPR knockout or activation screens in cardiomyocytes can identify novel genes that positively regulate relaxation. Coupling screens with calcium imaging or contractility readouts enables unbiased discovery of regulators.
How CRISPR Can Be Used to Study GO:1901899 positive regulation of relaxation of cardiac muscle
Knockout
CRISPR knockout of genes such as ATP2A2, PLN, or RYR2 in cardiomyocytes or animal models can reveal their essential roles in cardiac relaxation. For example, RYR2 knockout reduces calcium leak and improves relaxation in failing hearts.
Point Mutation
Introducing point mutations (e.g., PLN S16A/T17A) via CRISPR can dissect the role of specific phosphorylation sites in regulating relaxation. Such models help determine whether particular residues are required for positive regulation.
Knock-in
Knock-in of disease-associated mutations (e.g., MYH7 mutations in HCM) allows study of impaired relaxation in a physiologically relevant context. These models can be used to test therapeutic interventions targeting relaxation.
Overexpression
CRISPR activation or cDNA overexpression of SERCA2a (ATP2A2) can enhance calcium reuptake and accelerate relaxation, serving as a potential therapeutic strategy. Overexpression models help validate gain-of-function effects on relaxation.
How EDITGENE Supports positive regulation of relaxation of cardiac muscle Research
Researchers studying positive regulation of relaxation of cardiac muscle-related genes often need to determine whether a candidate gene is causally involved in enhancing relaxation or is merely a bystander. EDITGENE provides a comprehensive suite of CRISPR-based services to enable such causal studies, from knockout to precise point mutations and overexpression.
Contact EDITGENE today to design your custom CRISPR model for positive regulation of relaxation of cardiac muscle research.
Frequently Asked Questions About positive regulation of relaxation of cardiac muscle
What is GO:1901899?
GO:1901899 is a Gene Ontology term for 'positive regulation of relaxation of cardiac muscle', defined as any process that activates or increases the frequency, rate or extent of cardiac muscle relaxation.
What genes are involved in positive regulation of relaxation of cardiac muscle?
Key genes include ATP2A2 (SERCA2a), PLN (phospholamban), RYR2 (ryanodine receptor 2), ADRB1/2 (beta-adrenergic receptors), CALM1/2/3 (calmodulin), and EGFR/IGF1R.
How does calcium reuptake affect cardiac relaxation?
Calcium reuptake into the sarcoplasmic reticulum by SERCA2a (ATP2A2) is the primary driver of cardiac myocyte relaxation; its activity is regulated by phospholamban.
What role does RYR2 play in relaxation?
RYR2 is a calcium release channel; excessive diastolic leak through RYR2 impairs relaxation, and its inhibition can improve relaxation and prevent arrhythmias.
How is adrenergic signaling linked to cardiac relaxation?
Catecholamines activate beta-adrenergic receptors, leading to PKA-mediated phosphorylation of phospholamban and RYR2, which accelerates calcium reuptake and relaxation.
What diseases are associated with impaired cardiac relaxation?
Heart failure with preserved ejection fraction, hypertrophic cardiomyopathy, and arrhythmias are linked to impaired relaxation.
Can CRISPR be used to study cardiac relaxation?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models enable causal dissection of genes regulating relaxation.
What methods measure cardiac relaxation?
Calcium imaging, traction force microscopy, and engineered heart tissue assays are commonly used to measure relaxation kinetics.
What is the role of calmodulin in cardiac relaxation?
Calmodulin regulates calcium channels and excitation-contraction coupling, influencing the kinetics of relaxation.
How does hyperthyroidism affect cardiac relaxation?
Hyperthyroidism alters the expression of calcium-handling proteins and affects cardiac papillary muscle relaxation.
Conclusion
Positive regulation of relaxation of cardiac muscle (GO:1901899) is a vital biological process that ensures proper diastolic function and cardiac output. Its molecular underpinnings involve calcium reuptake, adrenergic signaling, and calmodulin-dependent regulation, with key roles for ATP2A2, PLN, RYR2, and beta-adrenergic receptors. Dysregulation of this process contributes to heart failure, hypertrophic cardiomyopathy, and arrhythmias, making it a prime target for therapeutic intervention. CRISPR-based models and advanced screening methods offer powerful tools to dissect these mechanisms and identify new drug targets. EDITGENE provides comprehensive services to support such research, from knockout to overexpression and bioinformatics analysis.
References
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- 4. Joshi P et al.. 2023. Ryanodine receptor 2 inhibition reduces dispersion of cardiac repolarization, improves contractile function, and prevents sudden arrhythmic death in failing hearts.. Elife 12 PMID: 38078905
- 5. Dillmann WH. 1996. Regulation of expression of cardiac sarcoplasmic reticulum proteins under pathophysiological conditions.. Mol Cell Biochem 157(1-2):125-8 PMID: 8739238
- 6. Vieira FF et al.. 2016. Functional Effects of Hyperthyroidism on Cardiac Papillary Muscle in Rats.. Arq Bras Cardiol 107(6):542-549 PMID: 28558076
- 7. Yang D et al.. 2003. Calmodulin regulation of excitation-contraction coupling in cardiac myocytes.. Circ Res 92(6):659-67 PMID: 12609973
- 8. Algül S et al.. 2023. EGFR/IGF1R Signaling Modulates Relaxation in Hypertrophic Cardiomyopathy.. Circ Res 133(5):387-399 PMID: 37477020
