GO:0060087 relaxation of vascular associated smooth muscle: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0060087 describes the biological process by which vascular smooth muscle relaxes, primarily through decreased myosin light chain phosphorylation.
• Relaxation is driven by removal of cytoplasmic Ca2+ via Ca2+ ATPases (SERCA) and by calcium-independent activation of myosin light chain phosphatase.
• Key molecular players include endothelial nitric oxide (NO), EDHF, and direct-acting vasodilators that modulate smooth muscle tone.
• Impaired vascular smooth muscle relaxation is linked to aging, hypertension, and vascular inflammation.
• Experimental models for studying this process include isolated aorta contraction/relaxation assays, endothelial denudation, and pharmacological interventions.
• CRISPR-based editing of genes such as KLF4, Nox1, and LRRC8 can help dissect their causal roles in vascular smooth muscle relaxation.
Description
GO:0060087, relaxation of vascular associated smooth muscle, is a biological process that negatively regulates smooth muscle contraction, resulting in decreased vascular tone. This process is essential for maintaining blood flow and arterial compliance, and its dysregulation contributes to cardiovascular diseases such as hypertension and atherosclerosis. The relaxation is mediated by a decrease in the phosphorylation state of myosin light chain, achieved through calcium removal from the cytoplasm to the sarcoplasmic reticulum via Ca2+ ATPases, leading to reduced myosin light chain kinase activity, and through calcium-independent pathways that increase myosin light chain phosphatase activity. Researchers study this process to understand vascular physiology and to identify therapeutic targets for vascular disorders. Experimental models, including isolated aorta preparations and pharmacological interventions, have been instrumental in defining the mechanisms of vascular smooth muscle relaxation.
relaxation of vascular associated smooth muscle At A Glance
| GO ID | GO:0060087 |
|---|---|
| GO term | relaxation of vascular associated smooth muscle |
| Ontology | biological_process |
| Synonym | negative regulation of relaxation of vascular smooth muscle; positive regulation of relaxation of vascular smooth muscle; regulation of relaxation of vascular smooth muscle; relaxation of vascular smooth muscle; vascular smooth muscle relaxation |
| Major function | Negative regulation of smooth muscle contraction leading to vasodilation |
| Key mechanism | Decreased myosin light chain phosphorylation via Ca2+ removal and increased myosin light chain phosphatase activity |
| Associated cellular components | Sarcoplasmic reticulum, plasma membrane, contractile apparatus |
| Related processes | Calcium signaling, nitric oxide signaling, EDHF-mediated relaxation |
What Is GO:0060087?
GO:0060087 is defined as a negative regulation of smooth muscle contraction that results in relaxation of vascular smooth muscle. The relaxation is mediated by a decrease in the phosphorylation state of myosin light chain. This can be achieved by removal of calcium from the cytoplasm to the sarcoplasmic reticulum lumen through the action of Ca2+ ATPases, leading to a decrease in myosin light chain kinase activity, and through calcium-independent pathways leading to an increase in myosin light chain phosphatase activity.
Why Is relaxation of vascular associated smooth muscle Important in Cell Biology?
Relaxation of vascular associated smooth muscle is critical for regulating blood pressure, tissue perfusion, and arterial compliance. Dysfunction in this process is a hallmark of cardiovascular diseases, including hypertension, aging-related vascular stiffness, and inflammation-associated vascular dysfunction. Understanding the molecular mechanisms of vascular smooth muscle relaxation provides insights into therapeutic strategies for cardiovascular disorders.
• Maintains vascular tone and blood pressure homeostasis.
• Regulates large artery compliance and prevents stiffness.
• Dysregulated in aging and hypertension.
• Modulated by endothelial factors such as nitric oxide and EDHF.
• Target of pharmacological agents like cicletanine and vildagliptin.
• Involved in vascular inflammation via Nox1-derived superoxide and LRRC8 channels.
• Affected by direct-acting compounds such as methylmethacrylate.
• Phenotypic modulation of smooth muscle cells by KLF4 influences relaxation capacity.
• Key for understanding doxorubicin-induced vascular senescence.
• Provides experimental readouts for drug screening and gene function studies.
What Happens During relaxation of vascular associated smooth muscle?
Calcium removal and decreased myosin light chain kinase activity
In simple terms: Calcium is pumped out of the cell, so the enzyme that adds phosphate to myosin slows down.
A primary step in vascular smooth muscle relaxation is the removal of cytoplasmic Ca2+ into the sarcoplasmic reticulum lumen via Ca2+ ATPases (SERCA). This decrease in intracellular calcium reduces the activity of myosin light chain kinase (MLCK), leading to decreased phosphorylation of myosin light chain and subsequent relaxation.
Calcium-independent activation of myosin light chain phosphatase
In simple terms: Even without calcium changes, the enzyme that removes phosphate from myosin can be activated to promote relaxation.
Relaxation can also occur through calcium-independent pathways that increase the activity of myosin light chain phosphatase (MLCP). MLCP dephosphorylates myosin light chain, counteracting MLCK activity and promoting smooth muscle relaxation.
Endothelial nitric oxide and EDHF signaling
In simple terms: The inner lining of blood vessels releases signals like nitric oxide that tell smooth muscle to relax.
Endothelial cells release nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF), which diffuse to vascular smooth muscle cells and activate pathways that lead to relaxation. NO activates soluble guanylate cyclase, increasing cGMP and activating protein kinase G, which reduces calcium sensitivity and promotes MLCP activity.
Pharmacological modulation of relaxation
In simple terms: Certain drugs can directly relax blood vessels by mimicking or enhancing natural relaxation pathways.
Compounds such as cicletanine and vildagliptin have been shown to improve vascular smooth muscle relaxation in aged or doxorubicin-treated aortas, partly through nitric oxide-dependent mechanisms. Methylmethacrylate monomer produces direct relaxation of vascular smooth muscle in vitro, indicating that exogenous agents can bypass endothelial signaling.
Role of ion channels and oxidative stress
In simple terms: Ion channels and reactive oxygen species can influence how easily blood vessels relax.
Nox1-derived superoxide and LRRC8 anion channels contribute to vascular inflammation and modulate smooth muscle contractility. Dysregulation of these pathways can impair relaxation and promote vascular dysfunction.
Key Genes Involved in GO:0060087 relaxation of vascular associated smooth muscle
The following genes and proteins are key players in the relaxation of vascular associated smooth muscle, based on experimental evidence from the cited literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MYLK | Myosin light chain kinase; phosphorylates myosin light chain to promote contraction | Target for studying calcium-dependent relaxation mechanisms |
| PPP1R12A | Myosin light chain phosphatase regulatory subunit; activates MLCP to promote relaxation | Key node in calcium-independent relaxation |
| NOS3 | Endothelial nitric oxide synthase; produces NO to induce relaxation | Central to endothelial-dependent vasodilation |
| GUCY1A1 | Soluble guanylate cyclase subunit; mediates NO signaling | Downstream effector of NO-induced relaxation |
| PRKG1 | cGMP-dependent protein kinase; reduces calcium sensitivity | Mediates NO/cGMP relaxation pathway |
| KLF4 | Transcription factor regulating smooth muscle cell phenotype | Modulates contractile/relaxation gene programs |
| NOX1 | NADPH oxidase; produces superoxide in vascular inflammation | Links oxidative stress to impaired relaxation |
| LRRC8A | Anion channel subunit; involved in volume regulation and vascular tone | Modulates smooth muscle contractility |
| ATP2A2 | SERCA2; pumps calcium into sarcoplasmic reticulum | Key for calcium removal during relaxation |
| ATP2B1 | Plasma membrane Ca2+ ATPase; extrudes calcium | Contributes to calcium homeostasis |
| EDN1 | Endothelin-1; potent vasoconstrictor | Counteracts relaxation; used to pre-contract vessels in assays |
| ACE | Angiotensin-converting enzyme; regulates angiotensin II | Indirectly affects vascular tone and relaxation |
| AGTR1 | Angiotensin II receptor type 1; mediates vasoconstriction | Modulates relaxation capacity |
| ADORA2A | Adenosine receptor; can induce relaxation | Potential modulator of vascular tone |
| KCNMA1 | Large-conductance calcium-activated potassium channel | Influences membrane potential and relaxation |
| ABCC9 | SUR2 subunit of KATP channels | Regulates vascular tone in response to metabolic signals |
| CACNA1C | L-type calcium channel; mediates calcium influx | Contraction initiator; its inhibition promotes relaxation |
| ROCK1 | Rho-associated kinase; inhibits MLCP | Modulates calcium sensitization |
How Is relaxation of vascular associated smooth muscle Regulated?
The relaxation of vascular associated smooth muscle is regulated by multiple signaling pathways. Endothelial-derived nitric oxide (NO) activates soluble guanylate cyclase, increasing cGMP and activating protein kinase G, which reduces intracellular calcium and promotes myosin light chain phosphatase activity. Endothelium-derived hyperpolarizing factor (EDHF) also contributes to relaxation by hyperpolarizing smooth muscle cells. In addition, RhoA/Rho-kinase pathway inhibits MLCP, thereby increasing calcium sensitivity and opposing relaxation. Pharmacological agents such as vildagliptin can improve relaxation in aged or stressed vessels, partly by reducing oxidative stress and senescence.
relaxation of vascular associated smooth muscle and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NOS3 | Hypertension, endothelial dysfunction | KO or overexpression in endothelial cells; aorta relaxation assays |
| NOX1 | Vascular inflammation, oxidative stress | KO or point mutation in smooth muscle cells; LRRC8 channel studies |
| KLF4 | Atherosclerosis, smooth muscle phenotype switching | KO or overexpression in SMCs; contractility assays |
| ATP2A2 | Hypertension, calcium handling defects | Knock-in of SERCA2 mutants; calcium imaging |
| PPP1R12A | Vascular tone disorders | Point mutation or KO; MLCP activity assays |
Hypertension and arterial stiffness
Impaired relaxation of vascular smooth muscle contributes to increased arterial stiffness and hypertension. Studies in isolated aorta show that smooth muscle contraction and relaxation are critical regulators of large artery compliance, and dysfunction in these processes leads to reduced compliance. Aging is associated with decreased vascular smooth muscle and endothelial functions, further promoting hypertension.
Vascular inflammation and oxidative stress
Vascular inflammation, driven by Nox1-derived superoxide and LRRC8 anion channels, impairs smooth muscle relaxation and promotes vascular dysfunction. This link suggests that anti-inflammatory or antioxidant strategies may improve relaxation.
Doxorubicin-induced vascular senescence
Doxorubicin treatment induces vascular senescence and impairs vascular smooth muscle relaxation. Vildagliptin improves relaxation and decreases cellular senescence in the aorta of doxorubicin-treated rats, indicating a potential therapeutic approach.
Aging-related vascular dysfunction
Aging leads to changes in vascular smooth muscle and endothelial functions, including reduced relaxation capacity. Studies on aged Wistar aorta show that cicletanine-induced relaxation is nitric oxide-dependent, highlighting the role of NO in age-related vascular changes.
From relaxation of vascular associated smooth muscle-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X regulate vascular smooth muscle relaxation? | Knockout of gene X in smooth muscle cells followed by aorta relaxation assays |
| Does a specific point mutation in gene Y alter relaxation? | Point mutation knock-in in mice or cells; measure relaxation responses |
| Does overexpression of gene Z enhance relaxation? | Overexpression of gene Z in vascular smooth muscle cells; assess relaxation |
| Does tagging gene W affect its function in relaxation? | Tagged knock-in (e.g., GFP) to track localization and function |
| Can CRISPR library screening identify novel relaxation regulators? | CRISPR knockout library in smooth muscle cells; screen for relaxation phenotypes |
| Does pharmacological intervention improve relaxation in disease models? | Doxorubicin-treated rats or aged aorta; treat with vildagliptin or cicletanine |
How to Study the relaxation of vascular associated smooth muscle Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Isolated aorta relaxation assay | Force of contraction/relaxation | Testing gene function or drug effects |
| Calcium imaging | Intracellular Ca2+ concentration | Assessing calcium removal during relaxation |
| Phospho-MLC Western blot | Myosin light chain phosphorylation | Evaluating MLCK/MLCP activity |
| NO measurement (Griess assay) | Nitric oxide production | Endothelial function assessment |
| CRISPR knockout in SMCs | Gene function loss | Identifying causal genes in relaxation |
| RNA-seq | Transcriptomic changes | Discovering pathways regulating relaxation |
| Proteomics | Protein expression and modifications | Mapping signaling networks |
| Immunohistochemistry | Protein localization in tissue | Validating expression in vascular wall |
Isolated aorta relaxation assays
Isolated aorta rings are pre-contracted with agents like phenylephrine or endothelin-1, then exposed to relaxants. The force of contraction is measured isometrically to quantify relaxation.
Calcium imaging and phosphorylation assays
Intracellular calcium levels can be measured using fluorescent dyes, and myosin light chain phosphorylation status can be assessed by Western blot with phospho-specific antibodies to dissect relaxation mechanisms.
Genetic manipulation in animal models
Knockout, knock-in, or transgenic mice targeting genes such as NOS3, NOX1, or KLF4 allow causal testing of their roles in vascular relaxation.
Pharmacological profiling
Dose-response curves to vasodilators (e.g., acetylcholine, sodium nitroprusside) and inhibitors (e.g., L-NAME) help identify pathways involved in relaxation.
How CRISPR Can Be Used to Study GO:0060087 relaxation of vascular associated smooth muscle
Knockout
CRISPR knockout of candidate genes (e.g., NOS3, NOX1, KLF4) in vascular smooth muscle cells or animal models can determine whether the gene is necessary for relaxation. For example, Nox1 knockout reduces oxidative stress and may improve relaxation.
Point Mutation
Introducing point mutations in genes such as ATP2A2 or PPP1R12A can mimic human variants or alter enzyme activity, allowing precise dissection of their roles in calcium handling and MLCP function during relaxation.
Knock-in
Knock-in of tagged versions (e.g., GFP, HA) of genes like KLF4 enables tracking of protein localization and interaction dynamics in live cells or tissues, providing insights into their function in relaxation.
Overexpression
Overexpression of relaxation-promoting genes (e.g., NOS3, PRKG1) in vascular smooth muscle cells can enhance relaxation and serve as a gain-of-function model to study therapeutic potential.
How EDITGENE Supports relaxation of vascular associated smooth muscle Research
Researchers studying relaxation of vascular associated smooth muscle-related genes often need to determine whether a candidate gene is causally involved in the process or merely correlated. EDITGENE provides comprehensive CRISPR-based services to enable such causal studies.
Contact EDITGENE today to design your custom CRISPR model for relaxation of vascular associated smooth muscle research.
Frequently Asked Questions About relaxation of vascular associated smooth muscle
What is GO:0060087?
GO:0060087 is the Gene Ontology term for relaxation of vascular associated smooth muscle, a biological process that negatively regulates smooth muscle contraction, leading to vasodilation.
What genes are involved in relaxation of vascular associated smooth muscle?
Key genes include NOS3, MYLK, PPP1R12A, KLF4, NOX1, and ATP2A2, among others.
How is vascular smooth muscle relaxation measured?
It is commonly measured using isolated aorta relaxation assays, calcium imaging, and phospho-myosin light chain Western blots.
What is the role of nitric oxide in vascular smooth muscle relaxation?
Nitric oxide produced by endothelial NOS diffuses to smooth muscle cells, activates guanylate cyclase, and promotes relaxation via cGMP signaling.
What diseases are associated with impaired vascular smooth muscle relaxation?
Hypertension, arterial stiffness, aging-related vascular dysfunction, and doxorubicin-induced vascular senescence.
Can CRISPR be used to study vascular smooth muscle relaxation?
Yes, CRISPR knockout, knock-in, and overexpression models can dissect gene function in this process.
What is the role of KLF4 in vascular smooth muscle relaxation?
KLF4 is a transcription factor that modulates smooth muscle cell phenotype and can influence contractile and relaxation gene programs.
How does aging affect vascular smooth muscle relaxation?
Aging is associated with decreased vascular smooth muscle and endothelial functions, leading to impaired relaxation.
What is the role of Nox1 in vascular smooth muscle relaxation?
Nox1-derived superoxide contributes to vascular inflammation and can impair relaxation; Nox1 inhibition may improve it.
What experimental models are used to study vascular smooth muscle relaxation?
Isolated aorta rings, cultured smooth muscle cells, and genetically modified mice are commonly used.
Conclusion
GO:0060087 relaxation of vascular associated smooth muscle is a fundamental biological process that regulates vascular tone and blood pressure. Its dysregulation is implicated in hypertension, aging, and vascular inflammation. Understanding the molecular mechanisms and key genes involved provides opportunities for therapeutic intervention. CRISPR-based models and advanced screening methods are powerful tools to dissect this process and identify new targets.
References
- 1. Mišúth S et al.. 2021. Vildagliptin improves vascular smooth muscle relaxation and decreases cellular senescence in the aorta of doxorubicin-treated rats.. Vascul Pharmacol 138:106855 PMID: 33744414
- 2. Leloup AJA et al.. 2019. Vascular smooth muscle cell contraction and relaxation in the isolated aorta: a critical regulator of large artery compliance.. Physiol Rep 7(4):e13934 PMID: 30810292
- 3. Lamb FS et al.. 2024. Vascular Inflammation and Smooth Muscle Contractility: The Role of Nox1-Derived Superoxide and LRRC8 Anion Channels.. Hypertension 81(4):752-763 PMID: 38174563
- 4. Yap C et al.. 2021. Six Shades of Vascular Smooth Muscle Cells Illuminated by KLF4 (Krüppel-Like Factor 4).. Arterioscler Thromb Vasc Biol 41(11):2693-2707 PMID: 34470477
- 5. Félétou M et al.. 2009. EDHF: an update.. Clin Sci (Lond) 117(4):139-55 PMID: 19601928
- 6. Chamiot-Clerc P et al.. 2000. Relaxation of vascular smooth muscle by cicletanine in aged wistar aorta under stress conditions: importance of nitric oxide.. Am J Hypertens 13(2):208-13 PMID: 10701822
- 7. Yildiz O. 2007. Vascular smooth muscle and endothelial functions in aging.. Ann N Y Acad Sci 1100:353-60 PMID: 17460198
- 8. Karlsson J et al.. 1995. Methylmethacrylate monomer produces direct relaxation of vascular smooth muscle in vitro.. Acta Anaesthesiol Scand 39(5):685-9 PMID: 7572021
