Smooth Muscle Signal Transduction Mechanisms

Smooth muscle cells orchestrate involuntary contractions across vascular, respiratory, gastrointestinal and uterine systems, adapting organ function to physiological demands. At its core, contraction is triggered by an elevation of cytosolic calcium, which binds to calmodulin and activates myosin light chain kinase (MLCK). MLCK phosphorylates the regulatory light chain of myosin, enabling cross-bridge cycling and force generation. Relaxation ensues when myosin light chain phosphatase (MLCP) dephosphorylates the same substrate, a process that is finely tuned by several signal transduction pathways. G-protein-coupled receptor activation of RhoA stimulates Rho-associated kinase (ROCK) to phosphorylate and inhibit MLCP, thereby enhancing calcium sensitivity. In contrast, endothelial nitric oxide synthase releases nitric oxide to activate soluble guanylate cyclase, raise cGMP and trigger protein kinase G (PKG), which promotes MLCP activity and reduces intracellular calcium. Beyond these classical pathways, recent insights suggest that integrin-mediated mechanotransduction, lipid second messengers and oxidative cues modulate cytoskeletal remodelling and contractile protein expression. Cross-talk with protein kinase C and mitogen-activated protein kinase cascades shapes long-term smooth muscle plasticity, with implications for vascular tone, airway resistance, peristalsis and uterine contractility. Dysregulation of these mechanisms underlies hypertension, asthma, gastrointestinal dysmotility and metabolic disease, stimulating the development of microphysiological platforms and genetic models to unravel the spatiotemporal complexity of smooth muscle signalling and identify novel therapeutic targets.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Smooth Muscle Signal Transduction Mechanisms publication trend

The graph below shows the total number of articles in smooth muscle signal transduction mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

Myosin light chain kinase (MLCK): A Ca2+–calmodulin-dependent enzyme that phosphorylates the regulatory light chain of myosin, initiating smooth muscle contraction.

Myosin light chain phosphatase (MLCP): A serine/threonine phosphatase complex that dephosphorylates myosin regulatory light chain, promoting relaxation of smooth muscle.

Rho-associated kinase (ROCK): A downstream effector of RhoA that phosphorylates MYPT1 and inhibits MLCP, thereby increasing calcium sensitivity.

Protein kinase G (PKG): A cGMP-activated kinase that phosphorylates MLCP subunits and other targets to facilitate smooth muscle relaxation.

Integrins: Transmembrane proteins that connect the extracellular matrix to the cytoskeleton and transduce mechanical signals affecting contractility.

Calcium sensitisation: The enhancement of contractile force at a given intracellular calcium concentration, often mediated by inhibition of MLCP.

References

1. Smooth Muscle-Alpha Actin R149C Pathogenic Variant Downregulates Integrin Recruitment at Cell-Matrix Adhesions and Decreases Cellular Contractility. International Journal of Molecular Sciences (2023).
2. Smoothelin-like protein 1 promotes insulin sensitivity and modulates the contractile properties of endometrial epithelial cells with insulin resistance. Frontiers in Endocrinology (2024).
3. Alanine mutation of the targeting subunit of the myosin phosphatase, MYPT1 at threonine 696 reduces cGMP responsiveness of mouse femoral arteries. European Journal of Pharmacology (2024).
4. Mechanisms of Vascular Smooth Muscle Contraction and the Basis for Pharmacologic Treatment of Smooth Muscle Disorders. Pharmacological Reviews (2016).
5. Calcium in Vascular Smooth Muscle Cell Elasticity and Adhesion: Novel Insights Into the Mechanism of Action. Frontiers in Physiology (2019).
6. Inhibitory Phosphorylation Site for Rho-associated Kinase on Smooth Muscle Myosin Phosphatase*. Journal of Biological Chemistry (1999).