scholarly journals Actin cytoskeletal dynamics in smooth muscle: a new paradigm for the regulation of smooth muscle contraction

2008 ◽  
Vol 295 (3) ◽  
pp. C576-C587 ◽  
Author(s):  
Susan J. Gunst ◽  
Wenwu Zhang
Keyword(s):  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Actin Polymerization ◽  
Muscle Cells ◽  
Smooth Muscle Contraction ◽  
Mechanical Tension ◽  
Muscle Tissues ◽  
Cytoskeletal Dynamics

A growing body of data supports a view of the actin cytoskeleton of smooth muscle cells as a dynamic structure that plays an integral role in regulating the development of mechanical tension and the material properties of smooth muscle tissues. The increase in the proportion of filamentous actin that occurs in response to the stimulation of smooth muscle cells and the essential role of stimulus-induced actin polymerization and cytoskeletal dynamics in the generation of mechanical tension has been convincingly documented in many smooth muscle tissues and cells using a wide variety of experimental approaches. Most of the evidence suggests that the functional role of actin polymerization during contraction is distinct and separately regulated from the actomyosin cross-bridge cycling process. The molecular basis for the regulation of actin polymerization and its physiological roles may vary in diverse types of smooth muscle cells and tissues. However, current evidence supports a model for smooth muscle contraction in which contractile stimulation initiates the assembly of cytoskeletal/extracellular matrix adhesion complex proteins at the membrane, and proteins within this complex orchestrate the polymerization and organization of a submembranous network of actin filaments. This cytoskeletal network may serve to strengthen the membrane for the transmission of force generated by the contractile apparatus to the extracellular matrix, and to enable the adaptation of smooth muscle cells to mechanical stresses. Better understanding of the physiological function of these dynamic cytoskeletal processes in smooth muscle may provide important insights into the physiological regulation of smooth muscle tissues.

scholarly journals Different DNA methylome, transcriptome and histological features in uterine fibroids with and without MED12 mutations

2021 ◽  
Author(s):  
Ryo Maekawa ◽  
Shun Sato ◽  
Tetsuro Tamehisa ◽  
Takahiro Sakai ◽  
Takuya Kajimura ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Blood Vessels ◽  
Uterine Fibroids ◽  
Muscle Cells ◽  
Histological Features ◽  
Dna Methylome

Abstract Background: Somatic mutations in Mediator complex subunit 12 (MED12m) have been reported as a biomarker of uterine fibroids (UFs). However, the role of MED12m is still unclear in the pathogenesis of UFs. Therefore, we investigated the differences in DNA methylome, transcriptome, and histological features between MED12m-positive and -negative UFs. Methods: DNA methylomes and transcriptomes were obtained from MED12m-positive and -negative UFs and myometrium, and hierarchically clustered. Differentially expressed genes in comparison with the myometrium and co-expressed genes detected by weighted gene co-expression network analysis were subjected to gene ontology enrichment analyses. The amounts of collagen fibers and the number of blood vessels and smooth muscle cells were histologically evaluated. Results: Hierarchical clustering based on DNA methylation clearly separated the myometrium, MED12m-positive, and MED12m-negative UFs. MED12m-positive UFs had the increased activities of extracellular matrix formation, whereas MED12m-negative UFs had the increased angiogenic activities and smooth muscle cell proliferation. Conclusion: The MED12m-positive and -negative UFs had different DNA methylation, gene expression, and histological features. The MED12m-positive UFs form the tumor with a rich extracellular matrix and poor blood vessels and smooth muscle cells compared to the MED12m-negative UFs, suggesting MED12 mutations affect the tissue composition of UFs.

scholarly journals Phosphorylated HSP27 essential for acetylcholine-induced association of RhoA with PKCα

2004 ◽  
Vol 286 (4) ◽  
pp. G635-G644 ◽  
Author(s):  
Suresh B. Patil ◽  
Mercy D. Pawar ◽  
Khalil N. Bitar
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Contraction ◽  
Membrane Fraction ◽  
Muscle Cells ◽  
Smooth Muscle Contraction ◽  
Cell Length ◽  
Sustained Contraction ◽  
Hsp 27

Reorganization of the cytoskeleton and association of contractile proteins are important steps in modulating smooth muscle contraction. Heat shock protein (HSP) 27 has significant effects on actin cytoskeletal reorganization during smooth muscle contraction. We investigated the role of phosphorylated HSP27 in modulating acetylcholine-induced sustained contraction of smooth muscle cells from the rabbit colon by transfecting smooth muscle cells with phosphomimic (3D) or nonphosphomimic (3G) HSP27. In 3G cells, the initial peak contractile response at 30 s was inhibited by 25% (24.0 ± 4.5% decrease in cell length, n = 4). The sustained contraction was greatly inhibited by 75% [9.3 ± .9% decreases in cell length ( n = 4)]. Furthermore, in 3D cells, translocation of both PKCα and of RhoA was greatly enhanced and resulted in a greater association of PKCα-RhoA in the membrane fraction. In 3G transfected cells, PKCα and RhoA failed to translocate in response to stimulation with acetylcholine, resulting in an inhibition of association of PKCα-RhoA in the membrane fraction. Studies using GST-RhoA fusion protein indicate that there is a direct association of RhoA with PKCα and with HSP27. The results suggest that phosphorylated HSP27 plays a crucial role in the maintenance of association of PKCα-RhoA in the membrane fraction and in the maintenance of acetylcholine-induced sustained contraction.

Stretch-dependent growth and differentiation in vascular smooth muscle: role of the actin cytoskeleton

2005 ◽  
Vol 83 (10) ◽  
pp. 869-875 ◽  
Author(s):  
Per Hellstrand ◽  
Sebastian Albinsson
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Actin Polymerization ◽  
Muscle Cells ◽  
Intraluminal Pressure ◽  
Marker Genes ◽  
Signal Pathways ◽  
Differentiation Markers ◽  
Contractile Phenotype

The smooth muscle cells in the vascular wall are constantly exposed to distending forces from the intraluminal pressure. A rise in blood pressure triggers growth of the vessel wall, which is characterized primarily by hypertrophy of smooth muscle cells with maintained differentiation in a contractile phenotype. Growth factor stimulation of dissociated smooth muscle cells, on the other hand, causes proliferative growth with loss of contractility. This type of response is also found in neointima development following angioplasty and in atherosclerotic lesions. An intact tissue environment is therefore critical for preserved differentiation. Recent advances point to a role of actin polymerization in the expression of smooth muscle differentiation marker genes, in concert with serum response factor (SRF) and cofactors, such as myocardin. Stretch of intact venous smooth muscle activates Rho and inhibits the actin filament severing factor cofilin, resulting in increased actin polymerization. Concomitantly, the rates of synthesis of SRF-regulated differentiation markers, such as SM22α, calponin, and α-actin, are increased. This increase in differentiation signals is parallel with activation of the mitogen-activated protein (MAP) kinase pathway. Thus stretch-induced growth in a maintained contractile phenotype occurs by dual activation of signal pathways regulating both growth and differentiation. A current challenge is to identify sites of crosstalk between these pathways in intact smooth muscle tissue.Key words: stretch, hypertension, ERK, Rho, caveolae.

HSP27 phosphorylation and interaction with actin-myosin in smooth muscle contraction

2002 ◽  
Vol 282 (5) ◽  
pp. G894-G903 ◽  
Author(s):  
Khalil N. Bitar
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Signal Transduction Pathway ◽  
Muscle Cells ◽  
Smooth Muscle Contraction ◽  
Thin Filament Regulation ◽  
Kinase C ◽  
Hsp27 Phosphorylation ◽  
Myosin Interaction

We have investigated the role of heat shock protein 27 (HSP27) phosphorylation and the association of HSP27 with contractile proteins actin, myosin, and tropomyosin. Smooth muscle cells were labeled with [32P]orthophosphate. C2-ceramide (0.1 μM), an activator of protein kinase C (PKC), induced a sustained increase in HSP27 phosphorylation that was inhibited by calphostin C. C2-ceramide-induced (0.1 μM) sustained colonic smooth muscle cell contraction was accompanied by significant increases in the association of HSP27 with tropomyosin and in the association of HSP27 with actin. The significant increases occurred at 30 s after stimulation and were sustained at 4 min. Contraction was also associated with strong colocalization of HSP27 with tropomyosin and with actin as observed after immunofluorescent labeling of tropomyosin, actin, and HSP27 followed by confocal microscopy. Transfection of smooth muscle cells with HSP27 phosphorylation mutants indicated that phosphorylation of HSP27 could affect myosin association with actin. In conclusion 1) HSP27 phosphorylation appears to be necessary for reorganization of HSP27 inside the cell and seems to be directly correlated with the PKC signal transduction pathway, and 2) agonist-induced phosphorylation of HSP27 modulates actin-myosin interaction through thin-filament regulation of tropomyosin.

scholarly journals Abl regulates smooth muscle cell proliferation by modulating actin dynamics and ERK1/2 activation

2012 ◽  
Vol 302 (7) ◽  
pp. C1026-C1034 ◽  
Author(s):  
Li Jia ◽  
Ruping Wang ◽  
Dale D. Tang
Keyword(s):  
Cell Proliferation ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Actin Polymerization ◽  
Muscle Cells ◽  
Smooth Muscle Cell Proliferation ◽  
Actin Dynamics

Abl is a nonreceptor tyrosine kinase that has a role in regulating migration and adhesion of nonmuscle cells as well as smooth muscle contraction. The role of Abl in smooth muscle cell proliferation has not been investigated. In this study, treatment with endothelin-1 (ET-1) and platelet-derived growth factor (PDGF) increased Abl phosphorylation at Tyr412 (an indication of Abl activation) in vascular smooth muscle cells. To assess the role of Abl in smooth muscle cell proliferation, we generated stable Abl knockdown cells by using lentivirus-mediated RNA interference. ET-1- and PDGF-induced cell proliferation was attenuated in Abl knockdown cells compared with cells expressing control shRNA and uninfected cells. Abl silencing also arrested cell cycle progression from G0/G1 to S phase. Furthermore, activation of smooth muscle cells with ET-1 and PDGF induced phosphorylation of ERK1/2 and Akt. Abl knockdown attenuated ERK1/2 phosphorylation in smooth muscle cells stimulated with ET-1 and PDGF. However, Akt phosphorylation upon stimulation with ET-1 and PDGF was not reduced. Because Abl is known to regulate actin polymerization in smooth muscle, we also evaluated the effects of inhibition of actin polymerization on phosphorylation of ERK1/2. Pretreatment with the actin polymerization inhibitor latrunculin-A also blocked ERK1/2 phosphorylation during activation with ET-1 and PDGF. The results suggest that Abl may regulate smooth muscle cell proliferation by modulating actin dynamics and ERK1/2 phosphorylation during mitogenic activation.

scholarly journals Dynamic Crosstalk between Vascular Smooth Muscle Cells and the Aged Extracellular Matrix

2021 ◽  
Vol 22 (18) ◽  
pp. 10175
Author(s):  
Joao Carlos Ribeiro-Silva ◽  
Patricia Nolasco ◽  
Jose Eduardo Krieger ◽  
Ayumi Aurea Miyakawa
Keyword(s):  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Elastic Fibers ◽  
Signaling Mechanisms ◽  
Arterial Aging ◽  
Underlying Mechanisms ◽  
Cell Phenotypes

Vascular aging is accompanied by the fragmentation of elastic fibers and collagen deposition, leading to reduced distensibility and increased vascular stiffness. A rigid artery facilitates elastin to degradation by MMPs, exposing vascular cells to greater mechanical stress and triggering signaling mechanisms that only exacerbate aging, creating a self-sustaining inflammatory environment that also promotes vascular calcification. In this review, we highlight the role of crosstalk between smooth muscle cells and the vascular extracellular matrix (ECM) and how aging promotes smooth muscle cell phenotypes that ultimately lead to mechanical impairment of aging arteries. Understanding the underlying mechanisms and the role of associated changes in ECM during aging may contribute to new approaches to prevent or delay arterial aging and the onset of cardiovascular diseases.

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