scholarly journals Actin polymerization in differentiated vascular smooth muscle cells requires vasodilator-stimulated phosphoprotein

2010 ◽  
Vol 298 (3) ◽  
pp. C559-C571 ◽  
Author(s):  
Hak Rim Kim ◽  
Philip Graceffa ◽  
François Ferron ◽  
Cynthia Gallant ◽  
Malgorzata Boczkowska ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Actin Filament ◽  
Hot Spots ◽  
Actin Polymerization ◽  
Muscle Cells ◽  
Cell Cortex ◽  
Sites Of Action

Our group has previously shown that vasoconstrictors increase net actin polymerization in differentiated vascular smooth muscle cells (dVSMC) and that increased actin polymerization is linked to contractility of vascular tissue (Kim et al., Am J Physiol Cell Physiol 295: C768–778, 2008). However, the underlying mechanisms are largely unknown. Here, we evaluated the possible functions of the Ena/vasodilator-stimulated phosphoprotein (VASP) family of actin filament elongation factors in dVSMC. Inhibition of actin filament elongation by cytochalasin D decreases contractility without changing myosin light-chain phosphorylation levels, suggesting that actin filament elongation is necessary for dVSM contraction. VASP is the only Ena/VASP protein highly expressed in aorta tissues, and VASP knockdown decreased smooth muscle contractility. VASP partially colocalizes with α-actinin and vinculin in dVSMC. Profilin, known to associate with G actin and VASP, also colocalizes with α-actinin and vinculin, potentially identifying the dense bodies and the adhesion plaques as hot spots of actin polymerization. The EVH1 domain of Ena/VASP is known to target these proteins to their sites of action. Introduction of an expressed EVH1 domain as a dominant negative inhibits stimulus-induced increases in actin polymerization. VASP phosphorylation, known to inhibit actin polymerization, is decreased during phenylephrine stimulation in dVSMC. We also directly visualized, for the first time, rhodamine-labeled actin incorporation in dVSMC and identified hot spots of actin polymerization in the cell cortex that colocalize with VASP. These results indicate a role for VASP in actin filament assembly, specifically at the cell cortex, that modulates contractility in dVSMC.

Abstract 429: The Effects of Fluvastatin and Methyl-β-Cyclodextrin-Mediated Cholesterol Depletion on the Biomechanics of Vascular Smooth Muscle Cells in Atherosclerosis

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Hanna J Sanyour ◽  
Zhongkui Hong
Keyword(s):  
Smooth Muscle ◽  
Cell Adhesion ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Atherosclerotic Plaque ◽  
Muscle Cells ◽  
Cell Cortex ◽  
Cholesterol Depletion ◽  
Progression Of Atherosclerosis

Atherosclerosis is a leading cause of death worldwide. Phenotypic shifting, alteration in cell adhesion, and migration toward inflammatory site of blood vessel wall are all critical contributions of vascular smooth muscle cells (VSMC) to the progression of atherosclerosis. Knowing that cholesterol is a main participant of fatty deposition in atherosclerotic lesions, cholesterol’s role in orchestrating cell migration, mechanics and spreading has grown more apparent. Growing evidences suggests that cholesterol loaded into VSMC in atherosclerosis is much larger than previously known, and about 40% of the total foam cells in the atherosclerotic plaque were VSMC-derived. Emerging studies have increasingly categorized cholesterol as major player in regulating VSMC stiffness and N-Cadherin mediated cell-cell adhesions. Modulating their activity or expression may block VSMC migration during the progression of atherosclerosis. In this study, the effects of a 3-hydroxy-3-methylglutaryl-coenzyme-A reductase inhibitor, fluvastatin and Methyl-β-Cyclodextrin-Mediated (MβCD) cholesterol depletion on VSMCs N-cadherin adhesion and cellular stiffness were addressed. VSMCs cholesterol quantification and lactate dehydrogenase assays demonstrated significant reduction in total cellular cholesterol content by approx. 67% for fluvastatin and 40% for MβCD. The atomic force microscope (AFM) was used to investigate real time adhesion and stiffness of living VSMCs. A proprietary software package written in Matlab was used to estimate Young’s modulus of the cell cortex. Cell adhesion was measured for 50-70% confluent cells with N-Cadherin coated stylus AFM probes on an AFM mounted on an inverted microscope. Our results suggested that fluvastatin and MβCD mediated cholesterol depletion increased N-cadherin mediated cell adhesion force by approx. 27% and 17% respectively. In addition, fluvastatin and MβCD respectively reduced VSMCs stiffness by approx. 24% and 29 % compared to control VSMCs. Altogether, the knowledge that we obtained in this project may lead to a novel therapeutic strategy that could potentially control and block VSMC migration and prevent atherosclerotic plaque formation by deciphering and regulating N-cadherin mediated adhesion

scholarly journals Actin Polymerization In Differentiated Vascular Smooth Muscle Cells Requires Vasodilator-Stimulated Phosphoprotein (VASP)

2009 ◽  
Vol 96 (3) ◽  
pp. 123a
Author(s):  
HakRim Kim ◽  
Francois Ferron ◽  
Malgorzata Boczkowska ◽  
Philip Graceffa ◽  
Cynthia Gallant ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Actin Polymerization ◽  
Muscle Cells

Imaging remodeling of the actin cytoskeleton in vascular smooth muscle cells after mechanosensitive arteriolar constriction

2005 ◽  
Vol 288 (2) ◽  
pp. H660-H669 ◽  
Author(s):  
Nicholas A. Flavahan ◽  
Simon R. Bailey ◽  
William A. Flavahan ◽  
Srabani Mitra ◽  
Sheila Flavahan
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Actin Cytoskeleton ◽  
Vascular Smooth Muscle Cells ◽  
Laser Scanning ◽  
Actin Polymerization ◽  
Muscle Cells ◽  
Cytochalasin D ◽  
Cell Periphery

Experiments were performed to determine whether remodeling of the actin cytoskeleton contributes to arteriolar constriction. Mouse tail arterioles were mounted on cannulae in a myograph and superfused with buffer solution. The α1-adrenergic agonist phenylephrine (0.1–1 μmol/l) caused constriction that was unaffected by cytochalasin D (300 nmol/l) or latrunculin A (100 nmol/l), inhibitors of actin polymerization. In contrast, each compound abolished the mechanosensitive constriction (myogenic response) evoked by elevation in transmural pressure (PTM; 10–60 or 90 mmHg). Arterioles were fixed, permeabilized, and stained with Alexa-568 phalloidin and Alexa-488 DNAse I to visualize F-actin and G-actin, respectively, using a Zeiss 510 laser scanning microscope. Elevation in PTM, but not phenylephrine (1 μmol/l), significantly increased the intensity of F-actin and significantly decreased the intensity of G-actin staining in arteriolar vascular smooth muscle cells (VSMCs). The increase in F-actin staining caused by an elevation in PTM was inhibited by cytochalasin D. In VSMCs at 10 mmHg, prominent F-actin staining was restricted to the cell periphery, whereas after elevation in PTM, transcytoplasmic F-actin fibers were localized through the cell interior, running parallel to the long axis of the cells. Phenylephrine (1 μmol/l) did not alter the architecture of the actin cytoskeleton. In contrast to VSMCs, the actin cytoskeleton of endothelial or adventitial cells was not altered by an elevation in PTM. Therefore, the actin cytoskeleton of VSMCs undergoes dramatic alteration after elevation in PTM of arterioles and plays a selective and essential role in mechanosensitive myogenic constriction.

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