The Dynamic Actin Cytoskeleton in Smooth Muscle

Smooth muscles develop isometric force over a very wide range of cell lengths. The molecular mechanisms of this phenomenon are undefined, but are described as reflecting "mechanical plasticity" of smooth muscle cells. Plasticity is defined here as a persistent change in cell structure or function in response to a change in the environment. Important environmental stimuli that trigger muscle plasticity include chemical (e.g., neurotransmitters, autacoids, and cytokines) and external mechanical signals (e.g., applied stress and strain). Both kinds of signals are probably transduced by ionic and protein kinase signaling cascades to alter gene expression patterns and changes in the cytoskeleton and contractile system. Defining the signaling mechanisms and effector proteins mediating phenotypic and mechanical plasticity of smooth muscles is a major goal in muscle cell biology. Some of the signaling cascades likely to be important include calcium-dependent protein kinases, small GTPases (Rho, Rac, cdc42), Rho kinase, protein kinase C (PKC), Src family tyrosine kinases, mitogen-activated protein (MAP) kinases, and p21 activated protein kinases (PAK). There are many potential targets for these signaling cascades including nuclear processes, metabolic pathways, and structural components of the cytoskeleton. There is growing appreciation of the dynamic nature of the actin cytoskeleton in smooth muscles and the necessity for actin remodeling to occur during contraction. The actin cytoskeleton serves many functions that are probably critical for muscle plasticity including generation and transmission of force vectors, determination of cell shape, and assembly of signal transduction machinery. Evidence is presented showing that actin filaments are dynamic and that actin-associated proteins comprising the contractile element and actin attachment sites are necessary for smooth muscle contraction.Key words: integrin, muscle mechanics, paxillin, Rho, HSP27.

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Rho GTPase signaling modulates cell shape and contractile phenotype in an isoactin-specific manner

AJP Cell Physiology ◽

10.1152/ajpcell.00177.2003 ◽

2003 ◽

Vol 285 (5) ◽

pp. C1116-C1121 ◽

Cited By ~ 28

Author(s):

Alexey Y. Kolyada ◽

Kathleen N. Riley ◽

Ira M. Herman

Keyword(s):

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Actin Cytoskeleton ◽

Cell Size ◽

Rho Gtpase ◽

Small Gtpases ◽

Protein Isoforms ◽

Stress Fibers ◽

Contractile Phenotype ◽

Specific Manner

Rho family small GTPases (Rho, Rac, and Cdc42) play an important role in cell motility, adhesion, and cell division by signaling reorganization of the actin cytoskeleton. Here, we report an isoactin-specific, Rho GTPase-dependent signaling cascade in cells simultaneously expressing smooth muscle and nonmuscle actin isoforms. We transfected primary cultures of microvascular pericytes, cells related to vascular smooth muscle cells, with various Rho-related and Rho-specific expression plasmids. Overexpression of dominant positive Rho resulted in the formation of nonmuscle actin-containing stress fibers. At the same time, α-vascular smooth muscle actin (αVSMactin) containing stress fibers were disassembled, resulting in a dramatic reduction in cell size. Rho activation also yielded a disassembly of smooth muscle myosin and nonmuscle myosin from stress fibers. Overexpression of wild-type Rho had similar but less dramatic effects. In contrast, dominant negative Rho and C3 exotransferase or dominant positive Rac and Cdc42 expression failed to alter the actin cytoskeleton in an isoform-specific manner. The loss of smooth muscle contractile protein isoforms in pericyte stress fibers, together with a concomitant decrease in cell size, suggests that Rho activation influences “contractile” phenotype in an isoactin-specific manner. This, in turn, should yield significant alteration in microvascular remodeling during developmental and pathologic angiogenesis.

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Retraction notice to “Statin blocks Rho/Rho-kinase signalling and disrupts the actin cytoskeleton: Relationship to enhancement of LPS-mediated nitric oxide synthesis in vascular smooth muscle cells” [Biochim. Biophys. Acta 1689 (2004) 267–272]

Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease ◽

10.1016/j.bbadis.2011.06.007 ◽

2011 ◽

Vol 1812 (9) ◽

pp. 1200

Author(s):

Tetsuya Kato ◽

Hiroko Hashikabe ◽

Chigusa Iwata ◽

Kazumi Akimoto ◽

Yoshiyuki Hattori

Keyword(s):

Nitric Oxide ◽

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cells ◽

Actin Cytoskeleton ◽

Vascular Smooth Muscle Cells ◽

Rho Kinase ◽

Muscle Cells ◽

Nitric Oxide Synthesis ◽

Retraction Notice

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CRP1, a LIM Domain Protein Implicated in Muscle Differentiation, Interacts with α-Actinin

The Journal of Cell Biology ◽

10.1083/jcb.139.1.157 ◽

1997 ◽

Vol 139 (1) ◽

pp. 157-168 ◽

Cited By ~ 80

Author(s):

Pascal Pomiès ◽

Heather A. Louis ◽

Mary C. Beckerle

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Actin Cytoskeleton ◽

Indirect Immunofluorescence ◽

Muscle Cells ◽

Muscle Differentiation ◽

Full Length ◽

Stress Fibers ◽

Lim Domain

Members of the cysteine-rich protein (CRP) family are LIM domain proteins that have been implicated in muscle differentiation. One strategy for defining the mechanism by which CRPs potentiate myogenesis is to characterize the repertoire of CRP binding partners. In order to identify proteins that interact with CRP1, a prominent protein in fibroblasts and smooth muscle cells, we subjected an avian smooth muscle extract to affinity chromatography on a CRP1 column. A 100-kD protein bound to the CRP1 column and could be eluted with a high salt buffer; Western immunoblot analysis confirmed that the 100-kD protein is α-actinin. We have shown that the CRP1–α-actinin interaction is direct, specific, and saturable in both solution and solid-phase binding assays. The Kd for the CRP1–α-actinin interaction is 1.8 ± 0.3 μM. The results of the in vitro protein binding studies are supported by double-label indirect immunofluorescence experiments that demonstrate a colocalization of CRP1 and α-actinin along the actin stress fibers of CEF and smooth muscle cells. Moreover, we have shown that α-actinin coimmunoprecipitates with CRP1 from a detergent extract of smooth muscle cells. By in vitro domain mapping studies, we have determined that CRP1 associates with the 27-kD actin–binding domain of α-actinin. In reciprocal mapping studies, we showed that α-actinin interacts with CRP1-LIM1, a deletion fragment that contains the NH2-terminal 107 amino acids (aa) of CRP1. To determine whether the α-actinin binding domain of CRP1 would localize to the actin cytoskeleton in living cells, expression constructs encoding epitope-tagged full-length CRP1, CRP1-LIM1(aa 1-107), or CRP1-LIM2 (aa 108-192) were microinjected into cells. By indirect immunofluorescence, we have determined that full-length CRP1 and CRP1-LIM1 localize along the actin stress fibers whereas CRP1-LIM2 fails to associate with the cytoskeleton. Collectively these data demonstrate that the NH2-terminal part of CRP1 that contains the α-actinin–binding site is sufficient to localize CRP1 to the actin cytoskeleton. The association of CRP1 with α-actinin may be critical for its role in muscle differentiation.

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Calponin isoforms CNN 1, CNN 2 and CNN 3: Regulators for actin cytoskeleton functions in smooth muscle and non-muscle cells

Gene ◽

10.1016/j.gene.2016.02.040 ◽

2016 ◽

Vol 585 (1) ◽

pp. 143-153 ◽

Cited By ~ 54

Author(s):

Rong Liu ◽

J.-P. Jin

Keyword(s):

Smooth Muscle ◽

Actin Cytoskeleton ◽

Muscle Cells

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Smooth muscle F-actin disassembly and RhoA/Rho-kinase signaling during endotoxin-induced alterations in pulmonary arterial compliance

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00219.2003 ◽

2004 ◽

Vol 287 (4) ◽

pp. L649-L655 ◽

Cited By ~ 12

Author(s):

Christa Boer ◽

Geerten P. van Nieuw Amerongen ◽

A. B. Johan Groeneveld ◽

Gert Jan Scheffer ◽

Jaap J. de Lange ◽

...

Keyword(s):

Smooth Muscle ◽

Actin Cytoskeleton ◽

Vascular Function ◽

Kinase Inhibitor ◽

Arterial Compliance ◽

Pulmonary Arteries ◽

Rho Kinase ◽

Kinase Signaling ◽

Arterial Mechanics ◽

Pulmonary Arterial

Endotoxemia is associated with changed pulmonary vascular function with respect to vasoreactivity, endothelial permeability, and activation of inducible nitric oxide synthase II (NOSII). However, whether altered passive arterial wall mechanics contribute to this endotoxin-induced pulmonary vascular dysfunction is still unknown. Therefore, we investigated whether endotoxin affects the passive arterial mechanics and compliance of isolated rat pulmonary arteries. Pulmonary arteries of pentobarbital-anesthetized Wistar rats ( n = 55) were isolated and exposed to Escherichia coli endotoxin (50 μg/ml) for 20 h. Endotoxin increased pulmonary artery diameter and compliance (transmural pressure = 13 mmHg) in an endothelium-, Ca2+-, or NOSII-induced NO release-independent manner. Interestingly, the endotoxin-induced alterations in the passive arterial mechanics were accompanied by disassembly of the smooth muscle cell (SMC) F-actin cytoskeleton. Disassembly of F-actin by incubation of control arteries with the cytoskeleton-disrupting agent cytochalasin B or the Rho-kinase inhibitor Y-27632 induced a similar increase in passive arterial diameter and compliance. In contrast, RhoA activation by lysophosphatidic acid prevented the endotoxin-induced alterations in the pulmonary SMC F-actin cytoskeleton and passive mechanics. In conclusion, these findings indicate that disassembly of the SMC F-actin cytoskeleton and RhoA/Rho-kinase signaling act as mediators of endotoxin-induced changes in the pulmonary arterial mechanics. They imply the involvement of F-actin rearrangement and RhoA/Rho-kinase signaling in endotoxemia-induced vascular lung injury.

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Role of the actin cytoskeleton in angiotensin II signaling in human vascular smooth muscle cells

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y05-006 ◽

2005 ◽

Vol 83 (1) ◽

pp. 91-97 ◽

Cited By ~ 21

Author(s):

Rhian M Touyz ◽

Guoying Yao ◽

Ernesto L Schiffrin

Keyword(s):

Smooth Muscle ◽

Angiotensin Ii ◽

Vascular Smooth Muscle ◽

Nadph Oxidase ◽

Actin Cytoskeleton ◽

Cytochalasin B ◽

Ros Generation ◽

Ang Ii ◽

Ros Formation

Angiotensin II (Ang II) regulates vascular smooth muscle cell (VSMC) function by activating signaling cascades that promote vasoconstriction, growth, and inflammation. Subcellular mechanisms coordinating these processes are unclear. In the present study, we questioned the role of the actin cytoskeleton in Ang II mediated signaling through mitogen-activated protein (MAP) kinases and reactive oxygen species (ROS) in VSMCs. Human VSMCs were studied. Cells were exposed to Ang II (10–7 mol/L) in the absence and presence of cytochalasin B (10–6 mol/L, 60 min), which disrupts the actin cytoskeleton. Phosphorylation of p38MAP kinase, JNK, and ERK1/2 was assessed by immuno blotting. ROS generation was measured using the fluoroprobe chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (4 µmol/L). Interaction between the cytoskeleton and NADPH oxidase was determined by evaluating the presence of p47phox in the Triton X-100 insoluble membrane fraction. Ang II significantly increased phosphorylation of p38MAP kinase, JNK, and ERK1/2 (two- to threefold above control, p < 0.05). Cytochalasin B pretreatment attenuated p38MAP kinase and JNK effects (p < 0.05) without altering ERK1/2 phosphorylation. ROS formation, which was increased in Ang II stimulated cells, was significantly reduced by cytochalasin B (p < 0.01). p47phox, critically involved in NADPH oxidase activation, colocalized with the actin cytoskeleton in Ang II stimulated cells. Our data demonstrate that Ang II mediated ROS formation and activation of p38MAP kinase and JNK, but not ERK1/2, involves the actin cytoskeleton in VSMCs. In addition, Ang II promotes interaction between actin and p47phox. These data indicate that the cytoskeleton is involved in differential MAP kinase signaling and ROS generation by Ang II in VSMCs. Together, these studies suggest that the cytoskeleton may be a central point of crosstalk in growth- and redox-signaling pathways by Ang II, which may be important in the regulation of VSMC function.Key words: superoxide, NADPH oxidase, p38MAP kinase, JNK, ERK1/2.

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