scholarly journals Actin polymerization stimulated by contractile activation regulates force development in canine tracheal smooth muscle

1999 ◽  
Vol 519 (3) ◽  
pp. 829-840 ◽  
Author(s):  
Dolly Mehta ◽  
Susan J. Gunst
Keyword(s):  
Smooth Muscle ◽  
Actin Polymerization ◽  
Tracheal Smooth Muscle ◽  
Force Development ◽  
Contractile Activation

scholarly journals Abl activation regulates the dissociation of CAS from cytoskeletal vimentin by modulating CAS phosphorylation in smooth muscle

2010 ◽  
Vol 299 (3) ◽  
pp. C630-C637 ◽  
Author(s):  
Li Jia ◽  
Dale D. Tang
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Actin Polymerization ◽  
Spatial Location ◽  
Smooth Muscle Contraction ◽  
Nonreceptor Tyrosine Kinase ◽  
Force Development ◽  
Muscle Inhibition ◽  
A Cell ◽  
Contractile Activation

Abl is a nonreceptor tyrosine kinase that is required for smooth muscle contraction. However, the mechanism by which Abl regulates smooth muscle contraction is not completely understood. In the present study, Abl underwent phosphorylation at Tyr412 (an index of Abl activation) in smooth muscle in response to contractile activation. Treatment with a cell-permeable decoy peptide, but not the control peptide, attenuated Abl phosphorylation during contractile stimulation. Treatment with the decoy peptide did not affect the association of Abl with the cytoskeletal protein vinculin and the spatial location of vinculin in smooth muscle. Inhibition of Abl phosphorylation by the decoy peptide attenuated the agonist-induced phosphorylation of Crk-associated substrate (CAS), an adapter protein participating in the signaling processes that regulate force development in smooth muscle. Additionally, previous studies have shown that contractile stimulation triggers the dissociation of CAS from the vimentin network, which is important for cytoskeletal signaling and contraction in smooth muscle. In this report, the decrease in the amount of CAS in cytoskeletal vimentin in response to contractile activation was reversed by the Abl inhibition with the decoy peptide. Moreover, force development and the enhancement of F-actin-to-G-actin ratios (an indication of actin polymerization) upon contractile activation were also attenuated by the Abl inhibition. However, myosin phosphorylation induced by contractile activation was not affected by the inhibition of Abl. These results suggest that Abl regulates the dissociation of CAS from the vimentin network, actin polymerization, and contraction by modulating CAS phosphorylation in smooth muscle.

Role of Rho in Ca2+-insensitive contraction and paxillin tyrosine phosphorylation in smooth muscle

2000 ◽  
Vol 279 (2) ◽  
pp. C308-C318 ◽  
Author(s):  
Dolly Mehta ◽  
Dale D. Tang ◽  
Ming-Fang Wu ◽  
Simon Atkinson ◽  
Susan J. Gunst
Keyword(s):  
Smooth Muscle ◽  
Tyrosine Phosphorylation ◽  
Actin Polymerization ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Cytochalasin D ◽  
Cytoskeletal Proteins ◽  
Tracheal Smooth Muscle ◽  
Contractile Activation ◽  
Mlc Phosphorylation

We investigated whether Rho activation is required for Ca2+-insensitive paxillin phosphorylation, myosin light chain (MLC) phosphorylation, and contraction in tracheal muscle. Tyrosine-phosphorylated proteins have been implicated in the Ca2+-insensitive contractile activation of smooth muscle tissues. The contractile activation of tracheal smooth muscle increases tyrosine phosphorylation of the cytoskeletal proteins paxillin and focal adhesion kinase. Paxillin is implicated in integrin-mediated signal transduction pathways that regulate cytoskeletal organization and cell motility. In fibroblasts and other nonmuscle cells, paxillin tyrosine phosphorylation depends on the activation of Rho and is inhibited by cytochalasin, an inhibitor of actin polymerization. In permeabilized muscle strips, we found that ACh induced Ca2+-insensitive contraction, MLC phosphorylation, and paxillin tyrosine phosphorylation. Ca2+-insensitive contraction and MLC phosphorylation induced by ACh were inhibited by C3 transferase, an inhibitor of Rho activation; however, C3 transferase did not inhibit paxillin tyrosine phosphorylation. Ca2+-insensitive paxillin tyrosine phosphorylation was also not inhibited by the Rho kinase inhibitor Y-27632, by cytochalasin D, or by the inhibition of MLC phosphorylation. We conclude that, in tracheal smooth muscle, Rho mediates Ca2+-insensitive contraction and MLC phosphorylation but that Rho is not required for Ca2+-insensitive paxillin tyrosine phosphorylation. Paxillin phosphorylation also does not require actomyosin activation, nor is it inhibited by the actin filament capping agent cytochalasin D.

Relationship between paxillin and myosin phosphorylation during muscarinic stimulation of smooth muscle

1998 ◽  
Vol 274 (3) ◽  
pp. C741-C747 ◽  
Author(s):  
Dolly Mehta ◽  
Zhonglin Wang ◽  
Ming-Fang Wu ◽  
Susan J. Gunst
Keyword(s):  
Smooth Muscle ◽  
Tyrosine Phosphorylation ◽  
Myosin Light Chain ◽  
Smooth Muscle Contraction ◽  
Maximal Increase ◽  
Force Development ◽  
Muscarinic Stimulation ◽  
Contractile Activation ◽  
Mlc Phosphorylation ◽  
Stimulation Of

The tyrosine phosphorylation of paxillin increases in association with force development during tracheal smooth muscle contraction, suggesting that paxillin plays a role in the contractile activation of smooth muscle [Z. L. Wang, F. M. Pavalko, and S. J. Gunst. Am. J. Physiol. 271 ( Cell Physiol. 40): C1594–C1602, 1996]. We compared the Ca2+ sensitivity of the tyrosine phosphorylation of paxillin and myosin light chain (MLC) phosphorylation in tracheal muscle and evaluated whether MLC phosphorylation is necessary to induce paxillin phosphorylation. Ca2+-depleted muscle strips were stimulated with 10−7–10−4M acetylcholine (ACh) in 0, 0.05, 0.1, or 0.5 mM extracellular Ca2+. In the absence of extracellular Ca2+, 10−4 M ACh induced a maximal increase in paxillin phosphorylation without increasing MLC phosphorylation or force. Increases in extracellular Ca2+ concentration did not further increase paxillin phosphorylation. However, during stimulation with 10−6 M ACh, paxillin phosphorylation increased with increases in extracellular Ca2+ concentration. We conclude that the tyrosine phosphorylation of paxillin can be stimulated by signaling pathways that do not depend on Ca2+ mobilization and that the activation of contractile proteins is not required to elicit paxillin phosphorylation.

scholarly journals Dissociation of Crk-associated substrate from the vimentin network is regulated by p21-activated kinase on ACh activation of airway smooth muscle

2007 ◽  
Vol 292 (1) ◽  
pp. L240-L248 ◽  
Author(s):  
Ruping Wang ◽  
Qing-Fen Li ◽  
Yana Anfinogenova ◽  
Dale D. Tang
Keyword(s):  
Smooth Muscle ◽  
Immunoblot Analysis ◽  
Smooth Muscle Contraction ◽  
Tracheal Smooth Muscle ◽  
Intermediate Filament Protein ◽  
Active Force ◽  
Force Development ◽  
Cellular Processes ◽  
P21 Activated Kinase ◽  
Filament Protein

The intermediate filament protein vimentin has been shown to be required for smooth muscle contraction. The adapter protein p130 Crk-associated substrate (CAS) participates in the signaling processes that regulate force development in smooth muscle. However, the interaction of vimentin filaments with CAS has not been well elucidated. In the present study, ACh stimulation of tracheal smooth muscle strips increased the ratio of soluble to insoluble vimentin (an index of vimentin disassembly) in association with force development. ACh activation also induced vimentin phosphorylation at Ser56 as assessed by immunoblot analysis. More importantly, CAS was found in the cytoskeletal vimentin fraction, and the amount of CAS in cytoskeletal vimentin was reduced in smooth muscle strips on contractile stimulation. CAS redistributed from the myoplasm to the periphery during ACh activation of smooth muscle cells. The ACh-elicited decrease in CAS distribution in cytoskeletal vimentin was attenuated by the downregulation of p21-activated kinase (PAK) 1 with antisense oligodeoxynucleotides. Vimentin phosphorylation at this residue, the ratio of soluble to insoluble vimentin, and active force in smooth muscle strips induced by ACh were also reduced in PAK-depleted tissues. These results suggest that PAK may regulate CAS release from the vimentin intermediate filaments by mediating vimentin phosphorylation at Ser56 and the transition of cytoskeletal vimentin to soluble vimentin. The PAK-mediated dissociation of CAS from the vimentin network may participate in the cellular processes that affect active force development during ACh activation of tracheal smooth muscle tissues.

Relationship between asynchronous Ca2+ waves and force development in intact smooth muscle bundles of the porcine trachea

2003 ◽  
Vol 285 (6) ◽  
pp. L1345-L1353 ◽  
Author(s):  
Kuo-Hsing Kuo ◽  
Jiazhen Dai ◽  
Chun Yong Seow ◽  
Cheng-Han Lee ◽  
Cornelis van Breemen
Keyword(s):  
Smooth Muscle ◽  
Calcium Concentration ◽  
Longitudinal Axis ◽  
Force Generation ◽  
Tracheal Smooth Muscle ◽  
Airway Smooth Muscle Cells ◽  
Muscle Bundle ◽  
Force Development ◽  
Smooth Muscle Bundle ◽  
Intracellular Ca

Fluctuations in intracellular calcium concentration ([Ca2+]i) constitute the main link in excitation-contraction coupling (E-C coupling) in airway smooth muscle cells (ASMC). It has recently been reported that ACh induces asynchronous recurring Ca2+ waves in intact ASMC of murine bronchioles. With the use of a novel technique allowing us to simultaneously measure subcellular [Ca2+]i and force generation in ASMC located within an intact tracheal muscle bundle, we examined a similar pattern of Ca2+ signaling in the trachea. We found that application of ACh resulted in the generation of recurring intracellular Ca2+ waves progressing along the longitudinal axis of the ribbon-shaped intact ASMC. These Ca2+ waves were not synchronized between neighboring cells, and induction of wave-like [Ca2+]i oscillations was temporally associated with development of force by the tracheal muscle bundle. By comparing the concentration dependence of force generation and the parameters characterizing the [Ca2+]i oscillations, we found that the concentration-dependent increase in ACh-induced force development by the tracheal smooth muscle bundle is achieved by differential recruitment of intact ASMC to initiate Ca2+ waves and by enhancement in the frequency of [Ca2+]i oscillations and elevation of interspike [Ca2+]i once the cells are recruited. Our findings demonstrate that asynchronous recurring Ca2+ waves underlie E-C coupling in ACh-induced contraction of the intact tracheal smooth muscle bundle. Furthermore, in contrast to what was reported in enzymatically dissociated ASMC, Ca2+ influx through the L-type voltage-gated Ca2+ channel was not an obligatory requirement for the generation of [Ca2+]i oscillations and development of force in ACh-stimulated intact ASMC.

Activation of the Arp2/3 complex by N-WASp is required for actin polymerization and contraction in smooth muscle

2005 ◽  
Vol 288 (5) ◽  
pp. C1145-C1160 ◽  
Author(s):  
Wenwu Zhang ◽  
Yidi Wu ◽  
Liping Du ◽  
Dale D. Tang ◽  
Susan J. Gunst
Keyword(s):  
Smooth Muscle ◽  
Actin Polymerization ◽  
Fluorescent Protein ◽  
Tracheal Smooth Muscle ◽  
Wild Type ◽  
Tension Development ◽  
Muscle Tissues ◽  
Muscarinic Stimulation ◽  
Mlc Phosphorylation

Contractile stimulation has been shown to initiate actin polymerization in smooth muscle tissues, and this actin polymerization is required for active tension development. We evaluated whether neuronal Wiskott-Aldrich syndrome protein (N-WASp)-mediated activation of the actin-related proteins 2 and 3 (Arp2/3) complex regulates actin polymerization and tension development initiated by muscarinic stimulation in canine tracheal smooth muscle tissues. In vitro, the COOH-terminal CA domain of N-WASp acts as an inhibitor of N-WASp-mediated actin polymerization; whereas the COOH-terminal VCA domain of N-WASp is constitutively active and is sufficient by itself to catalyze actin polymerization. Plasmids encoding EGFP-tagged wild-type N-WASp, the N-WASp VCA and CA domains, or enhanced green fluorescent protein (EGFP) were introduced into tracheal smooth muscle strips by reversible permeabilization, and the tissues were incubated for 2 days to allow for expression of the proteins. Expression of the CA domain inhibited actin polymerization and tension development in response to ACh, whereas expression of the wild-type N-WASp, the VCA domain, or EGFP did not. The increase in myosin light-chain (MLC) phosphorylation in response to contractile stimulation was not affected by expression of either the CA or VCA domain of N-WASp. Stimulation of the tissues with ACh increased the association of the Arp2/3 complex with N-WASp, and this association was inhibited by expression of the CA domain. The results demonstrate that 1) N-WASp-mediated activation of the Arp2/3 complex is necessary for actin polymerization and tension development in response to muscarinic stimulation in tracheal smooth muscle and 2) these effects are independent of the regulation of MLC phosphorylation.

Effects of chronic portal hypertension on agonist-induced actin polymerization in small mesenteric arteries

2006 ◽  
Vol 290 (5) ◽  
pp. H1915-H1921 ◽  
Author(s):  
Xuesong Chen ◽  
Kristin Pavlish ◽  
Hai-Ying Zhang ◽  
Joseph N. Benoit
Keyword(s):  
Smooth Muscle ◽  
Portal Hypertension ◽  
Vascular Smooth Muscle ◽  
Actin Polymerization ◽  
Smooth Muscle Contraction ◽  
Isometric Tension ◽  
Mesenteric Arteries ◽  
Dynamic Regulation ◽  
Force Development

The ability of arterial smooth muscle to respond to vasoconstrictor stimuli is reduced in chronic portal hypertension (PHT). Additional evidence supports the existence of a postreceptor defect in vascular smooth muscle excitation contraction coupling. However, the nature of this defect is unclear. Recent studies have shown that vasoconstrictor stimuli induce actin polymerization in smooth muscle and that the associated increase in F-actin is necessary for force development. In the present study we have tested the hypothesis that impaired actin polymerization contributes to reduced vasoconstrictor function in small mesenteric arteries derived from rats with chronic prehepatic PHT. In vitro studies were conducted on small mesenteric artery vessel rings isolated from normal and PHT rats. Isometric tension responses to incremental concentrations of phenylephrine were significantly reduced in PHT arteries. The ability to polymerize actin in portal hypertensive mesenteric arteries stimulated by phenylephrine was attenuated compared with control. Inhibition of cAMP-dependent protein kinase (PKA) restored agonist-induced actin polymerization of arteries from PHT rats to normal levels. Depolymerization of actin in arteries from normal rats reduced maximal contractile force but not myosin phosphorylation, suggesting a key role for the dynamic regulation of actin polymerization in the maintenance of vascular smooth muscle contraction. We conclude that reductions in agonist-induced maximal force development of PHT vascular smooth muscle is due, in part, to impaired actin polymerization, and prolonged PKA activation may underlie these changes.

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