scholarly journals Selected Contribution: Roles of focal adhesion kinase and paxillin in the mechanosensitive regulation of myosin phosphorylation in smooth muscle

2001 ◽  
Vol 91 (3) ◽  
pp. 1452-1459 ◽  
Author(s):  
Dale D. Tang ◽  
Susan J. Gunst
Keyword(s):  
Smooth Muscle ◽  
Focal Adhesion Kinase ◽  
Signaling Pathway ◽  
Focal Adhesion ◽  
Muscle Length ◽  
Cytoskeletal Proteins ◽  
Tracheal Smooth Muscle ◽  
Active Tension ◽  
Intracellular Ca ◽  
Mlc Phosphorylation

The increase in intracellular Ca2+ and myosin light chain (MLC) phosphorylation in response to the contractile activation of tracheal smooth muscle is greater at longer muscle lengths (21). However, MLC phosphorylation can also be stimulated by Ca2+-insensitive signaling pathways (19). The cytoskeletal proteins paxillin and focal adhesion kinase (FAK) mediate a Ca2+-independent length-sensitive signaling pathway in tracheal smooth muscle (30). We used α-toxin-permeabilized tracheal smooth muscle strips to determine whether the length sensitivity of MLC phosphorylation can be regulated by a Ca2+-insensitive signaling pathway and whether the length sensitivity of active tension depends on the length sensitivity of myosin activation. Although active tension remained length sensitive, ACh-induced MLC phosphorylation was the same at optimal muscle length ( L o) and 0.5 L o when intracellular Ca2+ was maintained at pCa 7. MLC phosphorylation was also the same at L o and 0.5 L o in strips stimulated with 10 μM Ca2+. In contrast, the Ca2+-insensitive tyrosine phosphorylation of FAK and paxillin stimulated by ACh was higher at L o than at 0.5 L o. We conclude that the length-sensitivity of MLC phosphorylation depends on length-dependent changes in intracellular Ca2+ but that length-dependent changes in MLC phosphorylation are not the primary mechanism for the length sensitivity of active tension.

scholarly journals Mechanosensitive tyrosine phosphorylation of paxillin and focal adhesion kinase in tracheal smooth muscle

1999 ◽  
Vol 276 (1) ◽  
pp. C250-C258 ◽  
Author(s):  
Dachun Tang ◽  
Dolly Mehta ◽  
Susan J. Gunst
Keyword(s):  
Smooth Muscle ◽  
Focal Adhesion Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Cell Structure ◽  
Muscle Length ◽  
Tracheal Smooth Muscle ◽  
Protein Activation ◽  
Associated Proteins

We investigated the role of the integrin-associated proteins focal adhesion kinase (FAK) and paxillin as mediators of mechanosensitive signal transduction in tracheal smooth muscle. In muscle strips contracted isometrically with ACh, we observed higher levels of tyrosine phosphorylation of FAK and paxillin at the optimal muscle length ( L o) than at shorter muscle lengths of 0.5 or 0.75 L o. Paxillin phosphorylation was also length sensitive in muscles activated by K+ depolarization and adjusted rapidly to changes in muscle length imposed after contractile activation by either ACh or K+depolarization. Ca2+ depletion did not affect the length sensitivity of paxillin and FAK phosphorylation in muscles activated with ACh, indicating that the mechanotransduction process can be mediated by a Ca2+-independent pathway. Since Ca2+-depleted muscles do not generate significant active tension, this suggests that the mechanotransduction mechanism is sensitive to muscle length rather than tension. We conclude that FAK and paxillin participate in an integrin-mediated mechanotransduction process in tracheal smooth muscle. We propose that this pathway may initiate alterations in smooth muscle cell structure and contractility via the remodeling of actin filaments and/or via the mechanosensitive regulation of signaling molecules involved in contractile protein activation.

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.

scholarly journals Stretch-induced phosphorylation of focal adhesion kinase in endothelial cells: role of mitochondrial oxidants

2006 ◽  
Vol 291 (1) ◽  
pp. L38-L45 ◽  
Author(s):  
Mir H. Ali ◽  
Paul T. Mungai ◽  
Paul T. Schumacker
Keyword(s):  
Signal Transduction ◽  
Endothelial Cells ◽  
Focal Adhesion Kinase ◽  
Signaling Pathway ◽  
Focal Adhesion ◽  
Cyclic Strain ◽  
Cytoskeletal Proteins ◽  
Cyclic Stretch ◽  
Mitochondrial Inhibitors ◽  
Mitochondrial Ros

Mechanical stretch activates a number of signaling pathways in endothelial cells, and it elicits a variety of functional responses including increases in the phosphorylation of focal adhesion kinase (FAK), a nonreceptor tyrosine kinase involved in integrin-mediated signal transduction. Stretch also triggers an increase in the generation of reactive oxygen species (ROS), which may function as second messengers in the signal transduction cascades that activate cellular responses to strain. Mitochondria represent an important source of ROS in the cell, and these organelles may release ROS in response to strain by virtue of their attachment to cytoskeletal proteins. We therefore tested whether cyclic stretch increases FAK phosphorylation at Tyr397 through a mitochondrial ROS signaling pathway in bovine pulmonary artery endothelial cells (BPAEC). Oxidant signaling, measured using 2′7′-dichlorofluorescin (DCFH), increased 152 ± 16% during 1.5 h of cyclic strain relative to unstrained controls. The mitochondrial inhibitors diphenylene iodonium (5 μM) or rotenone (2 μM) attenuated this increase, whereas l-nitroarginine (100 μM), allopurinol (100 μM), or apocynin (30 μM) had no effect. The antioxidants ebselen (5 μM) and dithiodidiethyldithiocarbamate (1 mM) inhibited the strain-induced increase in oxidant signaling, but Hb (5 μM) had no effect. These results indicate that strain induces oxidant release from mitochondria. Treatment with cytochalasin D (5 μM) abrogated strain-induced DCFH oxidation in BPAEC, indicating that actin filaments were required for stretch-induced mitochondrial ROS generation. Cyclic strain increased FAK phosphorylation at Tyr397, but this was abolished by mitochondrial inhibitors as well as by antioxidants. Strain-induced FAK phosphorylation was abrogated by inhibition of protein kinase C (PKC) with Ro-31-8220 or Gö-6976. These findings indicate that mitochondrial oxidants generated in response to endothelial strain trigger FAK phosphorylation through a signaling pathway that involves PKC.

Resveratrol inhibits glucose‐induced migration of vascular smooth muscle cells mediated by focal adhesion kinase

2014 ◽  
Vol 58 (7) ◽  
pp. 1389-1401 ◽  
Author(s):  
Yi‐Chiao Lin ◽  
Li‐Hsuen Chen ◽  
T. Varadharajan ◽  
May‐Jywan Tsai ◽  
Yi‐Chen Chia ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Focal Adhesion Kinase ◽  
Vascular Smooth Muscle Cells ◽  
Focal Adhesion ◽  
Muscle Cells

scholarly journals Focal adhesion kinase (FAK) and mechanical stimulation negatively regulate the transition of airway smooth muscle tissues to a synthetic phenotype

2016 ◽  
Vol 311 (5) ◽  
pp. L893-L902 ◽  
Author(s):  
Yidi Wu ◽  
Youliang Huang ◽  
Susan J. Gunst
Keyword(s):  
Smooth Muscle ◽  
Focal Adhesion Kinase ◽  
Airway Smooth Muscle ◽  
Focal Adhesion ◽  
Inflammatory Responses ◽  
Mechanical Load ◽  
Akt Activation ◽  
Lower Load ◽  
Synthetic Phenotype

The effects of mechanical forces and focal adhesion kinase (FAK) in regulating the inflammatory responses of airway smooth muscle (ASM) tissues to stimulation with interleukin (IL)-13 were investigated. Canine tracheal tissues were subjected to different mechanical loads in vitro, and the effects of mechanical load on eotaxin secretion and inflammatory signaling pathways in response to IL-13 were determined. Eotaxin secretion by tissues in response to IL-13 was significantly inhibited in muscles maintained at a higher (+) load compared with those at a lower (−) load as assessed by ELISA, and Akt activation was also reduced in the higher (+) loaded tissues. Conversely the (+) mechanical load increased activation of the focal adhesion proteins FAK and paxillin in the tissues. The role of FAK in regulating the mechanosensitive responses was assessed by overexpressing FAK-related nonkinase in the tissues, by expressing the FAK kinase-dead mutant FAK Y397F, or by treating tissues with the FAK inhibitor PF-573228. FAK inactivation potentiated Akt activity and increased eotaxin secretion in response to IL-13. FAK inhibition also suppressed the mechanosensitivity of Akt activation and eotaxin secretion. In addition, FAK inactivation suppressed smooth muscle myosin heavy chain expression induced by the higher (+) mechanical load. The results demonstrate that the imposition of a higher mechanical load on airway smooth muscle stimulates FAK activation, which promotes the expression of the differentiated contractile phenotype and suppresses the synthetic phenotype and the inflammatory responses of the muscle tissue.

Velocity-length-time relations in canine tracheal smooth muscle

1988 ◽  
Vol 64 (5) ◽  
pp. 2053-2057 ◽  
Author(s):  
C. Y. Seow ◽  
N. L. Stephens
Keyword(s):  
Smooth Muscle ◽  
Goodness Of Fit ◽  
Time Course ◽  
Muscle Length ◽  
Tracheal Smooth Muscle ◽  
Minimum Length ◽  
Shortening Velocity ◽  
Contracting Muscle ◽  
Parabolic Function ◽  
The Moment

Zero-load velocity (V0) as a function of the length of canine tracheal smooth muscle was obtained by applying zero-load clamps to isotonically contracting muscle under various loads. The load clamps were applied at a specific time after onset of contraction. The magnitude of the isotonic load therefore determines the length of the muscle at the moment of release or at the moment the unloaded shortening velocity was measured. A family of such V0-muscle length (L) curves was obtained at 1-s intervals in the time course of contraction. The V0-L curve was fitted by a parabolic function with satisfactory goodness of fit. The maximum shortening velocity at optimum muscle length varied with time, but the minimum length at which V0 diminished to zero was time independent.

Role of cyclic ADP-ribose in the regulation of [Ca2+]i in porcine tracheal smooth muscle

1998 ◽  
Vol 274 (6) ◽  
pp. C1653-C1660 ◽  
Author(s):  
Y. S. Prakash ◽  
Mathur S. Kannan ◽  
Timothy F. Walseth ◽  
Gary C. Sieck
Keyword(s):  
Smooth Muscle ◽  
Second Messenger ◽  
Ruthenium Red ◽  
Tracheal Smooth Muscle ◽  
Cyclic Adp Ribose ◽  
Intracellular Ca ◽  
Subsequent Exposure ◽  
Trisphosphate Receptor ◽  
Dose Dependent Increase

The purpose of the present study was to determine whether cyclic ADP-ribose (cADPR) acts as a second messenger for Ca2+ release through ryanodine receptor (RyR) channels in tracheal smooth muscle (TSM). Freshly dissociated porcine TSM cells were permeabilized with β-escin, and real-time confocal microscopy was used to examine changes in intracellular Ca2+ concentration ([Ca2+]i). cADPR (10 nM–10 μM) induced a dose-dependent increase in [Ca2+]i, which was blocked by the cADPR receptor antagonist 8-amino-cADPR (20 μM) and by the RyR blockers ruthenium red (10 μM) and ryanodine (10 μM), but not by the inositol 1,4,5-trisphosphate receptor blocker heparin (0.5 mg/ml). During steady-state [Ca2+]ioscillations induced by acetylcholine (ACh), addition of 100 nM and 1 μM cADPR increased oscillation frequency and decreased peak-to-trough amplitude. ACh-induced [Ca2+]ioscillations were blocked by 8-amino-cADPR; however, 8-amino-cADPR did not block the [Ca2+]iresponse to a subsequent exposure to caffeine. These results indicate that cADPR acts as a second messenger for Ca2+ release through RyR channels in TSM cells and may be necessary for initiating ACh-induced [Ca2+]ioscillations.

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