Prostaglandin E2-Dependent Blockade of Actomyosin and Stress Fibre Formation Is Mediated Through S1379 Phosphorylation of ROCK2

Lu/BCAM (Lutheran/basal cell-adhesion molecule) is a laminin 511/521 receptor expressed in erythroid and endothelial cells, and in epithelial tissues. The RK573–574 (Arg573-Lys574) motif of the Lu/BCAM cytoplasmic domain interacts with αI-spectrin, the main component of the membrane skeleton in red blood cells. In the present paper we report that Lu/BCAM binds to the non-erythroid αII-spectrin via the RK573–574 motif. Alanine substitution of this motif abolished the Lu/BCAM–spectrin interaction, enhanced the half-life of Lu/BCAM at the MDCK (Madin–Darby canine kidney) cell surface, and increased Lu/BCAM-mediated cell adhesion and spreading on laminin 511/521. We have shown that the Lu/BCAM–spectrin interaction mediated actin reorganization during cell adhesion and spreading on laminin 511/521. This interaction was involved in a laminin 511/521-to-actin signalling pathway leading to stress fibre formation. This skeletal rearrangement was associated with an activation of the small GTP-binding protein RhoA, which depended on the integrity of the Lu/BCAM laminin 511/521-binding site. It also required a Lu/BCAM–αII-spectrin interaction, since its disruption decreased stress fibre formation and RhoA activation. We conclude that the Lu/BCAM–spectrin interaction is required for stress fibre formation during cell spreading on laminin 511/521, and that spectrin acts as a signal relay between laminin 511/521 and actin that is involved in actin dynamics.

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Sphingosine 1-phosphate stimulates Rho-mediated tyrosine phosphorylation of focal adhesion kinase and paxillin in Swiss 3T3 fibroblasts

Biochemical Journal ◽

10.1042/bj3240481 ◽

1997 ◽

Vol 324 (2) ◽

pp. 481-488 ◽

Cited By ~ 78

Author(s):

Fang WANG ◽

Catherine D. NOBES ◽

Alan HALL ◽

Sarah SPIEGEL

Keyword(s):

Focal Adhesion Kinase ◽

Tyrosine Phosphorylation ◽

Focal Adhesion ◽

Stress Fibre ◽

3T3 Fibroblasts ◽

Fibre Formation ◽

Sphingosine 1 Phosphate ◽

Swiss 3T3 Fibroblasts ◽

Stress Fibre Formation ◽

Stimulation Of

Sphingosine 1-phosphate (SPP), a sphingolipid second messenger implicated in the mitogenic action of platelet-derived growth factor [Olivera, A. and Spiegel, S. (1993) Nature (London) 365, 557–560], induced rapid reorganization of the actin cytoskeleton resulting in stress-fibre formation. SPP also induced transient tyrosine phosphorylation of focal adhesion kinase (p125FAK), a cytosolic tyrosine kinase that localizes in focal adhesions, and of the cytoskeleton-associated protein paxillin. Exoenzyme C3 transferase, which ADP-ribosylates Rho (a Ras-related small GTP binding protein) on asparagine-41 and renders it biologically inactive, inhibited both stress-fibre formation and protein tyrosine phosphorylation induced by SPP. Thus Rho may be an upstream regulator of both stress-fibre formation and tyrosine phosphorylation of p125FAK and paxillin. Pretreatment with PMA, an activator of protein kinase C (PKC), inhibited the stimulation of stress-fibre formation induced by 1-oleoyl-lysophosphatidic acid (LPA) but not that by SPP. Similarly, PMA also decreased LPA-induced tyrosine phosphorylation of p125FAK and paxillin without abrogating the response to SPP. Thus PKC is involved in LPA- but not SPP-dependent signalling. The polyanionic drug suramin, a broad-specificity inhibitor of ligand–receptor interactions, did not inhibit either the mitogenic effect of SPP or its stimulation of tyrosine phosphorylation of p125FAK. However, suramin markedly inhibited these responses induced by LPA. These results suggest that in contrast with LPA, SPP may be acting intracellularly in Swiss 3T3 fibroblasts to stimulate tyrosine phosphorylation of p125FAK and paxillin and cell growth.

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The mammalian formin FHOD1 is activated through phosphorylation by ROCK and mediates thrombin-induced stress fibre formation in endothelial cells

The EMBO Journal ◽

10.1038/emboj.2008.7 ◽

2008 ◽

Vol 27 (4) ◽

pp. 618-628 ◽

Cited By ~ 91

Author(s):

Ryu Takeya ◽

Kenichiro Taniguchi ◽

Shuh Narumiya ◽

Hideki Sumimoto

Keyword(s):

Endothelial Cells ◽

Stress Fibre ◽

Fibre Formation ◽

Induced Stress ◽

Stress Fibre Formation

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Expression of BRG1, a human SWI/SNF component, affects the organisation of actin filaments through the RhoA signalling pathway

Journal of Cell Science ◽

10.1242/jcs.115.13.2735 ◽

2002 ◽

Vol 115 (13) ◽

pp. 2735-2746 ◽

Cited By ~ 1

Author(s):

Patrik Asp ◽

Margareta Wihlborg ◽

Mattias Karlén ◽

Ann-Kristin Östlund Farrants

Keyword(s):

Protein Level ◽

Actin Filaments ◽

Rho Kinase ◽

Stress Fibre ◽

Fibre Formation ◽

Downstream Effectors ◽

Rhoa Gtpase ◽

Filament Bundles ◽

Activity State ◽

Stress Fibre Formation

The human BRG1 (brahma-related gene 1) protein is a component of the SWI/SNF family of the ATP-dependent chromatin remodelling complexes. We show here that expression of the BRG1 protein, but not of an ATPase-deficient BRG1 protein, in BRG1-deficient SW13 cells alters the organisation of actin filaments. BRG1 expression induces the formation of thick actin filament bundles resembling stress-fibres, structures that are rarely seen in native SW13 cells. BRG1 expression does not influence the activity state of the RhoA-GTPase, which is involved in stress-fibre formation. We find that RhoA is equally activated by stimuli, such as serum, in BRG1-expressing cells,ATPase-deficient BRG1-expressing cells and native SW13 cells. However, the activation of RhoA by lysophosphatidic acid and serum does not trigger the formation of stress-fibre-like structures in SW13 cells. Activation of the RhoA-GTPase in BRG1-expressing cells induces stress-fibre-like structures,indicating that the BRG1 can couple RhoA activation to stress-fibre formation. At least two downstream effectors are involved in stress-fibre formation,Rho-kinase/ROCK and Dia. BRG1 expression, but not the expression of the ATP-deficient BRG1, increases the protein level of ROCK1, one form of the Rho-kinase/ROCK. That this is of importance is supported by the findings that an increased Rho-kinase/ROCK activity in SW13 cells, obtained by overexpressing wild-type ROCK1 and ROCK2, induces stress-fibre formation. No specificity between the two Rho-kinase/ROCK forms exists. Our results suggest that the BRG1 protein affects the RhoA pathway by increasing the protein level of ROCK1, which allows stress-fibre-like structures to form.

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