Growth Hormone Stimulates Tyrosine Phosphorylation of Focal Adhesion Kinase (p125FAK) and Actin Stress Fiber Formation in Human Osteoblast-like Cells, Saos2

1999 ◽  
Vol 263 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Michiko Okazaki Takahashi ◽  
Yutaka Takahashi ◽  
Keiji Iida ◽  
Yasuhiko Okimura ◽  
Hidesuke Kaji ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Focal Adhesion Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Actin Stress Fiber ◽  
Human Osteoblast ◽  
Stress Fiber Formation ◽  
Actin Stress Fiber Formation

Indomethacin Delays Gastric Restitution: Association with the Inhibition of Focal Adhesion Kinase and Tensin Phosphorylation and Reduced Actin Stress Fibers

2002 ◽  
Vol 227 (6) ◽  
pp. 412-424 ◽  
Author(s):  
Imre L. Szabó ◽  
Rama Pai ◽  
Michael K. Jones ◽  
George R. Ehring ◽  
Hirofumi Kawanaka ◽  
...  
Keyword(s):  
Cell Migration ◽  
Focal Adhesion ◽  
Focal Adhesions ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Stress Fibers ◽  
Actin Stress Fiber ◽  
Stress Fiber Formation ◽  
Actin Stress Fiber Formation

Repair of superficial gastric mucosal injury is accomplished by the process of restitution—migration of epithelial cells to restore continuity of the mucosal surface. Actin filaments, focal adhesions, and focal adhesion kinase (FAK) play crucial roles in cell motility essential for restitution. We studied whether epidermal growth factor (EGF) and/or indomethacin (IND) affect cell migration, actin stress fiber formation, and/or phosphorylation of FAK and tensin in wounded gastric monolayers. Human gastric epithelial monolayers (MKN 28 cells) were wounded and treated with either vehicle or 0.5 mM IND for 16 hr followed by EGF. EGF treatment significantly stimulated cell migration and actin stress fiber formation, and increased FAK localization to focal adhesions, and phosphorylation of FAK and tensin, whereas IND inhibited all these at the baseline and EGF-stimulated conditions. IND-induced inhibition of FAK phosphorylation preceded changes in actin polymerization, indicating that actin depolymerization might be the consequence of decreased FAK activity. In in vivo experiments, rats received either vehicle or IND (5 mg/kg i.g.), and 3 min later, they received water or 5% hypertonic NaCl; gastric mucosa was obtained at 1, 4, and 8 hr after injury. Four and 8 hr after hypertonic injury, FAK phosphorylation was induced in gastric mucosa compared with controls. IND pretreatment significantly delayed epithelial restitution in vivo, and reduced FAK phosphorylation and recruitment to adhesion points, as well as actin stress fiber formation in migrating surface epithelial cells. Our study indicates that FAK, tensin, and actin stress fibers are likely mediators of EGF-stimulated cell migration in wounded human gastric monolayers and potential targets for IND-induced inhibition of restitution.

scholarly journals Focal adhesion kinase signaling is decreased in polyamine-depleted IEC-6 cells

2001 ◽  
Vol 281 (2) ◽  
pp. C475-C485 ◽  
Author(s):  
Ramesh M. Ray ◽  
Mary Jane Viar ◽  
Shirley A. McCormack ◽  
Leonard R. Johnson
Keyword(s):  
Extracellular Matrix ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Focal Adhesions ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Integrin Signaling ◽  
Actin Stress Fiber ◽  
Stress Fiber Formation ◽  
And Migration

Polyamines are essential to the migration of epithelial cells in the intestinal mucosa. Cells depleted of polyamines do not attach as rapidly to the extracellular matrix and do not form the actin stress fibers essential for migration. Because both attachment and stress fiber formation depend on integrin signaling and the formation of focal adhesions, we examined these and related processes in polyamine-depleted IEC-6 cells. There was general decreased tyrosine phosphorylation of focal adhesion kinase (FAK), and, specifically, decreased phosphorylation of Tyr-925, the paxillin binding site. In control cells, FAK phosphorylation was rapid after attachment to the extracellular matrix, while attached cells depleted of polyamines had significantly delayed phosphorylation. FAK activity was also significantly inhibited in polyamine-depleted cells as was the phosphorylation of paxillin. Polyamine-depleted cells failed to spread normally after attachment, and immunocytochemistry showed little colocalization of FAK and actin compared with controls. Focal adhesion complex formation was greatly reduced in the absence of polyamines. These data suggest that defective integrin signaling may, at least in part, account for the decreased rates of attachment, actin stress fiber formation, spreading, and migration observed in polyamine-depleted cells.

Endothelial cytoskeletal reorganization in response to PAR1 stimulation is mediated by membrane rafts but not caveolae

2007 ◽  
Vol 293 (1) ◽  
pp. H366-H375 ◽  
Author(s):  
MaryEllen Carlile-Klusacek ◽  
Victor Rizzo
Keyword(s):  
Endothelial Cells ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Signaling Cascade ◽  
Membrane Rafts ◽  
Actin Stress Fiber ◽  
Caveolin 1 ◽  
Stress Fiber Formation ◽  
Mlc Phosphorylation ◽  
Actin Stress Fiber Formation

The vasoactive protease thrombin is a known activator of the protease-activated receptor-1 (PAR1) via cleavage of its NH2 terminus. PAR1 activation stimulates the RhoA/Rho kinase signaling cascade, leading to myosin light chain (MLC) phosphorylation, actin stress fiber formation, and changes in endothelial monolayer integrity. Previous studies suggest that some elements of this signaling pathway are localized to caveolin-containing cholesterol-rich membrane domains. Here we show that PAR1 and key components of the PAR-associated signaling cascade localize to membrane rafts and caveolae in bovine aortic endothelial cells (BAEC). To investigate the functional significance of this localization, BAEC were pretreated with filipin (5 μg/ml, 5 min) to ablate lipid rafts before thrombin (100 nM) or PAR agonist stimulation. We found that diphosphorylation of MLC and the actin stress fiber formation normally induced by PAR activation were attenuated after lipid raft disruption. To target caveolae specifically, we used a small interferring RNA approach to knockdown caveolin-1 expression. Thrombin-induced MLC phosphorylation and stress fiber formation were not altered in caveolin-1-depleted cells, suggesting that lipid rafts, but not necessarily caveolae, modulate thrombin-activated signaling pathways leading to alteration of the actin cytoskeleton in endothelial cells.

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