scholarly journals R-Ras Promotes Focal Adhesion Formation through Focal Adhesion Kinase and p130Cas by a Novel Mechanism That Differs from Integrins

2003 ◽  
Vol 23 (3) ◽  
pp. 933-949 ◽  
Author(s):  
Lina Kwong ◽  
Michele A. Wozniak ◽  
Asha S. Collins ◽  
Siobhan D. Wilson ◽  
Patricia J. Keely
Keyword(s):  
Focal Adhesion Kinase ◽  
Signaling Pathways ◽  
Focal Adhesion ◽  
Adhesion Formation ◽  
Integrin Signaling ◽  
Ras Signaling ◽  
Pharmacological Inhibition ◽  
Focal Adhesion Formation ◽  
And Migration ◽  
Α2β1 Integrin

ABSTRACT R-Ras regulates integrin function, but its effects on integrin signaling pathways have not been well described. We demonstrate that activation of R-Ras promoted focal adhesion formation and altered localization of the α2β1 integrin from cell-cell to cell-matrix adhesions in breast epithelial cells. Constitutively activated R-Ras(38V) dramatically enhanced focal adhesion kinase (FAK) and p130Cas phosphorylation upon collagen stimulation or clustering of the α2β1 integrin, even in the absence of increased ligand binding. Signaling events downstream of R-Ras differed from integrins and K-Ras, since pharmacological inhibition of Src or disruption of actin inhibited integrin-mediated FAK and p130Cas phosphorylation, focal adhesion formation, and migration in control and K-Ras(12V)-expressing cells but had minimal effect in cells expressing R-Ras(38V). Therefore, signaling from R-Ras to FAK and p130Cas has a component that is Src independent and not through classic integrin signaling pathways and a component that is Src dependent. R-Ras effector domain mutants and pharmacological inhibition suggest a partial role for phosphatidylinositol 3-kinase (PI3K), but not Raf, in R-Ras signaling to FAK and p130Cas. However, PI3K cannot account for the Src-independent pathway, since simultaneous inhibition of both PI3K and Src did not completely block effects of R-Ras on FAK phosphorylation. Our results suggest that R-Ras promotes focal adhesion formation by signaling to FAK and p130Cas through a novel mechanism that differs from but synergizes with the α2β1 integrin.

scholarly journals p130Cas contributes to cellular mechanosensing and force exertion

2018 ◽  
Author(s):  
Hedde van Hoorn ◽  
Dominique M. Donato ◽  
H. Emrah Balcioglu ◽  
Erik H. Danen ◽  
Thomas Schmidt
Keyword(s):  
Focal Adhesion ◽  
Adhesion Formation ◽  
Focal Adhesions ◽  
Full Length ◽  
Actin Dynamics ◽  
Knock Out ◽  
Focal Adhesion Formation ◽  
Pillar Arrays ◽  
Cellular Machinery ◽  
And Migration

AbstractCell survival, differentiation, and migration are all dependent on the cell’s interaction with its external environment. In addition to chemical cues, cells react to their physical environment, particularly the stiffness of the substrate. In order for cells to react to these elements, they must make use of cellular machinery to signal changes in their microenvironment. One such proposed machinery is the protein p130Cas, which has been shown to regulate focal adhesion turnover, actin dynamics, and cell migration. Here we show that p130Cas localizes to focal adhesions depending on substrate stiffness and subsequently modulates cellular force exertion. We compared on substrates of tunable stiffness knock-out CAS-/-cells to cells re-expressing either the full-length p130Cas or a mutant lacking the focal adhesion targeting domains. On polyacrylamide gels, we observed that p130Cas prevented focal adhesion formation at low stiffness. On structured micro-pillar arrays, p130Cas preferentially localized to sites of force exertion when the apparent Young’s modulus of the substrate was higher than E = 47 kPa. Stiffness-dependent localization of p130Cas coincided with slower, but increased force exertion for the full-length p130Cas. Cas localization to focal adhesions preceded force build-up by three minutes, suggesting a coordinating role for p130Cas in the cellular mechanoresponse. Thus, p130Cas appears to relay mechanosensory information in the cell through its ability to tune force exertion at the focal adhesion.

scholarly journals Activation of Rho-kinase and focal adhesion kinase regulates the organization of stress fibers and focal adhesions in the central part of fibroblasts

2017 ◽  
Author(s):  
Kazuo Katoh
Keyword(s):  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Adhesion Formation ◽  
Rho Kinase ◽  
Focal Adhesions ◽  
Fiber Formation ◽  
Stress Fibers ◽  
Focal Adhesion Formation ◽  
Specific Regulation

Specific regulation and activation of focal adhesion kinase (FAK) are thought to be important for focal adhesion formation, and activation of Rho-kinase has been suggested to play a role in determining the effects of FAK on the formation of stress fibers and focal adhesions. To clarify the role of FAK in stress fiber formation and focal adhesion organization, we examined the formation of new stress fibers and focal adhesions by activation of Rho-kinase in FAK knockout (FAK–/–) fibroblasts. FAK–/– cells were elliptical in shape, and showed reduced numbers of stress fibers and focal adhesions in the central part of the cells along with large focal adhesions in the peripheral regions. Activation of Rho-kinase in FAK–/– cells transiently increased the actin filaments in the cell center, but these did not form typical thick stress fibers. Moreover, only plaque-like structures as the origins of newly formed focal adhesions were observed in the center of the cell. Furthermore, introduction of an exogenous GFP-labeled FAK gene into FAK–/– cells resulted in increased numbers of stress fibers and focal adhesions in the center of the cells, which showed typical fibroblast morphology. These results indicated that FAK plays an important role in the formation of stress fibers and focal adhesions as well as in regulation of cell shape and morphology with the activation of Rho-kinase.

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.

scholarly journals Activation of Rho-kinase and focal adhesion kinase regulates the organization of stress fibers and focal adhesions in the central part of fibroblasts

2017 ◽  
Author(s):  
Kazuo Katoh
Keyword(s):  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Adhesion Formation ◽  
Rho Kinase ◽  
Focal Adhesions ◽  
Fiber Formation ◽  
Stress Fibers ◽  
Focal Adhesion Formation ◽  
Specific Regulation

Specific regulation and activation of focal adhesion kinase (FAK) are thought to be important for focal adhesion formation, and activation of Rho-kinase has been suggested to play a role in determining the effects of FAK on the formation of stress fibers and focal adhesions. To clarify the role of FAK in stress fiber formation and focal adhesion organization, we examined the formation of new stress fibers and focal adhesions by activation of Rho-kinase in FAK knockout (FAK–/–) fibroblasts. FAK–/– cells were elliptical in shape, and showed reduced numbers of stress fibers and focal adhesions in the central part of the cells along with large focal adhesions in the peripheral regions. Activation of Rho-kinase in FAK–/– cells transiently increased the actin filaments in the cell center, but these did not form typical thick stress fibers. Moreover, only plaque-like structures as the origins of newly formed focal adhesions were observed in the center of the cell. Furthermore, introduction of an exogenous GFP-labeled FAK gene into FAK–/– cells resulted in increased numbers of stress fibers and focal adhesions in the center of the cells, which showed typical fibroblast morphology. These results indicated that FAK plays an important role in the formation of stress fibers and focal adhesions as well as in regulation of cell shape and morphology with the activation of Rho-kinase.

scholarly journals Lung epithelial cell focal adhesion kinase signaling inhibits lung injury and fibrosis

2017 ◽  
Vol 312 (5) ◽  
pp. L722-L730 ◽  
Author(s):  
Amanda K. Wheaton ◽  
Manisha Agarwal ◽  
Shijing Jia ◽  
Kevin K. Kim
Keyword(s):  
Extracellular Matrix ◽  
Epithelial Cell ◽  
Lung Injury ◽  
Focal Adhesion Kinase ◽  
Signaling Pathways ◽  
Focal Adhesion ◽  
Intracellular Signaling ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Integrin Signaling ◽  
Dynamic Changes

Progressive pulmonary fibrosis is a devastating consequence of many acute and chronic insults to the lung. Lung injury leads to alveolar epithelial cell (AEC) death, destruction of the basement membrane, and activation of transforming growth factor-β (TGF-β). There is subsequent resolution of the injury and a coordinated and concurrent initiation of fibrosis. Both of these processes may involve activation of similar intracellular signaling pathways regulated in part by dynamic changes to the extracellular matrix. Matrix signaling can augment the profibrotic fibroblast response to TGF-β. However, similar matrix/integrin signaling pathways may also be involved in the inhibition of ongoing TGF-β-induced AEC apoptosis. Focal adhesion kinase (FAK) is an integrin-associated signaling molecule expressed by many cell types. We used mice with AEC-specific FAK deletion to isolate the epithelial aspect of integrin signaling in the bleomycin model of lung injury and fibrosis. Mice with AEC-specific deletion of FAK did not exhibit spontaneous lung injury but did have significantly greater terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling-positive cells (18.6 vs. 7.1) per ×200 field, greater bronchoalveolar lavage protein (3.2 vs. 1.8 mg/ml), and significantly greater death (77 vs. 19%) after bleomycin injury compared with littermate control mice. Within primary AECs, activated FAK directly associates with caspase-8 and inhibits activation of the caspase cascade resulting in less apoptosis in response to TGF-β. Our studies support a model in which dynamic changes to the extracellular matrix after injury promote fibroblast activation and inhibition of epithelial cell apoptosis in response to TGF-β through FAK activation potentially complicating attempts to nonspecifically target this pathway for antifibrotic therapy.

scholarly journals Integrin-specific signaling pathways controlling focal adhesion formation and cell migration

2003 ◽  
Vol 161 (1) ◽  
pp. 155-167 ◽  
Author(s):  
Zohreh Mostafavi-Pour ◽  
Janet A. Askari ◽  
Scott J. Parkinson ◽  
Peter J. Parker ◽  
Tony T.C. Ng ◽  
...  
Keyword(s):  
Cell Migration ◽  
Focal Adhesion ◽  
Adhesion Formation ◽  
Dominant Negative ◽  
Adhesive Properties ◽  
Functional Differences ◽  
Focal Adhesion Formation ◽  
Protein Kinase Cα ◽  
And Migration ◽  
Cell Surface Proteoglycan

The fibronectin (FN)-binding integrins α4β1 and α5β1 confer different cell adhesive properties, particularly with respect to focal adhesion formation and migration. After analyses of α4+/α5+ A375-SM melanoma cell adhesion to fragments of FN that interact selectively with α4β1 and α5β1, we now report two differences in the signals transduced by each receptor that underpin their specific adhesive properties. First, α5β1 and α4β1 have a differential requirement for cell surface proteoglycan engagement for focal adhesion formation and migration; α5β1 requires a proteoglycan coreceptor (syndecan-4), and α4β1 does not. Second, adhesion via α5β1 caused an eightfold increase in protein kinase Cα (PKCα) activation, but only basal PKCα activity was observed after adhesion via α4β1. Pharmacological inhibition of PKCα and transient expression of dominant-negative PKCα, but not dominant-negative PKCδ or PKCζ constructs, suppressed focal adhesion formation and cell migration mediated by α5β1, but had no effect on α4β1. These findings demonstrate that different integrins can signal to induce focal adhesion formation and migration by different mechanisms, and they identify PKCα signaling as central to the functional differences between α4β1 and α5β1.

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