Simulation of the Coupling of Cell Contractility and Focal Adhesion Formation

2007 ◽  
Author(s):  
Amit Pathak ◽  
Vikram S. Deshpande ◽  
Robert M. McMeeking ◽  
Anthony G. Evans
Keyword(s):  
Focal Adhesion ◽  
Adhesion Formation ◽  
High Stress ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Stress Fibers ◽  
Cell Contractility ◽  
Focal Adhesion Formation ◽  
Pattern Shape ◽  
Stress Dependent

The remodeling of the cytoskeleton and focal adhesion distributions for cells on substrates with micro-patterned ligand patches is investigated using a bio-chemo-mechanical model. All the cells have approximately the same area and we investigate the effect of ligand pattern shape on the cytoskeletal arrangements and focal adhesion distributions. The model for the cytoskeleton accounts for the dynamic rearrangement of the actin/myosin stress fibers and entails the highly non-linear interactions between signaling, the kinetics of tension-dependent stress-fiber formation/dissolution and stress dependent contractility. This model is coupled with a focal adhesion (FA) model that accounts for the mechano-sensitivity of the adhesions from thermodynamic considerations. This coupled stress fiber and focal adhesion model is shown to capture a variety of key experimental observations including: (i) the formation of high stress fiber and focal adhesion concentrations at the periphery of circular and triangular, convex–shaped ligand patterns; (ii) the development of high focal adhesion concentrations along the edges of the V, T, Y and U shaped concave ligand patterns; and (iii) the formation of highly aligned stress fibers along the un-adhered edges of cells on the concave ligand patterns. When appropriately calibrated, the model also accurately predicts the radii of curvature of the un-adhered edges of cells on the concave-shaped ligand patterns.

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

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4063 ◽  
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, the author 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.

Regulation of the RhoA pathway in human endothelial cell spreading on type IV collagen: role of calcium influx

1999 ◽  
Vol 112 (19) ◽  
pp. 3205-3213 ◽  
Author(s):  
L. Masiero ◽  
K.A. Lapidos ◽  
I. Ambudkar ◽  
E.C. Kohn
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Focal Adhesion ◽  
Type Iv Collagen ◽  
Cell Spreading ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Stress Fibers ◽  
Type Iv ◽  
Stress Fiber Formation

We have shown that nonvoltage-operated Ca(2+) entry regulates human umbilical vein endothelial cell adhesion, migration, and proliferation on type IV collagen. We now demonstrate a requirement for Ca(2+) influx for activation of the RhoA pathway during endothelial cell spreading on type IV collagen. Reorganization of actin into stress fibers was complete when the cells where fully spread at 90 minutes. No actin organization into stress fibers was seen in endothelial cells plated on type I collagen, indicating a permissive effect of type IV collagen. CAI, a blocker of nonvoltage-operated Ca(2+) channels, prevented development of stress fiber formation in endothelial cells on type IV collagen. This permissive effect was augmented by Ca(2+) influx, as stimulated by 0. 5 microM thapsigargin or 0.1 microM ionomycin, yielding faster development of actin stress fibers. Ca(2+) influx and actin rearrangement in response to thapsigargin and ionomycin were abrogated by CAI. Activated, membrane-bound RhoA is a substrate for C3 exoenzyme which ADP-ribosylates and inactivates RhoA, preventing actin stress fiber formation. Pretreatment of endothelial cells with C3 exoenzyme prevented basal and thapsigargin-augmented stress fiber formation. While regulation of Ca(2+) influx did not alter RhoA translocation, it reduced in vitro ADP-ribosylation of RhoA (P(2)<0. 05), suggesting Ca(2+) influx is needed for RhoA activation during spreading on type IV collagen; no Ca(2+) regulated change in RhoA was seen in HUVECs spreading on type I collagen matrix. Blockade of Ca(2+) influx of HUVEC spread on type IV collagen also reduced tyrosine phosphorylation of p190Rho-GAP and blocked thapsigargin-enhanced binding of p190Rho-GAP to focal adhesion kinase. Thus, Ca(2+) influx is necessary for RhoA activation and for linkage of the RhoA/stress fiber cascade to the focal adhesion/focal adhesion kinase pathway during human umbilical vein endothelial cell spreading on type IV collagen.

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 ARF1 Mediates Paxillin Recruitment to Focal Adhesions and Potentiates Rho-stimulated Stress Fiber Formation in Intact and Permeabilized Swiss 3T3 Fibroblasts

1998 ◽  
Vol 143 (7) ◽  
pp. 1981-1995 ◽  
Author(s):  
J.C. Norman ◽  
D. Jones ◽  
S.T. Barry ◽  
M.R. Holt ◽  
S. Cockcroft ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Focal Adhesions ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Stress Fibers ◽  
3T3 Fibroblasts ◽  
Stress Fiber Formation ◽  
Swiss 3T3 ◽  
Swiss 3T3 Fibroblasts ◽  
Actin Stress Fibers

Focal adhesion assembly and actin stress fiber formation were studied in serum-starved Swiss 3T3 fibroblasts permeabilized with streptolysin-O. Permeabilization in the presence of GTPγS stimulated rho-dependent formation of stress fibers, and the redistribution of vinculin and paxillin from a perinuclear location to focal adhesions. Addition of GTPγS at 8 min after permeabilization still induced paxillin recruitment to focal adhesion–like structures at the ends of stress fibers, but vinculin remained in the perinuclear region, indicating that the distributions of these two proteins are regulated by different mechanisms. Paxillin recruitment was largely rho-independent, but could be evoked using constitutively active Q71L ADP-ribosylation factor (ARF1), and blocked by NH2-terminally truncated Δ17ARF1. Moreover, leakage of endogenous ARF from cells was coincident with loss of GTPγS- induced redistribution of paxillin to focal adhesions, and the response was recovered by addition of ARF1. The ability of ARF1 to regulate paxillin recruitment to focal adhesions was confirmed by microinjection of Q71LARF1 and Δ17ARF1 into intact cells. Interestingly, these experiments showed that V14RhoA- induced assembly of actin stress fibers was potentiated by Q71LARF1. We conclude that rho and ARF1 activate complimentary pathways that together lead to the formation of paxillin-rich focal adhesions at the ends of prominent actin stress fibers.

Simulation of the Mechanical Response of Cells on Micropost Substrates

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
William Ronan ◽  
Amit Pathak ◽  
Vikram S. Deshpande ◽  
Robert M. McMeeking ◽  
J. Patrick McGarry
Keyword(s):  
Focal Adhesion ◽  
Computational Models ◽  
Mechanical Response ◽  
Adhesion Formation ◽  
Experimental Studies ◽  
Stress Fiber ◽  
Cell Behavior ◽  
Rate Dependent ◽  
Focal Adhesion Formation ◽  
Biomechanical Response

Experimental studies where cells are seeded on micropost arrays in order to quantify their contractile behavior are becoming increasingly common. Interpretation of the data generated by this experimental technique is difficult, due to the complexity of the processes underlying cellular contractility and mechanotransduction. In the current study, a coupled framework that considers strain rate dependent contractility and remodeling of the cytoskeleton is used in tandem with a thermodynamic model of tension dependent focal adhesion formation to investigate the biomechanical response of cells adhered to micropost arrays. Computational investigations of the following experimental studies are presented: cell behavior on different sized arrays with a range of post stiffness; stress fiber and focal adhesion formation in irregularly shaped cells; the response of cells to deformations applied locally to individual posts; and the response of cells to equibiaxial stretching of micropost arrays. The predicted stress fiber and focal adhesion distributions; in addition to the predicted post tractions are quantitatively and qualitatively supported by previously published experimental data. The computational models presented in this study thus provide a framework for the design and interpretation of experimental micropost studies.

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