scholarly journals Mapping the dynamics of shear stress-induced structural changes in endothelial cells

2007 ◽  
Vol 293 (5) ◽  
pp. C1616-C1626 ◽  
Author(s):  
Rosalind E. Mott ◽  
Brian P. Helmke
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Structural Dynamics ◽  
Focal Adhesion ◽  
Actin Polymerization ◽  
Lateral Displacement ◽  
Focal Adhesions ◽  
Stress Fibers ◽  
Cell Layers ◽  
Actin Stress Fibers

Hemodynamic shear stress regulates endothelial cell biochemical processes that govern cytoskeletal contractility, focal adhesion dynamics, and extracellular matrix (ECM) assembly. Since shear stress causes rapid strain focusing at discrete locations in the cytoskeleton, we hypothesized that shear stress coordinately alters structural dynamics in the cytoskeleton, focal adhesion sites, and ECM on a time scale of minutes. Using multiwavelength four-dimensional fluorescence microscopy, we measured the displacement of rhodamine-fibronectin and green fluorescent protein-labeled actin, vimentin, paxillin, and/or vinculin in aortic endothelial cells before and after onset of steady unidirectional shear stress. In the cytoskeleton, the onset of shear stress increased actin polymerization into lamellipodia, altered the angle of lateral displacement of actin stress fibers and vimentin filaments, and decreased centripetal remodeling of actin stress fibers in subconfluent and confluent cell layers. Shear stress induced the formation of new focal complexes and reduced the centripetal remodeling of focal adhesions in regions of new actin polymerization. The structural dynamics of focal adhesions and the fibronectin matrix varied with cell density. In subconfluent cell layers, shear stress onset decreased the displacement of focal adhesions and fibronectin fibrils. In confluent monolayers, the direction of fibronectin and focal adhesion displacement shifted significantly toward the downstream direction within 1 min after onset of shear stress. These spatially coordinated rapid changes in the structural dynamics of cytoskeleton, focal adhesions, and ECM are consistent with focusing of mechanical stress and/or strain near major sites of shear stress-mediated mechanotransduction.

A Theoretical Model of Stretch-Induced Stress Fiber Remodeling

2008 ◽  
Author(s):  
Roland Kaunas
Keyword(s):  
Focal Adhesion ◽  
Focal Adhesions ◽  
Dynamic Structure ◽  
Cytoskeletal Proteins ◽  
Stress Fibers ◽  
Cell Contractility ◽  
Maximum Stretch ◽  
Tensional Homeostasis ◽  
Tractional Forces ◽  
Actin Stress Fibers

Cyclic stretching of endothelial cells (ECs), such as occurs in arteries during the cardiac cycle, induces ECs and their actin stress fibers to orient perpendicular to the direction of maximum stretch. This perpendicular alignment response is strengthened by increasing the magnitudes of stretch and cell contractility (1). The actin cytoskeleton is a dynamic structure that regulates cell shape changes and mechanical properties. It has been shown that actin stress fibers are ‘prestretched’ under normal, non-perturbed, conditions (2), consistent with the ideas of ‘prestress’ that have motivated tensegrity cell models (3). It has also been shown that ‘tractional forces’ generated by cells at focal adhesions tend to increase proportionately with increasing focal adhesion area, thus suggesting that cells tend to maintain constant the stress borne by a focal adhesion (4). By implication, this suggests that cells try to maintain constant the stress in actin stress fibers. Thus, it seems that cells reorganize or turnover cytoskeletal proteins and adhesion complexes so as to maintain constant a preferred mechanical state. Mizutani et al. (5) referred to this as cellular tensional homeostasis, although they did not suggest a model or theory to account for this dynamic process.

scholarly journals Mechanical force mobilizes zyxin from focal adhesions to actin filaments and regulates cytoskeletal reinforcement

2005 ◽  
Vol 171 (2) ◽  
pp. 209-215 ◽  
Author(s):  
Masaaki Yoshigi ◽  
Laura M. Hoffman ◽  
Christopher C. Jensen ◽  
H. Joseph Yost ◽  
Mary C. Beckerle
Keyword(s):  
Shear Stress ◽  
Mechanical Stress ◽  
Actin Filaments ◽  
Focal Adhesions ◽  
Cyclic Stretch ◽  
Stress Fibers ◽  
Focal Adhesion Proteins ◽  
Cytoskeletal Responses ◽  
Actin Stress Fibers

Organs and tissues adapt to acute or chronic mechanical stress by remodeling their actin cytoskeletons. Cells that are stimulated by cyclic stretch or shear stress in vitro undergo bimodal cytoskeletal responses that include rapid reinforcement and gradual reorientation of actin stress fibers; however, the mechanism by which cells respond to mechanical cues has been obscure. We report that the application of either unidirectional cyclic stretch or shear stress to cells results in robust mobilization of zyxin from focal adhesions to actin filaments, whereas many other focal adhesion proteins and zyxin family members remain at focal adhesions. Mechanical stress also induces the rapid zyxin-dependent mobilization of vasodilator-stimulated phosphoprotein from focal adhesions to actin filaments. Thickening of actin stress fibers reflects a cellular adaptation to mechanical stress; this cytoskeletal reinforcement coincides with zyxin mobilization and is abrogated in zyxin-null cells. Our findings identify zyxin as a mechanosensitive protein and provide mechanistic insight into how cells respond to mechanical cues.

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.

scholarly journals SAPK2/p38-dependent F-Actin Reorganization Regulates Early Membrane Blebbing during Stress-induced Apoptosis

1998 ◽  
Vol 143 (5) ◽  
pp. 1361-1373 ◽  
Author(s):  
Jacques Huot ◽  
François Houle ◽  
Simon Rousseau ◽  
Réna G. Deschesnes ◽  
Girish M. Shah ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Map Kinase ◽  
Dna Fragmentation ◽  
Focal Adhesion ◽  
Actin Polymerization ◽  
Survival Function ◽  
Focal Adhesions ◽  
Actin Dynamics ◽  
Membrane Blebbing ◽  
Bleb Formation

In endothelial cells, H2O2 induces the rapid formation of focal adhesion complexes at the ventral face of the cells and a major reorganization of the actin cytoskeleton into dense transcytoplasmic stress fibers. This change in actin dynamics results from the activation of the mitogen-activated protein (MAP) kinase stress-activated protein kinase-2/p38 (SAPK2/p38), which, via MAP kinase-activated protein (MAPKAP) kinase-2/3, leads to the phosphorylation of the actin polymerization modulator heat shock protein of 27 kD (HSP27). Here we show that the concomitant activation of the extracellular signal-regulated kinase (ERK) MAP kinase pathway by H2O2 accomplishes an essential survival function during this process. When the activation of ERK was blocked with PD098059, the focal adhesion complexes formed under the plasma membrane, and the actin polymerization activity led to a rapid and intense membrane blebbing. The blebs were delimited by a thin F-actin ring and contained enhanced levels of HSP27. Later, the cells displayed hallmarks of apoptosis, such as DEVD protease activities and internucleosomal DNA fragmentation. Bleb formation but not apoptosis was blocked by extremely low concentrations of the actin polymerization inhibitor cytochalasin D or by the SAPK2 inhibitor SB203580, indicating that the two processes are not in the same linear cascade. The role of HSP27 in mediating membrane blebbing was assessed in fibroblastic cells. In control fibroblasts expressing a low level of endogenous HSP27 or in fibroblasts expressing a high level of a nonphosphorylatable HSP27, H2O2 did not induce F-actin accumulation, nor did it generate membrane blebbing activity in the presence or absence of PD098059. In contrast, in fibroblasts that expressed wild-type HSP27 to a level similar to that found in endothelial cells, H2O2 induced accumulation of F-actin and caused bleb formation when the ERK pathway was inhibited. Cis-platinum, which activated SAPK2 but induced little ERK activity, also induced membrane blebbing that was dependent on the expression of HSP27. In these cells, membrane blebbing was not followed by caspase activation or DNA fragmentation. We conclude that the HSP27-dependent actin polymerization–generating activity of SAPK2 associated with a misassembly of the focal adhesions is responsible for induction of membrane blebbing by stressing agents.

scholarly journals A Focal Adhesion Filament Cross-correlation Kit for fast, automated segmentation and correlation of focal adhesions and actin stress fibers in cells

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0250749
Author(s):  
Lara Hauke ◽  
Shwetha Narasimhan ◽  
Andreas Primeßnig ◽  
Irina Kaverina ◽  
Florian Rehfeldt
Keyword(s):  
Focal Adhesion ◽  
Cross Correlation ◽  
Focal Adhesions ◽  
Force Production ◽  
Traction Force ◽  
Stress Fibers ◽  
Coupled Analysis ◽  
Matrix Remodeling ◽  
Fiber System ◽  
Actin Stress Fibers

Focal adhesions (FAs) and associated actin stress fibers (SFs) form a complex mechanical system that mediates bidirectional interactions between cells and their environment. This linked network is essential for mechanosensing, force production and force transduction, thus directly governing cellular processes like polarization, migration and extracellular matrix remodeling. We introduce a tool for fast and robust coupled analysis of both FAs and SFs named the Focal Adhesion Filament Cross-correlation Kit (FAFCK). Our software can detect and record location, axes lengths, area, orientation, and aspect ratio of focal adhesion structures as well as the location, length, width and orientation of actin stress fibers. This enables users to automate analysis of the correlation of FAs and SFs and study the stress fiber system in a higher degree, pivotal to accurately evaluate transmission of mechanocellular forces between a cell and its surroundings. The FAFCK is particularly suited for unbiased and systematic quantitative analysis of FAs and SFs necessary for novel approaches of traction force microscopy that uses the additional data from the cellular side to calculate the stress distribution in the substrate. For validation and comparison with other tools, we provide datasets of cells of varying quality that are labelled by a human expert. Datasets and FAFCK are freely available as open source under the GNU General Public License.

scholarly journals Biomechanical regulation of focal adhesion and invadopodia formation

2020 ◽  
Vol 133 (20) ◽  
pp. jcs244848
Author(s):  
Or-Yam Revach ◽  
Inna Grosheva ◽  
Benjamin Geiger
Keyword(s):  
Focal Adhesion ◽  
Actin Polymerization ◽  
Protein Complexes ◽  
Focal Adhesions ◽  
Stress Fibers ◽  
Mechanical Forces ◽  
Molecular Machinery ◽  
Contractile Stress ◽  
Functionally Diverse ◽  
Invadopodia Formation

ABSTRACTIntegrin adhesions are a structurally and functionally diverse family of transmembrane, multi-protein complexes that link the intracellular cytoskeleton to the extracellular matrix (ECM). The different members of this family, including focal adhesions (FAs), focal complexes, fibrillar adhesions, podosomes and invadopodia, contain many shared scaffolding and signaling ‘adhesome’ components, as well as distinct molecules that perform specific functions, unique to each adhesion form. In this Hypothesis, we address the pivotal roles of mechanical forces, generated by local actin polymerization or actomyosin-based contractility, in the formation, maturation and functionality of two members of the integrin adhesions family, namely FAs and invadopodia, which display distinct structures and functional properties. FAs are robust and stable ECM contacts, associated with contractile stress fibers, while invadopodia are invasive adhesions that degrade the underlying matrix and penetrate into it. We discuss here the mechanisms, whereby these two types of adhesion utilize a similar molecular machinery to drive very different – often opposing cellular activities, and hypothesize that early stages of FAs and invadopodia assembly use similar biomechanical principles, whereas maturation of the two structures, and their ‘adhesive’ and ‘invasive’ functionalities require distinct sources of biomechanical reinforcement.

Nitric oxide modulation of focal adhesions in endothelial cells

1999 ◽  
Vol 276 (6) ◽  
pp. C1271-C1281 ◽  
Author(s):  
Michael S. Goligorsky ◽  
Husna Abedi ◽  
Eisei Noiri ◽  
Alice Takhtajan ◽  
Sheri Lense ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
De Novo ◽  
Focal Adhesions ◽  
No Synthase ◽  
Stress Fibers ◽  
No Donors ◽  
Tractional Forces

A permissive role of nitric oxide (NO) in endothelial cell migration and angiogenesis promoted by vascular endothelial growth factor (VEGF), endothelin, and substance P has previously been established. The present studies were designed to examine the mechanism(s) involved in the NO effect on focal adhesions. Time-lapse videomicroscopy of human umbilical vein endothelial cells (HUVECs) plated on the silicone rubber substrate revealed that unstimulated cells were constantly remodeling the wrinkling pattern, indicative of changing tractional forces. Application of NO donors reversibly decreased the degree of wrinkling, consistent with the release of tractional forces exerted by focal adhesions and stress fibers. Morphometric and immunocytochemical analyses showed that NO inhibited adhesion and spreading of HUVECs and attenuated recruitment of paxillin to focal adhesions. NO also had a profound dose-dependent effect on the formation of stress fibers by HUVECs. De novo formation of focal adhesions in HUVECs was significantly diminished in the presence of NO donors. Migration of HUVECs showed an absolute requirement for the functional NO synthase. NO donors did not interfere with focal adhesion kinase recruitment to focal adhesions but affected the state of its tyrosine phosphorylation, as judged from the results of immunoprecipitation and immunoblotting experiments. Videomicroscopy of HUVECs presented with VEGF in a micropipette showed that the rate of cell migration was slowed down by NO synthase inhibition as well as by inhibition of tyrosine phosphorylation. Collectively, these data indicate that NO reversibly releases tractional forces exerted by spreading endothelial cells via interference with the de novo formation of focal adhesions, tyrosine phosphorylation of components of focal adhesion complexes, and assembly of stress fibers.

scholarly journals P2Y2 receptor modulates shear stress-induced cell alignment and actin stress fibers in human umbilical vein endothelial cells

2016 ◽  
Vol 74 (4) ◽  
pp. 731-746 ◽  
Author(s):  
Ramasri Sathanoori ◽  
Paulina Bryl-Gorecka ◽  
Christa E. Müller ◽  
Laurie Erb ◽  
Gary A. Weisman ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Umbilical Vein ◽  
Stress Fibers ◽  
Cell Alignment ◽  
P2y2 Receptor ◽  
Human Umbilical Vein ◽  
Umbilical Vein Endothelial Cells ◽  
Actin Stress Fibers

Polychlorinated biphenyl quinone induces endothelial barrier dysregulation by setting the cross talk between VE-cadherin, focal adhesion, and MAPK signaling

2015 ◽  
Vol 308 (10) ◽  
pp. H1205-H1214 ◽  
Author(s):  
Pu Zhang ◽  
Shan Feng ◽  
Huiyuan Bai ◽  
Panying Zeng ◽  
Feng Chen ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Cancer Metastasis ◽  
Polychlorinated Biphenyl ◽  
Adhesion Formation ◽  
Focal Adhesions ◽  
Mapk Signaling ◽  
Stress Fibers ◽  
Vascular Endothelial ◽  
Environmental Toxicants ◽  
Actin Stress Fibers

Environmental hazardous material polychlorinated biphenyl (PCB) exposure is associated with vascular endothelial dysfunction, which may increase the risk of cardiovascular diseases and cancer metastasis. Our previous studies illustrated the cytotoxic, antiproliferative, and genotoxic effects of a synthetic, quinone-type, highly reactive metabolite of PCB, 2,3,5-trichloro-6-phenyl-[1,4]benzoquinone (PCB29-pQ). Here, we used it as the model compound to investigate its effects on vascular endothelial integrity and permeability. We demonstrated that noncytotoxic doses of PCB29-pQ induced vascular endothelial (VE)-cadherin junction disassembly by increasing the phosphorylation of VE-cadherin at Y658. We also found that focal adhesion assembly was required for PCB29-pQ-induced junction breakdown. Focal adhesion site-associated actin stress fibers may serve as holding points for cytoskeletal tension to regulate the cellular contractility. PCB29-pQ exposure promoted the association of actin stress fibers with paxillin-containing focal adhesion sites and enlarged the size/number of focal adhesions. In addition, PCB29-pQ treatment induced phosphorylation of paxillin at Y118. By using pharmacological inhibition, we further demonstrated that p38 activation was necessary for paxillin phosphorylation, whereas extracellular signal-regulated kinases-1/2 activation regulated VE-cadherin phosphorylation. In conclusion, these results indicated that PCB29-pQ stimulates endothelial hyperpermeability by mediating VE-cadherin disassembly, junction breakdown, and focal adhesion formation. Intervention strategies targeting focal adhesion and MAPK signaling could be used as therapeutic approaches for preventing adverse cardiovascular health effects induced by environmental toxicants such as PCBs.

scholarly journals A Focal Adhesion Filament Cross-correlation Kit for fast, automated segmentation and correlation of focal adhesions and actin stress fibers in cells

2021 ◽  
Author(s):  
Lara Hauke ◽  
Shwetha Narasimhan ◽  
Andreas Primeßnig ◽  
Irina Kaverina ◽  
Florian Rehfeldt
Keyword(s):  
Extracellular Matrix ◽  
Quantitative Analysis ◽  
Focal Adhesion ◽  
Cross Correlation ◽  
Focal Adhesions ◽  
Traction Force ◽  
Stress Fibers ◽  
Traction Force Microscopy ◽  
Force Microscopy ◽  
Actin Stress Fibers

AbstractFocal adhesions (FAs) and associated actin stress fibers (SFs) form a complex mechanical system that mediates bidirectional interactions between cells and their environment. This linked network is essential for mechanosensing, force production and force transduction, thus directly governing cellular processes like polarization, migration and extracellular matrix remodeling. We introduce a tool for fast and robust coupled analysis of both FAs and SFs named the Focal Adhesion Filament Cross-correlation Kit (FAFCK). Our software can detect and record location, axes lengths, area, orientation, and aspect ratio of focal adhesion structures as well as the location, length, width and orientation of actin stress fibers. This enables users to automate analysis of the correlation of FAs and SFs and study the stress fiber system in a higher degree, pivotal to accurately evaluate transmission of mechanocellular forces between a cell and its surroundings. The FAFCK is particularly suited for unbiased and systematic quantitative analysis of FAs and SFs necessary for novel approaches of traction force microscopy that uses the additional data from the cellular side to calculate the stress distribution in the substrate. For validation and comparison with other tools, we provide datasets of cells of varying quality that are labelled by a human expert. Datasets and FAFCK are freely available as open source under the GNU General Public License.Author summaryOur novel Focal Adhesion Filament Cross-correlation Kit (FAFCK) allows for fast, reliable, unbiased, and systematic detection of focal adhesions and actin stress fibers in cells and their mutual correlation. Detailed analysis of these structures which are both key elements in mechano-sensing and force transduction will help tremendously to improve quantitative analysis of mechanocellular experiments, key to understanding the complex interplay between cells and the extracellular matrix. In particular, sophisticated analysis methods such as model-based traction force microscopy will benefit from correlating the detailed datasets of stress fibers and focal adhesions.

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