scholarly journals Traction stress in focal adhesions correlates biphasically with actin retrograde flow speed

2008 ◽  
Vol 183 (6) ◽  
pp. 999-1005 ◽  
Author(s):  
Margaret L. Gardel ◽  
Benedikt Sabass ◽  
Lin Ji ◽  
Gaudenz Danuser ◽  
Ulrich S. Schwarz ◽  
...  
Keyword(s):  
Cell Migration ◽  
Focal Adhesions ◽  
Traction Force ◽  
Flow Speed ◽  
Retrograde Flow ◽  
Filamentous Actin ◽  
Rho Family ◽  
Guanosine Triphosphatase ◽  
Protein Density ◽  
Traction Stress

How focal adhesions (FAs) convert retrograde filamentous actin (F-actin) flow into traction stress on the extracellular matrix to drive cell migration is unknown. Using combined traction force and fluorescent speckle microscopy, we observed a robust biphasic relationship between F-actin speed and traction force. F-actin speed is inversely related to traction stress near the cell edge where FAs are formed and F-actin motion is rapid. In contrast, larger FAs where the F-actin speed is low are marked by a direct relationship between F-actin speed and traction stress. We found that the biphasic switch is determined by a threshold F-actin speed of 8–10 nm/s, independent of changes in FA protein density, age, stress magnitude, assembly/disassembly status, or subcellular position induced by pleiotropic perturbations to Rho family guanosine triphosphatase signaling and myosin II activity. Thus, F-actin speed is a fundamental regulator of traction force at FAs during cell migration.

scholarly journals Vinculin–actin interaction couples actin retrograde flow to focal adhesions, but is dispensable for focal adhesion growth

2013 ◽  
Vol 202 (1) ◽  
pp. 163-177 ◽  
Author(s):  
Ingo Thievessen ◽  
Peter M. Thompson ◽  
Sylvain Berlemont ◽  
Karen M. Plevock ◽  
Sergey V. Plotnikov ◽  
...  
Keyword(s):  
Focal Adhesions ◽  
Leading Edge ◽  
Flow Speed ◽  
Actin Binding ◽  
Retrograde Flow ◽  
Actin Assembly ◽  
Filamentous Actin ◽  
Primary Fibroblasts

In migrating cells, integrin-based focal adhesions (FAs) assemble in protruding lamellipodia in association with rapid filamentous actin (F-actin) assembly and retrograde flow. How dynamic F-actin is coupled to FA is not known. We analyzed the role of vinculin in integrating F-actin and FA dynamics by vinculin gene disruption in primary fibroblasts. Vinculin slowed F-actin flow in maturing FA to establish a lamellipodium–lamellum border and generate high extracellular matrix (ECM) traction forces. In addition, vinculin promoted nascent FA formation and turnover in lamellipodia and inhibited the frequency and rate of FA maturation. Characterization of a vinculin point mutant that specifically disrupts F-actin binding showed that vinculin–F-actin interaction is critical for these functions. However, FA growth rate correlated with F-actin flow speed independently of vinculin. Thus, vinculin functions as a molecular clutch, organizing leading edge F-actin, generating ECM traction, and promoting FA formation and turnover, but vinculin is dispensible for FA growth.

scholarly journals L1-dependent neuritogenesis involves ankyrinB that mediates L1-CAM coupling with retrograde actin flow

2003 ◽  
Vol 163 (5) ◽  
pp. 1077-1088 ◽  
Author(s):  
Kazunari Nishimura ◽  
Fumie Yoshihara ◽  
Takuro Tojima ◽  
Noriko Ooashi ◽  
Woohyun Yoon ◽  
...  
Keyword(s):  
Cell Adhesion Molecule ◽  
Traction Force ◽  
Neurite Growth ◽  
Growth Cones ◽  
Retrograde Flow ◽  
Actin Network ◽  
Filamentous Actin ◽  
Neurite Elongation ◽  
Neurite Initiation ◽  
Cell Adhesion Molecule L1

The cell adhesion molecule L1 (L1-CAM) plays critical roles in neurite growth. Its cytoplasmic domain (L1CD) binds to ankyrins that associate with the spectrin–actin network. This paper demonstrates that L1-CAM interactions with ankyrinB (but not with ankyrinG) are involved in the initial formation of neurites. In the membranous protrusions surrounding the soma before neuritogenesis, filamentous actin (F-actin) and ankyrinB continuously move toward the soma (retrograde flow). Bead-tracking experiments show that ankyrinB mediates L1-CAM coupling with retrograde F-actin flow in these perisomatic structures. Ligation of the L1-CAM ectodomain by an immobile substrate induces L1CD–ankyrinB binding and the formation of stationary ankyrinB clusters. Neurite initiation preferentially occurs at the site of these clusters. In contrast, ankyrinB is involved neither in L1-CAM coupling with F-actin flow in growth cones nor in L1-based neurite elongation. Our results indicate that ankyrinB promotes neurite initiation by acting as a component of the clutch module that transmits traction force generated by F-actin flow to the extracellular substrate via L1-CAM.

scholarly journals Does cellular adaptation to force loading rate determine the biphasic vs monotonic response of actin retrograde flow with substrate rigidity?

2021 ◽  
Author(s):  
Partho Sakha De ◽  
Rumi De
Keyword(s):  
Cancer Progression ◽  
Loading Rate ◽  
Focal Adhesions ◽  
Traction Force ◽  
Leading Edge ◽  
Substrate Stiffness ◽  
Retrograde Flow ◽  
Force Loading ◽  
Substrate Rigidity ◽  
Cell Traction

AbstractThe transmission of cytoskeletal forces to the extracellular matrix through focal adhesion complexes is essential for a multitude of biological processes such as cell migration, differentiation, tissue development, cancer progression, among others. During migration, focal adhesions arrest the actin retrograde flow towards the cell interior, allowing the cell front to move forward. Here, we address a puzzling observation of the existence of two distinct phenomena: a biphasic relationship of the retrograde flow and cell traction force with increasing substrate rigidity, with maximum traction force and minimum retrograde flow velocity being present at an optimal substrate stiffness; in contrast, a monotonic relationship between them where the retrograde flow decreases and traction force increases with substrate stiffness. We propose a theoretical model for cell-matrix adhesions at the leading edge of a migrating cell, incorporating a novel approach in force loading rate sensitive binding and reinforcement of focal adhesions assembly and the subsequent force-induced slowing down of actin flow. Our model unravels both biphasic and monotonic responses of the retrograde flow and cell traction force with increasing substrate rigidity, owing to the cell’s ability to sense and adapt to the fast-growing forces. Moreover, we also elucidate how the viscoelastic properties of the substrate regulate these nonlinear responses and alter cellular behaviours.

scholarly journals Force-FAK Signaling Coupling at Individual Focal Adhesions Coordinates Mechanosensing and Microtissue Repair

2020 ◽  
Author(s):  
Dennis Zhou ◽  
Marc Fernández-Yagüe ◽  
Elijah Holland ◽  
Andrés García ◽  
Nicolas Castro ◽  
...  
Keyword(s):  
Cell Migration ◽  
Magnetic Beads ◽  
Focal Adhesions ◽  
Traction Force ◽  
Binding Model ◽  
Wound Healing Model ◽  
External Forces ◽  
Biochemical Signals ◽  
Healing Model

Abstract How adhesive forces are transduced and integrated into biochemical signals at focal adhesions (FAs) is poorly understood. Using cells adhering to deformable micropillar arrays, we demonstrate that traction force and FAK localization as well as traction force and Y397-FAK phosphorylation are linearly coupled at individual FAs on stiff, but not soft, substrates. Similarly, FAK phosphorylation increases linearly with external forces applied to FAs using magnetic beads. This mechanosignaling coupling requires actomyosin contractility, talin-FAK binding, and full-length vinculin that binds talin and actin. Using an in vitro 3D biomimetic wound healing model, we show that force-FAK signaling coupling coordinates cell migration and tissue-scale forces to promote microtissue repair. A simple kinetic binding model of talin-FAK interactions under force can recapitulate the experimental observations. This study provides insights on how talin and vinculin convert forces into FAK signaling events regulating cell migration and tissue repair.

scholarly journals BNIP-2 retards breast cancer cell migration by coupling microtubule-mediated GEF-H1 and RhoA activation

2020 ◽  
Vol 6 (31) ◽  
pp. eaaz1534 ◽  
Author(s):  
Meng Pan ◽  
Ti Weng Chew ◽  
Darren Chen Pei Wong ◽  
Jingwei Xiao ◽  
Hui Ting Ong ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Migration ◽  
Focal Adhesions ◽  
Fine Tuning ◽  
Nucleotide Exchange ◽  
Microtubule Depolymerization ◽  
Cell Contractility ◽  
Rhoa Activity ◽  
Rhoa Activation ◽  
Guanosine Triphosphatase

Microtubules display dynamic turnover during cell migration, leading to cell contractility and focal adhesion maturation regulated by Rho guanosine triphosphatase activity. This interplay between microtubules and actomyosin is mediated by guanine nucleotide exchange factor (GEF)–H1 released after microtubule depolymerization or microtubule disconnection from focal adhesions. However, how GEF-H1 activates Rho upon microtubule disassembly remains elusive. Here, we found that BNIP-2, a BCH domain–containing protein that binds both RhoA and GEF-H1 and traffics with kinesin-1 on microtubules, is important for GEF-H1–driven RhoA activation upon microtubule disassembly. Depletion of BNIP-2 in MDA-MB-231 breast cancer cells decreases RhoA activity and promotes cell migration. Upon nocodazole-induced microtubule disassembly, the interaction between BNIP-2 and GEF-H1 increases, while knockdown of BNIP-2 reduces RhoA activation and cell rounding via uncoupling RhoA-GEF-H1 interaction. Together, these findings revealed that BNIP-2 couples microtubules and focal adhesions via scaffolding GEF-H1 and RhoA, fine-tuning RhoA activity and cell migration.

scholarly journals Zyxin Is Involved in Fibroblast Rigidity Sensing and Durotaxis

2021 ◽  
Vol 9 ◽  
Author(s):  
Ai Kia Yip ◽  
Songjing Zhang ◽  
Lor Huai Chong ◽  
Elsie Cheruba ◽  
Jessie Yong Xing Woon ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Cell Migration ◽  
Actin Cytoskeleton ◽  
Focal Adhesions ◽  
Wild Type ◽  
Actin Organization ◽  
Rigidity Sensing ◽  
Substrate Rigidity ◽  
Cell Traction ◽  
Traction Stress

Focal adhesions (FAs) are specialized structures that enable cells to sense their extracellular matrix rigidity and transmit these signals to the interior of the cells, bringing about actin cytoskeleton reorganization, FA maturation, and cell migration. It is known that cells migrate towards regions of higher substrate rigidity, a phenomenon known as durotaxis. However, the underlying molecular mechanism of durotaxis and how different proteins in the FA are involved remain unclear. Zyxin is a component of the FA that has been implicated in connecting the actin cytoskeleton to the FA. We have found that knocking down zyxin impaired NIH3T3 fibroblast’s ability to sense and respond to changes in extracellular matrix in terms of their FA sizes, cell traction stress magnitudes and F-actin organization. Cell migration speed of zyxin knockdown fibroblasts was also independent of the underlying substrate rigidity, unlike wild type fibroblasts which migrated fastest at an intermediate substrate rigidity of 14 kPa. Wild type fibroblasts exhibited durotaxis by migrating toward regions of increasing substrate rigidity on polyacrylamide gels with substrate rigidity gradient, while zyxin knockdown fibroblasts did not exhibit durotaxis. Therefore, we propose zyxin as an essential protein that is required for rigidity sensing and durotaxis through modulating FA sizes, cell traction stress and F-actin organization.

scholarly journals ARHGAP4-SEPT2-SEPT9 complex enables both up- and down-modulation of integrin-mediated focal adhesions, cell migration, and invasion

2021 ◽  
pp. mbc.E21-01-0010
Author(s):  
Kang Na ◽  
Tsubasa S. Matsui ◽  
Liu Shiyou ◽  
Shinji Deguchi
Keyword(s):  
Cell Migration ◽  
Rho Gtpase ◽  
Focal Adhesions ◽  
Migration And Invasion ◽  
Dependent Manner ◽  
Cell Migration And Invasion ◽  
Phenotypic Changes ◽  
Gtpase Activating Proteins ◽  
A Cell ◽  
Rho Family

The Rho family of GTPases are inactivated in a cell context-dependent manner by Rho-GTPase-activating proteins (Rho-GAPs), but their signaling mechanisms are poorly understood. Here we demonstrate that ARHGAP4, the Rho-GAPs, forms a complex with SEPT2 and SEPT9 via its Rho-GAP domain and SH3 domain to enable both up- and down-modulation of integrin-mediated focal adhesions (FAs). We show that silencing ARHGAP4 as well as overexpressing its two mutually independent upstream regulators SEPT2 and SEPT9 all induce reorganization of FAs to newly express Integrin Beta 1 and also enhance both cell migration and invasion. Interestingly, even if these cell migration/invasion-associated phenotypic changes are induced upon perturbations to the complex, it does not necessarily cause enhanced clustering of FAs. Instead, its extent depends on whether the microenvironment contains ligands suitable for the upregulated Integrin Beta 1. These results provide novel insights to cell migration, invasion, and microenvironment-dependent phenotypic changes regulated by the newly identified complex.

scholarly journals Discrete mechanical model of lamellipodial actin network implements molecular clutch mechanism and generates arcs and microspikes

2021 ◽  
Vol 17 (10) ◽  
pp. e1009506
Author(s):  
David M. Rutkowski ◽  
Dimitrios Vavylonis
Keyword(s):  
Actin Filaments ◽  
Actin Polymerization ◽  
Focal Adhesions ◽  
Leading Edge ◽  
Flow Speed ◽  
Viscous Drag ◽  
Stress Profile ◽  
Retrograde Flow ◽  
Actin Network ◽  
Clutch Mechanism

Mechanical forces, actin filament turnover, and adhesion to the extracellular environment regulate lamellipodial protrusions. Computational and mathematical models at the continuum level have been used to investigate the molecular clutch mechanism, calculating the stress profile through the lamellipodium and around focal adhesions. However, the forces and deformations of individual actin filaments have not been considered while interactions between actin networks and actin bundles is not easily accounted with such methods. We develop a filament-level model of a lamellipodial actin network undergoing retrograde flow using 3D Brownian dynamics. Retrograde flow is promoted in simulations by pushing forces from the leading edge (due to actin polymerization), pulling forces (due to molecular motors), and opposed by viscous drag in cytoplasm and focal adhesions. Simulated networks have densities similar to measurements in prior electron micrographs. Connectivity between individual actin segments is maintained by permanent and dynamic crosslinkers. Remodeling of the network occurs via the addition of single actin filaments near the leading edge and via filament bond severing. We investigated how several parameters affect the stress distribution, network deformation and retrograde flow speed. The model captures the decrease in retrograde flow upon increase of focal adhesion strength. The stress profile changes from compression to extension across the leading edge, with regions of filament bending around focal adhesions. The model reproduces the observed reduction in retrograde flow speed upon exposure to cytochalasin D, which halts actin polymerization. Changes in crosslinker concentration and dynamics, as well as in the orientation pattern of newly added filaments demonstrate the model’s ability to generate bundles of filaments perpendicular (actin arcs) or parallel (microspikes) to the protruding direction.

scholarly journals Force-FAK signaling coupling at individual focal adhesions coordinates mechanosensing and microtissue repair

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Dennis W. Zhou ◽  
Marc A. Fernández-Yagüe ◽  
Elijah N. Holland ◽  
Andrés F. García ◽  
Nicolas S. Castro ◽  
...  
Keyword(s):  
Cell Migration ◽  
Magnetic Beads ◽  
Focal Adhesions ◽  
Traction Force ◽  
Binding Model ◽  
Wound Healing Model ◽  
External Forces ◽  
Biochemical Signals ◽  
Healing Model

AbstractHow adhesive forces are transduced and integrated into biochemical signals at focal adhesions (FAs) is poorly understood. Using cells adhering to deformable micropillar arrays, we demonstrate that traction force and FAK localization as well as traction force and Y397-FAK phosphorylation are linearly coupled at individual FAs on stiff, but not soft, substrates. Similarly, FAK phosphorylation increases linearly with external forces applied to FAs using magnetic beads. This mechanosignaling coupling requires actomyosin contractility, talin-FAK binding, and full-length vinculin that binds talin and actin. Using an in vitro 3D biomimetic wound healing model, we show that force-FAK signaling coupling coordinates cell migration and tissue-scale forces to promote microtissue repair. A simple kinetic binding model of talin-FAK interactions under force can recapitulate the experimental observations. This study provides insights on how talin and vinculin convert forces into FAK signaling events regulating cell migration and tissue repair.

scholarly journals Stick-Slip Dynamics of Migrating Cells on Viscoelastic Substrates

2019 ◽  
Author(s):  
Partho Sakha De ◽  
Rumi De
Keyword(s):  
Focal Adhesions ◽  
Traction Force ◽  
Reaction Diffusion ◽  
Substrate Stiffness ◽  
Retrograde Flow ◽  
Stick Slip ◽  
Cell Substrate ◽  
Elastic Substrates ◽  
Individual Bond ◽  
Stick Slip Motion

Stick-slip motion, a common phenomenon observed during crawling of cells, is found to be strongly sensitive to the substrate stiffness. Stick-slip behaviours have previously been investigated typically using purely elastic substrates. For a more realistic understanding of this phenomenon, we propose a theoretical model to study the dynamics on a viscoelastic substrate. Our model based on a reaction-diffusion framework, incorporates known important interactions such as retrograde flow of actin, myosin contractility, force dependent assembly and disassembly of focal adhesions coupled with cell-substrate interaction. We show that consideration of a viscoelastic substrate not only captures the usually observed stick-slip jumps, but also predicts the existence of an optimal substrate viscosity corresponding to maximum traction force and minimum retrograde flow which was hitherto unexplored. Moreover, our theory predicts the time evolution of individual bond force that characterizes the stick-slip patterns on soft versus stiff substrates. Our analysis also elucidates how the duration of the stick-slip cycles are affected by various cellular parameters.

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