scholarly journals Contribution of Filopodia to Cell Migration: A Mechanical Link between Protrusion and Contraction

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Fei Xue ◽  
Deanna M. Janzen ◽  
David A. Knecht
Keyword(s):  
Cell Migration ◽  
Actin Polymerization ◽  
Myosin Ii ◽  
Temporal Distribution ◽  
Leading Edge ◽  
Distal Portion ◽  
Actin Binding ◽  
Actin Networks ◽  
Motile Cells ◽  
A Cell

Numerous F-actin containing structures are involved in regulating protrusion of membrane at the leading edge of motile cells. We have investigated the structure and dynamics of filopodia as they relate to events at the leading edge and the function of the trailing actin networks. We have found that although filopodia contain parallel bundles of actin, they contain a surprisingly nonuniform spatial and temporal distribution of actin binding proteins. Along the length of the actin filaments in a single filopodium, the most distal portion contains primarily T-plastin, while the proximal portion is primarily bound byα-actinin and coronin. Some filopodia are stationary, but lateral filopodia move with respect to the leading edge. They appear to form a mechanical link between the actin polymerization network at the front of the cell and the myosin motor activity in the cell body. The direction of lateral filopodial movement is associated with the direction of cell migration. When lateral filopodia initiate from and move toward only one side of a cell, the cell will turn opposite to the direction of filopodial flow. Therefore, this filopodia-myosin II system allows actin polymerization driven protrusion forces and myosin II mediated contractile force to be mechanically coordinated.

scholarly journals Cell migration without a lamellipodium

2005 ◽  
Vol 168 (4) ◽  
pp. 619-631 ◽  
Author(s):  
Stephanie L. Gupton ◽  
Karen L. Anderson ◽  
Thomas P. Kole ◽  
Robert S. Fischer ◽  
Aaron Ponti ◽  
...  
Keyword(s):  
Cell Migration ◽  
Epithelial Cells ◽  
Leading Edge ◽  
Actin Binding ◽  
Retrograde Flow ◽  
Actin Assembly ◽  
Migration Inhibition ◽  
Actin Networks ◽  
Actin Turnover ◽  
High Concentrations

The actin cytoskeleton is locally regulated for functional specializations for cell motility. Using quantitative fluorescent speckle microscopy (qFSM) of migrating epithelial cells, we previously defined two distinct F-actin networks based on their F-actin–binding proteins and distinct patterns of F-actin turnover and movement. The lamellipodium consists of a treadmilling F-actin array with rapid polymerization-dependent retrograde flow and contains high concentrations of Arp2/3 and ADF/cofilin, whereas the lamella exhibits spatially random punctae of F-actin assembly and disassembly with slow myosin-mediated retrograde flow and contains myosin II and tropomyosin (TM). In this paper, we microinjected skeletal muscle αTM into epithelial cells, and using qFSM, electron microscopy, and immunolocalization show that this inhibits functional lamellipodium formation. Cells with inhibited lamellipodia exhibit persistent leading edge protrusion and rapid cell migration. Inhibition of endogenous long TM isoforms alters protrusion persistence. Thus, cells can migrate with inhibited lamellipodia, and we suggest that TM is a major regulator of F-actin functional specialization in migrating cells.

scholarly journals Lamellipodin tunes cell migration by stabilizing protrusions and promoting adhesion formation

2019 ◽  
Author(s):  
Georgi Dimchev ◽  
Behnam Amiri ◽  
Ashley C. Humphries ◽  
Matthias Schaks ◽  
Vanessa Dimchev ◽  
...  
Keyword(s):  
Cell Migration ◽  
Actin Polymerization ◽  
Binding Protein ◽  
Critical Role ◽  
Adhesion Formation ◽  
Leading Edge ◽  
Actin Binding ◽  
Membrane Ruffling ◽  
Genetic Ablation ◽  
And Migration

ABSTRACTEfficient migration on adhesive surfaces involves the protrusion of lamellipodial actin networks and their subsequent stabilization by nascent adhesions. The actin binding protein lamellipodin (Lpd) is thought to play a critical role in lamellipodium protrusion, by delivering Ena/VASP proteins onto the growing plus ends of actin filaments and by interacting with the WAVE regulatory complex (WRC), an activator of the Arp2/3 complex, at the leading edge. Using B16-F1 melanoma cell lines, we demonstrate that genetic ablation of Lpd compromises protrusion efficiency and coincident cell migration without altering essential parameters of lamellipodia, including their maximal rate of forward advancement and actin polymerization. We also confirmed lamellipodia and migration phenotypes with CRISPR/Cas9-mediated Lpd knockout Rat2 fibroblasts, excluding cell type-specific effects. Moreover, computer-aided analysis of cell edge morphodynamics on B16-F1 cell lamellipodia revealed that loss of Lpd correlates with reduced temporal protrusion maintenance as a prerequisite of nascent adhesion formation. We conclude that Lpd optimizes protrusion and nascent adhesion formation by counteracting frequent, chaotic retraction and membrane ruffling.Summary statementWe describe how genetic ablation of the prominent actin- and VASP-binding protein lamellipodin combined with software-aided protrusion analysis uncovers mechanistic insights into its cellular function during cell migration.

scholarly journals Cell Mechanics at the Rear Act To Steer the Direction of Cell Migration

2018 ◽  
Author(s):  
Greg M. Allen ◽  
Kun Chun Lee ◽  
Erin L. Barnhart ◽  
Mark A. Tsuchida ◽  
Cyrus A. Wilson ◽  
...  
Keyword(s):  
Computational Model ◽  
Network Flow ◽  
Actin Polymerization ◽  
Myosin Ii ◽  
Leading Edge ◽  
Minor Role ◽  
List Type ◽  
Motile Cells ◽  
Cell Shapes ◽  
A Minor

SummaryMotile cells navigate complex environments by changing their direction of travel, generating left-right asymmetries in their mechanical subsystems to physically turn. Currently little is known about how external directional cues are propagated along the length scale of the whole cell and integrated with its force-generating apparatus to steer migration mechanically. We examine the mechanics of spontaneous cell turning in fish epidermal keratocytes and find that the mechanical asymmetries responsible for turning behavior predominate at the rear of the cell, where there is asymmetric centripetal actin flow. Using experimental perturbations we identify two linked feedback loops connecting myosin II contractility, adhesion strength and actin network flow in turning cells that are sufficient to recreate observed cell shapes and trajectories in a computational model. Surprisingly, asymmetries in actin polymerization at the cell leading edge play only a minor role in the mechanics of cell turning – that is, cells steer from the rear.HighlightsFish keratocytes can migrate with persistent angular velocity, straight or in circles.Asymmetry in protrusion at the leading edge is not sufficient to generate persistent turning.Asymmetries in myosin II contraction, actin flow and adhesion at the cell rear cause turns.Our new computational model of migration predicts observed cell trajectories.

scholarly journals Regulation of cell migration and survival by focal adhesion targeting of Lasp-1

2004 ◽  
Vol 165 (3) ◽  
pp. 421-432 ◽  
Author(s):  
Yi Hsing Lin ◽  
Zee-Yong Park ◽  
Dayin Lin ◽  
Anar A. Brahmbhatt ◽  
Marie-Christine Rio ◽  
...  
Keyword(s):  
Cell Migration ◽  
Growth Factors ◽  
Focal Adhesion ◽  
Large Scale ◽  
Actin Polymerization ◽  
Focal Adhesions ◽  
Leading Edge ◽  
Actin Binding ◽  
Cell Periphery ◽  
Ecm Proteins

Large-scale proteomic and functional analysis of isolated pseudopodia revealed the Lim, actin, and SH3 domain protein (Lasp-1) as a novel protein necessary for cell migration, but not adhesion to, the extracellular matrix (ECM). Lasp-1 is a ubiquitously expressed actin-binding protein with a unique domain configuration containing SH3 and LIM domains, and is overexpressed in 8–12% of human breast cancers. We find that stimulation of nonmotile and quiescent cells with growth factors or ECM proteins facilitates Lasp-1 relocalization from the cell periphery to the leading edge of the pseudopodium, where it associates with nascent focal complexes and areas of actin polymerization. Interestingly, although Lasp-1 dynamics in migratory cells occur independently of c-Abl kinase activity and tyrosine phosphorylation, c-Abl activation by apoptotic agents specifically promotes phosphorylation of Lasp-1 at tyrosine 171, which is associated with the loss of Lasp-1 localization to focal adhesions and induction of cell death. Thus, Lasp-1 is a dynamic focal adhesion protein necessary for cell migration and survival in response to growth factors and ECM proteins.

scholarly journals Arp2/3 complex–dependent actin networks constrain myosin II function in driving retrograde actin flow

2012 ◽  
Vol 197 (7) ◽  
pp. 939-956 ◽  
Author(s):  
Qing Yang ◽  
Xiao-Feng Zhang ◽  
Thomas D. Pollard ◽  
Paul Forscher
Keyword(s):  
Growth Cone ◽  
Myosin Ii ◽  
Rho Kinase ◽  
Leading Edge ◽  
Actin Dynamics ◽  
Actin Networks ◽  
Motile Cells ◽  
Nonmuscle Myosin Ii ◽  
Neuronal Growth Cone ◽  
Contractile Forces

The Arp2/3 complex nucleates actin filaments to generate networks at the leading edge of motile cells. Nonmuscle myosin II produces contractile forces involved in driving actin network translocation. We inhibited the Arp2/3 complex and/or myosin II with small molecules to investigate their respective functions in neuronal growth cone actin dynamics. Inhibition of the Arp2/3 complex with CK666 reduced barbed end actin assembly site density at the leading edge, disrupted actin veils, and resulted in veil retraction. Strikingly, retrograde actin flow rates increased with Arp2/3 complex inhibition; however, when myosin II activity was blocked, Arp2/3 complex inhibition now resulted in slowing of retrograde actin flow and veils no longer retracted. Retrograde flow rate increases induced by Arp2/3 complex inhibition were independent of Rho kinase activity. These results provide evidence that, although the Arp2/3 complex and myosin II are spatially segregated, actin networks assembled by the Arp2/3 complex can restrict myosin II–dependent contractility with consequent effects on growth cone motility.

scholarly journals Subcellular optogenetic activation of Cdc42 controls local and distal signaling to drive immune cell migration

2016 ◽  
Vol 27 (9) ◽  
pp. 1442-1450 ◽  
Author(s):  
Patrick R. O’Neill ◽  
Vani Kalyanaraman ◽  
N. Gautam
Keyword(s):  
Cell Migration ◽  
Intracellular Signaling ◽  
Immune Cell ◽  
Leading Edge ◽  
Signaling Networks ◽  
Membrane Protrusions ◽  
A Cell ◽  
Immune Cell Migration ◽  
Directional Cell Migration ◽  
Rhoa Signaling

Migratory immune cells use intracellular signaling networks to generate and orient spatially polarized responses to extracellular cues. The monomeric G protein Cdc42 is believed to play an important role in controlling the polarized responses, but it has been difficult to determine directly the consequences of localized Cdc42 activation within an immune cell. Here we used subcellular optogenetics to determine how Cdc42 activation at one side of a cell affects both cell behavior and dynamic molecular responses throughout the cell. We found that localized Cdc42 activation is sufficient to generate polarized signaling and directional cell migration. The optically activated region becomes the leading edge of the cell, with Cdc42 activating Rac and generating membrane protrusions driven by the actin cytoskeleton. Cdc42 also exerts long-range effects that cause myosin accumulation at the opposite side of the cell and actomyosin-mediated retraction of the cell rear. This process requires the RhoA-activated kinase ROCK, suggesting that Cdc42 activation at one side of a cell triggers increased RhoA signaling at the opposite side. Our results demonstrate how dynamic, subcellular perturbation of an individual signaling protein can help to determine its role in controlling polarized cellular responses.

scholarly journals Scribble, Lgl1, and myosin II form a complex in vivo to promote directed cell migration

2020 ◽  
Vol 31 (20) ◽  
pp. 2234-2248
Author(s):  
Maha Abedrabbo ◽  
Shoshana Ravid
Keyword(s):  
Cell Migration ◽  
Cell Adhesion ◽  
Myosin Ii ◽  
Leading Edge ◽  
Directed Cell Migration ◽  
Lethal Giant Larvae ◽  
And Migration ◽  
Migrating Cells

Here we show that Scribble (Scrib), Lethal giant larvae 1 (Lgl1), and myosin II form a complex in vivo and colocalize at the cell leading edge of migrating cells, and this colocalization is interdependent. Scrib and Lgl1 are required for proper cell adhesion, polarity, and migration.

scholarly journals The Huntingtin-interacting protein SETD2/HYPB is an actin lysine methyltransferase

2020 ◽  
Vol 6 (40) ◽  
pp. eabb7854 ◽  
Author(s):  
Riyad N. H. Seervai ◽  
Rahul K. Jangid ◽  
Menuka Karki ◽  
Durga Nand Tripathi ◽  
Sung Yun Jung ◽  
...  
Keyword(s):  
Cell Migration ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Scaffolding Protein ◽  
Actin Binding ◽  
Set Domain ◽  
Interacting Protein ◽  
Lysine Methyltransferase ◽  
Huntingtin Interacting Protein ◽  
In Cells

The methyltransferase SET domain–containing 2 (SETD2) was originally identified as Huntingtin (HTT) yeast partner B. However, a SETD2 function associated with the HTT scaffolding protein has not been elucidated, and no linkage between HTT and methylation has yet been uncovered. Here, we show that SETD2 is an actin methyltransferase that trimethylates lysine-68 (ActK68me3) in cells via its interaction with HTT and the actin-binding adapter HIP1R. ActK68me3 localizes primarily to the insoluble F-actin cytoskeleton in cells and regulates actin polymerization/depolymerization dynamics. Disruption of the SETD2-HTT-HIP1R axis inhibits actin methylation, causes defects in actin polymerization, and impairs cell migration. Together, these data identify SETD2 as a previously unknown HTT effector regulating methylation and polymerization of actin filaments and provide new avenues for understanding how defects in SETD2 and HTT drive disease via aberrant cytoskeletal methylation.

scholarly journals Shootin1–cortactin interaction mediates signal–force transduction for axon outgrowth

2015 ◽  
Vol 210 (4) ◽  
pp. 663-676 ◽  
Author(s):  
Yusuke Kubo ◽  
Kentarou Baba ◽  
Michinori Toriyama ◽  
Takunori Minegishi ◽  
Tadao Sugiura ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Leading Edge ◽  
Growth Cones ◽  
Axon Outgrowth ◽  
Actin Binding ◽  
Retrograde Flow ◽  
Environmental Chemical ◽  
Mechanical Coupling ◽  
Cell Adhesions ◽  
Force Transduction

Motile cells transduce environmental chemical signals into mechanical forces to achieve properly controlled migration. This signal–force transduction is thought to require regulated mechanical coupling between actin filaments (F-actins), which undergo retrograde flow at the cellular leading edge, and cell adhesions via linker “clutch” molecules. However, the molecular machinery mediating this regulatory coupling remains unclear. Here we show that the F-actin binding molecule cortactin directly interacts with a clutch molecule, shootin1, in axonal growth cones, thereby mediating the linkage between F-actin retrograde flow and cell adhesions through L1-CAM. Shootin1–cortactin interaction was enhanced by shootin1 phosphorylation by Pak1, which is activated by the axonal chemoattractant netrin-1. We provide evidence that shootin1–cortactin interaction participates in netrin-1–induced F-actin adhesion coupling and in the promotion of traction forces for axon outgrowth. Under cell signaling, this regulatory F-actin adhesion coupling in growth cones cooperates with actin polymerization for efficient cellular motility.

scholarly journals Nonpolarized signaling reveals two distinct modes of 3D cell migration

2012 ◽  
Vol 197 (3) ◽  
pp. 439-455 ◽  
Author(s):  
Ryan J. Petrie ◽  
Núria Gavara ◽  
Richard S. Chadwick ◽  
Kenneth M. Yamada
Keyword(s):  
Cell Migration ◽  
Intracellular Signaling ◽  
Myosin Ii ◽  
Three Dimensional ◽  
Leading Edge ◽  
Elastic Behavior ◽  
Collagen Gels ◽  
Primary Fibroblasts ◽  
Context Specific ◽  
3D Cell Migration

We search in this paper for context-specific modes of three-dimensional (3D) cell migration using imaging for phosphatidylinositol (3,4,5)-trisphosphate (PIP3) and active Rac1 and Cdc42 in primary fibroblasts migrating within different 3D environments. In 3D collagen, PIP3 and active Rac1 and Cdc42 were targeted to the leading edge, consistent with lamellipodia-based migration. In contrast, elongated cells migrating inside dermal explants and the cell-derived matrix (CDM) formed blunt, cylindrical protrusions, termed lobopodia, and Rac1, Cdc42, and PIP3 signaling was nonpolarized. Reducing RhoA, Rho-associated protein kinase (ROCK), or myosin II activity switched the cells to lamellipodia-based 3D migration. These modes of 3D migration were regulated by matrix physical properties. Specifically, experimentally modifying the elasticity of the CDM or collagen gels established that nonlinear elasticity supported lamellipodia-based migration, whereas linear elasticity switched cells to lobopodia-based migration. Thus, the relative polarization of intracellular signaling identifies two distinct modes of 3D cell migration governed intrinsically by RhoA, ROCK, and myosin II and extrinsically by the elastic behavior of the 3D extracellular matrix.

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