scholarly journals The Arp2/3 complex is required for lamellipodia extension and directional fibroblast cell migration

2012 ◽  
Vol 197 (2) ◽  
pp. 239-251 ◽  
Author(s):  
Praveen Suraneni ◽  
Boris Rubinstein ◽  
Jay R. Unruh ◽  
Michael Durnin ◽  
Dorit Hanein ◽  
...  
Keyword(s):  
Cell Migration ◽  
Critical Role ◽  
Embryonic Stem ◽  
Leading Edge ◽  
Fibroblast Cell ◽  
Fibroblast Cells ◽  
Actin Network ◽  
Directional Migration ◽  
Fibroblast Migration ◽  
Motile Cells

The Arp2/3 complex nucleates the formation of the dendritic actin network at the leading edge of motile cells, but it is still unclear if the Arp2/3 complex plays a critical role in lamellipodia protrusion and cell motility. Here, we differentiated motile fibroblast cells from isogenic mouse embryonic stem cells with or without disruption of the ARPC3 gene, which encodes the p21 subunit of the Arp2/3 complex. ARPC3−/− fibroblasts were unable to extend lamellipodia but generated dynamic leading edges composed primarily of filopodia-like protrusions, with formin proteins (mDia1 and mDia2) concentrated near their tips. The speed of cell migration, as well as the rates of leading edge protrusion and retraction, were comparable between genotypes; however, ARPC3−/− cells exhibited a strong defect in persistent directional migration. This deficiency correlated with a lack of coordination of the protrusive activities at the leading edge of ARPC3−/− fibroblasts. These results provide insights into the Arp2/3 complex’s critical role in lamellipodia extension and directional fibroblast migration.

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 TNFAIP8 is a novel phosphoinositide-binding inhibitory regulator of Rho GTPases that promotes cancer cell migration

2021 ◽  
Author(s):  
Mei Lin ◽  
Honghong Sun ◽  
Svetlana A. Fayngerts ◽  
Peiwei Huangyang ◽  
Youhai H. Chen
Keyword(s):  
Cell Migration ◽  
Rho Gtpases ◽  
Somatic Mutations ◽  
Leading Edge ◽  
Cancer Cell Migration ◽  
Directional Migration ◽  
Phosphoinositide Signaling ◽  
Hydrophobic Cavity ◽  
Cavity Structure ◽  
Molecular Bridge

More than half of human tumors exhibit aberrantly dysregulated phosphoinositide signaling, yet how this is controlled remains not fully understood. While somatic mutations of PI3K, PTEN and Ras account for many cases of the hyperactivated lipid signals, other mechanisms for these dysfunctions in cancer are also being discovered. We report here that TNFAIP8 interacts with PtdIns(4,5)P2 and PtdIns(3,4,5)P3 and is likely to be hijacked by cancer cells to facilitate directional migration during malignant transformation. TNFAIP8 maintains the quiescent cellular state by sequestering inactive Rho GTPases in the cytosolic pool, which can be set free upon chemoattractant activation at the leading edge. Consequently, loss of TNFAIP8 results in severe defects of chemotaxis and adhesion. Thus, TNFAIP8, whose expression can be induced by inflammatory cytokines such as TNFα from tumor microenvironment, represents a molecular bridge from inflammation to cancer by linking NF-κB pathway to phosphoinositide signaling. Our study on the conserved hydrophobic cavity structure will also advise in silico drug screening and development of new TNFAIP8-based strategies to combat malignant human diseases.

scholarly journals Mechanochemical coupling and junctional forces during collective cell migration

2019 ◽  
Author(s):  
J. Bui ◽  
D. E. Conway ◽  
R. L. Heise ◽  
S.H. Weinberg
Keyword(s):  
Cell Migration ◽  
Rho Gtpases ◽  
Cancer Metastasis ◽  
Rho Gtpase ◽  
Critical Role ◽  
Leading Edge ◽  
Collective Cell Migration ◽  
Gtpase Activity ◽  
Modeling Framework ◽  
Cell Cell

ABSTRACTCell migration, a fundamental physiological process in which cells sense and move through their surrounding physical environment, plays a critical role in development and tissue formation, as well as pathological processes, such as cancer metastasis and wound healing. During cell migration, dynamics are governed by the bidirectional interplay between cell-generated mechanical forces and the activity of Rho GTPases, a family of small GTP-binding proteins that regulate actin cytoskeleton assembly and cellular contractility. These interactions are inherently more complex during the collective migration of mechanically coupled cells, due to the additional regulation of cell-cell junctional forces. In this study, we present a minimal modeling framework to simulate the interactions between mechanochemical signaling in individual cells and interactions with cell-cell junctional forces during collective cell migration. We find that migration of individual cells depends on the feedback between mechanical tension and Rho GTPase activity in a biphasic manner. During collective cell migration, waves of Rho GTPase activity mediate mechanical contraction/extension and thus synchronization throughout the tissue. Further, cell-cell junctional forces exhibit distinct spatial patterns during collective cell migration, with larger forces near the leading edge. Larger junctional force magnitudes are associated with faster collective cell migration and larger tissue size. Simulations of heterogeneous tissue migration exhibit a complex dependence on the properties of both leading and trailing cells. Computational predictions demonstrate that collective cell migration depends on both the emergent dynamics and interactions between cellular-level Rho GTPase activity and contractility, and multicellular-level junctional forces.

scholarly journals Pointed-end capping by tropomodulin3 negatively regulates endothelial cell motility

2003 ◽  
Vol 161 (2) ◽  
pp. 371-380 ◽  
Author(s):  
Robert S. Fischer ◽  
Kimberly L. Fritz-Six ◽  
Velia M. Fowler
Keyword(s):  
Cell Migration ◽  
Cell Motility ◽  
Actin Filament ◽  
Actin Filaments ◽  
Critical Role ◽  
Leading Edge ◽  
Average Cell ◽  
Transient Overexpression ◽  
End Capping ◽  
Pointed End

Actin filament pointed-end dynamics are thought to play a critical role in cell motility, yet regulation of this process remains poorly understood. We describe here a previously uncharacterized tropomodulin (Tmod) isoform, Tmod3, which is widely expressed in human tissues and is present in human microvascular endothelial cells (HMEC-1). Tmod3 is present in sufficient quantity to cap pointed ends of actin filaments, localizes to actin filament structures in HMEC-1 cells, and appears enriched in leading edge ruffles and lamellipodia. Transient overexpression of GFP–Tmod3 leads to a depolarized cell morphology and decreased cell motility. A fivefold increase in Tmod3 results in an equivalent decrease in free pointed ends in the cells. Unexpectedly, a decrease in the relative amounts of F-actin, free barbed ends, and actin-related protein 2/3 (Arp2/3) complex in lamellipodia are also observed. Conversely, decreased expression of Tmod3 by RNA interference leads to faster average cell migration, along with increases in free pointed and barbed ends in lamellipodial actin filaments. These data collectively demonstrate that capping of actin filament pointed ends by Tmod3 inhibits cell migration and reveal a novel control mechanism for regulation of actin filaments in lamellipodia.

scholarly journals Memo–RhoA–mDia1 signaling controls microtubules, the actin network, and adhesion site formation in migrating cells

2008 ◽  
Vol 183 (3) ◽  
pp. 401-408 ◽  
Author(s):  
Kossay Zaoui ◽  
Stéphane Honoré ◽  
Daniel Isnardon ◽  
Diane Braguer ◽  
Ali Badache
Keyword(s):  
Cell Migration ◽  
Leading Edge ◽  
Site Formation ◽  
Actin Assembly ◽  
Actin Network ◽  
Adhesion Sites ◽  
Cell Front ◽  
Guanosine Triphosphatase ◽  
Adhesion Site ◽  
Migrating Cells

Actin assembly at the cell front drives membrane protrusion and initiates the cell migration cycle. Microtubules (MTs) extend within forward protrusions to sustain cell polarity and promote adhesion site turnover. Memo is an effector of the ErbB2 receptor tyrosine kinase involved in breast carcinoma cell migration. However, its mechanism of action remained unknown. We report in this study that Memo controls ErbB2-regulated MT dynamics by altering the transition frequency between MT growth and shortening phases. Moreover, although Memo-depleted cells can assemble the Rac1-dependent actin meshwork and form lamellipodia, they show defective localization of lamellipodial markers such as α-actinin-1 and a reduced number of short-lived adhesion sites underlying the advancing edge of migrating cells. Finally, we demonstrate that Memo is required for the localization of the RhoA guanosine triphosphatase and its effector mDia1 to the plasma membrane and that Memo–RhoA–mDia1 signaling coordinates the organization of the lamellipodial actin network, adhesion site formation, and MT outgrowth within the cell leading edge to sustain cell motility.

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 Leading edge stability in motile cells is an emergent property of branched actin network growth

2020 ◽  
Author(s):  
Rikki M. Garner ◽  
Julie A. Theriot
Keyword(s):  
High Speed ◽  
Noise Suppression ◽  
Animal Cell ◽  
Leading Edge ◽  
Lateral Spreading ◽  
Actin Network ◽  
Biological Noise ◽  
Network Growth ◽  
Motile Cells ◽  
Branch Formation

AbstractAnimal cell migration is predominantly driven by the coordinated, yet stochastic, polymerization of thousands of nanometer-scale actin filaments across micron-scale cell leading edges. It remains unclear how such inherently noisy processes generate robust cellular behavior. We employed high-speed, high-resolution imaging of migrating neutrophil-like HL-60 cells to explore the fine-scale dynamic shape fluctuations that emerge and relax throughout the process of leading edge maintenance. We then developed a minimal stochastic model of the leading edge that is able to reproduce this stable relaxation behavior. Remarkably, we find that lamellipodial stability naturally emerges from the interplay between branched actin network growth and leading edge shape – with no additional feedback required – based on a synergy between membrane-proximal branching and lateral spreading of filaments. These results thus demonstrate a novel biological noise-suppression mechanism based entirely on system geometry. Furthermore, our model suggests that the Arp2/3-mediated ∼70-80º branching angle optimally smooths lamellipodial shape, addressing its long-mysterious conservation from protists to mammals.One sentence summaryAn experimental and computational investigation of fluctuation dynamics at the leading edge of motile cells demonstrates that the specific angular geometry of Arp2/3-mediated actin network branch formation lies at the core of a successful biological noise-suppression strategy.

scholarly journals Sending messages in moving cells: mRNA localization and the regulation of cell migration

2019 ◽  
Vol 63 (5) ◽  
pp. 595-606 ◽  
Author(s):  
Shane P. Herbert ◽  
Guilherme Costa
Keyword(s):  
Cell Migration ◽  
Cell Polarity ◽  
Leading Edge ◽  
Regulatory Elements ◽  
Extrinsic Factors ◽  
Directed Movement ◽  
Molecular Control ◽  
Local Protein Synthesis ◽  
Motile Cells ◽  
Fundamental Biological Process

Abstract Cell migration is a fundamental biological process involved in tissue formation and homeostasis. The correct polarization of motile cells is critical to ensure directed movement, and is orchestrated by many intrinsic and extrinsic factors. Of these, the subcellular distribution of mRNAs and the consequent spatial control of translation are key modulators of cell polarity. mRNA transport is dependent on cis-regulatory elements within transcripts, which are recognized by trans-acting proteins that ensure the efficient delivery of certain messages to the leading edge of migrating cells. At their destination, translation of localized mRNAs then participates in regional cellular responses underlying cell motility. In this review, we summarize the key findings that established mRNA targetting as a critical driver of cell migration and how the characterization of polarized mRNAs in motile cells has been expanded from just a few species to hundreds of transcripts. We also describe the molecular control of mRNA trafficking, subsequent mechanisms of local protein synthesis and how these ultimately regulate cell polarity during migration.

scholarly journals Type Iγ phosphatidylinositol phosphate kinase is required for EGF-stimulated directional cell migration

2007 ◽  
Vol 178 (2) ◽  
pp. 297-308 ◽  
Author(s):  
Yue Sun ◽  
Kun Ling ◽  
Matthew P. Wagoner ◽  
Richard A. Anderson
Keyword(s):  
Cell Migration ◽  
Growth Factor ◽  
Egf Receptor ◽  
Adhesion Formation ◽  
Leading Edge ◽  
Directional Migration ◽  
Phosphatidylinositol Phosphate ◽  
Phospholipase Cγ1 ◽  
Directional Cell Migration ◽  
Phosphatidylinositol Phosphate Kinase

Phosphatidylinositol 4,5-bisphosphate (PI4,5P2) modulates a plethora of cytoskeletal interactions that control the dynamics of actin assembly and, ultimately, cell migration. We show that the type Iγ phosphatidylinositol phosphate kinase 661 (PIPKIγ661), an enzyme that generates PI4,5P2, is required for growth factor but not G protein–coupled receptor–stimulated directional migration. By generating PI4,5P2 and regulating talin assembly, PIPKIγ661 modulates nascent adhesion formation at the leading edge to facilitate cell migration. The epidermal growth factor (EGF) receptor directly phosphorylates PIPKIγ661 at tyrosine 634, and this event is required for EGF-induced migration. This phosphorylation regulates the interaction between PIPKIγ661 and phospholipase Cγ1 (PLCγ1, an enzyme previously shown to be involved in the regulation of EGF-stimulated migration). Our results suggest that phosphorylation events regulating specific PIPKIγ661 interactions are required for growth factor–induced migration. These interactions in turn define the spatial and temporal generation of PI4,5P2 and derived messengers required for directional migration.

scholarly journals Intracellular Mechanics of Migrating Fibroblasts

2005 ◽  
Vol 16 (1) ◽  
pp. 328-338 ◽  
Author(s):  
Thomas P. Kole ◽  
Yiider Tseng ◽  
Ingjye Jiang ◽  
Joseph L. Katz ◽  
Denis Wirtz
Keyword(s):  
Mechanical Properties ◽  
Cell Migration ◽  
Leading Edge ◽  
Microtubule Network ◽  
Directed Cell Migration ◽  
Motile Cells ◽  
Cytoskeleton Reorganization ◽  
Scratch Wound ◽  
Mechanical Polarization ◽  
Biochemical Signals

Cell migration is a highly coordinated process that occurs through the translation of biochemical signals into specific biomechanical events. The biochemical and structural properties of the proteins involved in cell motility, as well as their subcellular localization, have been studied extensively. However, how these proteins work in concert to generate the mechanical properties required to produce global motility is not well understood. Using intracellular microrheology and a fibroblast scratch-wound assay, we show that cytoskeleton reorganization produced by motility results in mechanical stiffening of both the leading lamella and the perinuclear region of motile cells. This effect is significantly more pronounced in the leading edge, suggesting that the mechanical properties of migrating fibroblasts are spatially coordinated. Disruption of the microtubule network by nocodazole treatment results in the arrest of cell migration and a loss of subcellular mechanical polarization; however, the overall mechanical properties of the cell remain mostly unchanged. Furthermore, we find that activation of Rac and Cdc42 in quiescent fibroblasts elicits mechanical behavior similar to that of migrating cells. We conclude that a polarized mechanics of the cytoskelton is essential for directed cell migration and is coordinated through microtubules.

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