scholarly journals Actin retrograde flow actively aligns and orients ligand-engaged integrins in focal adhesions

2017 ◽  
Vol 114 (40) ◽  
pp. 10648-10653 ◽  
Author(s):  
Vinay Swaminathan ◽  
Joseph Mathew Kalappurakkal ◽  
Shalin B. Mehta ◽  
Pontus Nordenfelt ◽  
Travis I. Moore ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Focal Adhesions ◽  
Leading Edge ◽  
Retrograde Flow ◽  
Molecular Scaffold ◽  
Cell Adhesion And Migration ◽  
Αvβ3 Integrins ◽  
Mediate Cell ◽  
And Migration ◽  
Migrating Cells

Integrins are transmembrane receptors that, upon activation, bind extracellular ligands and link them to the actin filament (F-actin) cytoskeleton to mediate cell adhesion and migration. Cytoskeletal forces in migrating cells generated by polymerization- or contractility-driven “retrograde flow” of F-actin from the cell leading edge have been hypothesized to mediate integrin activation for ligand binding. This predicts that these forces should align and orient activated, ligand-bound integrins at the leading edge. Here, polarization-sensitive fluorescence microscopy of GFP-αVβ3 integrins in fibroblasts shows that integrins are coaligned in a specific orientation within focal adhesions (FAs) in a manner dependent on binding immobilized ligand and a talin-mediated linkage to the F-actin cytoskeleton. These findings, together with Rosetta modeling, suggest that integrins in FA are coaligned and may be highly tilted by cytoskeletal forces. Thus, the F-actin cytoskeleton sculpts an anisotropic molecular scaffold in FAs, and this feature may underlie the ability of migrating cells to sense directional extracellular cues.

scholarly journals Actin retrograde flow actively aligns and orients ligand-engaged integrins in focal adhesions

2016 ◽  
Author(s):  
Vinay Swaminathan ◽  
Joseph Mathew Kalappurakkal ◽  
Shalin B. Mehta ◽  
Pontus Nordenfelt ◽  
Travis I. Moore ◽  
...  
Keyword(s):  
Focal Adhesions ◽  
Leading Edge ◽  
Αvβ3 Integrin ◽  
Retrograde Flow ◽  
Molecular Scaffold ◽  
Transmembrane Receptors ◽  
Cell Adhesion And Migration ◽  
Mediate Cell Adhesion ◽  
Mediate Cell ◽  
And Migration

Integrins are transmembrane receptors that, upon activation, bind extracellular matrix (ECM) or cell surface ligands and link them to the actin cytoskeleton to mediate cell adhesion and migration1,2. One model for the structural transitions mediating integrin activation termed “the cytoskeletal force hypothesis” posits that force transmitted from the cytoskeleton to ligand-bound integrins acts as an allosteric stabilizer of the extended-open, high-affinity state3. Since cytoskeletal forces in migrating cells are generated by centripetal “retrograde flow” of F-actin from the cell leading edge, where integrin-based adhesions are initiated4,5, this model predicts that F-actin flow should align and orient activated, ligand-bound integrins in integrin-based adhesions. Here, polarization-sensitive fluorescence microscopy of GFP-αVβ3 integrin chimeras in migrating fibroblasts shows that integrins are aligned with respect to the axis of FAs and the direction of F-actin flow, and this alignment requires binding immobilized ligand and talin-mediated linkage to a flowing cytoskeleton. Polarization imaging and Rosetta modelling of chimeras engineered to orient GFP differentially with respect to the integrin headpiece suggest that ligand-bound αVβ3 integrin may be markedly tilted by the force of F-actin flow. These results show that actin cytoskeletal forces actively sculpt an anisotropic molecular scaffold in FAs that may underlie the ability of cells to sense directional ECM and physical cues.

scholarly journals Paxillin kinase linker (PKL) regulates Vav2 signaling during cell spreading and migration

2013 ◽  
Vol 24 (12) ◽  
pp. 1882-1894 ◽  
Author(s):  
Matthew C. Jones ◽  
Kazuya Machida ◽  
Bruce J. Mayer ◽  
Christopher E. Turner
Keyword(s):  
Cell Migration ◽  
Rho Gtpases ◽  
Focal Adhesions ◽  
Leading Edge ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Gtpase Activating Proteins ◽  
And Migration ◽  
Migrating Cells

The Rho family of GTPases plays an important role in coordinating dynamic changes in the cell migration machinery after integrin engagement with the extracellular matrix. Rho GTPases are activated by guanine nucleotide exchange factors (GEFs) and negatively regulated by GTPase-activating proteins (GAPs). However, the mechanisms by which GEFs and GAPs are spatially and temporally regulated are poorly understood. Here the activity of the proto-oncogene Vav2, a GEF for Rac1, RhoA, and Cdc42, is shown to be regulated by a phosphorylation-dependent interaction with the ArfGAP PKL (GIT2). PKL is required for Vav2 activation downstream of integrin engagement and epidermal growth factor (EGF) stimulation. In turn, Vav2 regulates the subsequent redistribution of PKL and the Rac1 GEF β-PIX to focal adhesions after EGF stimulation, suggesting a feedforward signaling loop that coordinates PKL-dependent Vav2 activation and PKL localization. Of interest, Vav2 is required for the efficient localization of PKL and β-PIX to the leading edge of migrating cells, and knockdown of Vav2 results in a decrease in directional persistence and polarization in migrating cells, suggesting a coordination between PKL/Vav2 signaling and PKL/β-PIX signaling during cell migration.

scholarly journals Rab40/Cullin5 complex regulates EPLIN and actin cytoskeleton dynamics during cell migration and invasion

2021 ◽  
Author(s):  
Erik S Linklater ◽  
Emily Duncan ◽  
Ke Jun Han ◽  
Algirdas Kaupinis ◽  
Mindaugas Valius ◽  
...  
Keyword(s):  
Cell Migration ◽  
Actin Cytoskeleton ◽  
Focal Adhesion ◽  
Focal Adhesions ◽  
Leading Edge ◽  
Stress Fibers ◽  
Actin Dynamics ◽  
Migration And Invasion ◽  
Matrix Remodeling ◽  
Cell Migration And Invasion

Rab40b is a SOCS box containing protein that regulates the secretion of MMPs to facilitate extracellular matrix remodeling during cell migration. Here we show that Rab40b interacts with Cullin5 via the Rab40b SOCS domain. We demonstrate that loss of Rab40b/Cullin5 binding decreases cell motility and invasive potential, and show that defective cell migration and invasion stem from alteration to the actin cytoskeleton, leading to decreased invadopodia formation, decreased actin dynamics at the leading edge, and an increase in stress fibers. We also show that these stress fibers anchor at less dynamic, more stable focal adhesions. Mechanistically, changes in the cytoskeleton and focal adhesion dynamics are mediated in part by EPLIN, which we demonstrate to be a binding partner of Rab40b and a target for Rab40b/Cullin5 dependent localized ubiquitylation and degradation. Thus, we propose a model where the Rab40b/Cullin5 dependent ubiquitylation regulates EPLIN localization to promote cell migration and invasion by altering focal adhesion and cytoskeletal dynamics.

scholarly journals Hyperphosphorylated FAK Delocalizes from Focal Adhesions to Membrane Ruffles

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Abdelkader Hamadi ◽  
Therese B. Deramaudt ◽  
Kenneth Takeda ◽  
Philippe Rondé
Keyword(s):  
Tumor Metastasis ◽  
Focal Adhesions ◽  
Downstream Signaling ◽  
Astrocytoma Cells ◽  
Src Inhibitor ◽  
Human Astrocytoma ◽  
Cell Adhesion And Migration ◽  
And Migration ◽  
Downstream Signaling Pathway ◽  
Human Astrocytoma Cells

Cell adhesion and migration are key determinants in tumor metastasis. Adherence of tumor cell to the extracellular matrix is mediated via integrin containing focal adhesions (FAs). Binding of integrins to ECM triggers phosphorylation of two major components of FAs, focal adhesion kinase (FAK) and Src, activating downstream signaling pathway which leads to FA disassembly and cell migration. In this paper, we analyze how phosphorylation of FAK regulates its trafficking at FAs in living human astrocytoma cells. Upon pervanadate-induced FAK phosphorylation, phosphorylated FAK appeared highly expressed at newly formed membrane ruffles. This effect was abolished in presence of the specific Src inhibitor PP2. Our findings demonstrate that upon phosphorylation, FAK delocalizes from FAs to membrane ruffles.

scholarly journals Piezo2 channel regulates RhoA and actin cytoskeleton to promote cell mechanobiological responses

2018 ◽  
Vol 115 (8) ◽  
pp. 1925-1930 ◽  
Author(s):  
Carlos Pardo-Pastor ◽  
Fanny Rubio-Moscardo ◽  
Marina Vogel-González ◽  
Selma A. Serra ◽  
Alexandros Afthinos ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
Nuclear Translocation ◽  
Focal Adhesions ◽  
Leading Edge ◽  
Force Transmission ◽  
Cellular Processes ◽  
Fyn Kinase ◽  
Downstream Effector ◽  
Metastatic Cells

Actin polymerization and assembly into stress fibers (SFs) is central to many cellular processes. However, how SFs form in response to the mechanical interaction of cells with their environment is not fully understood. Here we have identified Piezo2 mechanosensitive cationic channel as a transducer of environmental physical cues into mechanobiological responses. Piezo2 is needed by brain metastatic cells from breast cancer (MDA-MB-231-BrM2) to probe their physical environment as they anchor and pull on their surroundings or when confronted with confined migration through narrow pores. Piezo2-mediated Ca2+ influx activates RhoA to control the formation and orientation of SFs and focal adhesions (FAs). A possible mechanism for the Piezo2-mediated activation of RhoA involves the recruitment of the Fyn kinase to the cell leading edge as well as calpain activation. Knockdown of Piezo2 in BrM2 cells alters SFs, FAs, and nuclear translocation of YAP; a phenotype rescued by overexpression of dominant-positive RhoA or its downstream effector, mDia1. Consequently, hallmarks of cancer invasion and metastasis related to RhoA, actin cytoskeleton, and/or force transmission, such as migration, extracellular matrix degradation, and Serpin B2 secretion, were reduced in cells lacking Piezo2.

scholarly journals Clathrin-independent carriers form a high capacity endocytic sorting system at the leading edge of migrating cells

2010 ◽  
Vol 190 (4) ◽  
pp. 675-691 ◽  
Author(s):  
Mark T. Howes ◽  
Matthew Kirkham ◽  
James Riches ◽  
Katia Cortese ◽  
Piers J. Walser ◽  
...  
Keyword(s):  
High Capacity ◽  
Leading Edge ◽  
Cellular Adhesion ◽  
Endocytic Pathway ◽  
Membrane Turnover ◽  
Major Pathway ◽  
Endocytic Sorting ◽  
And Migration ◽  
Sorting Station ◽  
Migrating Cells

Although the importance of clathrin- and caveolin-independent endocytic pathways has recently emerged, key aspects of these routes remain unknown. Using quantitative ultrastructural approaches, we show that clathrin-independent carriers (CLICs) account for approximately three times the volume internalized by the clathrin-mediated endocytic pathway, forming the major pathway involved in uptake of fluid and bulk membrane in fibroblasts. Electron tomographic analysis of the 3D morphology of the earliest carriers shows that they are multidomain organelles that form a complex sorting station as they mature. Proteomic analysis provides direct links between CLICs, cellular adhesion turnover, and migration. Consistent with this, CLIC-mediated endocytosis of key cargo proteins, CD44 and Thy-1, is polarized at the leading edge of migrating fibroblasts, while transient ablation of CLICs impairs their ability to migrate. These studies provide the first quantitative ultrastructural analysis and molecular characterization of the major endocytic pathway in fibroblasts, a pathway that provides rapid membrane turnover at the leading edge of migrating cells.

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 PAK4 methylation by the methyltransferase SETD6 attenuates cell adhesion

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zlata Vershinin ◽  
Michal Feldman ◽  
Dan Levy
Keyword(s):  
Cell Adhesion ◽  
Mammalian Cells ◽  
Focal Adhesions ◽  
Vital Role ◽  
Migration And Invasion ◽  
Wild Type ◽  
Set Domain ◽  
Cell Adhesion And Migration ◽  
P21 Activated Kinase ◽  
And Migration

Abstract P21-activated kinase 4 (PAK4), a member of serine/threonine kinases family is over-expressed in numerous cancer tumors and is associated with oncogenic cell proliferation, migration and invasion. Our recent work demonstrated that the SET-domain containing protein 6 (SETD6) interacts with and methylates PAK4 at chromatin in mammalian cells, leading to activation of the Wnt/β-catenin signaling pathway. In our current work, we identified lysine 473 (K473) on PAK4 as the primary methylation site by SETD6. Methylation of PAK4 at K473 activates β-catenin transcriptional activity and inhibits cell adhesion. Specific methylation of PAK4 at K473 also attenuates paxillin localization to focal adhesions leading to overall reduction in adhesion-related features, such as filopodia and actin structures. The altered adhesion of the PAK4 wild-type cells is accompanied with a decrease in the migrative and invasive characteristics of the cells. Taken together, our results suggest that methylation of PAK4 at K473 plays a vital role in the regulation of cell adhesion and migration.

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