scholarly journals Polarized Exocytosis Induces Compensatory Endocytosis by Sec4p-Regulated Cortical Actin Polymerization

PLoS Biology ◽  
2016 ◽  
Vol 14 (8) ◽  
pp. e1002534 ◽  
Author(s):  
Jesper Johansen ◽  
Gabriel Alfaro ◽  
Christopher T. Beh
Keyword(s):  
Actin Polymerization ◽  
Cortical Actin ◽  
Polarized Exocytosis

scholarly journals Dynamic cortical actin remodeling by ERM proteins controls BCR microcluster organization and integrity

2011 ◽  
Vol 208 (5) ◽  
pp. 1055-1068 ◽  
Author(s):  
Bebhinn Treanor ◽  
David Depoil ◽  
Andreas Bruckbauer ◽  
Facundo D. Batista
Keyword(s):  
Actin Cytoskeleton ◽  
B Cell ◽  
Protein Function ◽  
Actin Polymerization ◽  
Lymphocyte Activation ◽  
Dominant Negative ◽  
Temporary Increase ◽  
Cortical Actin ◽  
Erm Proteins ◽  
Diffusion Dynamics

Signaling microclusters are a common feature of lymphocyte activation. However, the mechanisms controlling the size and organization of these discrete structures are poorly understood. The Ezrin-Radixin-Moesin (ERM) proteins, which link plasma membrane proteins with the actin cytoskeleton and regulate the steady-state diffusion dynamics of the B cell receptor (BCR), are transiently dephosphorylated upon antigen receptor stimulation. In this study, we show that the ERM proteins ezrin and moesin influence the organization and integrity of BCR microclusters. BCR-driven inactivation of ERM proteins is accompanied by a temporary increase in BCR diffusion, followed by BCR immobilization. Disruption of ERM protein function using dominant-negative or constitutively active ezrin constructs or knockdown of ezrin and moesin expression quantitatively and qualitatively alters BCR microcluster formation, antigen aggregation, and downstream BCR signal transduction. Chemical inhibition of actin polymerization also altered the structure and integrity of BCR microclusters. Together, these findings highlight a crucial role for the cortical actin cytoskeleton during B cell spreading and microcluster formation and function.

scholarly journals Small GTP-binding Protein TC10 Differentially Regulates Two Distinct Populations of Filamentous Actin in 3T3L1 Adipocytes

2002 ◽  
Vol 13 (7) ◽  
pp. 2334-2346 ◽  
Author(s):  
Makoto Kanzaki ◽  
Robert T. Watson ◽  
June Chunqiu Hou ◽  
Mark Stamnes ◽  
Alan R. Saltiel ◽  
...  
Keyword(s):  
Protein Trafficking ◽  
Actin Polymerization ◽  
Coat Proteins ◽  
Filamentous Actin ◽  
Cortical Actin ◽  
Amino Terminal ◽  
Gtp Binding ◽  
Subcellular Compartmentalization ◽  
Constitutively Active

TC10 is a member of the Rho family of small GTP-binding proteins that has previously been implicated in the regulation of insulin-stimulated GLUT4 translocation in adipocytes. In a manner similar to Cdc42-stimulated actin-based motility, we have observed that constitutively active TC10 (TC10/Q75L) can induce actin comet tails in Xenopus oocyte extracts in vitro and extensive actin polymerization in the perinuclear region when expressed in 3T3L1 adipocytes. In contrast, expression of TC10/Q75L completely disrupted adipocyte cortical actin, which was specific for TC10, because expression of constitutively active Cdc42 was without effect. The effect of TC10/Q75L to disrupt cortical actin was abrogated after deletion of the amino terminal extension (ΔN-TC10/Q75L), whereas this deletion retained the ability to induce perinuclear actin polymerization. In addition, alteration of perinuclear actin by expression of TC10/Q75L, a dominant-interfering TC10/T31N mutant or a mutant N-WASP protein (N-WASP/ΔVCA) reduced the rate of VSV G protein trafficking to the plasma membrane. Furthermore, TC10 directly bound to Golgi COPI coat proteins through a dilysine motif in the carboxyl terminal domain consistent with a role for TC10 regulating actin polymerization on membrane transport vesicles. Together, these data demonstrate that TC10 can differentially regulate two types of filamentous actin in adipocytes dependent on distinct functional domains and its subcellular compartmentalization.

Abstract 20484: Enah/Vasp-Like Protein is a Critical Component in S1P-Mediated Endothelial Lamellipodia Formation

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Joseph B Mascarenhas ◽  
Ghassan Mouneimne ◽  
Carol C Gregorio ◽  
Mary E Brown ◽  
Ting Wang ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Human Lung ◽  
Actin Binding ◽  
Lipid Mediator ◽  
Dependent Manner ◽  
Cortical Actin ◽  
Pulmonary Endothelial Cells ◽  
Sphingosine 1 Phosphate ◽  
Barrier Regulation ◽  
Lamellipodia Formation

Ena/VASP like protein, or EVL, is an actin-binding protein that regulates cancer cell lamellipodia protrusive activity and cell motility via an actomyosin contractility-dependent mechanism. The function of EVL in human lung endothelial cell (EC) barrier regulation, especially by the endogenous bioactive lipid mediator sphingosine-1-phosphate (S1P), is largely unknown. In this current study, we demonstrated that EVL is an active component in S1P-mediated EC barrier enhancement and lamellipodia formation. Compared to other focal adhesion (FA) proteins such as paxillin, EVL protein expression is very low in human pulmonary endothelial cells (ECs). S1P (1 μM) challenge stimulates translocation of cytosolic EVL to FAs in ECs, which was attenuated by EVL knockdown (KD) by its selective siRNA. S1P also promoted significant EVL translocation to lamellipodia, further confirmed by tracking translocation of EVL-GFP fusion protein upon S1P stimulation in a time-dependent manner. In addition, S1P-mediated cortical actin filament formation is attenuated by EVL KD, further confirming the function of EVL in S1P-induced lamellipodia formation/cortical actin polymerization. S1P stimulates EVL phosphorylation by tyrosine kinase c-Abl which is attenuated by the c-Abl inhibitor, imatinib. Finally, EVL KD attenuated S1P-mediated EC barrier enhancement and paracellular gap resealing reflected by reduced transendothelial electrical resistance (TER) measurements. These findings confirm a novel role for EVL in human lung vascular barrier enhancement and cytoskeleton rearrangement by S1P.

scholarly journals Actin polymerization and intracellular solvent flow in cell surface blebbing.

1995 ◽  
Vol 129 (6) ◽  
pp. 1589-1599 ◽  
Author(s):  
C C Cunningham
Keyword(s):  
Cell Surface ◽  
Actin Polymerization ◽  
Surface Membrane ◽  
Control Cell ◽  
Cortical Actin ◽  
Final Size ◽  
Actin Structure ◽  
Close Study ◽  
A Cell ◽  
Solvent Flow

The cortical actin gel of eukaryotic cells is postulated to control cell surface activity. One type of protrusion that may offer clues to this regulation are the spherical aneurysms of the surface membrane known as blebs. Blebs occur normally in cells during spreading and alternate with other protrusions, such as ruffles, suggesting similar protrusive machinery is involved. We recently reported that human melanoma cell lines deficient in the actin filament cross-linking protein, ABP-280, show prolonged blebbing, thus allowing close study of blebs and their dynamics. Blebs expand at different rates of volume increase that directly predict the final size achieved by each bleb. These rates decrease as the F-actin concentration of the cells increase over time after plating on a surface, but do so at lower concentrations in ABP-280 expressing cells. Fluorescently labeled actin and phalloidin injections of blebbing cells indicate that a polymerized actin structure is not present initially, but appears later and is responsible for stopping further bleb expansion. Therefore, it is postulated that blebs occur when the fluid-driven expansion of the cell membrane is sufficiently rapid to initially outpace the local rate of actin polymerization. In this model, the rate of intracellular solvent flow driving this expansion decreases as cortical gelation is achieved, whether by factors such as ABP-280, or by concentrated actin polymers alone, thereby leading to decreased size and occurrence of blebs. Since the forces driving bleb extension would always be present in a cell, this process may influence other cell protrusions as well.

scholarly journals Actin polymerization controls the activation of multidrug efflux at fertilization by translocation and fine-scale positioning of ABCB1 on microvilli

2012 ◽  
Vol 23 (18) ◽  
pp. 3663-3672 ◽  
Author(s):  
Kristen Whalen ◽  
Adam M. Reitzel ◽  
Amro Hamdoun
Keyword(s):  
Cell Surface ◽  
Actin Polymerization ◽  
Sea Urchins ◽  
Three Dimensional ◽  
Cortical Reorganization ◽  
Fine Scale ◽  
Multidrug Efflux ◽  
Cortical Actin ◽  
Contrast Enhanced ◽  
And Function

Fertilization changes the structure and function of the cell surface. In sea urchins, these changes include polymerization of cortical actin and a coincident, switch-like increase in the activity of the multidrug efflux transporter ABCB1a. However, it is not clear how cortical reorganization leads to changes in membrane transport physiology. In this study, we used three-dimensional superresolution fluorescence microscopy to resolve the fine-scale movements of the transporter along polymerizing actin filaments, and we show that efflux activity is established after ABCB1a translocates to the tips of the microvilli. Inhibition of actin poly­merization or bundle formation prevents tip localization, resulting in the patching of ABCB1a at the cell surface and decreased efflux activity. In contrast, enhanced actin polymerization promotes tip localization. Finally, interference with Rab11, a regulator of apical recycling, inhibits activation of efflux activity in embryos. Together our results show that actin-mediated, short-range traffic and positioning of transporters at the cell surface regulates multidrug efflux activity and highlight the multifaceted roles of microvilli in the spatial distribution of membrane proteins.

Wave of cortical actin polymerization in the sea urchin egg

1987 ◽  
Vol 7 (1) ◽  
pp. 46-53 ◽  
Author(s):  
Shigenobu Yonemura ◽  
Issei Mabuchi
Keyword(s):  
Sea Urchin ◽  
Actin Polymerization ◽  
Cortical Actin ◽  
Sea Urchin Egg

scholarly journals The TRE17 Oncogene Encodes a Component of a Novel Effector Pathway for Rho GTPases Cdc42 and Rac1 and Stimulates Actin Remodeling

2003 ◽  
Vol 23 (6) ◽  
pp. 2151-2161 ◽  
Author(s):  
Jeffrey M. Masuda-Robens ◽  
Sara N. Kutney ◽  
Hongwei Qi ◽  
Margaret M. Chou
Keyword(s):  
Plasma Membrane ◽  
Rho Gtpases ◽  
Actin Polymerization ◽  
Dependent Manner ◽  
Cortical Actin ◽  
Actin Remodeling ◽  
Membrane Recruitment ◽  
Truncation Mutant ◽  
Effector Pathway

ABSTRACT The Rho family GTPases Cdc42 and Rac1 play fundamental roles in transformation and actin remodeling. Here, we demonstrate that the TRE17 oncogene encodes a component of a novel effector pathway for these GTPases. TRE17 coprecipitated specifically with the active forms of Cdc42 and Rac1 in vivo. Furthermore, the subcellular localization of TRE17 was dramatically regulated by these GTPases and mitogens. Under serum-starved conditions, TRE17 localized predominantly to filamentous structures within the cell. Epidermal growth factor (EGF) induced relocalization of TRE17 to the plasma membrane in a Cdc42-/Rac1-dependent manner. Coexpression of activated alleles of Cdc42 or Rac1 also caused complete redistribution of TRE17 to the plasma membrane, where it partially colocalized with the GTPases in filopodia and ruffles, respectively. Membrane recruitment of TRE17 by EGF or the GTPases was dependent on actin polymerization. Finally, we found that a C-terminal truncation mutant of TRE17 induced the accumulation of cortical actin, mimicking the effects of activated Cdc42. Together, these results identify TRE17 as part of a novel effector complex for Cdc42 and Rac1, potentially contributing to their effects on actin remodeling. The present study provides insights into the regulation and cellular function of this previously uncharacterized oncogene.

scholarly journals Arp2/3- and Cofilin-coordinated Actin Dynamics Is Required for Insulin-mediated GLUT4 Translocation to the Surface of Muscle Cells

2010 ◽  
Vol 21 (20) ◽  
pp. 3529-3539 ◽  
Author(s):  
Tim Ting Chiu ◽  
Nish Patel ◽  
Alisa E. Shaw ◽  
James R. Bamburg ◽  
Amira Klip
Keyword(s):  
Actin Polymerization ◽  
Molecular Mechanisms ◽  
Muscle Cells ◽  
Actin Dynamics ◽  
Cell Cortex ◽  
Glut4 Translocation ◽  
Filamentous Actin ◽  
Cortical Actin ◽  
Rac Gtpase ◽  
Skeletal Myoblasts

GLUT4 vesicles are actively recruited to the muscle cell surface upon insulin stimulation. Key to this process is Rac-dependent reorganization of filamentous actin beneath the plasma membrane, but the underlying molecular mechanisms have yet to be elucidated. Using L6 rat skeletal myoblasts stably expressing myc-tagged GLUT4, we found that Arp2/3, acting downstream of Rac GTPase, is responsible for the cortical actin polymerization evoked by insulin. siRNA-mediated silencing of either Arp3 or p34 subunits of the Arp2/3 complex abrogated actin remodeling and impaired GLUT4 translocation. Insulin also led to dephosphorylation of the actin-severing protein cofilin on Ser-3, mediated by the phosphatase slingshot. Cofilin dephosphorylation was prevented by strategies depolymerizing remodeled actin (latrunculin B or p34 silencing), suggesting that accumulation of polymerized actin drives severing to enact a dynamic actin cycling. Cofilin knockdown via siRNA caused overwhelming actin polymerization that subsequently inhibited GLUT4 translocation. This inhibition was relieved by reexpressing Xenopus wild-type cofilin-GFP but not the S3E-cofilin-GFP mutant that emulates permanent phosphorylation. Transferrin recycling was not affected by depleting Arp2/3 or cofilin. These results suggest that cofilin dephosphorylation is required for GLUT4 translocation. We propose that Arp2/3 and cofilin coordinate a dynamic cycle of actin branching and severing at the cell cortex, essential for insulin-mediated GLUT4 translocation in muscle cells.

scholarly journals The Transcription Factor AP-1 Is Required for EGF-induced Activation of Rho-like GTPases, Cytoskeletal Rearrangements, Motility, and In Vitro Invasion of A431 Cells

1998 ◽  
Vol 143 (4) ◽  
pp. 1087-1099 ◽  
Author(s):  
Angeliki Malliri ◽  
Marc Symons ◽  
Robert F. Hennigan ◽  
Adam F.L. Hurlstone ◽  
Richard F. Lamb ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Cortical Actin ◽  
A431 Cells ◽  
Membrane Ruffling ◽  
In Vitro Invasion ◽  
Cytoskeletal Rearrangements ◽  
Lamellipodia Formation

Human squamous cell carcinomas (SCC) frequently express elevated levels of epidermal growth factor receptor (EGFR). EGFR overexpression in SCC-derived cell lines correlates with their ability to invade in an in vitro invasion assay in response to EGF, whereas benign epidermal cells, which express low levels of EGFR, do not invade. EGF-induced invasion of SCC-derived A431 cells is inhibited by sustained expression of the dominant negative mutant of c-Jun, TAM67, suggesting a role for the transcription factor AP-1 (activator protein-1) in regulating invasion. Significantly, we establish that sustained TAM67 expression inhibits growth factor–induced cell motility and the reorganization of the cytoskeleton and cell-shape changes essential for this process: TAM67 expression inhibits EGF-induced membrane ruffling, lamellipodia formation, cortical actin polymerization and cell rounding. Introduction of a dominant negative mutant of Rac and of the Rho inhibitor C3 transferase into A431 cells indicates that EGF-induced membrane ruffling and lamellipodia formation are regulated by Rac, whereas EGF-induced cortical actin polymerization and cell rounding are controlled by Rho. Constitutively activated mutants of Rac or Rho introduced into A431 or A431 cells expressing TAM67 (TA cells) induce equivalent actin cytoskeletal rearrangements, suggesting that the effector pathways downstream of Rac and Rho required for these responses are unimpaired by sustained TAM67 expression. However, EGF-induced translocation of Rac to the cell membrane, which is associated with its activation, is defective in TA cells. Our data establish a novel link between AP-1 activity and EGFR activation of Rac and Rho, which in turn mediate the actin cytoskeletal rearrangements required for cell motility and invasion.

scholarly journals Microvilli-like structures are associated with the internalization of virulent capsulatedNeisseria meningitidisinto vascular endothelial cells

2002 ◽  
Vol 115 (6) ◽  
pp. 1231-1241 ◽  
Author(s):  
Emmanuel Eugène ◽  
Isabelle Hoffmann ◽  
Céline Pujol ◽  
Pierre-Olivier Couraud ◽  
Sandrine Bourdoulous ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Rho Gtpases ◽  
Actin Polymerization ◽  
Vascular Endothelial Cells ◽  
Transmembrane Proteins ◽  
Bacterial Attachment ◽  
Dominant Negative ◽  
Cortical Actin ◽  
Phagocytic Cells ◽  
Type Iv

Bacterial pathogens are internalized into non-phagocytic cells either by a zipper mechanism involving a direct contact between a bacterial ligand and a cellular receptor or a trigger mechanism secondary to the formation of membrane ruffles. Here we show that internalization of capsulated Neisseria meningitidis within endothelial cells following type IV pilus-mediated adhesion is associated with the formation of cellular protrusions at the site of bacterial attachment. These protrusions, like microvilli, are highly enriched in ezrin and moesin, two members of the ERM(ezrin/radixin/moesin) family, whereas vinculin and paxillin are absent. ERM-binding transmembrane proteins, such as CD44, and cortical actin polymerization colocalized within these membrane protrusions. Expression of dominant-negative ezrin largely prevented cortical actin polymerization, thus confirming the role of this molecule in bacteria-induced cytoskeletal modifications. Moreover, using selective inhibitors and dominant-negative mutants of the Rho family GTPases, we show that bacteria-induced actin polymerization required the activation of both Rho and Cdc42 but not of Rac1. Whereas GTPase inhibition dramatically reduced actin polymerization at the site of bacterial attachment, ezrin recruitment was not affected, indicating that bacterial adhesion promotes ezrin recruitment independently of the activity of the Rho-GTPases. Furthermore, GTPase inhibition largely reduced N. meningitidis entry into endothelial cells without affecting adhesion. We thus propose that following pilus-mediated adhesion, capsulated N. meningitidis recruit ERM-binding transmembrane proteins, as well as ezrin and moesin, and that both Rho and Cdc42 are critical for the subsequent cytoskeletal modifications responsible for the formation of microvilli-like cellular protrusions and bacterial internalization.

Sign in / Sign up

Export Citation Format

Share Document