Cell adhesion and the actin cytoskeleton of the enveloping layer in the zebrafish embryo during epiboly

1999 ◽  
Vol 77 (6) ◽  
pp. 527-542 ◽  
Author(s):  
Sara E Zalik ◽  
Ewa Lewandowski ◽  
Zvi Kam ◽  
Benjamin Geiger
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Zebrafish Embryo ◽  
Cultured Cells ◽  
Kinase Inhibitor ◽  
Embryonic Cells ◽  
Cortical Actin ◽  
Actin Cables

As the zebrafish embryo undergoes gastrulation and epiboly, the cells of the enveloping layer (EVL) expand, covering the entire yolk cell. During the epiboly process, the EVL cells move as a coherent layer, remaining tightly attached to each other and to the underlying yolk syncytial layer (YSL). In view of the central role of the actin cytoskeleton, in both cell motility and cell cell adhesion, we have labeled these cells in situ with fluorescent phalloidin and anti-actin antibodies. We show that, throughout their migration, the EVL cells retain a conspicuous cortical actin cytoskeletal belt coinciding with cell surface cadherins. At the margins approaching the YSL, the EVL cells extend, from their apicolateral domains, actin-rich filopodial protrusions devoid of detectable cadherin. We have studied the role of the actin cytoskeleton in the maintenance of EVL cohesion during epiboly. Cytochalasin treatment of embryos induces EVL dissociation accompanied by general detachment of the rest of the embryonic cells. In the dissociating EVL cells, the cortical actin belt undergoes fragmentation with the formation of actin aggregates; cadherins, on the other hand, remain evenly distributed at the junctional cell surface. Removal of Ca2+ by ethyleneglycolbis (amino-ethyl-ether)-tetraacetic acid (EGTA) treatment also induces cell dissociation without visible disruption of the cortical actin belt. The protein kinase inhibitor (1-isoquinolinylsulfonyl)-2-methyl-piperazine dihydrochloride (H-7), which blocks acto-myosin contractility and disrupts actin cables in cultured cells, also potentiates cytochalasin-induced dissociation and promotes the projection of numerous actin-rich lamellipodial extensions. The fact that EVL cells produce microspike-like structures towards the YSL and are capable of lamellipodial activity lend further support to the suggestion (R.W. Keller and J.P. Trinkaus. 1987. Dev. Biol. 120: 12-24) that the EVL cells are not passively mobilized on the expanding YSL but actively participate in epiboly.Key words: actin, adhesion, cadherin, cytochalasin, embryo, zebrafish.

scholarly journals Dual role of the actin cytoskeleton in regulating cell adhesion mediated by the integrin lymphocyte function-associated molecule-1.

1997 ◽  
Vol 8 (2) ◽  
pp. 341-351 ◽  
Author(s):  
M Lub ◽  
Y van Kooyk ◽  
S J van Vliet ◽  
C G Figdor
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Ligand Binding ◽  
Actin Cytoskeleton ◽  
Interleukin 2 ◽  
Peripheral Blood Lymphocytes ◽  
Lymphocyte Function ◽  
Intracellular Signals ◽  
Cytoskeletal Elements

Intracellular signals are required to activate the leukocyte-specific adhesion receptor lymphocyte function-associated molecule-1 (LFA-1; CD11a/CD18) to bind its ligand, intracellular adhesion molecule-1 (ICAM-1). In this study, we investigated the role of the cytoskeleton in LFA-1 activation and demonstrate that filamentous actin (F-actin) can both enhance and inhibit LFA-1-mediated adhesion, depending on the distribution of LFA-1 on the cell surface. We observed that LFA-1 is already clustered on the cell surface of interleukin-2/phytohemagglutinin-activated lymphocytes. These cells bind strongly ICAM-1 and disruption of the actin cytoskeleton inhibits adhesion. In contrast to interleukin-2/phytohemagglutinin-activated peripheral blood lymphocytes, resting lymphocytes, which display a homogenous cell surface distribution of LFA-1, respond poorly to intracellular signals to bind ICAM-1, unless the actin cytoskeleton is disrupted. On resting peripheral blood lymphocytes, uncoupling of LFA-1 from the actin cytoskeleton induces clustering of LFA-1 and this, along with induction of a high-affinity form of LFA-1, via "inside-out" signaling, results in enhanced binding to ICAM-1, which is dependent on intact intermediate filaments, microtubules, and metabolic energy. We hypothesize that linkage of LFA-1 to cytoskeletal elements prevents movement of LFA-1 over the cell surface, thus inhibiting clustering and strong ligand binding. Release from these cytoskeletal elements allows lateral movement and activation of LFA-1, resulting in ligand binding and "outside-in" signaling, that subsequently stimulates actin polymerization and stabilizes cell adhesion.

scholarly journals Role of Actin and Myo2p in Polarized Secretion and Growth ofSaccharomyces cerevisiae

2000 ◽  
Vol 11 (5) ◽  
pp. 1727-1737 ◽  
Author(s):  
Tatiana S. Karpova ◽  
Samara L. Reck-Peterson ◽  
N. Barry Elkind ◽  
Mark S. Mooseker ◽  
Peter J. Novick ◽  
...  
Keyword(s):  
Cell Surface ◽  
Surface Growth ◽  
Polarized Growth ◽  
Tail Domain ◽  
Filamentous Actin ◽  
Cortical Actin ◽  
Polarized Secretion ◽  
Actin Patch ◽  
Actin Cables

We examined the role of the actin cytoskeleton in secretion inSaccharomyces cerevisiae with the use of several quantitative assays, including time-lapse video microscopy of cell surface growth in individual living cells. In latrunculin, which depolymerizes filamentous actin, cell surface growth was completely depolarized but still occurred, albeit at a reduced level. Thus, filamentous actin is necessary for polarized secretion but not for secretion per se. Consistent with this conclusion, latrunculin caused vesicles to accumulate at random positions throughout the cell. Cortical actin patches cluster at locations that correlate with sites of polarized secretion. However, we found that actin patch polarization is not necessary for polarized secretion because a mutant,bee1Δ(las17Δ), which completely lacks actin patch polarization, displayed polarized growth. In contrast, a mutant lacking actin cables, tpm1-2 tpm2Δ, had a severe defect in polarized growth. The yeast class V myosin Myo2p is hypothesized to mediate polarized secretion. A mutation in the motor domain of Myo2p,myo2-66, caused growth to be depolarized but with only a partial decrease in the level of overall growth. This effect is similar to that of latrunculin, suggesting that Myo2p interacts with filamentous actin. However, inhibition of Myo2p function by expression of its tail domain completely abolished growth.

Trimers of the fibronectin cell adhesion domain localize to actin filament bundles and undergo rearward translocation

2002 ◽  
Vol 115 (12) ◽  
pp. 2581-2590 ◽  
Author(s):  
Françoise Coussen ◽  
Daniel Choquet ◽  
Michael P. Sheetz ◽  
Harold P. Erickson
Keyword(s):  
Cell Adhesion ◽  
Fluorescence Microscopy ◽  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Fiber Bundles ◽  
Cell Surfaces ◽  
Actin Fiber ◽  
Filament Bundles ◽  
Necessary And Sufficient ◽  
Small Clusters

Previous studies have shown that small beads coated with FN7-10, a four-domain cell adhesion fragment of fibronectin, bind to cell surfaces and translocate rearward. Here we investigate whether soluble constructs containing two to five FN7-10 units might be sufficient for activity. We have produced a monomer, three forms of dimers, a trimer and a pentamer of FN7-10,on the end of spacer arms. These oligomers could bind small clusters of up to five integrins. Fluorescence microscopy showed that the trimer and pentamer bound strongly to the cell surface, and within 5 minutes were prominently localized to actin fiber bundles. Monomers and dimers showed only diffuse localization. Beads coated with a low concentration (probably one complex per bead) of trimer or pentamer showed prolonged binding and rearward translocation, presumably with the translocating actin cytskeleton. Beads containing monomer or dimer showed only brief binding and diffusive movements. We conclude that clusters of three integrin-binding ligands are necessary and sufficient for coupling to and translocating with the actin cytoskeleton.

Potential Therapeutic Role of the Selective Adhesion Molecule (SAM) Inhibitor Natalizumab in Multiple Myeloma.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1850-1850 ◽  
Author(s):  
Klaus Podar ◽  
Alexander Zimmerhackl ◽  
Ursula Hainz ◽  
Mariateresa Fulciniti ◽  
Sonia Vallet ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Cell Migration ◽  
Cell Adhesion ◽  
Cell Surface ◽  
Adhesion Molecule ◽  
Research Funding ◽  
Therapeutic Role ◽  
Potential Therapeutic Role

Abstract Abstract 1850 Poster Board I-876 Multiple Myeloma (MM) is characterized by the clonal proliferation of malignant plasma cells in the bone marrow. Despite current therapeutic approach and prolongation of the median survival, new therapies are urgently needed. Integrins are cell surface receptors which mediate both cell-cell adhesion and cell-extracellular matrix (ECM) protein adhesion. beta1-integrins, including very-late antigen-4 (VLA-4;á4β1), are typically expressed on MM cells. In MM, VLA-4-mediated binding to ECMS and bone marrow stromal cells (BMSCs) confers protection against drug-induced apoptosis and triggers transcription and secretion of IL-6, the major MM growth and survival factor. In addition to up-regulation of cell surface-clustering, integrin activity can also be triggered by multiple agonists through ‘inside-out’ signaling, independent of changes in integrin expression levels. Importantly, VEGF-induced migration of MM cells on fibronectin is also associated with β1-integrin- and PI3-kinase- dependent PKC activation. Targeting VLA-4 is therefore of potential high therapeutic interest in MM. Indeed, an antibody against murine á4 induces inhibition of MM growth in a murine model. Natalizumab is a recombinant humanized IgG4 monoclonal antibody, which belongs to a new class of molecules known as selective adhesion molecule (SAM) inhibitors and binds to á4-integrin. Clinically, Natalizumab has demonstrated activity in patients with multiple sclerosis and Crohn's disease. Here we tested the potential therapeutic role of Natalizumab on MM cell survival, and migration in the BM microenvironment. VLA-4 is expressed by all MM cell lines investigated (NCIH929, RPMI8226, INA-6, MM.1S, and OPM2). Functionally, Natalizumab but not a control antibody, triggered dose-dependent inhibition of MM cell adhesion to fibronectin, BMSCs, and endothelial cells (ECs). Importantly, inhibition of adhesion to fibronectin, BMSCs, or ECs was observed in MM cells pretreated with Natalizumab. Moreover, inhibition of MM cell adhesion to fibronectin, BMSCs, or ECs was also observed when Natalizumab was added to already adherent MM cells. Taken together, Natalizumab decreases adhesion of non-adherent MM cells as well as binding of already adherent MM cells to non-cellular and cellular components of the microenvironment. Given the protective role of the microenvironment on MM cell survival, we next sought to evaluate the chemosensitizing activity of Natalizumab. Specifically, we investigated dose- and time- dependent effects of Natalizumab, alone and when combined with conventional and novel therapies, on MM cells. Our results show that Natalizumab alone did not inhibit growth or survival of MM cells when cultured without components of the microenvironment. However, Natalizumab enhanced sensitivity of tumor cells to both bortezomib and dexamethasone in MM-BMSC and, MM-EC co-cultures. These data indicate a potential role of Natalizumab in bortezomib- and dexamethasone-containing treatment regimens including MPV. Moreover, Natalizumab decreases IL-6 and VEGF secretion triggered in MM-BMSC co-cultures. Consequently, angiogenesis triggered by supernatants of Natalizumab- treated MM-BMSC co-cultures was inhibited. Moreover, Natalizumab blocked MM cell migration on fibronectin triggered by both VEGF and IGF-1. Finally, our previous results implicate an PKC signaling in MM cell migration on fibronectin, and our current results show that Natalizumab inhibits phosphorylation of á4 integrins and PKC induced by co-stimulation with VEGF/ fibronectin, IGF-1/ fibronectin, and patient serum. Taken together, our data indicate a potential therapeutic role of Natalizumab in MM. Ongoing studies evaluating the effect of Natalizumab in a SCID-hu murine model of MM will also be reported. Disclosures: Podar: Biogen Idec: Research Funding. Off Label Use: natalizumab, integrin inhibitor. Zimmerhackl:Biogen Idec: Research Funding. Olsen:Biogen Idec: Employment.

Calreticulin and focal-contact-dependent adhesion

2009 ◽  
Vol 87 (4) ◽  
pp. 545-556 ◽  
Author(s):  
Maria Villagomez ◽  
Eva Szabo ◽  
Alexey Podcheko ◽  
Tianshu Feng ◽  
Sylvia Papp ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Tyrosine Phosphorylation ◽  
Binding Proteins ◽  
Expression Level ◽  
Cellular Proteins ◽  
Focal Contact ◽  
Cellular Compartments

Cell adhesion is regulated by a variety of Ca2+-regulated pathways that depend on Ca2+-binding proteins. One such protein is calreticulin, an ER-resident protein. Calreticulin signalling from within the ER can affect processes outside the ER, such as expression of several adhesion-related genes, most notably vinculin and fibronectin. In addition, changes in the expression level of calreticulin strongly affect tyrosine phosphorylation of cellular proteins, which is known to affect many adhesion-related functions. While calreticulin has been localized to cellular compartments other than the ER, it appears that only the ER-resident calreticulin affects focal-contact-dependent adhesion. In contrast, calreticulin residing outside the ER may be involved in contact disassembly and other adhesion phenomena. Here, we review the role of calreticulin in focal contact initiation, stabilization, and turnover. We propose that calreticulin may regulate cell–substratum adhesion by participating in an “ER-to-nucleus” signalling and in parallel “ER-to-cell surface” signalling based on posttranslational events.

scholarly journals Novel insights into Entamoeba cyst wall formation and the importance of actin cytoskeleton

2020 ◽  
Author(s):  
Deepak Krishnan ◽  
Santhoshi Nayak ◽  
Sudip Kumar Ghosh
Keyword(s):  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Cyst Wall ◽  
Distinct Point ◽  
New Drugs ◽  
Chitin Synthase ◽  
Cortical Actin ◽  
Wall Formation ◽  
Entamoeba Invadens ◽  
Wall Components

AbstractThe cyst wall of Entamoeba histolytica, the causative agent of the amoebiasis, is a potential target for new drugs. The “Wattle and Daub” model of cyst wall formation of Entamoeba invadens had already been reported. In this study, we demonstrate in more detail the morphological stages of chitin wall formation in E. invadens using fluorescent chitin-binding dyes and immunolocalization of the cyst wall proteins. Here, the expression and localization of chitin synthase and the importance of actin cytoskeleton dynamics at cellular level, during encystations have been demonstrated for the first time. Chitin deposition was found to be initiated on the cell surface mostly from one distinct point, though multipoint initiation was also observed sometimes. From these points, the wall grew outwards and gradually covered the entire cyst surface with time. The initiation of chitin deposition was guided by the localization of chitin synthase 1 on the plasma membrane. The gradual formation of the cyst wall follows the Wattle and daub model. The chitin deposition occurred on the foundation of Jacob lectin at the cell membrane, and the other cyst wall components, like chitinase, and Jessie were also found to be present in the growing incomplete walls. In contrary to the Wattle and daub model, Jessie was found to be expressed and localized in the growing wall at the early hours of encystations. During encystation, F-actin was reorganized into the cortical region within an hour encystation initiation and remained intact until the completion of the chitin wall. Disruption of cortical actin polymerization with 2, 3-Butanedione monoxime inhibited proper wall formation but produced wall-less cysts or cysts with defective chitin wall. Malformations of cyst-walls were mainly due to improper localization and activity of chitin synthases, which indicates the indispensability of cortical actin cytoskeleton for the proper cyst wall formation.Author SummaryEntamoeba parasites reach new hosts using the resistant cyst form, so preventing its formation can stop the spread of amoebiasis. The resistant nature of the cyst is due to the chitin wall, and thus identifying the critical steps of wall formation could provide targets for designing new drugs. Here we studied the morphological stages of the cyst wall formation by observing how the chitin and other cell wall components were deposited on the cell surface using fluorescent chitin-binding dyes and antibodies against cyst wall proteins. In most cases, the chitin wall was found to start from one distinct point from which it spread all over the cell surface, guided by chitin synthase. The composition of these incomplete walls was the same as a mature cyst wall indicating that the wall may be a result of extracellular self-assembly of its constituents from one starting point. We have also observed that F-actin polymerized in the cortex of encysting cells and its disruption resulted in wall-less cysts or cysts with aberrant walls showing the importance of actin cytoskeleton in proper chitin deposition.

scholarly journals The role of spectrin in cell adhesion and cell–cell contact

2019 ◽  
Vol 244 (15) ◽  
pp. 1303-1312 ◽  
Author(s):  
Beata Machnicka ◽  
Renata Grochowalska ◽  
Dżamila M Bogusławska ◽  
Aleksander F Sikorski
Keyword(s):  
Extracellular Matrix ◽  
Cell Adhesion ◽  
Cell Surface ◽  
Cell Biology ◽  
Membrane Integrity ◽  
Cell Contact ◽  
Surface Activities ◽  
New Findings ◽  
Cell Cell

Spectrins are proteins that are responsible for many aspects of cell function and adaptation to changing environments. Primarily the spectrin-based membrane skeleton maintains cell membrane integrity and its mechanical properties, together with the cytoskeletal network a support cell shape. The occurrence of a variety of spectrin isoforms in diverse cellular environments indicates that it is a multifunctional protein involved in numerous physiological pathways. Participation of spectrin in cell–cell and cell–extracellular matrix adhesion and formation of dynamic plasma membrane protrusions and associated signaling events is a subject of interest for researchers in the fields of cell biology and molecular medicine. In this mini-review, we focus on data concerning the role of spectrins in cell surface activities such as adhesion, cell–cell contact, and invadosome formation. We discuss data on different adhesion proteins that directly or indirectly interact with spectrin repeats. New findings support the involvement of spectrin in cell adhesion and spreading, formation of lamellipodia, and also the participation in morphogenetic processes, such as eye development, oogenesis, and angiogenesis. Here, we review the role of spectrin in cell adhesion and cell–cell contact.Impact statementThis article reviews properties of spectrins as a group of proteins involved in cell surface activities such as, adhesion and cell–cell contact, and their contribution to morphogenesis. We show a new area of research and discuss the involvement of spectrin in regulation of cell–cell contact leading to immunological synapse formation and in shaping synapse architecture during myoblast fusion. Data indicate involvement of spectrins in adhesion and cell–cell or cell–extracellular matrix interactions and therefore in signaling pathways. There is evidence of spectrin’s contribution to the processes of morphogenesis which are connected to its interactions with adhesion molecules, membrane proteins (and perhaps lipids), and actin. Our aim was to highlight the essential role of spectrin in cell–cell contact and cell adhesion.

scholarly journals Essential role of MARCKS in cortical actin dynamics during gastrulation movements

2004 ◽  
Vol 164 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Hidekazu Iioka ◽  
Naoto Ueno ◽  
Noriyuki Kinoshita
Keyword(s):  
Wnt Pathway ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Convergent Extension ◽  
Embryonic Cells ◽  
Cortical Actin ◽  
Morphogenetic Movements ◽  
Kinase Substrate ◽  
Cytoskeletal Regulation

Myristoylated alanine-rich C kinase substrate (MARCKS) is an actin-binding, membrane-associated protein expressed during Xenopus embryogenesis. We analyzed its function in cytoskeletal regulation during gastrulation. Here, we show that blockade of its function impaired morphogenetic movements, including convergent extension. MARCKS was required for control of cell morphology, motility, adhesion, protrusive activity, and cortical actin formation in embryonic cells. We also demonstrate that the noncanonical Wnt pathway promotes the formation of lamellipodia- and filopodia-like protrusions and that MARCKS is necessary for this activity. These findings show that MARCKS regulates the cortical actin formation that is requisite for dynamic morphogenetic movements.

Cdc42 and RhoA have opposing roles in regulating membrane type 1-matrix metalloproteinase localization and matrix metalloproteinase-2 activation

2008 ◽  
Vol 295 (3) ◽  
pp. C600-C610 ◽  
Author(s):  
Eric Ispanovic ◽  
Damiano Serio ◽  
Tara L. Haas
Keyword(s):  
Endothelial Cells ◽  
Cell Surface ◽  
Matrix Metalloproteinase ◽  
Actin Cytoskeleton ◽  
Cortical Actin ◽  
Rhoa Activity ◽  
Surface Localization ◽  
Cell Surface Localization ◽  
Membrane Type

Proteolysis of the basement membrane and interstitial matrix occurs early in the angiogenic process and requires matrix metalloproteinase (MMP) activity. Skeletal muscle microvascular endothelial cells exhibit robust actin stress fibers, low levels of membrane type 1 (MT1)-MMP expression, and minimal MMP-2 activation. Depolymerization of the actin cytoskeleton increases MT1-MMP expression and MMP-2 activation. Rho family GTPases are regulators of actin cytoskeleton dynamics, and their activity can be modulated in response to angiogenic stimuli such as vascular endothelial growth factor (VEGF). Therefore, we investigated their roles in MMP-2 and MT1-MMP production. Endothelial cells treated with H1152 [an inhibitor of Rho kinase (ROCK)] induced stress fiber depolymerization and an increase in cortical actin. Both MMP-2 and MT1-MMP mRNA increased, which translated into greater MMP-2 protein production and activation. ROCK inhibition rapidly increased cell surface localization of MT1-MMP and increased PI3K activity, which was required for MMP-2 activation. Constitutively active Cdc42 increased cortical actin polymerization, phosphatidylinositol 3-kinase activity, MT1-MMP cell surface localization, and MMP-2 activation similarly to inhibition of ROCK. Activation of Cdc42 was sufficient to decrease RhoA activity. Capillary sprout formation in a three-dimensional collagen matrix was increased in cultures treated with RhoAN19 or Cdc42QL and, conversely, decreased in cultures treated with dominant negative Cdc42N17. VEGF stimulation also induced activation of Cdc42 while inhibiting RhoA activity. Furthermore, VEGF-dependent activation of MMP-2 was reduced by inhibition of Cdc42. These results suggest that Cdc42 and RhoA have opposing roles in regulating cell surface localization of MT1-MMP and MMP-2 activation.

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