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Results for “Cell Adhesion”

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PubMed2000

Rho family proteins in cell adhesion and cell migration.

Cell migration and the regulation of cadherin-mediated homotypic cell-cell interactions are critical events during development, morphogenesis and wound healing. Aberrations in signalling pathways involved in the regulation of cell migration and cadherin-mediated cell-cell adhesion contribute to tumour invasion and metastasis. The rho family proteins, including cdc42, rac1 and rhoA, regulate signalling pathways that mediate the distinct actin cytoskeleton changes required for both cellular motility and cell-cell adhesion. Recent studies indicate that rac directly influences rho activity at the GTPase level and that the reciprocal balance between rac and rho activity can determine epithelial or mesenchymal cell morphology and migratory behaviour of epithelial (tumour) cells.

Cadherins↗

PubMed2001

Alteration of cell adhesion and cell cycle properties of ES cells by an inducible dominant interfering Myb mutant.

The Myb transcription factors, c-Myb, A-Myb, and B-Myb, regulate cell differentiation and/or proliferation. To investigate the role of B-Myb in embryogenesis, we introduced an inducible dominant interfering Myb protein (MERT) into embryonic stem (ES) cells, which express B-Myb as an exclusive member of Myb family. Disruption of normal B-Myb function by the conditional activation of MERT caused a drastic morphological alteration of ES cells and G(1)-S cell cycle arrest. The inhibition of B-Myb function by MERT dissociated tightly packed ES cell colonies into dispersed single cells that subsequently detached from the culture dish. Cell adhesion analyses revealed that suppression of B-Myb function reduced the adhesion with extracellular matrix proteins, such as laminin, collagen, and fibronectin. This reduction was presumably due to decreased cell surface expression of beta1 integrin. Embryoid body formation was also severely retarded by the activation of MERT. This impairment was attributed to reduced expression of E-cadherin, which functions as a homophilic intercellular adhesion molecule. Simultaneously, blocking B-Myb function did not alter the expression of differentiation markers. Our data indicate that B-Myb plays important roles in regulating cell adhesion and cell cycle progression. These results are well consistent with the recent report on the phenotype of B-Myb null mice and show that the regulation of cell adhesion is an important B-Myb function that has not yet been assumed.

Animals↗

PubMed2005

Regulation of cell adhesion.

Cell function usually requires an accurate control of attachment to and detachment from many other cells or biological surfaces. This is usually achieved by a combination of multiple cell processes the relative importance of which may be difficult to assess. The aim of this review is to discuss the role of different mechanisms used to control adhesion on the basis of selected examples and recently developed methodologies allowing quantitative study of cell adhesion. It is concluded that cells control adhesion by modifying (i) adhesion receptor expression, as a consequence of exocytosis, endocytosis, or proteolytic mechanisms, (ii) adhesion receptor intrinsic activity, through a variety of conformational changes, (iii) receptor organisation in cell membranes, as a consequence of topographical distribution and clustering, lateral mobility, and strength of anchoring to the cytoskeleton, and (iv) general processes unrelated to a specific receptors, such as glycocalyx changes or modification of cell shape or surface mechanical properties.

Animals↗

PubMed2001

Expression of neural cell adhesion molecules (polysialylated form of neural cell adhesion molecule and L1-cell adhesion molecule) on resected small cell lung cancer specimens: in relation to proliferation state.

BACKGROUND AND OBJECTIVES: Alteration of homotypic cell-cell adhesion has been suggested to play an important role in tumor progression. The present study examined the relationship between neural cell adhesion molecules and state of proliferation of small cell lung cancer (SCLC) cells. METHODS: Seventeen surgically resected specimens of SCLC were immunohistochemically examined, by using monoclonal antibodies against neural cell adhesion molecule (NCAM) and its polysialic acid side chains, and L1 cell adhesion molecule (L1-CAM). Ki-67 labeling indices were also determined immunohistochemically. RESULTS: All patients were positive for L1-CAM. Fifteen patients (88.2%) were positive for NCAM. Among the fifteen patients, nine (60.0%) were positive for NCAM PSA side chain. The probability of survival of the NCAM without PSA side chain group was significantly higher than that of the NCAM with PSA side chain group (log-rank test; P = 0.500). CONCLUSIONS: The expression of NCAM with PSA side chains might be a prognostic factor and NCAM a marker for SCLC. L1-CAM may be synthesized independent of state of proliferation of individual tumor cell and may affect clinical feature of SCLC.

Adolescent↗

PubMed1991

Identification of cytoskeletal, focal adhesion, and cell adhesion proteins in growth cone particles isolated from developing chick brain.

Growth cones are intimately involved in determining the direction and extent of neurite elongation during development. They are able to monitor their environment and respond to it by undergoing directed motility. We have isolated a fraction enriched in growth cone particles from embryonic chick brain. Assayed by immunoblots, this fraction is enriched in GAP-43, and contains the cytoskeletal proteins actin, myosin II, neurofilament protein, tubulin, kinesin, and dynamin. All of the major components of focal adhesions are also present: alpha-actinin, vinculin, talin, and integrin. In addition to integrin, we also identify the cell adhesion molecules A-CAM, L1, fibronectin, and laminin in these particles. This preparation of isolated growth cone particles may be a useful model system for studying growth cone adhesion and motility.

Actinin↗

PubMed1997

Correlation between substratum roughness and wettability, cell adhesion, and cell migration.

Cell adhesion and spreading of chick embryo vascular and corneal explants grown on rough and smooth poly (methyl methacrylate) (PMMA) were analyzed to test the cell response specificity to substratum surface properties. Different degrees of roughness were obtained by sand-blasting PMMA with alumina grains. Hydrophilic and hydrophobic components of the surface free energy (SFE) were calculated according to Good-van Oss's model. Contact angles were determined using a computerized angle meter. The apolar component of the SFE gamma s(LW), increased with a slight roughness whereas the basic component, gamma s-, decreased. The acido-basic properties disappeared as roughness increased. Incubation of PMMA in culture medium, performed to test the influence if the biological environment, allowed surface adsorption of medium proteins which annihilated roughness effect and restored hydrophilic properties. An organotypic culture assay was carried out in an attempt to relate the biocompatibility to substratum surface state. Cell migration was calculated from the area of cell layer. Cellular adhesion was determined by measuring the kinetic of release of enzymatically dissociated cells. A slight roughness raised the migration are to an upper extent no matter which cell type. Enhancement of the cell adhesion potential was related to the degree of roughness and the hydrophobicity.

Animals↗

PubMed1991

Tumor necrosis factor combines with IL-4 or IFN-gamma to selectively enhance endothelial cell adhesiveness for T cells. The contribution of vascular cell adhesion molecule-1-dependent and -independent binding mechanisms.

The adhesion of lymphocytes to vascular endothelium is the first step in their passage from the blood into inflammatory tissues. By modulating endothelial cell (EC) adhesiveness for lymphocytes, cytokines may regulate lymphocyte accumulation and hence the nature and progression of inflammatory responses. IL-1, TNF, IFN-gamma, and IL-4 each increase EC adhesiveness for T cells when used alone in adhesion assays in vitro. As cytokines are more likely to act in combination at sites of inflammation in vivo, we have studied the stimulating effect of different combinations of cytokines on EC adhesiveness for T cells and polymorphonuclear leukocytes (PMN). Acting alone IL-1, TNF, IFN-gamma, and IL-4 each significantly enhanced EC adhesiveness for T cells (p less than 0.005), whereas only IL-1 (p less than 0.005) and TNF (p less than 0.005) but not IFN-gamma or IL-4 significantly enhanced adhesiveness for PMN. When EC were stimulated with optimal concentrations of TNF in combination with IL-4 or IFN-gamma, there was a significant further increase in adhesiveness for T cells (p less than 0.003), but not PMN, over that seen with TNF alone. The additive effect of TNF and IL-4 was more marked than that of TNF and IFN-gamma. Although approximately equal proportions of T cells and PMN bound to TNF-stimulated EC, nearly double the proportion of T cells compared with PMN bound EC preincubated with TNF and IL-4 together. A similar interaction with IL-4 or IFN-gamma was exhibited by lymphotoxin. mAb-inhibition studies indicated that the extra increase in binding caused by stimulating EC with TNF and IL-4 in combination was mediated by VCAM-1 whereas that caused by stimulating with TNF and IFN-gamma in combination was substantially mediated through leukocyte function-associated Ag-1- and VCAM-1-independent mechanisms. These observations suggest that whereas IL-1 and TNF alone are unselective in terms of leukocyte adhesion to EC, the combination of TNF (or LT) with IL-4 or IFN-gamma may be of key importance in determining the recruitment of a lymphocyte-predominant infiltrate in immune mediated inflammation, and in initiating the transition from acute to chronic inflammation.

Antibodies, Monoclonal↗

PubMed2004

Expression of cholecystokinin-2/gastrin receptor in the murine pancreas modulates cell adhesion and cell differentiation in vivo.

The presence of gastrin and cholecystokinin-2 (CCK2) receptors in human preneoplastic and neoplastic gastrointestinal lesions suggests a role in cancer development. In addition to the growth-promoting action of gastrin, recently a role of the cholecystokinin-2/gastrin receptor (CCK2-R) modulating cellular morphology in cultured epithelial cells has been shown. Here, we have investigated in transgenic (ElasCCK2) mice whether ectopic expression of human CCK2-R in the exocrine pancreas affected epithelial differentiation. Cellular localization of cell adhesion molecules, differentiation markers, and transcription factors was determined using immunofluorescence techniques. Before tumor formation, expression and subcellular localization of proteins of the adherens junction complex, differentiation markers, and transcription factors were altered in ElasCCK2 exocrine pancreas, indicating an evolution from an acinar to a ductal phenotype. Loss of cell polarity, defective secretion, and loss of intercellular adhesion in acini of ElasCCK2 mice was confirmed by ultrastructural analysis. Finally, expression of the transgene in mice treated with the carcinogen azaserine resulted in enhanced size of preneoplastic lesions as well as an increased degree of acinar-ductal transdifferentiation. Thus, these data represent the first evidence for the CCK2-R modulating intercellular adhesion and cell fate in vivo and show that these alterations may contribute to enhanced sensitivity of ElasCCK2 pancreas to chemical carcinogens.

Animals↗

PubMed1998

A novel Dictyostelium cell surface protein important for both cell adhesion and cell sorting.

A mutant of Dictyostelium that is aberrant in the process of tip formation (dtfA-: defective in tip formation A) has been isolated by gene tagging. The dtfA gene is predicted to encode a protein of 163 kDa. There are no extensive sequence homologies between DTFA and previously identified proteins, but four short N-terminal sequence motifs show partial homology to repeats found in mammalian mucins. Immunofluorescence reveals a lattice-like arrangement of DTFA protein at the cell surface. When developing on a bacterial lawn, cells of the mutant strain (dtfA- cells) aggregate to form tight mounds, but development then becomes arrested. When developed in the absence of nutrients, a fraction of dtfA- cells complete development, but there is a long delay at the tight mound stage and the culminants that eventually form are aberrant. In such dtfA- mounds the prestalk cells fail to move to the apex on cue and so tip formation is delayed. dtfA- cells also show a conditional defect in early development, in that they are unable to aggregate when plated at low density. In addition dtfA- cells do not agglomerate efficiently when shaken in suspension. In combination, these results suggest that DTFA may form part of a cell-cell adhesion system that is needed both for optimal aggregation and for efficient cell sorting during multicellular development. The DTFA protein also appears to be important during cell growth, because cytokinesis is defective and the actin cytoskeleton aberrant in growing dtfA- cells.

Amino Acid Sequence↗

PubMed2000

Roles for the protein tyrosine phosphatase SHP-2 in cytoskeletal organization, cell adhesion and cell migration revealed by overexpression of a dominant negative mutant.

SHP-2, a SRC homology 2 domain-containing protein tyrosine phosphatase, mediates activation of Ras and mitogen-activated protein kinase by various mitogens and cell adhesion. Inhibition of endogenous SHP-2 by overexpression of a catalytically inactive (dominant negative) mutant in Chinese hamster ovary cells or Rat-1 fibroblasts has now been shown to induce a marked change in cell morphology (from elongated to less polarized) that is accompanied by substantial increases in the numbers of actin stress fibers and focal adhesion contacts. Overexpression of the SHP-2 mutant also increased the strength of cell-substratum adhesion and resulted in hyperphosphorylation of SHPS-1, a substrate of SHP-2 that contributes to cell adhesion-induced signaling. Inhibition of SHP-2 also markedly increased the rate of cell attachment to and cell spreading on extracellular matrix proteins such as fibronectin and vitronectin, effects that were accompanied by enhancement of adhesion-induced tyrosine phosphorylation of paxillin and p130Cas. In addition, cell migration mediated by fibronectin or vitronectin, but not that induced by insulin, was impaired by overexpression of the SHP-2 mutant. These results suggest that SHP-2 plays an important role in the control of cell shape by contributing to cytoskeletal organization, and that it is an important regulator of integrin-mediated cell adhesion, spreading, and migration as well as of tyrosine phosphorylation of focal adhesion contact-associated proteins.

Animals↗

PubMed1992

Effects of fibronectin-type V collagen recombinant fusion protein on cell adhesion and cell proliferation.

An expression vector pTF7520-Col-V-In, which encodes a fusion protein of the cell-binding domain of fibronectin (C277) and the insulin- and heparin-binding domain of the alpha 1 chain of human type V collagen, was constructed. E. coli transfected with this plasmid synthesized a 50-kDa fusion protein. This fusion protein, C277-V, was purified from the crude extract by a single step heparin HPLC. Similar amounts of insulin bound to purified C277-V and to the alpha 1 chain of type V collagen as judged by the binding of peroxidase-conjugated insulin. Cell-adhesive activity of C277-V was lower than that of the original fibronectin fragment C274, but similar numbers of cells adhered to both protein substrates when the culture dishes were coated with 1 mM of each protein. Insulin bound to the C277-V substratum stimulated the growth of mouse mammary tumor MTD cells in serum-free culture medium.

Amino Acid Sequence↗

PubMed2004

Introduction of bisecting GlcNAc into integrin alpha5beta1 reduces ligand binding and down-regulates cell adhesion and cell migration.

The enzyme beta1,4-N-acetylglucosaminyltransferase III (GnT-III) catalyzes the addition of a bisecting GlcNAc residue to glycoproteins, resulting in a modulation in biological function. Our previous studies showed that the transfection of the GnT-III gene into B16 melanoma cells results in a suppression of invasive ability and lung colonization. The suppression has been postulated to be due to an increased level of E-cadherin expression on the cell surface, which in turn leads to the up-regulation of cell-cell adhesion. In this study, we report on the effects of overexpression of GnT-III on cell-matrix adhesion. The overexpression of GnT-III, but not that of an enzymatic inactive GnT-III (D323A), inhibits cell spreading and migration on fibronectin, a specific ligand for integrin alpha(5)beta(1), and the focal adhesion kinase phosphorylation. E(4)-PHA lectin blot analyses showed that the levels of bisecting GlcNAc structures on the integrin alpha(5) subunit as well as alpha(2) and alpha(3) subunits immunoprecipitated from GnT-III transfectants were substantially increased. In addition, the affinity of the binding of integrin alpha(5)beta(1) to fibronectin was significantly reduced by the introduction of the bisecting GlcNAc, to the alpha(5) subunit. These findings suggest that the modification of N-glycan of integrin by GnT-III inhibits its ligand binding ability, subsequently leading to the down-regulation of integrin-mediated signaling.

Acetylglucosamine↗

PubMed2001

Regulated expression of human filaggrin in keratinocytes results in cytoskeletal disruption, loss of cell-cell adhesion, and cell cycle arrest.

Filaggrin is an intermediate filament (IF)-associated protein that aggregates keratin IFs in vitro and is thought to perform a similar function during the terminal differentiation of epidermal keratinocytes. To further explore the role of filaggrin in the cytoskeletal rearrangement that accompanies epidermal differentiation, we generated keratinocyte cell lines that express human filaggrin using a tetracycline-inducible promoter system. Filaggrin expression resulted in reduced keratinocyte proliferation and caused an alteration in cell cycle distribution consistent with a post-G1 phase arrest. Keratin filament distribution was disrupted in filaggrin-expressing lines, while the organization of actin microfilaments and microtubules was more mildly affected. Evidence for direct interaction of filaggrin and keratin IFs was seen by overlay assays of GFP-filaggrin with keratin proteins in vitro and by filamentous filaggrin distribution in cells with low levels of expression. Cells expressing moderate to high levels of filaggrin showed a rounded cell morphology, loss of cell-cell adhesion, and compacted cytoplasm. There was also partial or complete loss of the desmosomal proteins desmoplakin, plakoglobin, and desmogleins from cell-cell borders, while the distribution of the adherens junction protein E-cadherin was not affected. No alterations in keratin cytoskeleton, desmosomal protein distribution, or cell shape were observed in control cell lines expressing beta-galactosidase. Filaggrin altered the cell shape and disrupted the actin filament distribution in IF-deficient SW13 cells, demonstrating that filaggrin can affect cell morphology independent of the presence of a cytoplasmic IF network. These studies demonstrate that filaggrin, in addition to its known effects on IF organization, can affect the distribution of other cytoskeletal elements including actin microfilaments, which can occur in the absence of a cytoplasmic IF network. Further, filaggrin can disrupt the distribution of desmosome proteins, suggesting an additional role(s) for this protein in the cytoskeletal and desmosomal reorganization that occurs at the granular to cornified cell transition during terminal differentiation of epidermal keratinocytes.

Adherens Junctions↗

PubMed2000

Semaphorin SEMA3F localization in malignant human lung and cell lines: A suggested role in cell adhesion and cell migration.

Semaphorins/collapsins are a family of secreted and membrane-associated proteins involved in nerve growth cone migration. However, some are expressed widely in adult tissues suggesting additional functions. SEMA3F/H.SemaIV was previously isolated from a 3p21.3 homozygous deletion region in human lung cancer. We studied SEMA3F cellular localization using our previously characterized anti-SEMA3F antibody. In normal lung, SEMA3F was found in all epithelial cells at the cytoplasmic membrane and, to a lesser extent, in the cytoplasm. In lung tumors, the localization was predominantly cytoplasmic, and the levels were comparatively reduced. In non-small-cell lung carcinomas, low levels correlated with higher stage. In all tumors, an exclusive cytoplasmic localization of SEMA3F correlated with high levels of vascular endothelial growth factor and was related to the grade and aggressiveness. This suggests that vascular endothelial growth factor might compete with SEMA3F for binding to their common receptors, neuropilin-1 and -2 and might contribute to SEMA3F delocalization and deregulation in lung tumor. In parallel studies, SEMA3F distribution was examined in cell cultures by confocal microscopy. Marked staining was observed in pseudopods and in the leading edge or ruffling membranes of lamellipods or cellular protrusions in motile cells. SEMA3F was also observed at the interface of adjacent interacting cells suggesting a role in cell motility and cell adhesion.

Adenocarcinoma↗

PubMed1998

Activity of Rap1 is regulated by bombesin, cell adhesion, and cell density in NIH3T3 fibroblasts.

Rap1 and Ras are homologous GTPases that are implicated in cell proliferation and differentiation. At present, little is known about the regulation of Rap1 activity. Using a recently developed assay with activation-specific probes, we found increased activity of endogenous Rap1 in NIH3T3 cells after stimulation with the neuropeptide growth factor bombesin in a concentration- and time-dependent manner. The activity of endogenous Ras was unaffected. Analysis of putative effectors showed no activation of c-Raf-1 or B-Raf after bombesin stimulation. However, MAPK/Erk-phosphorylation and the proliferation rate was increased. In addition, Rap1 was activated during cell adhesion to coated and uncoated tissue culture plates, as well as in response to various mitogens. Surprisingly, the basal Rap1 activity was observed to be cell density-dependent, with low levels when cells were reaching confluency. The results suggest that Rap1 acts as an important mediator of mitogenic signals distinct to Ras activation.

3T3 Cells↗

PubMed1992

Cell surface carbohydrate in cell adhesion. Sperm cells and leukocytes bind to their target cells through specific oligosaccharide ligands.

During the past few years it has become increasingly evident that specific oligosaccharides in glycoproteins/glycolipids may play a central role in mammalian cell adhesion. This review deals with two of the best studied systems, the interaction of sperm cells with the Zona pellucida layer surrounding mammalian eggs, and the binding of leukocytes to endothelial cells. In the sperm cell-Zona pellucida system, it is known that a specific oligosaccharide(s) in the Zona pellucida glycoprotein 3 is responsible for binding. In the leukocyte-endothelial cell interaction, sialyl Le(x), sialyl Le(a), sulfatides, and other less well-defined sugar structures are involved in cellular binding. Oligosaccharides involved in these adhesion events may turn out to have clinically important applications.

Animals↗

PubMed1996

A fundamental subdivision of circulating lymphocytes defined by adhesion to mucosal addressin cell adhesion molecule-1. Comparison with vascular cell adhesion molecule-1 and correlation with beta 7 integrins and memory differentiation.

The leukocyte integrin alpha 4 beta 7 is a receptor for the vascular mucosal addressin cell adhesion molecule-1 (MAdCAM-1). Most circulating B and T lymphocytes in man are alpha 4+, and on these cells the regulated display of the beta 7 integrin chain determines the expression of alpha 4 beta 7 and, in large part, binding to MAdCAM-1. Among CD4+ T cells, beta 7 high memory cells (including the L-selectin+ subset) bind MAdCAM-1 better than beta 7int naive cells; whereas beta 7- memory cells,including skin homing lymphocytes, interact poorly if at all. Circulating alpha E beta 7+ T cells are alpha 4 beta 7high and also bind MAdCAM-1 well. B cells are also subdivided by beta 7 expression, and beta 7+ B cells bind MAdCAM-1 better than the beta 7low/- subset. The related vascular ligand vascular cell adhesion molecule-1 (VCAM-1), expressed on endothelium primarily in nonmucosal sites of inflammation, interacts with blood lymphocytes (including beta 7high T cells) almost exclusively via alpha 4 beta 1 and binds beta 7low/-(beta 1high) better than beta 7+ B cells and memory cells better than naive CD4+ cells. beta 7-(beta 1high) memory T cells are somewhat enriched over beta 7high memory cells at low (but not at high) VCAM-1 densities. Interestingly, CD56+ NK cells, which express both alpha 4 beta 7 and alpha 4 beta 1, bind well to VCAM-1 but poorly to MAdCAM-1. The findings indicate that the display and function of alpha 4 beta 7 determine integrin-dependent blood lymphocyte interactions with MAdCAM-1, thus delineating discrete mucosal vs nonmucosal lymphocyte populations in vivo; that alpha 4 beta 1 dominates blood lymphocyte interactions with VCAM-1; and that quantitative and qualitative regulation of MAdCAM-1 vs VCAM-1 can critically control the recruitment of specialized lymphocyte subsets during inflammation.

Adult↗

PubMed2002

p38 kinase and c-Jun N-terminal kinase oppositely regulates tumor necrosis factor alpha-induced vascular cell adhesion molecule-1 expression and cell adhesion in chondrosarcoma cells.

We investigated signaling pathways leading to tumor necrosis factor (TNF) alpha-induced intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 expression in chondrosarcoma cells, and determined the functional significance of their expression by examining Jurkat T cell adhesion. TNFalpha induced VCAM-1 and ICAM-1 expression and Jurkat T cell binding. Antibody blocking assay indicated that VCAM-1 mediates TNFalpha-induced Jurkat T cell adhesion. TNFalpha caused activation of mitogen-activated protein (MAP) kinase subtypes, extracellular signal-regulated protein kinase, p38 kinase, and c-jun N-terminal kinase (JNK). ICAM-1 expression was not altered by the inhibition of MAP kinases. However, VCAM-1 expression and Jurkat T cell adhesion was blocked by the inhibition of p38 kinase, whereas inhibition of JNK enhanced VCAM-1 expression and cell adhesion without any modulation of NFkappaB activation. Our results, therefore, indicate that p38 kinase mediates TNFalpha-induced VCAM-1 expression and cell adhesion, whereas JNK suppresses VCAM-1 expression that is independent to NFkappaB activation.

Blotting, Western↗