Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: UMLS:C0001511 (Adhesion)
5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adhesion to mucosal cells is an important virulence attribute of bacterial pathogens colonizing these sites. Bacteria of the upper respiratory system, such as members of the genus Bordetella, have well-defined adhesins. The main adhesin of B. pertussis is the filamentous hemagglutinin which can be used by other bacteria for attachment. The main adhesin of B. bronchiseptica is the bovine erythrocyte hemagglutinin. In both Bordetella species the presence of fimbriae does not appear critical to adhesion. In contrast, atrophic rhinitis (AR)-producing strains of Pasteurella multocida colonize poorly the pig's nasal mucosa. We performed an in vitro trial using newborn pigs' turbinate explants and showed that two toxigenic strains (serotype D fimbria + and serotype A fimbria -) were adherent when observed by scanning electron microscopy (SEM). Intranasal inoculation of both six week old and newborn SPF pigs with various strains of P. multocida also resulted in colonization. Adhesion was best achieved by toxigenic strains, regardless of possession of fimbria, hemagglutinin or capsular serotype. Colonization was more abundant and constant in tonsils. Nasal colonization was sporadic and sparse. Colonization of trachea and lung was only observed with serotype A strains. The results showed that toxigenic P. multocida can colonize the upper respiratory tract, especially the tonsils, of pigs.
...
PMID:Bacterial adhesion to mucosal surfaces with special reference to Pasteurella multocida isolates from atrophic rhinitis. 214 99

We have investigated the role of alpha 4 beta 1 and alpha 5 beta 1 integrins in adhesion and migration of T lymphocytes to extracellular matrix proteins. Fibronectin, collagen type IV, and laminin promoted haptotactic and chemotactic migration of lymphoid T cell lines and 12-O-tetradecanoylphorbol 13-acetate-stimulated blood lymphocytes, as determined using a modified Boyden chamber system. Adhesion studies of the T cell lines indicated involvement of both alpha 4 beta 1 and alpha 5 beta 1 integrins in the binding to fibronectin. In contrast, migration assays demonstrated that haptotactic and chemotactic migration to fibronectin in most cases was mediated by only one of the beta 1 integrins. FACS analysis demonstrated comparable amounts of alpha 4 beta 1 and alpha 5 beta 1 on the various cell lines, indicating that utilization of the integrins for migration is not determined by their expression on the cells. Haptotactic migration toward a 120-kDa fibronectin fragment containing the RGD sequence, confirmed the selectivity of the different beta 1 integrins in directing migration. Thus, T cells using alpha 5 beta 1 for haptotaxis against fibronectin were migrating against the 120 kDa fragment whereas T cells using alpha 4 beta 1 were not. These results indicate that the response of T cells to haptotactic and chemotactic signals usually is mediated selectively via alpha 4 beta 1 or alpha 5 beta 1 although binding of fibronectin to the cells is not restricted to only one of the integrins. Cholera toxin and 8-Br-cAMP but not pertussis toxin inhibited migration of T cell lines to fibronectin. Adhesion of these cells to fibronectin was not influenced by any of the toxins. Thus, both in their integrin utilization and in their signaling pathways, adhesion and migration show substantial differences in T cells.
...
PMID:Functional specialization of fibronectin-binding beta 1-integrins in T lymphocyte migration. 802 66

We have extended our previous studies of adherent neutrophils and compared actin depolymerization and intracellular calcium changes induced by adherence to laminin and fibronectin. In order to accurately assess cellular actin changes, F-actin depolymerization in the cell lysates must be inhibited. We found that phalloidin or 3.7% formaldehyde treatment effectively inhibited the depolymerization of F-actin fragments following cell lysis. Formaldehyde and phalloidin treatment reduced G-actin levels 75-80% in suspended cells, 35-73% in cells adherent for 1 min, and about 50% for cells adherent for 3 min. When the actin was fixed, there were highly significant differences in G-actin levels between the suspended and adherent cells as compared with unfixed cells. Adhesion to both laminin and fibronectin initiated a rapid rise in G-actin with a corresponding decrease in F-actin. However, the changes were more pronounced in cells adherent to laminin. The peak of depolymerization occurred by 1 min and, thereafter, G-actin decreased and F-actin increased reaching a steady state at 5 min. Adhesion to both laminin- and fibronectin-coated surfaces was accompanied by an increase of [Ca2+]i with a peak at 3 min, followed by a decrease from 3-5 min and a steady state attained between 5 and 10 min. The rise of [Ca2+]i in laminin-adherent cells was about twice that in fibronectin-adherent cells at 3 min (P < 0.02). Pertussis toxin, H-7, and staurosporin treatments did not alter the dynamic changes of actin in adherent cells, suggesting that these metabolic events are transduced by a G-protein and Protein Kinase C independent mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Assembly dynamics of actin in adherent human neutrophils. 829 48

Distinctions between chemotaxis and haptotaxis of cells to extracellular matrix proteins have not been defined in terms of mechanisms or signaling pathways. Migration of A2058 human melanoma cells to soluble (chemotaxis) and substratum-bound (haptotaxis) vitronectin, mediated by alphav beta3, provided a system with which to address these questions. Both chemotaxis and haptotaxis were completely inhibited by treatment with RGD-containing peptides. Chemotaxis was abolished by a blocking antibody to alphavbeta3 (LM609), whereas haptotaxis was inhibited only by approximately 50%, suggesting involvement of multiple receptors and/or signaling pathways. However, blocking antibodies to alphavbeta5, also present on A2058 cells, did not inhibit. Pertussis toxin treatment of cells inhibited chemotaxis by >80%, but did not inhibit haptotaxis. Adhesion and spreading over vitronectin induced the phosphorylation of paxillin on tyrosine. In cells migrating over substratum-bound vitronectin, tyrosine phosphorylation of paxillin increased 5-fold between 45 min and 5 h. Dilutions of anti- alphavbeta3 that inhibited haptotaxis also inhibited phosphorylation of paxillin (by approximately 50%) and modestly reduced cell spreading. In contrast, soluble vitronectin (50-100 microg/ml) did not induce tyrosine phosphorylation of paxillin. The data suggest that soluble vitronectin stimulates chemotaxis predominantly through a G protein-mediated pathway that is functionally linked to alphavbeta3. Haptotaxis is analogous to directional cell spreading and requires alphavbeta3-mediated tyrosine phosphorylation of paxillin.
...
PMID:Integrin alphavbeta3 mediates chemotactic and haptotactic motility in human melanoma cells through different signaling pathways. 862 27

The sperm acrosome reaction is a Ca(2+)-dependent secretory event required for fertilization. Adhesion to the egg's zona pellucida promotes Ca2+ influx through voltage-sensitive channels, thereby initiating secretion. We used potentiometric fluorescent probes to determine the role of sperm membrane potential in regulating Ca2+ entry. ZP3, the glycoprotein agonist of the zona pellucida, depolarizes sperm membranes by activating a pertussis toxin-insensitive mechanism with the characteristics of a poorly selective cation channel. ZP3 also activates a pertussis toxin-sensitive pathway that produces a transient rise in internal pH. The concerted effects of depolarization and alkalinization open voltage-sensitive Ca2+ channels. These observations suggest that mammalian sperm utilize membrane potential-dependent signal transduction mechanisms and that a depolarization pathway is an upstream transducing element coupling adhesion to secretion during fertilization.
...
PMID:ZP3-dependent activation of sperm cation channels regulates acrosomal secretion during mammalian fertilization. 870 44

The CC chemokines regulated on activation normal T expressed and secreted (RANTES) and monocyte chemotactic protein 3 (MCP-3), and the anaphylatoxin C5a, induce activation, degranulation, chemotaxis, and transendothelial migration of eosinophils. Adhesion assays on purified ligands showed differential regulation of beta 1 and beta 2 integrin avidity in eosinophils. Adhesiveness of VLA-4 (alpha 4 beta 1, CD29/CD49d) for vascular cell adhesion molecule 1 or fibronectin was rapidly increased but subsequently reduced by RANTES, MCP-3, or C5a. The deactivation of VLA-4 lead to cell detachment, whereas phorbol 12-myristate 13-acetate induced sustained activation of VLA-4. In contrast, chemoattractants stimulated a prolonged increase in the adhesiveness of Mac-1 (alpha M beta 2, CD11b/CD18) for intercellular adhesion molecule 1. Inhibition by pertussis toxin confirmed signaling via G protein-coupled receptors. Chemoattractants induced transient, while phorbol 12-myristate 13-acetate induced sustained actin polymerization. Disruption of actin filaments by cytochalasins inhibited increases in avidity of VLA-4 but not of Mac-1. Chemoattractants did not upregulate a Mn2+-inducible beta 1 neoepitope defined by the mAb 9EG7, but induced prolonged expression of a Mac-1 activation epitope recognized by the mAb CBRM1/5. This mAb inhibited chemoattractant-stimulated adhesion of eosinophils to intercellular adhesion molecule 1. Thus, regulation of VLA-4 was dependent on the actin cytoskeleton, whereas conformational changes appeared to be crucial for activation of Mac-1. To our knowledge, this is the first demonstration that physiological agonists, such as chemoattractants, can differentially regulate the avidity of a beta 1 and a beta 2 integrin expressed on the same leukocyte.
...
PMID:Differential regulation of beta 1 and beta 2 integrin avidity by chemoattractants in eosinophils. 885 87

The monomeric G-protein Ras is now considered to function as an initial regulator of multiple signaling pathways in both normal and transformed cell types. Adhesion and chemoattractant receptors are known to trigger activation of Ras in human neutrophils, but the signaling mechanism that activates Ras has only been partially elucidated. The present results show that in neutrophils, a time- and dose-dependent f-Met-Leu-Phe (FMLP)-induced activation of Ras is mediated by Gi2-proteins, because such activation is inhibited by pertussis toxin and because direct stimulation of heterotrimeric G-proteins with AlF4- is sufficient to activate Ras. Pretreatment of neutrophils with tyrosine kinase inhibitors, i.e. genistein or erbstatin that completely block FMLP-stimulated protein tyrosine phosphorylations, did not affect the FMLP-induced activation of Ras. Moreover, FMLP did not induce any detectable translocation of Grb2 and Sos to the plasma membrane of neutrophils. Other signaling molecules, such as protein kinase C, phosphatidylinositol 3-kinase and Ca2+, do not appear to be involved in the FMLP-induced Ras activation. Instead, stimulation of neutrophils with FMLP or C5a, the latter of which also activates Gi2-proteins, resulted in transient inhibition of the activity of Ras GTPase-activating proteins (GAP) with kinetics that correlated well with the kinetics of Ras activation. Moreover, decreased Ras-GAP activity was found in p120-GAP but not in neurofibromin immunoprecipitates of FMLP-stimulated cells. These results suggest that tyrosine kinase-dependent Ras exchange factors do not contribute to the FMLP-induced activation of Ras but that such activation is mediated via inhibition of p120-GAP in neutrophils.
...
PMID:Chemotactic peptide-induced activation of Ras in human neutrophils is associated with inhibition of p120-GAP activity. 928 61

Adult T-cell leukemia (ATL) is characterized by massive infiltration of circulating ATL cells into a variety of tissues, a finding often associated with poor prognosis. Leukocyte migration from circulation into tissue depends on integrin-mediated adhesion to endothelium, and integrins are tightly regulated by several stimuli, such as inflammatory chemokines. However, the exact mechanisms that enhance adherence of leukemic cells to the endothelium and infiltration into tissues remain to be fully understood. We investigated the mechanisms of extravasation of leukemic cells using ATL cells and report the following novel features of endogenous chemokine-induced adhesion of ATL cells to the endothelium. ATL cells spontaneously adhered to endothelial cells without exogenous stimulation. Integrin leukocyte function-associated antigen-1 (LFA-1) on ATL cells was spontaneously activated. ATL cells produced high amounts of chemokines, macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta. Adhesion of ATL cells to endothelial cells and the expression of activated form of LFA-1 were reduced by pretreatment with pertussis toxin, wortmannin, or anti-MIP-1alpha and MIP-1beta antibodies or transfection with antisense of MIP-1alpha or MIP-1beta. Spontaneous polymerization of cytoskeletal F-actin was observed in ATL cells, which was also inhibited by pertussis toxin and wortmannin. We propose that ATL cells adhere to endothelial cells through an adhesion cascade similar to normal leukocytes and that the chemokines produced by ATL cells are involved in triggering integrin LFA-1 through cytoskeletal rearrangement induced by G-protein-dependent activation of phosphoinositide 3-kinases in an autocrine manner. These events result in a strong adhesion of ATL cells to the endothelium and spontaneous transendothelial migration.
...
PMID:Constitutive chemokine production results in activation of leukocyte function-associated antigen-1 on adult T-cell leukemia cells. 957 29

The process of haemopoietic cell homing to the microenvironment includes migration and adhesion. SDF-1 is a C-X-C chemokine that acts as a chemoattractant for haemopoietic progenitors. Adhesion of haemopoietic progenitors to immobilized fibronectin is up-regulated by stimulation with cytokines. We assessed the effects of SDF-1 on cytokine-induced adhesion of progenitor cells to fibronectin. In factor-dependent human MO7e cells and primary CD34+ cord blood cells, treatment with SDF-1 dose-dependently suppressed cytokine-induced adhesion. Pretreatment with pertussis toxin reversed adhesion-inhibition, suggesting that activation of G-coupled proteins are involved in the intracellular signalling of this process. These data suggest that SDF-1 not only acts as a chemoattractant but also participates in modulating adhesiveness of haemopoietic progenitors to extracellular matrix components.
...
PMID:SDF-1 suppresses cytokine-induced adhesion of human haemopoietic progenitor cells to immobilized fibronectin. 1044 82

The adhesive function of integrins is regulated through cytoplasmic signaling. The present study was performed to investigate the relevance of cytoplasmic signaling and cytoskeletal assembly to integrin-mediated adhesion induced by chemokines. Adhesion of T cells induced by chemokines macrophage inflammatory protein (MIP)-1alpha and MIP-1beta was inhibited by pertussis toxin, wortmannin, and cytochalasin B, suggesting that both G protein-sensitive phosphatidylinositol (PI) 3-kinase activation and cytoskeletal assemblies are involved. The chemokine-induced T cell adhesion could be mimicked by expression of small G proteins, fully activated H-RasV12, or H-RasV12Y40C mutant, which selectively binds to PI 3-kinase, in T cells, inducing activated form of LFA-1alpha and LFA-1-dependent adhesion to ICAM-1. H-Ras expression also induced F-actin polymerization which colocalized with profilin in T cells. Adult T cell leukemia (ATL) cells spontaneously adhered to ICAM-1, which depended on endogenous MIP-1alpha and MIP-1beta through activation of G protein-sensitive PI 3-kinase. H-Ras signal pathway, leading to PI 3-kinase activation, also induced active configuration of LFA-1 and LFA-1-mediated adhesion of ATL cells, whereas expression of a dominant-negative H-Ras mutant failed to do. Profilin-dependent spontaneous polymerization of F-actin in ATL cells was reduced by PI 3-kinase inhibitors. In this paper we propose that H-Ras-mediated activation of PI 3-kinase can be involved in induction of LFA-1-dependent adhesion of T cells, which is relevant to chemokine-mediated signaling, and that profilin may form an important link between chemokine- and/or H-Ras-mediated signals and F-actin polymerization, which results in triggering of LFA-1 on T cells or leukemic T cells.
...
PMID:H-Ras signals to cytoskeletal machinery in induction of integrin-mediated adhesion of T cells. 1057 Mar 13


1 2 3 Next >>

---