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At least 469 records · Page 26Linked to original sources
PubMed2006

A pseudosymmetric cell adhesion regulatory domain in the beta7 tail of the integrin alpha4beta7 that interacts with focal adhesion kinase and src.

The beta7 integrins alpha4beta7 and alphaEbeta7 play key roles in forming the gut-associated lymphoid tissue, and contribute to chronic inflammation. The alpha4beta7 integrin-mediated adhesion of activated lymphocytes is largely due to a transient increase in avidity from ligand-induced clustering of alpha4beta7 at the cell-surface. Here, we report that L and D enantiomers of a cell-permeable peptide YDRREY encompassing residues 735-740 of the cytoplasmic tail of the beta7 subunit inhibit the adhesion of T cells to beta7 integrin ligands. The YDRREY peptide abrogated mucosal addressin cell adhesion molecule-1-induced clustering of alpha4beta7 on the surface of activated T cells. A mutated form of the YDRREY peptide carrying either single or double conservative mutations at Tyr(735)Phe and Tyr(740)Phe was unable to inhibit T cell adhesion, suggesting that both tandem tyrosines are critical for activity. The YDRREY peptide was bound and phosphorylated by focal adhesion kinase and src, which may serve to sequester cytoskeletal proteins to the cytoplasmic domain of alpha4beta7. The quasi-palindromic sequence YDRREY within the beta7 cytoplasmic tail constitutes a cell adhesion regulatory domain that modulates the interaction of beta7-expressing leukocytes with their endothelial and epithelial ligands. Cell-permeable peptidomimetics based on this motif have utility as anti-inflammatory reagents for the treatment of chronic inflammatory disease.

Amino Acid Sequence↗
PubMed2006

Gangliosides promote platelet adhesion and facilitate neuroblastoma cell adhesion under dynamic conditions simulating blood flow.

BACKGROUND: Aberrant gangliosides are produced and shed by some tumors into the extracellular milieu. Their concentration is related to disease progression in children with neuroblastoma and in experimental models. The mechanism for this tumor promoting effect is not known. PURPOSE: Here, we investigated the effect of gangliosides on platelet and tumor cell adhesion under shear forces simulating venous and arterial flow. RESULTS: High shear force increased platelet adhesion 2.5-fold compared to low force. Pre-incubation of platelets with gangliosides increased adhesion at low shear to a level comparable to high shear alone. The addition of gangliosides to platelets perfused at high shear did not further increase adhesion. LAN1 neuroblastoma cells are adherent to collagen in static assays. No effect of either shear or gangliosides was observed on cell adhesion under dynamic conditions. However, when perfused in the presence of platelets, an increase in binding of tumor cells was observed at both shear forces compared to cells alone. CONCLUSIONS: These results demonstrate that shear and gangliosides increase dynamic platelet adhesion to collagen. In addition, platelets facilitate tumor cell binding. Therefore, by acting as a mediator of platelet activation, gangliosides may promote blood borne metastasis by increasing platelet binding to the vessel wall and in turn facilitate tumor cell arrest in circulation.

Blood Flow Velocity↗
PubMed2000

Intercellular adhesion molecule-1 is required for chemoattractant-induced leukocyte adhesion in resting, but not inflamed, venules in vivo.

The leukocyte integrins LFA-1 and Mac-1 bind to endothelial intercellular adhesion molecule-1 (ICAM-1). Leukocyte adhesion induced by micropipette injection of formylmethionylleucylphenylalanine (fMLP) or macrophage inflammatory protein 2 (MIP-2) next to a venule in the exteriorized mouse cremaster muscle was almost completely blocked after intravenous injection of the ICAM-1 mAb YN-1. In contrast, after 2-h pretreatment with TNF-alpha, leukocyte adhesion induced in postcapillary venules by fMLP or MIP-2 was not blocked by the ICAM-1 mAb. Leukocyte adhesion was significantly reduced by mAb GAME-46 to CD18 even after TNF-alpha treatment. We conclude that ICAM-1 is necessary for neutrophil adhesion to unstimulated endothelium, but not for adhesion to cytokine-stimulated endothelium. Although ICAM-1 is expressed at high levels after TNF-alpha, ICAM-1 either is not functional or is redundant with other endothelial ligands for beta(2) integrins.

Animals↗
PubMed2005

Nitric oxide mediates the effect of fluvastatin on intercellular adhesion molecule-1 and platelet endothelial cell adhesion molecule-1 expression on human endothelial cells.

Leukocyte and platelet adhesion to endothelial cells, an early step in the pathogenesis of atherosclerosis, is mediated through adhesion molecules. It has been shown that statins decrease adhesion molecule expression. We examined the hypothesis that fluvastatin decreased intercellular adhesion molecule-1 (ICAM-1) and platelet endothelial cell adhesion molecule-1 (PECAM-1) expression through a nitric oxide-mediated pathway. Human iliac artery endothelial cells were exposed to fluvastatin in the presence or absence of 2 mM N-monomethyl-L-arginine (L-NMMA). Flow cytometry analysis was used to measure ICAM-1 and PECAM-1 expression. In a separate experiment, confluent cell cultures were exposed in a serum-free medium to fluvastatin 20 microM, and the supernatant was collected for nitrate/nitrite determination after 6 and 48 hr of incubation. Protein was isolated and processed for immunoblotting with monoclonal antibodies specific for endothelial nitric oxide synthase (eNOS), Ser(1177)-phosphorylated eNOS, and AMP kinase. Relative band intensity was assessed with densitometry. Results are presented as the mean +/- standard deviation (SD), and p < 0.05 was considered significant. ICAM-1 and PECAM-1 were expressed constitutively. Human iliac artery endothelial cells (HIAECS) treated with 5 microM fluvastatin did not exhibit reduced expression of PECAM-1 or ICAM-1. Incubation with 10 microM fluvastatin reduced basal expression of both ICAM-1 and PECAM-1. Fluorescence intensity (FI) for these substance was as follows: 3638 +/- 1671, p = 0.01 and PECAM-1 vs. control FI 276 +/- 52 vs. 522 +/- 78, p = 0.02. In the presence of 2 mM L-NMMA, fluvastatin failed to decrease the expression of ICAM-1 (fluvastatin 10 microM + L-NMMA: FI was 3042 +/- 1378 vs. 3638 +/- 1671 for the control p = 0.01) or PECAM-1 (fluvastatin 10 microM + L-NMMA: FI was 415 +/- 188 vs. 522 +/- 78 for the control, p = 0.1). Incubation with 20 microM fluvastatin similarly reduced ICAM-1 expression (FI was 2014 +/- 1595 vs. 3638 +/- 1671 for the control, p = 0.02) and PECAM-1 expression (FI was 196 +/- 109 vs. 522 +/- 78 for the control, p = 0.02). This reduction was prevented in the presence of 2 mM L-NMMA. L-NMMA in a concentration of 2 mM had no significant effect on adhesion molecule expression (p > 0.05 for all comparisons of the control FI versus 2 mM L-NMMA mean FI). After a 48 hr incubation with 20 microM fluvastatin there was a 219 +/- 35% increase in the cell eNOS protein content (p = 0.01) and a 170 +/- 26% increase in the cell AMPK protein content (p = 0.02). Ser(1177)-phosphorylated eNOS protein levels were increased by 41 +/- 8% (p = 0.03). The nitric oxide concentration in the medium of the HIAEC treated with 20 microM fluvastatin for 48 hr was significantly higher than that in the control (p = 0.0004), pointing to increased production during the incubation period. Fluvastatin thus decreases basal expression of ICAM-1 and PECAM-1. Competitive inhibition of eNOS with L-NMMA abolishes the effect of fluvastatin on ICAM-1 and PECAM-1 expression. The statin up-regulates eNOS and AMP kinase, one of the enzymes that activates eNOS via phosphorylation at Ser(1177). We have shown that after a 48-hr exposure to fluvastatin there is an increased amount of the phosphorylated enzyme in the endothelial cells.

Blotting, Western↗
PubMed2005

Conjugated linoleic acids have no effect on TNF alpha-induced adhesion molecule expression, U937 monocyte adhesion, and chemokine release in human aortic endothelial cells.

Leukocyte recruitment and adhesion to the endothelium are critical steps in the early phase of atherosclerosis. Synthetic ligands of peroxisome proliferator-activated receptors (PPARs) were shown to reduce cytokine-stimulated leukocyte-endothelial cell interactions by inhibiting the NF-kappaB mediated inflammatory response. Conjugated linoleic acids (CLA), which are natural ligands of PPARs, were demonstrated to have anti-inflammatory and anti-atherogenic properties in vivo. With a view to elucidating the anti-atherogenic mechanisms of CLA, the present study aimed to explore the effects of cis-9, trans-11 CLA and trans-10, cis-12 CLA on cytokine-induced chemokine release, surface expression of adhesion molecules (ICAM-1, VCAM-1, and E-selectin) and U937 monocyte adhesion in human aortic endothelial cells (HAEC). Treatment of HAECs with 2 ng/mL of TNFalpha markedly increased expression of adhesion molecules, U937 monocyte adhesion, and release of the monocyte chemoattractant protein (MCP)-1. However, treatment of HAECs with either CLA isomer or linoleic acid did not modulate the cytokine-induced expression of ICAM-1, VCAM-1, and E-selectin, U937 cell adhesion and MCP-1 release. In addition, both CLA isomers and linoleic acid slightly increased PPARgamma DNA-binding activity, but did not alter DNA-binding activity of NF-kappaB. In conclusion, CLA isomers showed no effect on cytokine-induced monocyte-endothelial cell interactions and on the molecular mechanisms regulating these processes in HAEC. This study suggests that anti-atherogenic effects of CLA observed in vivo are probably not mediated by reduced monocyte-endothelial cell interactions.

Adult↗
PubMed2004

Prevention of macrophage adhesion molecule-1 (Mac-1)-dependent neutrophil firm adhesion by taxifolin through impairment of protein kinase-dependent NADPH oxidase activation and antagonism of G protein-mediated calcium influx.

Taxifolin has been reported to down-regulate the expression of intercellular adhesion molecule-1 (ICAM-1), a receptor-mediating firm adhesion with beta2 integrin (e.g., Mac-1) expressed on leukocytes. To evaluate whether taxifolin could modulate Mac-1-dependent firm adhesion by neutrophils, and the possible mechanism(s) underlying its anti-inflammatory action, its effects on N-formyl-methionyl-leucyl-phenylalanine (fMLP) or phorbol-12-myristate-13-acetate (PMA)-activated peripheral human neutrophils were studied. Pretreatment with taxifolin (1-100 microM) concentration-dependently diminished fMLP- or (PMA)-induced Mac-1-dependent firm adhesion and upexpression of surface Mac-1. Mobilisation of intracellular calcium and production of reactive oxygen species (ROS) signal the upexpression of Mac-1 and firm adhesion by neutrophils. Taxifolin impeded the calcium influx induced by fMLP (a receptor-mediated activator) or AlF(4)(-) (a G protein-mediated activator). Taxifolin also effectively inhibited the fMLP- or PMA-induced ROS production with 50% inhibitory concentration (IC(50)) less than 10microM, possibly through impairing the activation of NADPH oxidase, a major ROS-generating enzyme in neutrophils, by restricting the activation of p38 mitogen-activated protein kinase (p38 MAPK) and protein kinase C (PKC). In conclusion, we propose that impairment of ROS production by NADPH oxidase through interfering with p38 MAPK- and/or PKC-dependent signals, and antagonism of G protein-mediated calcium influx may account for the inhibition of Mac-1-dependent neutrophil firm adhesion that confers taxifolin the anti-inflammatory activity.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMedDate not supplied

Cerivastatin ameliorates high insulin-enhanced neutrophil-endothelial cell adhesion and endothelial intercellular adhesion molecule-1 expression by inhibiting mitogen-activated protein kinase activation.

BACKGROUND AND AIMS: There is growing evidence that hyperinsulinemia is linked to the development of atherosclerosis in patients with diabetes. We demonstrated previously that high insulin exacerbates neutrophil-endothelial cell adhesion and endothelial intercellular adhesion molecule (ICAM)-1 expression through activation of protein kinase C (PKC) and mitogen-activated protein (MAP) kinase. Though 3-hydroxymethyl-3-glutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have been employed as therapeutic agents in the treatment of dyslipidemia, which is frequently accompanied by diabetes mellitus; it is not known whether statins protect against leukocyte-endothelial interactions, especially in hyperinsulinemia. In this study, we determined which statin(s) could protect against endothelial reactions to high insulin. METHODS: Studies of adhesion between neutrophils from healthy volunteers and human umbilical vein endothelial cells incubated in regular insulin-rich medium with or without statins were performed. Adhered neutrophils were quantified by measuring their myeloperoxidase (MPO) activities, and endothelial expression of ICAM-1 was examined using an enzyme immunoassay. RESULTS: Both the increased neutrophil-endothelial cell adhesion and ICAM-1 expression caused by high insulin (100 microU/ml) for 48 h were significantly attenuated by pretreatment with cerivastatin (0.01 microM), but not by fluvastatin (0.5 microM) or pravastatin (0.05 microM). These protective actions of cerivastatin were attenuated by a key intermediate in the cholesterol biosynthesis pathway, mevalonate (400 microM). In addition, cerivastatin attenuated both neutrophil-endothelial cell adhesion and endothelial ICAM-1 expression enhanced by a MAP kinase activator, anisomycin (1 microM) but not by a PKC activator, PMA (10 nM). CONCLUSIONS: These results suggest that through inhibiting MAP kinase but not PKC activation therapy with cerivastatin would be promising strategy for inhibiting neutrophil-endothelial cell adhesion and endothelial ICAM-1 expression enhanced by high insulin, which is closely correlated with atherosclerosis.

Cell Adhesion↗
PubMed1993

Adhesive interactions in thymic development: does selective expression of CD45 isoforms promote stage-specific microclustering in the assembly of functional adhesive complexes on differentiating T lineage lymphocytes?

CD45 isoform transitions appear to play essential roles in both life and death, and correlate with the stages of thymocyte development during which there is a change in physical location from medullary and/or outer cortical areas to the inner cortex. This work speculates that CD45 isoforms, through a focal role in the assembly of adhesive complexes mediated by the external domains, participate in the maintenance and/or modulation of migratory behaviour by differentiating thymocytes, or alternatively in the anchoring of thymocytes in a generative micro-environment. The objective of the sections that follow is to formulate the hypothesis that CD45 isoforms, through their differential interactions with adhesion molecules expressed by T cells, profoundly influence cell motility and consequent micro-environmental localization. An adhesive assembly of CD45 and adhesion molecules on the outside, and of the adhesive complex with the cytoskeleton on the inside, would promote CD45-mediated regulation of adhesion/de-adhesion through lateral external interactions mediated by external domains of CD45 isoforms, through enzymatic modulation of the cytoplasmic domains of adhesion molecules by the CD45 tyrosine phosphatase activity, and through phosphatase control of cytoskeletal assembly and disassembly.

Animals↗
PubMed2000

Focal adhesion kinase: a regulator of focal adhesion dynamics and cell movement.

Engagement of integrin receptors with extracellular ligands gives rise to the formation of complex multiprotein structures that link the ECM to the cytoplasmic actin cytoskeleton. These adhesive complexes are dynamic, often heterogeneous structures, varying in size and organization. In motile cells, sites of adhesion within filopodia and lamellipodia are relatively small and transient and are referred to as 'focal complexes,' whereas adhesions underlying the body of the cell and localized to the ends of actin stress fibers are referred to as 'focal adhesions'. Signal transduction through focal complexes and focal adhesions has been implicated in the regulation of a number of key cellular processes, including growth factor induced mitogenic signals, cell survival and cell locomotion. The formation and remodeling of focal contacts is a dynamic process under the regulation of protein tyrosine kinases and small GTPases of the Rho family. In this review, we consider the role of the focal complex associated protein tyrosine kinase, Focal Adhesion Kinase (FAK), in the regulation of cell movement with the emphasis on how FAK regulates the flow of signals from the ECM to the actin cytoskeleton.

Actins↗
PubMed2006

Tamoxifen treatment promotes phosphorylation of the adhesion molecules, p130Cas/BCAR1, FAK and Src, via an adhesion-dependent pathway.

Reports that the adhesion-associated molecule p130Cas/BCAR1 promotes resistance to tamoxifen suggested that adhesion-mediated signalling may be altered by tamoxifen treatment. We find that p130Cas/BCAR1 phosphorylation is enhanced in tamoxifen-treated estrogen receptor (ER)-positive MCF-7 breast cancer cells. The effects of estrogen and tamoxifen were assessed independently and in combination, and the results demonstrate that tamoxifen antagonizes estrogen regulation of p130Cas/BCAR1 phosphorylation. Phosphorylation correlates with tamoxifen ER antagonist effects, as phosphorylation effects are replicated by the pure antiestrogen ICI 182, 780. Correspondingly, phosphorylation is not changed in ER-negative cells exposed to tamoxifen. We show that deletion of the p130Cas/BCAR1 substrate domain substantially reduces tamoxifen-induced phosphorylation of p130Cas/BCAR1 and confers enhanced sensitivity to tamoxifen. P130Cas/BCAR1 forms a phosphorylation-dependent signalling complex with focal adhesion kinase (FAK) and Src kinase that promotes adhesion-mediated cell survival. Therefore, we examined the kinetics of p130Cas/BCAR1, Src and FAK phosphorylation over a 14-day time course and find sustained phosphorylation of these molecules after 7 days exposure to tamoxifen. Inhibition of Src kinase is shown to reduce tamoxifen-promoted p130Cas/BCAR1 phosphorylation and reduce cell viability. Stimulation of the Src/FAK/p130Cas/BCAR1 adhesion signalling pathway in tamoxifen-treated MCF-7 cells does not cause increased migration; however, there is Src-dependent phosphorylation of the cell survival molecule Akt. Correspondingly, Akt inhibition reduces cell viability in cells treated with tamoxifen. We propose that prolonged activation of adhesion-dependent signalling may confer a survival advantage in response to additional cellular insults or alternatively, may poise cells to develop a migratory phenotype in response to additional cellular cues.

Antineoplastic Agents, Hormonal↗
PubMed1997

Intercellular adhesion molecule-1 and CD18 are involved in neutrophil adhesion and its cytotoxicity to cultured sinusoidal endothelial cells in rats.

The expression of several adhesion molecules is increased on the hepatic sinusoidal endothelial cells (SECs) in various liver diseases. The objective of this study is to assess the roles of intercellular adhesion molecule 1 (ICAM-1) and of CD18 in the interaction between the neutrophils (polymorphonuclear leukocytes [PMNs]) and SECs and in the injury to SECs mediated by PMNs. Rat PMNs was perfused on SECs stimulated with tumor necrosis factor alpha (TNF-alpha) using an in vitro flow system. The number of adhered PMNs to SECs and that of PMNs migrated under SECs was counted and the effects of anti-ICAM-1, anti-CD18, and dexamethasone were studied. We also define the effect of these antibodies on the SEC injury mediated by PMNs stimulated with phorbol 12-myristate 13-acetate (PMA) or N-formyl-methionyl-leucyl-phenylalanine (fMLP). TNF-alpha significantly increased the adhesion of PMNs to SECs (322 +/- 26 cells/mm2) compared with controls (194 +/- 22 cells/mm2). Anti-ICAM-1 and anti-CD18 significantly inhibited the adhesion of PMNs (131 +/- 10 and 51 +/- 30 cells/mm2, respectively). These antibodies also decreased the migration rate of PMNs (6.0% and 7.9%, respectively) compared with controls (migration rate, 21.2%). The SEC injury induced by PMA- and fMLP-activated PMNs was prevented by anti-ICAM-1 and anti-CD18. The adhesion of PMNs induced by TNF-alpha was inhibited by the treatment with dexamethasone (160 +/- 20 cells/mm2) via a down-regulation of ICAM-1 expression on SECs. The interactions between ICAM-1 and CD18 appeared to be important in the adhesion and the migration of PMNs to SECs. The injury to SECs was induced by the close interaction between the activated PMNs and SECs mediated via ICAM-1 and CD18.

Animals↗
PubMed2004

Mechanism of homophilic adhesion by the neural cell adhesion molecule: use of multiple domains and flexibility.

The extracellular regions of adhesion proteins of the Ig superfamily comprise multiple, tandemly arranged domains. We used directforce measurements to investigate how this modular architecture contributes to the adhesive interactions of the neural cell adhesion molecule (NCAM), a representative of this protein class. The extracellular region of NCAM comprises five immunoglobulin and two fibronectin domains. Previous investigations generated different models for the mechanism of homophilic adhesion that each use different domains. We use force measurements to demonstrate that NCAM binds in two spatially distinct configurations. Igdomain deletion mutants identified the domains responsible for each of the adhesive bonds. The measurements also confirmed the existence of a flexible hinge that alters the orientation of the adhesive complexes and the intermembrane distance. These results suggest that a combination of multiple bound states and internal molecular flexibility allows for sequentially synergistic bond formation and the ability to accommodate differences in intercellular space.

Animals↗
PubMed2003

The CD81 tetraspanin facilitates instantaneous leukocyte VLA-4 adhesion strengthening to vascular cell adhesion molecule 1 (VCAM-1) under shear flow.

Leukocyte integrins must rapidly strengthen their binding to target endothelial sites to arrest rolling adhesions under physiological shear flow. We demonstrate that the integrin-associated tetraspanin, CD81, regulates VLA-4 and VLA-5 adhesion strengthening in monocytes and primary murine B cells. CD81 strengthens multivalent VLA-4 contacts within subsecond integrin occupancy without altering intrinsic adhesive properties to low density ligand. CD81 facilitates both VLA-4-mediated leukocyte rolling and arrest on VCAM-1 under shear flow as well as VLA-5-dependent adhesion to fibronectin during short stationary contacts. CD81 also augments VLA-4 avidity enhancement induced by either chemokine-stimulated Gi proteins or by protein kinase C activation, although it is not required for Gi protein or protein kinase C signaling activities. In contrast to other proadhesive integrin-associated proteins, CD81-promoted integrin adhesiveness does not require its own ligand occupancy or ligation. These results provide the first demonstration of an integrin-associated transmembranal protein that facilitates instantaneous multivalent integrin occupancy events that promote leukocyte adhesion to an endothelial ligand under shear flow.

Animals↗
PubMed2004

Two variable regions in carcinoembryonic antigen-related cell adhesion molecule1 N-terminal domains located in or next to monoclonal antibody and adhesion epitopes show evidence of recombination in rat but not in human.

In this paper, we have characterized the structure, evolutionary origin, and function of rat and human carcinoembryonic antigen-related cell adhesion molecule1 (CEACAM1) multifunctional Ig-like cell adhesion proteins that are expressed by many epithelial tissues. Restriction enzyme digestion reverse transcriptase-PCR analysis identified three cDNAs encoding novel CEACAM1 N-domains. Comparative sequence analysis showed that human and rat CEACAM1 N-domains segregated into two groups differing in similarity to rat CEACAM1(a)-4L and human CEACAM1. Sequence variability analysis indicated that both human and rat N-domains possessed two variable regions, and one contained a major adhesive epitope. Recombination analysis showed that the group of rat but not human N-domains with high sequence similarity was derived at least in part by recombination. Binding assays revealed that three monoclonal antibodies with strong reactivity for the CEACAM1(a)-4L N-domain showed no reactivity with CEACAM1(b)-4S, an allele with a different N-domain sequence. CEACAM1(b)-4S displayed adhesive activity efficiently blocked by a synthetic peptide corresponding to the adhesive epitope in CEACAM1(a)-4L. Blocking analysis also showed that the adhesive epitope for rat CEACAM1 was located downstream from the equivalent human and mouse epitopes. Glycosylation analysis demonstrated O-linked sugars on rat CEACAM1(b)-4S from COS-1 cells. However, this was not the alteration responsible for the lack of monoclonal antibody reactivity. When considered together with previous studies, our findings suggest an inverse relationship between functionality and amino acid sequence similarity to CEACAM1. Like IgG, the N-domain of CEACAM1 appears to tolerate 10-15% sequence diversification without loss of function but begins to show either altered specificity or diminished functionality at higher levels.

Amino Acid Sequence↗
PubMed2004

Direct evidence that neural cell adhesion molecule (NCAM) polysialylation increases intermembrane repulsion and abrogates adhesion.

Molecular force measurements quantified the impact of polysialylation on the adhesive properties both of membrane-bound neural cell adhesion molecule (NCAM) and of other proteins on the same membrane. These results show quantitatively that NCAM polysialylation increases the range and magnitude of intermembrane repulsion. The repulsion is sufficient to overwhelm both homophilic NCAM and cadherin attraction at physiological ionic strength, and it abrogates the protein-mediated intermembrane adhesion. The steric repulsion is ionic strength dependent and decreases substantially at high monovalent salt concentrations with a concomitant increase in the intermembrane attraction. The magnitude of the repulsion also depends on the amount of polysialic acid (PSA) on the membranes, and the PSA-dependent attenuation of cadherin adhesion increases with increasing PSA-NCAM:cadherin ratios. These findings agree qualitatively with independent reports based on cell adhesion studies and reveal the likely molecular mechanism by which NCAM polysialylation regulates cell adhesion and intermembrane space.

Animals↗
PubMed2003

Some fundamentals of adhesion in synthetic adhesives.

Various adhesion mechanisms that have been understood in the field of synthetic adhesives are described and these are linked with situations relevant to fouling issues. The review mainly deals with mechanical aspects of adhesion phenomena, with an emphasis on the role of the elasticity of the bodies, called substrata, attached by adhesive. The consequences of thin film geometry of the adhesive material are described, such as various heterogeneous deformations upon traction. The importance of the bonding process is discussed, as well as some examples of non-wetting surfaces. Some basic ideas of fracture mechanics are provided and in particular, the behavior of layered systems is discussed. Rolling sticky objects and peeled (flexible) adhesive tapes display similar mechanisms and it is shown how they differ from the normal separation of rigid bodies. Some issues directly related to fouling issues are also discussed, such as forces and torques acting on shells, the advantages of gregarious settlement behavior and concepts for fouling release and antifouling.

Adhesiveness↗
PubMed2001

Chlamydia trachomatis infection induces mucosal addressin cell adhesion molecule-1 and vascular cell adhesion molecule-1, providing an immunologic link between the fallopian tube and other mucosal tissues.

The development of a protective vaccine against the sexually transmitted disease caused by Chlamydia trachomatis may prevent complications associated with insidious infection. Vaccination via the vaginal route may not be practical, and other routes should be investigated. To this end, the adhesion molecules induced on the fallopian tube endothelium during infection with C. trachomatis were characterized. Adhesion molecules were identified in fallopian tube biopsy specimens cultured with 5 x 10(6) infection-forming units of C. trachomatis serovar E. Frozen sections were prepared from these tissues and were stained by immunohistochemical techniques. Infection with live, but not UV-inactivated, C. trachomatis induced a significant increase in levels of vascular cell adhesion molecule-1 and the mucosal addressin cell adhesion molecule-1 but not of other adhesion molecules. Therefore, infection with C. trachomatis induces adhesion molecules that are associated with other mucosal tissues and inflammatory sites, which suggests that mucosal routes of immunization may be effective.

Biopsy↗
PubMed1991

Artificial cell adhesive proteins engineered by grafting the Arg-Gly-Asp cell recognition signal: factors modulating the cell adhesive activity of the grafted signal.

An artificial cell adhesive protein could be engineered by grafting the RGDS tetrapeptide, the core sequence of the major cell adhesive site of fibronectin, to a truncated form of Staphylococcal protein A (tSPA) via cassette mutagenesis of the tSPA expression vector pRIT2T [T. Maeda et al. (1989) J. Biol. Chem. 264, 15165-15168]. We synthesized a panel of tSPA derivatives grafted with various RGDS-containing oligopeptides to address the problem of how the cell adhesive activity of the resulting tSPA derivatives was affected by the length and amino acid sequence of the grafted oligopeptides and by the sites on tSPA where the extra oligopeptides were inserted. The results showed that (i) the amino acid residues flanking the RGDS core sequence played a key role in modulating the cell adhesive activity of the grafted RGDS signal; (ii) at least two sites on tSPA, each corresponding to on e of the two HindIII sites of pRIT2T, were competent in sustaining the cell adhesive activity of the grafted signal; and (iii) the divalent tSPA containing the RGDS signal at both sites was more active than monovalent derivatives containing only one signal at either site. These results provide a strategic basis for engineering of artificial cell adhesive proteins by grafting the RGDS signal.

Amino Acid Sequence↗