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

Tissues are composed of cells and extracellular matrix (EM). Adhesion of cells to extracellular matrix is mediated by membrane-bound glycoproteins such as fibronectin, laminin and others. Elastonectin was shown recently to be involved in the mediation of interactions between elastic fibers and cells such as human skin fibroblasts (FB) and smooth muscle cells (SMC) from the media of the aorta. A strong interaction between fibers and cells is important for the maintenance of the quality of the vascular wall. We studied the action of procyanidolic oligomers (PCO) on the attachment of fibroblasts from human skin and smooth muscle cells from porcin aorta to elastic fibers. A dose-dependent increase of cell-fiber interaction could be demonstrated with both cell-types. Elastonectin is located on the cell membrane as well as an elastolytic serine-protease exhibiting an age- and pathology-dependent increase in activity. This will result in a degradation of elastic lamellae, the detachment of cells from elastic fibers and a weakening of the vascular wall. The activity of procyanidolic oligomers increasing the resistance of elastic fibers to degradation by elastases and enhancing the interaction between fibers and cells can be considered as favouring the maintenance of the normal functional state of the vascular wall.
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PMID:[The effect of procyanidolic oligomers on mesenchymal cells in culture. II--Attachment of elastic fibers to the cells]. 237 96

The mechanism by which unstimulated human neutrophils initiate a respiratory burst on adherence to a surface has been examined. When neutrophils adhere to a plastic surface, they immediately generate a sustained burst of superoxide (O2-). However, this respiratory burst is not initiated by adherence alone, since neutrophils attached to fibronectin fail to mount a response. Adhesion to plastic is calcium (Ca2+) independent, but O2- production requires Ca2(+)-containing buffer in the initiation phase, that is, during adhesion and the early phase of O2- production. The Ca2(+)-dependent step was shown to involve protein kinase C (PK-C) in that the O2- production, but not adherence, was blocked with 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), and PK-C was found to translocate from the cytosol to the membrane on adhesion. Furthermore, it may be inferred that this translocation results in the generation of a Ca2+ independent form of PK-C, PK-M, since leupeptin, which inhibits the generation of PK-M, also blocked O2- production. This finding was corroborated by showing that after 5 minutes in a Ca2(+)-containing buffer, enough time to initiate O2- production and PK-C translocation, Ca2+ is no longer required for sustained O2- release. These results, in aggregate, demonstrate that neutrophils are activated by adhesion to plastic to generate O2-, a PK-C-dependent process that appears to involve a Ca2(+)-independent form of the kinase, PK-M. Why adherent neutrophils generate a respiratory burst on plastic and not fibronectin surfaces probably reflects activation of distinct receptors, whose nature must still be defined. Another issue to address is the priming effect of adhesion, since cells adherent to plastic- or fibronectin-coated surfaces have an enhanced O2- response to formylmethionyl-leucine-phenylalanine (FMLP) compared with neutrophils stimulated in suspension. This may relate to increased Ca2+ mobilization, an important mediator of priming for FMLP responses. Thus, adhesion as a priming event does not necessarily initiate cell effector function, and the further elucidation of the plastic and fibronectin models suggests a means of characterizing the crucial event that control neutrophil activation.
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PMID:Activation mechanisms of adherent human neutrophils. 240 Aug 11

Adhesion and spreading of BHK21 cells on adsorbed bovine and foetal bovine serum require addition to the medium of a divalent cation. Divalent cations are effective in the order Mn2+ greater than Co2+ greater than Mg2+ greater than Ca2+, with Ca2+ ineffective below 10(-4)M. On purified fibronectin, however, no added divalent cation is required, since the requirement is largely met by adventitious Ca2+ (circa 10(-5)M) in nominally divalent cation-free saline. In such background Ca2+, adhesion and spreading on fibronectin are only slightly slower than in optimal Mg2+, and appear identical, morphologically, and in sensitivity to cytochalasin D. Cells also spread on fibronectin in response to Mg2+, when Ca2+ is buffered below 10(-6)M, showing that external Ca2+ is not needed as a source for an increase in internal Ca2+. Cells can be induced to spread on serum in low Ca2+ by substantially increasing the fibronectin concentration; this supports other evidence that at its unsupplemented concentration, fibronectin contributes little to the spreading of these cells on serum. The Ca2+ requirement for spreading on preparations of vitronectin (serum spreading factor), partially purified from bovine serum, is similar to that on whole serum. Thus the difference in divalent cation requirement between serum and fibronectin may arise because, on serum, the dominant protein responsible for induction of spreading is vitronectin rather than fibronectin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A major difference between serum and fibronectin in the divalent cation requirement for adhesion and spreading of BHK21 cells. 244 8

In allergic and nonallergic lung diseases, if intraluminal mast cells adhere to airway epithelium, inflammatory mediators released from activated mast cells may reach high local concentrations and thus greatly affect airway function. To determine whether mast cells adhere to airway epithelial cells, radiolabeled or unlabeled dog mastocytoma cells were incubated with cultured dog tracheal epithelial cells, with extracellular matrix substrates, and with cryostat-cut sections of dog trachea. Mast cells adhered well to cultured epithelial cells (35 +/- 13% adhesion, mean +/- 1 SD, n = 23) but adhered poorly to types I and IV collagen or to fibronectin (less than 7.5% mean adhesion in all cases). Similarly, in tracheal tissue sections, mast cells adhered preferentially to epithelial cells in surface epithelium or in submucosal glands but not to basal membrane or connective tissue. Adhesion to cultured epithelial cells was a characteristics of a subpopulation of mast cells, could persist for more than 48 h, did not require energy or the presence of divalent cations, and was not mediated by a known family of leukocyte-associated adhesion glycoproteins. Adhesion was completely abolished by pretreatment of mast cells with pronase E or proteinase K but not with trypsin (up to 10 micrograms/ml at 37 degrees C for 20 min each). In contrast, pretreatment of cultured epithelial cells with any of these proteinases had no effect on adhesion. It is concluded that dog mastocytoma mast cells adhere to dog tracheal epithelial cells and do so selectively. It is suggested that mast cell adhesion to airway epithelium may play a role in the effectiveness of mast cell-epithelial cell interactions, and thus, in certain lung diseases, airway function may be affected by intraluminal mast cells more than is currently appreciated.
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PMID:Selective adhesion of mast cells to tracheal epithelial cells in vitro. 245 Sep 14

Human umbilical vein endothelial cells (ECs) adhere in vitro to proteins of the extracellular matrix including fibronectin (fn) and vitronectin (vn). Specific receptors for fn and vn have been previously characterized. These receptors belong to a family of membrane glycoproteins characterized (a) by being a transmembrane complex of two noncovalently linked subunits and (b) by recognizing the tripeptide Arg-Gly-Asp on their respective ligands. In this paper we investigated how vn and fn control the organization of their respective receptors over the surface of ECs. It was found that the clustering of individual receptors and the organization thereafter of focal contacts occurred only when ECs were exposed to the specific ligand and did not occur on the opposite ligand. The shape of receptor clusters was slightly different and a colocalization of the two receptors was found when ECs were cultured on a mixed matrix of fn plus vn. Adhesion was selectively inhibited by vn or fn receptor antibodies on their respective substrates. The clustering of both receptors preceded the association of vinculin with focal contacts and stress fiber formation. Also, the vn receptor, in the absence of associated fn receptor, was capable of inducing the organization of the membrane-microfilament interaction complex. Overall, these results indicate that individual matrix ligands induce only the clustering of their respective membrane receptors. The clustering of only one receptor is capable of supporting the subsequent formation of focal contacts and the local assembly of related cytoskeletal proteins.
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PMID:Fibronectin and vitronectin regulate the organization of their respective Arg-Gly-Asp adhesion receptors in cultured human endothelial cells. 245 62

Adhesion and spreading of cell lines on dishes coated with serum-derived proteins were studied after removal of cell-surface proteoglycans. A mixture of glycosaminoglycans lyases from heparin-induced Flavobacterium heparinum removed 80% of the [35S]sulphate-labelled glycosaminoglycans from the surface of attached cells within 30 min, but this had little effect on cell morphology. The rate of cell attachment to dishes coated with serum was unaffected by prior treatment of cells with this mixture of glycosaminoglycan lyases. While a heparan sulphate lyase preparation abolished cell spreading in response to fibronectin there was no effect of the enzyme on the spreading mediated by vitronectin. These results suggest that, although heparan sulphate is required for spreading on purified fibronectin, the spreading stimulated by serum under routine culture conditions requires neither cellular heparan sulphate nor serum-derived fibronectin.
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PMID:Cell spreading on serum is not identical to spreading on fibronectin. 245 45

We have prepared protein-peptide conjugates composed of bovine serum albumin (BSA) derivatized with short peptides containing the Arg-Gly-Asp (RGD) sequence derived from the adhesion site of fibronectin. The RGD-BSA conjugates were used to coat tissue culture plastic surfaces which then served as substrata in cell adhesion experiments. Our results indicate that the efficiency of adhesion to RGD-BSA-coated surfaces is highly dependent on the valency of the (RGD)n-BSA conjugates. For example, on surfaces with approximately equal amounts of RGD ligand, CHO cells adhered virtually 100% to the (RGD)n-BSA (n = 20.8) conjugate and not at all to the (RGD)n-BSA (n = 3.5) conjugate. Adhesion on (RGD)n-BSA-coated substrata and on fibronectin- or vitronectin-coated substrata was also examined in terms of the relationship between cell adhesion and the intermolecular distances of adsorbed proteins. It was observed that for substrata coated with relatively compact, symmetric molecules, such as RGD-BSA or vitronectin, adhesion dropped off sharply as intermolecular distances increased; by contrast, for fibronectin, a large asymmetric molecule, adhesion declined more gradually as intermolecular distances increased. Finally, we have examined the role of different cell-surface receptors in the process of adhesion to RGD-BSA substrata. Interestingly, competition and blocking experiments with antibodies and with soluble competing proteins suggest that it is the vitronectin receptor rather than the fibronectin receptor which mediates adhesion to RGD-BSA.
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PMID:(Arg-Gly-Asp)n-albumin conjugates as a model substratum for integrin-mediated cell adhesion. 246 96

Microvascular endothelial cells (MEC) must use a set of surface receptors to adhere not only to the vascular basement membrane but, during angiogenic stimulation, to the interstitium. We examined how cultured MEC isolated from human foreskin interact with their subendothelial matrix. MEC were able to attach to diverse extracellular matrix proteins, including fibronectin (Fn), vitronectin (Vn), laminin (Ln), type I and IV collagen, as well as to fibrinogen and gelatin. Adhesion to Fn, but not to laminin or collagens, was specifically blocked in the presence of Arg-Gly-Asp (RGD)-containing peptides. When surface radioiodinated MEC were solubilized and subjected to affinity chromatography on Fn-Sepharose columns, two polypeptides of 150 and 125 kD, corresponding to the integrin heterodimer alpha 5 beta 1, were identified. MEC also express a complex of 150 (alpha) and 95 kD (beta 3) that is related to the Vn receptor. Immunofluorescent staining of MEC cultures with antibodies to the integrin beta 1 subunit demonstrated receptors on the basolateral surface at focal adhesion plaques that co-localized with vinculin and with Fn-positive matrix fibers. Occasionally, antibodies to the Vn receptor stained the vinculin-positive focal adhesion plaques that frequently co-localized with the beta 1 complex. However, in cultures of MEC that were attached to substrates coated with alternating strips of Fn and Vn, the beta 1 complex was preferentially localized to the Fn substrate, while the Vn receptor was concentrated on the Vn substrate. The results indicate that MEC express at least two different heterodimer adhesion receptors that belong to the integrin super-family and appear to have distinct ligand specificities: the Fn receptor and the Vn receptor. These receptors mediate cell adhesion to the extracellular matrix and presumably have an important role in hemostasis and neovascularization.
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PMID:Human microvascular endothelial cells express integrin-related complexes that mediate adhesion to the extracellular matrix. 246 86

We have demonstrated previously that chick embryo fibroblasts synthesize and secrete a large chondroitin sulfate proteoglycan (designated PG-M) that binds to fibronectin. We now report the possibility that PG-M interactions with cell surfaces can modulate cell-substrate adhesion. When PG-M was added to the medium, various types of trypsinized cells failed to adhere not only to fibronectin-coated substrates but also to collagen- or vitronectin-coated substrates. Adhesion of the cells to laminin or glycyl-arginyl-glycyl-aspartyl-serine derivatized serum albumin (arginyl-glycyl-aspartic acid-containing molecules with no capacity to bind PG-M) was also inhibited by PG-M. Treatment of the proteoglycan with either proteolytic enzymes or chondroitinase abolished its inhibitory effects on the cell adhesion. These results suggest that direct binding between PG-M and fibronectin, if any, is not a cause of the inhibition by PG-M and that only the proteoglycan form is responsible for the activity. When the immobilization of added PG-M to available plastic surfaces of coated dishes was blocked by pretreating the dishes with serum albumin, the inhibitory effect of PG-M was abolished, suggesting that the immobilized fraction of PG-M can act as a cell adhesion inhibitor. In immobilized form, both cartilage chondroitin sulfate proteoglycan (designated PG-H) and chondroitin sulfate-derivatized serum albumin also inhibited cell adhesion. In contrast, heparan sulfate proteoglycan form LD and heparan sulfate-derivatized serum albumin had far lower inhibitory activities, indicating that the active site for the interaction between cells and PG-M is on the chondroitin sulfate chains.
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PMID:Regulation of cell-substrate adhesion by proteoglycans immobilized on extracellular substrates. 247 Jul 39

The receptors for fibronectin (FN-R) and vitronectin (VN-R) belong to a family of integral membrane glycoproteins known to be involved in cell-extracellular matrix and cell-cell interactions named integrins (FN-R = beta 1 integrin and VN-R = beta 3 integrin). Adhesion studies using FN-coated plastic dishes and highly purified subpopulations of peripheral blood mononuclear cells (PBMCs) showed a strong binding of monocytes and T lymphocytes to FN but virtually no binding of B cells to FN. Binding of monocytes and T cells to FN could be partially inhibited by a hexapeptide (GRGDSP) containing the adhesive peptide sequence Arg-Gly-Asp (RGD) as well as by an anti-FN-R antibody. The distribution of beta 1 and beta 3 integrin complexes on PBMCs was characterized by immunoprecipitation of detergent extracts of 125I-labeled cells using polyclonal antibodies against these two receptors. Two surface polypeptides corresponding to the alpha and beta chains of FN-R and VN-R were found on all three cell types. To characterize these receptors further, monoclonal antibodies (MoAbs) against the very late antigens (VLAs) 1, 3, and 5 were used for immunoprecipitation studies. Monocytes and T cells reacted with VLA 5 that was previously identified as the human FN receptor, whereas no labeling with anti-VLA 5 could be shown for B cells. When cell populations were cultured in 10% human serum for 24 hours, an increase in beta 1-integrin+ monocytes and T cells was observed. The number of beta 3-integrin+ cells remained essentially unchanged. The presence of beta 1 and beta 3 integrins on monocytes as well as on T and B lymphocytes may be of significance in the ability of these cells to interact with each other and participate in hematopoiesis and certain immune reactions.
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PMID:Distribution of integrins on human peripheral blood mononuclear cells. 247 87


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