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

Starch-activated mouse peritoneal macrophages (STpMAC) plated on plastic demonstrate the adhesive properties typical for activated pMAC: attaching as round cells and, within 15 min, spreading out with marginal membrane ruffles. These attached STpMAC were labeled by lactoperoxidase-catalysed 125I surface iodination, sodium dodecyl-sulfate-lysed, and the lysates electrophoresed on polyacrylamide gels which were examined by autoradiography. The STpMAC morphological phenotype correlates with the labeling of a particular protein (195,000, estimated mol wt). Normal pMAC (NpMAC), from unstimulated mice, do not spread and do not display the 195,000 band. Both pMAC band patterns, including the 195,000 band, are relatively resistant to trypsin digestion, as is pMAC adhesion itself trypsin-resistant. Neither class of pMAC exhibits fibronectin (Cell Adhesion Factor, LETS protein) which is a component in the adhesive matrix of cells forming trypsin-sensitive monolayers. When pMAC are tested against antifibronectin antibody, these cells do not give immunofluorescent staining. In summary, two functions in pMAC adhesion, enzyme resistance and the ability to spread, appear related to molecular properties distinctive for pMAC surface protein.
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PMID:Identification of macrophage external membrane proteins and their possible role in cell adhesion. 70 74

Glomerular epithelial cells (GEC) maintain glomerular permselectivity and are a target of immunological glomerular injury, which may lead to proliferation or detachment from extracellular matrix (ECM). We studied adhesion mechanisms in rat GEC in culture, focusing on adhesion molecules of the beta 1 integrin family. At early time points (1 hr after plating of cells into culture wells that had been pre-incubated with purified ECM proteins), adhesion of GEC to collagen I, collagen IV, laminin, and fibronectin was inhibited with anti-beta 1 integrin antibody. The peptide RGDS inhibited adhesion to fibronectin and laminin. Immunoprecipitation studies demonstrated the presence of alpha 2, alpha 3, and beta 1 integrins; the alpha 1, alpha 4, alpha 5, alpha 6, alpha v, and beta 3 subunits were undetectable. Adhesion to all ECM proteins was dependent on divalent cations, but the effects of individual cations varied among substrata. In rat GEC, alpha 2 beta 1 and/or alpha 3 beta 1 integrins appear to mediate adhesion to collagen I, collagen IV, and laminin. The alpha 3 beta 1 integrin is also the likely receptor for fibronectin, interacting through an RGD binding site. Furthermore, single integrins or combinations of integrins appear to have distinct ligand-binding functions that are differentially regulated by divalent cations. Characterization of GEC adhesion molecules may facilitate the understanding of mechanisms of glomerular development, and cell detachment or proliferation in immune glomerular injury.
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PMID:Adhesion of rat glomerular epithelial cells to extracellular matrices: role of beta 1 integrins. 128 Jul 1

We have previously reported that fibrinogen/fibrin can induce the migration of vascular smooth muscle cells in vitro. In this study, we examined the effect of substrate-bound fibrinogen/fibrin and other cell attachment-promoting proteins on the adhesion of vascular smooth muscle cells. The amount of fibrinogen/fibrin adsorbed to plastic wells and the adhesion of smooth muscle cells to the wells were found to depend on the concentration of fibrinogen used for coating the wells. The effect of fibrinogen/fibrin was comparable to that of so-called cell attachment-promoting proteins (fibronectin, vitronectin, and type I collagen). Adhesion of smooth muscle cells to fibrinogen/fibrin-coated wells was inhibited by the synthetic peptide GRGDS, but not by a control peptide, GRGES. Vitronectin, fibronectin, type I collagen, denatured type I collagen and commercial gelatin also induced smooth muscle cell adhesion. The adhesion induced by vitronectin, denatured type I collagen, and commercial gelatin was inhibited by GRGDS. However, the adhesion induced by type I collagen was not influenced and that induced by fibronectin was only slightly inhibited. These observations suggest that fibrinogen/fibrin deposited extracellularly in the arterial intima may act as a scaffold in the process of smooth muscle cell migration.
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PMID:Substrate-bound fibrinogen, fibrin and other cell attachment-promoting proteins as a scaffold for cultured vascular smooth muscle cells. 128 31

The morphological and biochemical events following Trypanosoma cruzi trypomastigote-fibronectin (Fn) interactions have been studied. Adhesion of trypomastigotes to Fn-coated surfaces is followed by Fn degradation. The proteolytic cleavage of Fn was demonstrated by qualitative and quantitative measurement of Fn degradation after its exposure to trypomastigotes as well as polyacrylamide gel analysis of Fn proteolysis by a parasite protease (s). The released Fn peptide fragments stimulated the transformation of trypomastigotes to amastigotes. The gelatin (45 kDa) and heparin (40 kDa) binding fragments were shown to be able to promote trypomastigote differentiation. In contrast, native Fn and the 120 kDa fragment (cell attachment domain) were inactive. Complementary investigations showed that the gelatin and heparin binding fragments stimulated parasite RNA synthesis and protein synthesis and phosphorylation but not DNA replication and increased parasite intracellular cAMP concentrations. These findings suggest that the proteolysis of Fn by parasite proteases, which occurs under physiological conditions, might facilitate invasion of target cells by trypomastigotes. The Fn peptides released during this process may act as "growth factor-like" substances.
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PMID:Fibronectin cleavage fragments provide a growth factor-like activity for the differentiation of Trypanosoma cruzi trypomastigotes to amastigotes. 128 73

An appropriate balance of matrix synthesis and degradation is required for normal morphogenesis and maintenance of tissue architecture. Extracellular matrix molecules and their receptors, as well as proteinases and their inhibitors, are all involved in matrix remodeling. This report examines the idea that extracellular matrix receptors can regulate matrix remodeling. Rabbit synovial fibroblasts and human embryonic lung fibroblasts (MRC-5) were cultured under two sets of conditions. First, they were plated in serum and allowed to establish an extracellular matrix over a 48 h period. Rat monoclonal antibody to the alpha 5/beta 1 integrin fibronectin receptor or normal rat IgG was added to the medium and the expression of the metalloproteinases was examined. Cells treated with anti-alpha 5/beta 1 expressed procollagenase and prostromelysin, whereas the control cells did not. In both cases the cells were well spread and maintained a well-organized cytoskeleton. In the second condition, cells were plated in serum-free medium on intact fibronectin, anti-alpha 5/beta 1, or fragments of fibronectin that contained the cell-binding domain. Cells attached and spread on all these substrates in a fibronectin receptor-dependent manner. They expressed collagenase and stromelysin on anti-alpha 5/beta 1 and on several fibronectin fragments, but not on intact fibronectin. These data support the hypothesis that the fibronectin receptor can exist in more than one functional state and that these functional states provide information that influences gene expression. Adhesion and spreading are supported by all states, whereas only a subset permits collagenase and stromelysin expression.
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PMID:Signal transduction via the fibronectin receptor: do integrins regulate matrix remodeling? 128 60

Regulation of a number of adhesion molecules during neural crest cell migration was studied. The neural crest, a transient embryonic neural epithelium structure, undergoes mesenchymal transformation (epithelial-mesenchymal transition). The cells then migrate, giving rise to a variety of elements including the peripheral nervous system and melanocytes. During migration, neural crest cells do not express functional cell Adhesion Molecules but interact specifically with cell-binding domains in fibronectin molecules. A rat bladder carcinoma cell line was used as an in vitro model to study conversion of epithelial cells to a migratory fibroblast-like state. Conversion can be induced by culture on collagen or exposure to acidic Fibroblast Growth Factor (aFGF). Furthermore, constitutive fibroblast-like transformation can be induced by transfection with cDNA encoding aFGF. Growth factor-producing clones exhibit increased invasive and metastatic properties as compared with non-FGF-producing control cells. This model may provide increased understanding of the role of the different adhesion molecules in processes involving cell remodeling, such as tumor spread and development of metastases.
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PMID:[Adhesion and mobility of embryonic and tumoral cells]. 128 12

We examined the fibronectin-adhesive properties of clones from a rat colonic cell line exhibiting distinct tumorigenicity in a syngeneic host. These cells were originally selected on the basis of differential adhesion to plastic surfaces. The TR cell line, when injected subcutaneously, forms a tumour which grows progressively and gives off metastases, whereas the TS cell line forms a small tumour which regresses within a few weeks. The regression is largely mediated by immunological factors and involves a fibroblastic reaction. REGb, a clone from the TS subline, adhered better to fibronectin or RGDS tetrapeptide than did PROb, a clone from the TR subline. However, there was little binding to the RGD tripeptide with either clone. The degree of adhesion was dependent on time and substrate concentration. After 6 h of incubation, 38% and 55% respectively of PROb and REGb cells bound to plates coated with 10 micrograms/ml fibronectin. Adhesion of both clones to fibronectin was inhibited to various degrees when cells were preincubated with RGDS, GRGDS or GRADSPK peptides, whereas other synthetic peptides such as RGD, GRGD or GRGFSPK were ineffective. Binding experiments using 125I-labelled fibronectin showed 39,000 fibronectin receptor sites on REGb cells but only 17,000 on PROb cells. Flow cytometry analysis using both anti-alpha 5 and anti-beta 1 integrins showed more fibronectin receptor sites on REGb than on PROb cells. Both approaches were in accordance with the higher adhesiveness of the REGb clone to fibronectin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential adhesion of rat colon carcinoma cells to fibronectin in relation to their tumorigenicity. 130 47

Integrin matrix receptors on glomerular epithelial cells (GEC) may play an important role in adhesion of GEC to the glomerular basement membrane (GBM) and in the maintenance of normal glomerular permeability. Therefore, the author determined the types of matrix receptors present on cultured rat GEC and examined their interactions with several components of the extracellular matrix. Beta 1 integrin matrix receptors were detected on all three glomerular cell types in rat kidney in vivo and at areas of cell-cell contact on cultured GEC. Glomerular epithelial cell adhesion to types I and IV collagen was slightly greater than to laminin and fibronectin. Adhesion to fibronectin was significantly inhibited by a synthetic peptide containing the RGD adhesion sequence. Immunoprecipitation of lysates of surface-iodinated GEC showed the presence of alpha 3 beta 1 integrin. Chromatography of lysates on immobilized collagen showed alpha 3 beta 1 integrin and a 70- to 75-kd protein band as the collagen receptors on GEC. Chromatography on the 120-kd cell-binding fragment of fibronectin disclosed only alpha 3 beta 1 as a specific fibronectin receptor. Antibody to the beta 1 integrin chain inhibited adhesion to laminin and collagen. These studies demonstrate that in vitro, as in vivo, GEC appear to express only alpha 3 beta 1 integrin. Furthermore, this matrix receptor is capable of mediating GEC adhesion to collagen, fibronectin, and laminin, components of the GBM, and presumably plays a similar role in promoting GEC adhesion to GBM in vivo.
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PMID:Characterization of glomerular epithelial cell matrix receptors. 132 40

For immune surveillance and function to be effective, T lymphocytes constantly recirculate via lymph and blood between lymphoid organs and body tissues. To enable efficient cell movement and migration, cell adhesion to components of the basement membrane and the extracellular matrix (ECM) must be a rapid and transitory process. Whether phosphorylation and dephosphorylation of cellular proteins are involved in this phenomena was explored by monitoring the adhesion of T cells to immobilized ECM proteins. A short exposure of 51Cr-labeled human CD4+ T cells to phorbol esters in vitro induced a rapid beta 1-integrin-mediated adhesion to both fibronectin and laminin, as determined by inhibition with anti-integrin antibodies. Adhesion was reversible; detachment from the immobilized ECM ligands occurred between 20 and 120 min without further intervention. This T cell adhesion was regulated by the activation of protein kinase C because (a) staurosporine and H-7 inhibitors of protein kinase C suppressed T cell adhesion, and (b) PMA-induced down-regulation of intracellular levels of protein kinase C was associated with the abrogation of the T cell adhesiveness to fibronectin and laminin. Furthermore, inhibition of protein phosphatases activity by okadaic acid delayed the detachment of the T cells from fibronectin or laminin. Thus, we suggest that T cell-ECM interactions such as adhesion and detachment are regulated, respectively, by protein kinase C and protein phosphatases.
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PMID:Involvement of a protein kinase C and protein phosphatases in adhesion of CD4+ T cells to and detachment from extracellular matrix proteins. 132 39

The expression of the VLA-integrins alpha 2, alpha 3, alpha 5 and alpha 6 was studied immunohistochemically in tissue samples from ductal pancreatic cancer, chronic pancreatitis, normal pancreas and in 8 cell lines of ductal human pancreatic cancer. Furthermore, adhesion assays on purified extracellular matrix (ECM)-compounds were used to define the function of alpha 2, alpha 3, alpha 5 and alpha 6 in pancreatic cancer cells. Immunohistochemically, VLA alpha 2 and VLA alpha 6 were moderately to strongly expressed on the basal surface of ductal and acinar cells in normal pancreatic tissue, while centro-acinar cells predominantly expressed VLA alpha 3 and VLA alpha 5. Pancreatic carcinoma showed intense staining for VLA alpha 2 and VLA alpha 6 with a diffuse distribution on the cell surface. The redistribution of VLA alpha 2 and VLA alpha 6 may reflect a loss of spatial arrangement of tumor cells and their ability to interact randomly with extracellular matrix structures during invasion and metastasis. Expression of VLA alpha 3 and VLA alpha 5 in pancreatic carcinoma was heterogeneous, ranging from moderate to weak, and was lost in about 50% of the cells. Two pancreatic carcinoma cell lines (PC 3, PC 44) were further investigated in adhesion assays. Monoclonal antibodies (MAbs) against alpha 2 (GI 9, 10-G-11) were able to inhibit tumor-cell adhesion to collagen IV (59%-72%) in both cell lines. A MAb against alpha 6 (GoH3) inhibited tumor-cell adhesion to laminin (52%-86%) in both cell lines. These results suggest that alpha 2 is a collagen-binding site and alpha 6 a laminin-binding site in pancreatic cancer cells. The anti-alpha 5-MAb SAM I inhibited adhesion of PC3 to fibronectin (76%), being without effect in PC44. Adhesion of both cell lines to fibronectin was almost completely inhibited by RGDS (85%-88%). Thus, alpha 5 is a functionally important fibronectin binding site in some pancreatic carcinoma cells, suggesting further RGD-dependent fibronectin binding sites in other pancreatic carcinoma cells.
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PMID:Expression and function of VLA-alpha 2, -alpha 3, -alpha 5 and -alpha 6-integrin receptors in pancreatic carcinoma. 133 Sep 37


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