Elicitation of Selective T and B Lymphocyte Responses by Cell Surface Binding Ligands

We report that the isolated C-terminal domain of progelatinase A is inhibitory to the activation of this proenzyme by primary skin fibroblast plasma membranes but is unable to inhibit organomercurial-induced self-cleavage and activation. Ligand binding studies demonstrate that fibroblasts stimulated with concanavalin A to activate progelatinase A have a significantly enhanced level of cell surface-associated progelatinase A. Tissue inhibitor of metalloproteinases-2 (TIMP-2), an effective inhibitor of membrane-mediated progelatinase A activation, is able to abolish the enhanced level of cell surface-associated progelatinase A that occurs following stimulation. TIMP-1, a poor inhibitor of membrane activation, is unable to inhibit the cell surface binding of progelatinase A. The enhancement in the binding of 125I-progelatinase A to fibroblasts following concanavalin A stimulation can be blocked by the inclusion of excess C-terminal gelatinase A but not by a truncated form of gelatinase A lacking the C-terminal domain. Scatchard analysis of the binding of 125I-progelatinase A to concanavalin A-stimulated fibroblasts has identified 950,000 gelatinase binding sites per cell with a Kd of 1.3 x 10(-8) M. Analysis of non-stimulated fibroblasts has identified 500,000 sites per cell with a Kd of 2.6 x 10(-8) M. We propose that membrane-mediated activation of progelatinase A involves binding of the proenzyme through its C-terminal domain to the cell surface and that TIMP-2 can inhibit activation by interaction with progelatinase A through the C-terminal domain, thus preventing binding of the proenzyme.

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Cell surface binding of adenosine toDictyosteliumand inhibition of pulsatile signalling

FEMS Microbiology Letters ◽

10.1111/j.1574-6968.1982.tb08298.x ◽

1982 ◽

Vol 13 (4) ◽

pp. 417-421 ◽

Cited By ~ 23

Author(s):

Peter C. Newell

Keyword(s):

Cell Surface ◽

Surface Binding ◽

Cell Surface Binding

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Locomotory competence and laminin-specific cell surface binding sites are lost during myoblast differentiation

Development ◽

10.1242/dev.105.4.795 ◽

1989 ◽

Vol 105 (4) ◽

pp. 795-802

Author(s):

S.L. Goodman ◽

R. Deutzmann ◽

V. Nurcombe

Keyword(s):

Cell Surface ◽

Binding Sites ◽

Radioligand Binding ◽

Specific Interaction ◽

Myoblast Differentiation ◽

Specific Cell ◽

Surface Binding ◽

Cell Surface Binding ◽

Locomotory Response ◽

Specific Cell Surface

The specific interaction of embryonal cells with the extracellular matrix (ECM) is one of the principal forces influencing embryonal development (Hay, 1984; Trinkaus, 1984). We used a muscle satellite cell line (MM14dy) to determine the relationship between locomotory response to laminin and the expression of specific cell surface binding sites for it. Time lapse videomicroscopic analysis was used to study the locomotory response and radioligand binding assays and cell attachment assays were used to follow the expression levels of binding sites for laminin and its subfragments E8 and E1–4. We report here the novel finding that the ability of MM14dy to locomote over laminin diminishes and finally vanishes as the cells differentiate. The simultaneous drop in expression of binding sites for laminin is interpreted as being of potential significance during development and repair.

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Transforming growth factor beta increases cell surface binding and assembly of exogenous (plasma) fibronectin by normal human fibroblasts

Molecular and Cellular Biology ◽

10.1128/mcb.8.10.4234-4242.1988 ◽

1988 ◽

Vol 8 (10) ◽

pp. 4234-4242

Author(s):

B L Allen-Hoffmann ◽

C L Crankshaw ◽

D F Mosher

Keyword(s):

Extracellular Matrix ◽

Growth Factor ◽

Cell Surface ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Human Fibroblasts ◽

Tgf Beta ◽

Surface Binding ◽

Amino Terminal ◽

Cell Surface Binding

Transforming growth factor beta (TGF-beta) enhances the cell surface binding of 125I-fibronectin by cultured human fibroblasts. The effect of TGF-beta on cell surface binding was maximal after 2 h of exposure to TFG-beta and did not require epidermal growth factor or protein synthesis. The enhancement was dose dependent and was found with the 125I-labeled 70-kilodalton amino-terminal fragment of fibronectin as well as with 125I-fibronectin. Treatment of cultures with TGF-beta for 6 h resulted in a threefold increase in the estimated number of fibronectin binding sites. The increase in number of binding sites was accompanied by an increased accumulation of labeled fibronectin in detergent-insoluble extracellular matrix. The effect of TGF-beta was biphasic; after 6 h of exposure, less labeled fibronectin bound to treated cultures than to control cultures. Exposure of cells to TGF-beta for greater than 6 h caused a two- to threefold increase in the accumulation of cellular fibronectin in culture medium as detected by a quantitative enzyme-linked immunosorbent assay. The second phase of the biphasic effect and the increase in soluble cellular fibronectin were blocked by cycloheximide. Immunofluorescence staining of fibroblast cultures with antifibronectin revealed that TGF-beta caused a striking increase in fibronectin fibrils. The 70-kilodalton amino-terminal fragment of fibronectin, which blocks incorporation of fibronectin into extracellular matrix, blocked anchorage-independent growth of NRK-49F cells in the presence of epidermal growth factor. Our results show that an increase in the binding and rate of assembly of exogenous fibronectin is an early event preceding the increase in expression of extracellular matrix proteins. Such an early increase in cell surface binding of exogenous fibronectin may be a mechanism whereby TGF-beta can modify extracellular matrix characteristics rapidly after tissue injury or during embryonic morphogenesis.

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