Surface Of Several Cell Types Research Articles

The effect of diacylglycerols on fibronectin release and its reversal by retinoic acid in cell culture

Previous work from our laboratory showed that tumor promoters such as phorbol ester (TPA) stimulated the release of fibronectin (FN) from the surface of several cell types in culture, and that this stimulation was counteracted by retinoic acid. Diacylglycerols (DAGs) are the endogenous ligands of the TPA receptor and can activate and translocate protein kinase C (PKC) in a manner similar to TPA. To show that the release of FN is related to activation of PKC, we tested the action of DAGs on FN release from human lung fibroblasts and its counteraction by retinoic acid. We found that DAGs stimulated the release of FN in a concentration- and time-dependent manner. The stimulation of the release of FN correlated with the translocation-activation of PKC by DAG. Retinoic acid reversed the action of DAG with respect to stimulation of FN release and inhibited this release even in the absence of DAG. These results suggest that the release of FN is in some way related to translocation-activation of PKC.

Interaction of endothelial cell growth factor with heparin: characterization by receptor and antibody recognition.

Endothelial cell growth factor (ECGF) binds specifically in vitro to membrane receptors present on the surface of several cell types, including murine and human endothelial cells and fibroblasts. Monoclonal antibodies prepared against ECGF that inhibit the mitogenic activity of the growth factor prevent receptor occupancy by the ligand. Heparin interacts structurally with ECGF [Maciag, T., Mehlman, T., Friesel, R. & Schreiber, A. B. (1984) Science 225, 932-935], potentiates the mitogenic activity of the polypeptide, restores the biological activity to inactivate ECGF, enhances the affinity of the ligand to cell surface receptors, and modifies antibody recognition of ECGF. These data suggest that the association between heparin and ECGF induces a conformational change in the polypeptide that increases or stabilizes the biological activity of the mitogen.

Mapping of concanavalin a binding sites on the surface of several cell types

Hemocyanin labeled concanavalin A was used to study the distribution of sugar residues on the surface of various cell types.