Cell-Cell and Cell-Substrate Contacts : Investigation by Functionally Active Monoclonal Antibodies

Summary

It has previously been shown that the anti-FC-1 antibody prevents cell-substrate adhesion of fibroblasts, and the FC-1 antigen has been characterized as a focal contact protein of cells in tissue culture (Oesch and Birchmeier, Cell, 31: 671–679).

In the present study, we show that the enrichment of the FC-1 antigen in the focal contacts depends on the nature of the substrate; it is present in the contacts when cells are grown on components of the basement membrane such as laminin, collagen IV, or fibronectin, but absent on collagen I or Concanavalin A. Basement membrane components seem also to influence the distribution of the FC-1 antigen in vivo; immunolocalization on frozen sections of various chicken tissues revealed that the antigen is concentrated at the basement membrane but not the junctional complex of different epithelia.

In contrast, the monoclonal antibody anti-Arc-1 interferes with cell-cell contacts and changes the morphology of MDCK (canine kidney) epithelial cells in vitro (Imhof et al., Cell, 35: 667–675).

In this communication we demonstrate that the Arc-1 antigen is enriched at the cell-cell contacts both of MDCK cells in tissue culture and of cells in various canine tissues. In the intestinal epithelium the antigen could be localized at the region of the junctional complex. It is therefore plausible that the anti-Arc-1 antibody acts by direct binding to components of the intercellular junctions. We further examined possible mechanisms by which the antibody might produce its cell dissociating effect. Antibody action was inhibited in the presence of colchicine but not cytochalasin B, and when the cellular cAMP level was raised.