CELL-SURFACE MORPHOLOGY AND ADHESIVE PROPERTIES OF NORMAL AND VIRALLY TRANSFORMED-CELLS TREATED WITH TUNICAMYCIN, AN INHIBITOR OF PROTEIN GLYCOSYLATION

Normal and virally transformed mouse (3T3) fibroblasts were treated with tunicamycin, a fungal antibiotic that specifically inhibits the synthesis of peptidyl asparaginyl-linked oligosaccharides. All cell lines exhibited changes in cell surface morphology, surface-associated proteins and adhesion to the culture plate in the presence of tunicamycin. Scanning electron microscopy (SEM) revealed that treated fibroblasts assumed a spherical shape and were partially detached from the substratum. In addition, the 3T3 cells showed numerous cell surface ruffles. Tunicamycin-treated cells exhibited no marked ultrastructural changes when compared with control cells. There were indications, however, that the rough endoplasmic reticulum was dilated and that there were fewer membrane-bound ribosomes in treated 3T3 cells. Surface iodination of pretrypsinized tunicamycin-treated cells, followed by analysis of the labeled proteins on sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis, showed a marked reduction in a cell surface protein, identical or similar to fibronectin. Both tunicamycin-treated 3T3 and transformed 3T3 cells demonstrated a reduction in plating efficiency as shown by attachment assays of viable cells. In addition, treated cells showed a reduction in adhesiveness and a delay in spreading. The latter changes were more pronounced in the virally transformed cell lines. These findings suggest that cell surface glycoproteins, including fibronectin, play a role in determining the surface morphology and adhesive properties of cells. © 1978.