LOCALIZATION OF NCAM ON NCAM-B-EXPRESSING CELLS WITH INHIBITED MIGRATION IN COLLAGEN

The extracellular matrix is a key element in neuronal development and tumour invasion, providing a substratum which sustains the adhesion an d migration of cells. In order to study interactions between the neura l cell adhesion molecule (NCAM) and collagen, we transfected mouse L c ells with cDNA encoding the human transmembrane NCAM isoform of 140 kD a (NCAM-B). An L-cell/collagen type I system was used to study the inf luence of NCAM expression on in vitro invasion. We here report that mi gration of NCAM-expressing cells in collagen was inhibited compared to that of NCAM-negative cells transfected with the empty vector. Immuno fluorescence confocal laser scanning microscopy (CLSM) and immunogold electron microscopy using anti-human NCAM antibodies demonstrated a he terogeneous distribution of NCAM on the plasma membrane of transfected L cells grown on collagen. NCAM was preferentially located at the sur face of broad cytoplasmic protrusions and slender extensions, some of which were facing the collagen. This was in contrast to the homogeneou s surface distribution of NCAM on cells grown on plastic. These data s uggest that NCAM and collagen type I interact, and that this might lea d to the migration inhibition of NCAM-expressing cells.