Localization of NCAM on NCAM‐B‐expressing cells with inhibited migration in collagen

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Abstract
The extracellular matrix is a key element in neuronal development and tumour invasion, providing a substratum which sustains the adhesion and migration of cells. In order to study interactions between the neural cell adhesion molecule (NCAM) and collagen, we transfected mouse L cells with cDNA encoding the human transmembrane NCAM isoform of 140 kDa (NCAM‐B). An L‐cell/collagen type I system was used to study the influence of NCAM expression on in vitro invasion. We here report that migration of NCAM‐expressing cells in collagen was inhibited compared to that of NCAM‐negative cells transfected with the empty vector. Immunofluorescence confocal laser scanning microscopy (CLSM) and immunogold electron microscopy using anti‐human NCAM antibodies demonstrated a heterogeneous distribution of NCAM on the plasma membrane of transfected L cells grown on collagen. NCAM was preferentially located at the surface of broad cytoplasmic protrusions and slender extensions, some of which were facing the collagen. This was in contrast to the homogeneous surface distribution of NCAM on cells grown on plastic. These data suggest that NCAM and collagen type I interact, and that this might lead to the migration inhibition of NCAM‐expressing cells.