Abstract
F3 is a 135kDa glycoprotein expressed at the surface of cultured neuronal cells and released in soluble form in the culture medium. Its structural properties, mainly derived from biochemical and molecular biology studies, revealed that it belongs to two families of cell interaction molecules: the HNK-1 family and the immunoglobulin supergene family. In particular, F3 is built of two kinds of distinct domains: Immunoglobulin type C2 and Fibronectin type III ones. This association is often found in the case of those surface glycoproteins bearing a predominant axonal localization. Accordingly, F3 expression was mainly restricted to neurites in brain primary cultures and to axon tracts in vivo. The molecule expression was found to be developmentally regulated with a peak in phases of the postnatal development characterized by extensive axonal growth and synaptogenesis. Functionally, we demonstrated its ability to mediate heterophilic interactions between nerve cells and to control key developmental processes as neurite outgrowth. On the basis of the above data we suggest that regulation of F3 gene expression during development is provided of key significance in neural morphogenesis.
