Transgenic models for studying expression and function of axonal adhesive glycoproteins.

In this study, by using two transgenic models, we address the general topic of the significance of axonal glycoproteins regulated expression in nervous tissue maturation. The immunoglobulin superfamily components F3/Contactin (F3) and TAG-1 are used as the molecular models in this respect. First, a minigene including the relevant regulatory sequences of the F3 gene, deduced by a previous in vitro study, has been fused to an EGFP (Enhanced Green Fluorescent Protein) reporter and expressed in transgenic mice, which provided information about the profile of F3 gene developmental activation. In a complementary model, transgenic mice have been generated which express the F3 cDNA under control of a selected regulatory region from the TAG-1 gene. While leading to ectopic expression of F3, this perturbed neuronal precursor proliferation and differentiation. The arising effects were even stronger than those coming from the overall suppression of the F3 or, respectively, TAG-1 genes, thus supporting the hypothesis that the mechanisms underlying axonal glycoprotein regulated expression are themselves endowed with a key significance in neural development.