Study of the neurodifferentiative role of GM1 oligosaccharide chain in mouse primary cerebellar neurons

One of the best studied ganglioside for its neurotrophic function is ganglioside GM1. GM1 neuro-properties are exerted when the GM1 membrane content increases in membrane microdomains, known as lipid rafts. This local enrichment could be responsible for (i) the GM1 content-dependent membrane reorganization, that alter the membrane properties, ensures that the physical parameters required for proper protein function is reached, (ii) the GM1 oligosaccharide-protein direct interactions, which can stereo chemically and allosterically modify protein structure and function. Despite several experimental data have been demonstrated the GM1 involvement in neuronal differentiation, the molecular mechanism by which GM1 exerts its neurotrophic action has not yet been elucidated. In this view, we decide to investigate the importance of its oligosaccharide portion by using primary neurons from mice cerebellum. We found that the GM1 oligosaccharide portion is able to influence the differentiation of these cells. By morphological analysis we evidenced the outstanding ability of oligosaccharidetreated cells to aggregate forming clusters. Moreover, the immunoblotting analysis highlighted the acceleration of the neuronal differentiation: there is an increase in the expression of neurodifferentiation markers such as MAP2, Synapsin and Neuroglican C, with respect to untreated cells. We also found an increase in GTPase RAC3 expression, that is involved in radial and tangential migration. Our results suggest that the oligosaccharide portion of GM1 is responsible for the ability of GM1 to induce neuritogenesis. We surmise that the neurotrophic effect of GM1 is due to a direct interaction with extracellular domain plasma membrane proteins.