GFAP null astrocytes are a favorable substrate for neuronal survival and neurite growth

During the development of the CNS, astrocytes play a key role as a substrate for neuronal migration and axonal growth. These neuron-astrocyte interactions could be regulated, in part, by the astrocytic cytoskeleton. Nestin, vimentin, and glial fibrillary acidic protein (GFAP) are the three identified proteins constitutive of intermediate filaments present in astrocytes. In the present study, we used mice deficient in GFAP to define the influence of the major protein of the astrocytic cytoskeleton on neuron survival and axonal growth in a model of neuron-astrocyte coculture. We observed that GFAP null astrocytes are a better substrate for neuronal survival and neurite outgrowth than wild-type astrocytes. This may be correlated with the relatively late occurrence of GFAP expression in astrocyte maturation when the early steps of neurogenesis are completed.