Neurite formation induced in neuroblastoma cells and genetically altered non-neuronal cells

Ultrastructural changes associated with neurite formation were examined in suitably cultured neuroblastoma cells (Neuro-2a) and drebrin (developmentally regulated brain protein) gene-transfected fibroblasts (L cells) in culture. Both neuroblastoma cells and fibroblasts initially were flattened and epitheloid, with many microspikes or microvilli diffusely distributed over their surfaces. Intracellular organelles were abundant and diffusely arranged. In the transformed state, both cell types were round to oval with long processes where microspikes were concentrated. A constant arrangement of surface and intracellular structures was apparent, though drebrin gene-transfected fibroblasts retained some of their original characteristics. Neurite formation programmed by genes may be initiated by environmental factors in neuroblastoma cells. Neurite-like processes in fibroblasts may be formed due to changes in microfilaments resulting from transfection of the drebrin (actin-binding protein) gene.