NEURITE FORMATION INDUCED IN NEUROBLASTOMA-CELLS AND GENETICALLY ALTERED NONNEURONAL CELLS

Ultrastructural changes associated with neurite formation were examine d in suitably cultured neuroblastoma cells (Neuro-2a) and drebrin (dev elopmentally 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 dif fusely distributed over their surfaces. Intracellular organelles were abundant and diffusely arranged. In the transformed state, both cell t ypes were round to oval with long processes where microspikes were con centrated. A constant arrangement of surface and intracellular structu res 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 ce lls. Neurite-like processes in fibroblasts may be formed due to change s in microfilaments resulting from transfection of the drebrin (actin- binding protein) gene.