EFFECTS OF NEUROTROPHIC FACTORS AND CELL SUBSTRATES ON THE DIFFERENTIATION OF A SYMPATHOADRENAL PROGENITOR-CELL LINE

The detailed spatial organization of cytoskeletal proteins in an immor talized sympathoadrenal precursor cell line, termed MAH, was studied w hen the cells were grown on cellular substrates and when treated with combinations of recombinant nerve growth factor, ciliary neurotrophic factor and basic fibroblast growth factor. Zn response to growth facto rs, MAH cells expressed appropriate distributions of phosphorylated an d non-phosphorylated neurofilaments, and dendrite and axon specific mi crotubule associated proteins. Sequential stages of maturation and axo n formation were identified as the MAH cells established neuronal pola rity and developed into sympathetic-like neurons. Combinations of the growth factors initiated growth associated protein-43 expression in pr ocesses and promoted the MAH cells to acquire sympathetic-like neuron characteristics with long, thin processes that branched and often term inated in elaborate growth cones. When treated with the three trophic factors, 15% of the MAH cells differentiated into sympathetic-like neu rons, in contrast to less than 10% when cultured with ciliary neurotro phic factor plus nerve growth factor. An enhanced cholinergic phenotyp e was evident in the MAH cells when grown with ciliary neurotrophic fa ctor. MAH cells also expressed neuron-specific markers when co-culture d on enriched substrates of smooth muscle, fibroblasts or Schwann cell s. The results indicate that this sympathoadrenal cell lineage, carryi ng the v-myc oncogene, can express appropriate cytoskeletal markers in the process of neuronal differentiation when induced by neurotrophic factors or by specific cellular conditions in vitro.