NG108-15 cells induce the expression of muscular acetylcholinesterase when co-cultured with myotubes

Although muscular activity has been demonstrated to regulate the expression of acetylcholinesterase (AChE) in cultured myotubes, the exact role of the presynaptic terminus in regulating AChE expression at the neuromuscular junctions is not known. A chimeric cc-culture of neuroblastoma x glioma hybrid NG108-15 cells with chick myotubes was established. By using chick-specific anti-AChE antibody, a protein of similar to 105 kDa in size corresponding to chick AChE catalytic subunit was revealed by Western blot analysis from the extracts of neuron-muscle co-cultures. In the co-cultures, NG108-15 cells induced the up regulation of muscle AChE expression by similar to 2.5-fold, while the control protein, chick muscle alpha-actinin at similar to 100 kDa, remained relatively unchanged. The NG108-15 cell-induced muscle AChE expression in the co-cultures was persistent when the muscular activity was blocked by ac-bungarotoxin. In order to determine the AChE-inducing activity derived from NG108-15 cells, the cultured chick myotubes were treated with either conditioned medium of NG108-15 cells or its cell lysate. However, the muscle AChE, both in protein and activity levels, remained relatively unchanged. Our finding suggests that an AChE-inducing factor(s) is derived from the neuroblastoma cells in the co-cultures, but that may require the nerve-muscle contacts in culture. (C) 1997 Elsevier Science Ireland Ltd.