NG108-15 CELLS INDUCE THE EXPRESSION OF MUSCULAR ACETYLCHOLINESTERASEWHEN COCULTURED WITH MYOTUBES

Although muscular activity has been demonstrated to regulate the expre ssion of acetylcholinesterase (AChE) in cultured myotubes, the exact r ole of the presynaptic terminus in regulating AChE expression at the n euromuscular junctions is not known. A chimeric cc-culture of neurobla stoma x glioma hybrid NG108-15 cells with chick myotubes was establish ed. By using chick-specific anti-AChE antibody, a protein of similar t o 105 kDa in size corresponding to chick AChE catalytic subunit was re vealed 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 p rotein, chick muscle alpha-actinin at similar to 100 kDa, remained rel atively 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. H owever, the muscle AChE, both in protein and activity levels, remained relatively unchanged. Our finding suggests that an AChE-inducing fact or(s) is derived from the neuroblastoma cells in the co-cultures, but that may require the nerve-muscle contacts in culture. (C) 1997 Elsevi er Science Ireland Ltd.