REGULATION BY ARIA NEUREGULIN OF ACETYLCHOLINE-RECEPTOR GENE-TRANSCRIPTION AT THE NEUROMUSCULAR-JUNCTION/

Transcription of genes encoding nicotinic acetylcholine receptor (AChR ) subunits (alpha, beta, gamma, epsilon, and delta) is highest in nucl ei localized to the synaptic region of the muscle which contributes to maintain a high density of AChRs at the postjunctional membrane. ARIA (AChR inducing activity) is believed to be the trophic factor utilize d by motor neurons to stimulate AChR synthesis in the subsynaptic area . ARIA stimulates tyrosine phosphorylation of the erbB proteins and ac tivates the MAP kinase pathway which is required for the ARIA-mediated induction of AChR genes.