Two signal transduction pathways involved in the catecholaminergic differentiation of avian neural crest-derived cells in vitro

Molecules derived from the neural tube and found in chick embryo extract (C EE) and bone morphogenetic proteins (BMP) support the differentiation of ne ural crest-derived catecholaminergic (CA) neurons. We now report that intra cellular signaling resulting in the activation of Map kinase (MapK) or tran slocation of Smad1 mediate the differentiation of CA neurons in response to CEE or BMP 4, respectively. The differentiation of CA neurons was signific antly reduced by inhibiting MapK using PD98059 or by pan-specific blockade of tyrosine kinases using Herbimycin A. In the presence of BMP 4 and inhibi tors of MapK signaling, differentiation of CA neurons was only moderately r educed. Independent of MapK, BMP 4 induced translocation of Smad1 from the cytosol to the nucleus and induced transcription of dHAND, a DNA binding pr otein required for the differentiation of CA neurons. The data suggest that CEE-derived factors and BMP4 support the differentiation of CA neurons via independent signaling pathways.