Bone morphogenetic proteins (BMPs) induce autonomic neurogenesis in neural
crest cultures and stimulate sympathetic neuron development when overexpres
sed in vivo. We demonstrate that inhibition of BMPs in the chick embryo by
the BMP antagonist Noggin prevents sympathetic neuron generation. In Noggin
-treated embryos, the noradrenergic marker genes tyrosine hydroxylase (TH)
and dopamine-beta-hydroxylase (DBH), panneuronal neurofilament 160 (NF160)
and SCG10 genes, and the transcriptional regulators Phox2b and Phox2a are n
ot expressed in sympathetic ganglia. Whereas initial ganglion development i
s not affected, the expression of the basic helix-loop-helix transcription
factor cash-1 is strongly reduced. These results demonstrate that BMPs are
essential for sympathetic neuron development and establish Cash-1 and Phox2
genes as downstream effecters of BMPs in this lineage.