Involvement of bone morphogenetic protein-4 and bone morphogenetic protein-7 in the differentiation of the adrenergic phenotype in developing sympathetic neurons.

The neurotransmitter phenotype of sympathetic neurons is specified by interactions with the surrounding embryonic tissues. Adrenergic differentiation is elicited early during development in the vicinity of notochord and dorsal aorta and the importance of axial midline tissues for adrenergic differentiation has been well documented. We now provide evidence that bone morphogenetic proteins, BMP-4 and BMP-7 are signals produced by the dorsal aorta that direct sympathetic neuron differentiation. BMP-4 and BMP-7 are expressed in the dorsal aorta at critical times during sympathetic neuron differentiation and have the ability to enhance the formation of adrenergic sympathetic neurons both in cultures of neural crest cells and when ectopically expressed in the developing embryo.