Expression of a constitutively active type I BMP receptor using a retroviral vector promotes the development of adrenergic cells in neural crest cultures.

Previous work has demonstrated that the bone morphogenetic proteins (BMP)-2, BMP-4, and BMP-7 can promote the development of tyrosine hydroxylase (TH)-positive and catecholamine-positive cells in quail trunk neural crest cultures. In the present work, we showed that mRNA for the type I bone morphogenetic protein receptor IA (BMPR-IA) was present in neural crest cells grown in the absence or presence of BMP-4. We have used a replication-competent avian retrovirus to express a constitutively active form of BMPR-IA in neural crest cells in culture. Cultures grown in the absence of BMP-4 and infected with retrovirus containing a construct encoding this activated BMPR-IA developed five times more TH-immunoreactive and catecholamine-positive cells than uninfected control cultures or cultures infected with virus bearing the wild-type BMPR-IA cDNA. The number of TH-positive cells which developed was dependent on the concentration of virus bearing the activated receptor cDNA used in the experiments. Most TH-positive cells which developed also contained viral p19 protein. Total cell number was not affected by infection with the virus containing the activated receptor construct. The effect of the activated receptor was phenotype-specific since infection with the virus bearing the activated receptor cDNA did not alter the number or morphology of microtubule-associated protein (MAP)2-immunoreactive cells, which are distinct from the TH-positive cell population. These findings are consistent with the observation that MAP2-positive cells are not affected by the presence of BMP-4. Taken together, these results suggest that activity of BMPR-IA is an important element in promoting the development of the adrenergic phenotype in neural crest cultures.