The temporal requirement for endothelin receptor-B signalling during neural crest development

Endothelin receptor B (EDNRB) is a G-protein-coupled receptor with seven tr ansmembrane domains which is required for the development of melanocytes an d enteric neurons. Mice that are homozygous for a null mutation in the Ednr b gene are almost completely white and die as juveniles from megacolon, To determine when EDNRB signalling is required during embryogenesis, we have e xploited the tetracycline-inducible system to generate strains of mice in w hich the endogenous Ednrb locus is under the control of the tetracycline-de pendant transactivators tTa or rtTA. By using this system to express Ednrb at different stages of embryogenesis, we have determined that EDNRB is requ ired during a restricted period of neural crest development between embryon ic days 10 and 12.5. Moreover, our results imply that EDNRB is required for the migration of both melanoblasts and enteric neuroblasts.