Endothelin signalling in the development of neural crest-derived melanocytes

In both mice and humans, mutations in the genes encoding the endothelin B r eceptor and its ligand endothelin 3 lead to deficiencies in neural crest-de rived melanocytes and enteric neurons. The discrete steps at which endothel ins exert their functions in melanocyte development were examined in mouse neural crest cell cultures. Such cultures, kept in the presence of fetal ca lf serum, gave rise to cells expressing the early melanoblast marker Dct ev en in the absence of the phorbol eater tetradecanoyl phorbol acetate (TPA) or endothelins. However, these early Dct(+) cells did not proliferate and p igmented cells never formed unless TPA or endothelins were added. In fact, endothelin 2 was as potent as TPA in promoting the generation of both Dctmelanoblasts and pigmented cells, and endothelin 1 or endothelin 3 stimulat ed the generation of melanoblasts and of pigmented cells to an even greater extent. The inhibition of this stimulation by the selective endothelin B r eceptor antagonist BQ-788 (N-cis-2,6-dimethylpiperidinocarbonyl-L-alpha-met hylleucyl-D-1-methoxycarbonyltryptophanyl-D-norleucine) suggested that the three endothelins all signal through the endothelin B receptor. This recept or was indeed expressed in Dct(+) melanoblasts, in addition to cells lackin g Dct expression. The results demonstrate that endothelins are potent stimu lators of melanoblast proliferation and differentiation.