The c-myb proto-oncogene and its oncogenic derivative v-mybAMV encode transcriptional regulators engaged in the commitment of hematopoietic cells. While the c-Myb protein is important for the formation and differentiation of various progenitors, the v-MybAMV oncoprotein induces in chicks a progression and transformation of the single (monoblastic) cell lineage. Here we present the first evidence of cell fate-directing abilities of c-Myb and v-MybAMV proteins in avian neural crest (NC), where both proteins determine melanocytogenesis. The increased concentration of c-Myb induces progression into dendritic melanocytes and differentiation. The v-myb oncogene converts essentially all NC cells into melanocytes and causes their transformation. Both Myb proteins activate in NC cells expression of the c-kit gene and stem cell factor c-Kit signaling--one of the essential pathways in melanocyte development. These observations suggest that the c-myb-c-kit pathway represents a common regulatory scheme for both hematopoietic and neural progenitors and establishes a novel experimental model for studies of melanocytogenesis and melanocyte transformation.

Department of Molecular Virology Institute of Molecular Genetics AS CR v v i Videnska 1083 Prague 4 14220 Czech Republic