[Molecular analysis of the development of the rhombencephalon]

Hindbrain development involves a segmentation process which in particular governs cranial-motor nerves organization. We have initiated a molecular analysis of this morphogenetic process by searching for genes expressed in specific hindbrain segments (rhombomeres). We have identified a gene encoding a transcription factor, Krox-20, which is specific of rhombomeres 3 and 5 and several genes encoding receptor tyrosine kinases which are also segment-specific. The study of Krox-20 has allowed the identification of its nucleotide target, the localization of the functional domains of the protein and the demonstration of its involvement in the transcriptional activation of the Hoxb-2 gene and in the control of normal hindbrain development.