THE AVIAN FLI GENE IS SPECIFICALLY EXPRESSED DURING EMBRYOGENESIS IN A SUBSET OF NEURAL CREST CELLS GIVING RISE TO MESENCHYME

The ets-family of transcription factors is involved in the development of endothelial and hematopoietic cells. Among these genes, fli was sh own to be responsible for erythroblastomas and Ewing's sarcomas. Its i nvolvement in Ewing's sarcoma, a putative neurectodermal tumor, as wel l as the in situ hybridization studies performed in mice and Xenopus s uggested a role in neural crest development. We cloned quail iii cDNA in order to analyze in more detail its expression in neural crest cell s, which have been extensively studied in avian species. Fli gene maps on chicken chromosome 1 to band q31-->q33. Two RNAs are transcribed, most likely arising from two different promoters. The analysis of its expression in neural crest cells reveals that it is expressed rather l ate, when the neural crest cells reach their target. Among the various lineages derived from the crest, it is restricted to the mesenchymal one. It is maintained at later stages in the cartilage of neural crest but also of mesodermal origin. In addition, iii is expressed in sever al mesoderm-derived cells: endothelial cells as well as intermediate a nd splanchnopleural mesoderm.