THE BREATHLESS FGF RECEPTOR HOMOLOG, A DOWNSTREAM TARGET OF DROSOPHILA C EBP IN THE DEVELOPMENTAL CONTROL OF CELL-MIGRATION/

To investigate the molecular mechanisms responsible for the temporal a nd spatial control of cell movements during development, we have been studying the migration of a small group of follicle cells, called the border cells, in the Drosophila ovary, Timely initiation of border cel l migration requires the product of the slow border cells (slbo) locus , which encodes the Drosophila homolog of the transcription factor C/E BP, Here we report evidence that one target of C/EBP in the control of border cell migration is the FGF receptor homolog encoded by the brea thless (btl) locus, btl expression in the ovary was border eel-specifi c, beginning just prior to the migration, and this expression was redu ced slbo mutants, btl mutations dominantly enhanced the border cell mi gration defects found in weak slbo alleles, Furthermore, C/EBP-indepen dent btl expression was able to rescue the migration defects of hypomo rphic slbo alleles, Purified Drosophila C/EBP bound eight sites in the btl 5' flanking region by DNAse I footprinting, Taken together these results suggest that bd is a key, direct target for C/EBP in the regul ation of border cell migration.