title: The Drosophila Extradenticle and Homothorax selector proteins control branchless/FGF expression in mesodermal bridge-cells.
abstract: The stereotyped outgrowth of tubular branches of the Drosophila tracheal system is orchestrated by the local and highly dynamic expression profile of branchless (bnl), which encodes a secreted fibroblast growth factor (FGF)-like molecule. Despite the importance of the spatial and temporal bnl regulation, little is known about the upstream mechanisms that establish its complex expression pattern. Here, we show that the Extradenticle and Homothorax selector proteins control bnl transcription in a single cell per segment, the mesodermal bridge-cell. In addition, we observed that a key determinant of bridge-cell specification, the transcription factor Hunchback, is also required for bnl expression. Therefore, we propose that one of the functions of the bridge-cell is to synthesize and secrete the chemoattractant Bnl. These findings provide a hitherto unknown and interesting link between combinatorial inputs of transcription factors, cell-specific ligand expression and organ morphogenesis.
authors: Biozentrum der Universität Basel, Switzerland.
authors: Samir
authors: S
authors: Merabet
authors: Andreas
authors: A
authors: Ebner
authors: Markus
authors: M
authors: Affolter
mesh_terms: D000483:Alleles; D000818:Animals; D004268:DNA-Binding Proteins / Q000502:physiology; D029721:Drosophila Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000502:physiology*; D004331:Drosophila melanogaster; D005346:Fibroblast Growth Factors / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000502:physiology*; D006720:Homozygote; D017403:In Situ Hybridization; D008024:Ligands; D008648:Mesoderm / Q000378:metabolism*; D009154:Mutation; D011994:Recombinant Proteins / Q000737:chemistry; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic; D019076:Transgenes
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D008024:Ligands; D011994:Recombinant Proteins; D014157:Transcription Factors; C102644:bnl protein, Drosophila; C083405:exd protein, Drosophila; C061245:hb protein, Drosophila; C108704:hth protein, Drosophila; D049452:Green Fluorescent Proteins; D005346:Fibroblast Growth Factors