Spatially distinct downregulation of Capicua repression and tailless activation by the Torso RTK pathway in the Drosophila embryo.
Specification of the terminal regions of the Drosophila embryo depends on the Torso RTK pathway, which triggers expression of the zygotic genes tailless and huckebein at the embryonic poles. However, it has been shown that the Torso signalling pathway does not directly activate expression of these zygotic genes; rather, it induces their expression by inactivating, at the embryonic poles, a uniformly distributed repressor activity. In particular, it has been shown that Torso signalling regulates accumulation of the Capicua transcriptional repressor: as a consequence of Torso signalling Capicua is downregulated specifically at the poles of blastoderm stage embryos. Extending the current model, we show that activation of the Torso pathway can trigger tailless expression without eliminating Capicua. In addition, analysis of gene activation by the Torso pathway and downregulation of Capicua unveil differences between the terminal and the central embryonic regions that are independent of Torso signalling, hitherto thought to be the only system responsible for confering terminal specificities. These data provide new insights into the mode of action of the Torso signalling pathway and on the events patterning the early Drosophila embryo.
de las Heras
José Manuel
JM
Institut de Biologia Molecular de Barcelona (CSIC) and Institut de Recerca Biomèdica, Parc Científic de Barcelona, C/ Josep Samitier 1-5, 08028 Barcelona, Spain.
Casanova
Jordi
J
D000483:Alleles; D000818:Animals; D030801:Animals, Genetically Modified; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation; D004330:Drosophila; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D024002:HMGB Proteins; D008024:Ligands; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism* / Q000502:physiology*; D012097:Repressor Proteins / Q000378:metabolism* / Q000502:physiology*; D015398:Signal Transduction; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D019076:Transgenes
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D024002:HMGB Proteins; D008024:Ligands; D012097:Repressor Proteins; C074090:TLL protein, Drosophila; C404284:cic protein, Drosophila; D020794:Receptor Protein-Tyrosine Kinases; C080148:tor protein, Drosophila