Capicua integrates input from two maternal systems in Drosophila terminal patterning

• Published in: The EMBO journal Vol. 23; no. 23; pp. 4571 - 4582
• Main Authors: Cinnamon, Einat, Gur-Wahnon, Devorah, Helman, Aharon, St Johnston, Daniel, Jiménez, Gerardo, Paroush, Ze'ev
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 24.11.2004; Blackwell Publishing Ltd; Nature Publishing Group
• Subjects: Animals; Body Patterning - genetics; Body Patterning - physiology; capicua; DNA-Binding Proteins - biosynthesis; DNA-Binding Proteins - genetics; Drosophila; Drosophila melanogaster - embryology; Drosophila melanogaster - metabolism; Drosophila Proteins - biosynthesis; Drosophila Proteins - genetics; Drosophila Proteins - physiology; Embryo, Nonmammalian - embryology; Embryo, Nonmammalian - physiology; Embryos; Gene Expression Regulation, Developmental; HMGB Proteins; Mutation; nanos; Promoter Regions, Genetic; Receptor Protein-Tyrosine Kinases - physiology; Repressor Proteins - biosynthesis; Repressor Proteins - genetics; Repressor Proteins - physiology; Response Elements; Signal Transduction - physiology; tailless; terminal patterning; Transcription, Genetic
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1038/sj.emboj.7600457

In Drosophila, the maternal terminal system specifies cell fates at the embryonic poles via the localised stimulation of the Torso receptor tyrosine kinase (RTK). Signalling by the Torso pathway relieves repression mediated by the Capicua and Groucho repressors, allowing the restricted expression of the zygotic terminal gap genes tailless and huckebein. Here we report a novel positive input into tailless and huckebein transcription by maternal posterior group genes, previously implicated in abdomen and pole cell formation. We show that absence of a subset of posterior group genes, or their overactivation, leads to the spatial reduction or expansion of the tailless and huckebein posterior expression domains, respectively. We demonstrate that the terminal and posterior systems converge, and that exclusion of Capicua from the termini of posterior group mutants is ineffective, accounting for reduced terminal gap gene expression in these embryos. We propose that the terminal and posterior systems function coordinately to alleviate transcriptional silencing by Capicua, and that the posterior system fine‐tunes Torso RTK signalling output, ensuring precise spatial domains of tailless and huckebein expression.