Dpp signaling thresholds in the dorsal ectoderm of the Drosophila embryo.
The dorsal ectoderm of the Drosophila embryo is subdivided into different cell types by an activity gradient of two TGF(&bgr;) signaling molecules, Decapentaplegic (Dpp) and Screw (Scw). Patterning responses to this gradient depend on a secreted inhibitor, Short gastrulation (Sog) and a newly identified transcriptional repressor, Brinker (Brk), which are expressed in neurogenic regions that abut the dorsal ectoderm. Here we examine the expression of a number of Dpp target genes in transgenic embryos that contain ectopic stripes of Dpp, Sog and Brk expression. These studies suggest that the Dpp/Scw activity gradient directly specifies at least three distinct thresholds of gene expression in the dorsal ectoderm of gastrulating embryos. Brk was found to repress two target genes, tailup and pannier, that exhibit different limits of expression within the dorsal ectoderm. These results suggest that the Sog inhibitor and Brk repressor work in concert to establish sharp dorsolateral limits of gene expression. We also present evidence that the activation of Dpp/Scw target genes depends on the Drosophila homolog of the CBP histone acetyltransferase.
Ashe
H L
HL
Department of Molecular and Cell Biology, Division of Genetics and Development, University of California, Berkeley, CA 94720, USA.
Mannervik
M
M
Levine
M
M
D000818:Animals; D001426:Bacterial Proteins; D050882:CREB-Binding Protein; D004330:Drosophila / Q000196:embryology* / Q000378:metabolism; D029721:Drosophila Proteins; D004475:Ectoderm / Q000378:metabolism; D005775:Gastrula / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D018398:Homeodomain Proteins / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D009687:Nuclear Proteins / Q000378:metabolism; D012097:Repressor Proteins; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors
D001426:Bacterial Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C118082:brk protein, Drosophila; C064196:dpp protein, Drosophila; C052837:eve protein, Drosophila; C091428:sog protein, Drosophila; D050882:CREB-Binding Protein