Target genes of Dpp/BMP signaling pathway revealed by transcriptome profiling in the early D.melanogaster embryo.

In the early Drosophila melanogaster embryo, the gene regulatory network controlled by Dpp signaling is involved in the subdivision of dorsal ectoderm into the presumptive dorsal epidermis and amnioserosa. In this work, we aimed to identify new Dpp downstream targets involved in dorsal ectoderm patterning. We used oligonucleotide D. melanogaster microarrays to identify the set of genes that are differential expressed between wild type embryos and embryos that overexpress Dpp (nos-Gal4>UAS-dpp) during early stages of embryo development. By using this approach, we identified 358 genes whose relative abundance significantly increased in response to Dpp overexpression. Among them, we found the entire set of known Dpp target genes that function in dorsal ectoderm patterning (zen, doc, hnt, pnr, ush, tup, and others) in addition to several up-regulated genes of unknown functions. Spatial expression pattern of up-regulated genes in response to Dpp overexpression as well as their opposing transcriptional responses to Dpp loss- and gain-of-function indicated that they are new candidate target genes of Dpp signaling pathway. We further analyse one of the candidate genes, CG13653, which is expressed at the dorsal-most cells of the embryo during a restricted period of time. CG13653 orthologs were not detected in basal lineages of Dipterans, which unlike D. melanogaster develop two extra-embryonic membranes, amnion and serosa. We characterized the enhancer region of CG13653 and revealed that CG13653 is directly regulated by Dpp signaling pathway.