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

Abstract

In the early Drosophilamelanogaster 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 newDpp downstreamtargets involved in dorsal ectodermpatterning.We used oligonucleotide D.melanogaster microarrays to identify the set of genes that are differential expressed betweenwild type embryos and embryos that overexpress Dpp (nos-Gal4NUAS-dpp) during early stages ofembryo development. By using this approach, weidentified 358 geneswhose relative abundance significantly increased in response toDpp 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 aswell 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.