|Title||Localized repressors delineate the neurogenic ectoderm in the early Drosophila embryo.|
|Publication Type||Journal Article|
|Year of Publication||2005|
|Authors||Stathopoulos, A, Levine, M|
|Date Published||2005 Apr 15|
|Keywords||Amino Acid Motifs, Animals, Base Sequence, Binding Sites, Body Patterning, Computational Biology, Drosophila, Drosophila melanogaster, Ectoderm, Embryo, Nonmammalian, Enhancer Elements, Genetic, Gene Expression Regulation, Developmental, Gene Silencing, In Situ Hybridization, Lac Operon, Mesoderm, Models, Genetic, Molecular Sequence Data, Neurons, Oligonucleotides, Antisense, Plasmids, RNA, Sequence Homology, Nucleic Acid|
The Dorsal gradient produces sequential patterns of gene expression across the dorsoventral axis of early embryos, thereby establishing the presumptive mesoderm, neuroectoderm, and dorsal ectoderm. Spatially localized repressors such as Snail and Vnd exclude the expression of neurogenic genes in the mesoderm and ventral neuroectoderm, respectively. However, no repressors have been identified that establish the dorsal limits of neurogenic gene expression. To investigate this issue, we have conducted an analysis of the ind gene, which is selectively expressed in lateral regions of the presumptive nerve cord. A novel silencer element was identified within the ind enhancer that is essential for eliminating expression in the dorsal ectoderm. Evidence is presented that the associated repressor can function over long distances to silence neighboring enhancers. The ind enhancer also contains a variety of known activator and repressor elements. We propose a model whereby Dorsal and EGF signaling, together with the localized Schnurri repressor, define a broad domain of ind expression throughout the entire presumptive neuroectoderm. The ventral limits of gene expression are defined by the Snail and Vnd repressors, while the dorsal border is established by the newly defined silencer element.
|Alternate Journal||Dev. Biol.|