title: Combinatorial activation and concentration-dependent repression of the Drosophila even skipped stripe 3+7 enhancer.
abstract: Despite years of study, the precise mechanisms that control position-specific gene expression during development are not understood. Here, we analyze an enhancer element from the even skipped (eve) gene, which activates and positions two stripes of expression (stripes 3 and 7) in blastoderm stage Drosophila embryos. Previous genetic studies showed that the JAK-STAT pathway is required for full activation of the enhancer, whereas the gap genes hunchback (hb) and knirps (kni) are required for placement of the boundaries of both stripes. We show that the maternal zinc-finger protein Zelda (Zld) is absolutely required for activation, and present evidence that Zld binds to multiple non-canonical sites. We also use a combination of in vitro binding experiments and bioinformatics analysis to redefine the Kni-binding motif, and mutational analysis and in vivo tests to show that Kni and Hb are dedicated repressors that function by direct DNA binding. These experiments significantly extend our understanding of how the eve enhancer integrates positive and negative transcriptional activities to generate sharp boundaries in the early embryo.
authors.affiliation: Department of Biology, New York University, New York, NY 10003, USA.
authors.forename: Paolo
authors.initials: P
authors.lastname: Struffi
authors.forename: Maria
authors.initials: M
authors.lastname: Corado
authors.forename: Leah
authors.initials: L
authors.lastname: Kaplan
authors.forename: Danyang
authors.initials: D
authors.lastname: Yu
authors.forename: Christine
authors.initials: C
authors.lastname: Rushlow
authors.forename: Stephen
authors.initials: S
authors.lastname: Small
mesh_terms: D000818:Animals; D001483:Base Sequence; D003433:Crosses, Genetic; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics* / Q000502:physiology; D008954:Models, Biological; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D019076:Transgenes; D020798:Two-Hybrid System Techniques
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C052837:eve protein, Drosophila; C061245:hb protein, Drosophila; C074089:kni protein, Drosophila; C512295:zld protein, Drosophila