Regulation of two pair-rule stripes by a single enhancer in the Drosophila embryo.
Previous studies on the regulation of the segmentation gene even-skipped (eve) have centered on the transcription of stripe 2. Here, we characterize another enhancer module contained within the complex eve promoter that directs expression of stripes 3 and 7. This enhancer is approximately 500 bp in length and maps approximately 3.3 kb upstream of the transcription start site. The stripe 3 + 7 enhancer appears to be regulated by one or more ubiquitously distributed activators, including components of a JAK-Stat pathway. The two-stripe pattern results via multiple tiers of repressors which delimit this ubiquitous activation. The zinc finger repressor hunchback appears to be responsible for establishing the anterior border of stripe 3 and the posterior border of stripe 7. knirps, a member of the nuclear receptor family of transcription factors, appears to establish the posterior border of stripe 3 and the anterior border of stripe 7. Activator and repressor proteins bind in vitro to several sites within the enhancer. These findings suggest a general model for the regulation of segmentation stripes, whereby enhancers integrate positional information provided by broadly distributed activators and spatially restricted repressors.
Small
S
S
Department of Biology, New York University, New York 10003, USA.
Blair
A
A
Levine
M
M
D000483:Alleles; D000818:Animals; D030801:Animals, Genetically Modified; D001426:Bacterial Proteins; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000502:physiology; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000648:ultrastructure; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D012097:Repressor Proteins / Q000502:physiology; D016415:Sequence Alignment; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic; D019076:Transgenes; D015053:Zygote / Q000378:metabolism
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C052837:eve protein, Drosophila; C061245:hb protein, Drosophila; C074089:kni protein, Drosophila