title: Activation and repression of transcription by the gap proteins hunchback and Krüppel in cultured Drosophila cells.
abstract: We have studied the ability of the Drosophila gap proteins Krüppel and hunchback to function as transcriptional regulators in cultured cells. Both proteins bind to specific sites in a 100-bp DNA fragment located upstream of the segment polarity gene engrailed, which also contains functional binding sites for a number of homeo box proteins. The hunchback protein is a strikingly concentration-dependent activator of transcription, capable of functioning both by itself and also synergistically with the pair-rule proteins fushi tarazu and paired. In contrast, Krüppel is a transcriptional repressor that can block transcription induced either by hunchback or by several different homeo box proteins. While repression of the homeo box protein activators requires a Krüppel-binding site on the DNA, repression of hunchback can occur efficiently in the absence of a Krüppel-binding site. We discuss the possible molecular mechanisms underlying these activities, as well as the potential significance of these results with respect to segmentation in Drosophila.
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York 10027.
authors.forename: P
authors.initials: P
authors.lastname: Zuo
authors.forename: D
authors.initials: D
authors.lastname: Stanojević
authors.forename: J
authors.initials: J
authors.lastname: Colgan
authors.forename: K
authors.initials: K
authors.lastname: Han
authors.forename: M
authors.initials: M
authors.lastname: Levine
authors.forename: J L
authors.initials: JL
authors.lastname: Manley
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015153:Blotting, Western; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D007605:Juvenile Hormones / Q000235:genetics* / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D007605:Juvenile Hormones; C497244:Kr protein, Drosophila; D051741:Kruppel-Like Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors; C061245:hb protein, Drosophila