title: The iab-7 polycomb response element maps to a nucleosome-free region of chromatin and requires both GAGA and pleiohomeotic for silencing activity.
abstract: In the work reported here we have undertaken a functional dissection of a Polycomb response element (PRE) from the iab-7 cis-regulatory domain of the Drosophila melanogaster bithorax complex (BX-C). Previous studies mapped the iab-7 PRE to an 860-bp fragment located just distal to the Fab-7 boundary. Located within this fragment is an approximately 230-bp chromatin-specific nuclease-hypersensitive region called HS3. We have shown that HS3 is capable of functioning as a Polycomb-dependent silencer in vivo, inducing pairing-dependent silencing of a mini-white reporter. The HS3 sequence contains consensus binding sites for the GAGA factor, a protein implicated in the formation of nucleosome-free regions of chromatin, and Pleiohomeotic (Pho), a Polycomb group protein that is related to the mammalian transcription factor YY1. We show that GAGA and Pho interact with these sequences in vitro and that the consensus binding sites for the two proteins are critical for the silencing activity of the iab-7 PRE in vivo.
authors.affiliation: Département de Zoologie et Biologie Animale, Université de Genève, 1211 Geneva 4, Switzerland.
authors.forename: R K
authors.initials: RK
authors.lastname: Mishra
authors.forename: J
authors.initials: J
authors.lastname: Mihaly
authors.forename: S
authors.initials: S
authors.lastname: Barges
authors.forename: A
authors.initials: A
authors.lastname: Spierer
authors.forename: F
authors.initials: F
authors.lastname: Karch
authors.forename: K
authors.initials: K
authors.lastname: Hagstrom
authors.forename: S E
authors.initials: SE
authors.lastname: Schweinsberg
authors.forename: P
authors.initials: P
authors.lastname: Schedl
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002843:Chromatin / Q000235:genetics; D002874:Chromosome Mapping; D017124:Conserved Sequence; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D005127:Eye Color / Q000235:genetics; D020868:Gene Silencing; D017344:Genes, Insect; D018398:Homeodomain Proteins; D019476:Insect Proteins / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D009707:Nucleosomes / Q000235:genetics; D010641:Phenotype; D063150:Polycomb Repressive Complex 1; D014157:Transcription Factors
chemical_list: D002843:Chromatin; D017931:DNA Primers; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D009707:Nucleosomes; C066770:Pc protein, Drosophila; D014157:Transcription Factors; C063460:Trl protein, Drosophila; D063150:Polycomb Repressive Complex 1