title: The centrosomal protein CP190 is a component of the gypsy chromatin insulator.
abstract: Chromatin insulators, or boundary elements, affect promoter-enhancer interactions and buffer transgenes from position effects. The gypsy insulator of Drosophila is bound by a protein complex with two characterized components, the zinc finger protein Suppressor of Hairy-wing [Su(Hw)] and Mod(mdg4)2.2, which is one of the multiple spliced variants encoded by the modifier of mdg4 [mod(mdg4)] gene. A genetic screen for dominant enhancers of the mod(mdg4) phenotype identified the Centrosomal Protein 190 (CP190) as an essential constituent of the gypsy insulator. The function of the centrosome is not affected in CP190 mutants whereas gypsy insulator activity is impaired. CP190 associates physically with both Su(Hw) and Mod(mdg4)2.2 and colocalizes with both proteins on polytene chromosomes. CP190 does not interact directly with insulator sequences present in the gypsy retrotransposon but binds to a previously characterized endogenous insulator, and it is necessary for the formation of insulator bodies. The results suggest that endogenous gypsy insulators contain binding sites for CP190, which is essential for insulator function, and may or may not contain binding sites for Su(Hw) and Mod(mdg4)2.2.
authors.affiliation: Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, USA.
authors.forename: Chi-Yun
authors.initials: CY
authors.lastname: Pai
authors.forename: Elissa P
authors.initials: EP
authors.lastname: Lei
authors.forename: Dolanchanpa
authors.initials: D
authors.lastname: Ghosh
authors.forename: Victor G
authors.initials: VG
authors.lastname: Corces
mesh_terms: D000483:Alleles; D000818:Animals; D030801:Animals, Genetically Modified; D001665:Binding Sites; D018385:Centrosome / Q000648:ultrastructure*; D002843:Chromatin / Q000737:chemistry* / Q000378:metabolism; D002875:Chromosomes / Q000378:metabolism / Q000648:ultrastructure; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004251:DNA Transposable Elements; D018076:DNA, Complementary / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster; D004591:Electrophoresis, Polyacrylamide Gel; D004742:Enhancer Elements, Genetic; D005799:Genes, Dominant; D005838:Genotype; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism; D010641:Phenotype; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D014921:Wings, Animal / Q000196:embryology; D016335:Zinc Fingers
chemical_list: C107964:CP190 protein, Drosophila; D002843:Chromatin; D004251:DNA Transposable Elements; D018076:DNA, Complementary; D029721:Drosophila Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; C110987:mdg4 protein (gypsy); D004247:DNA