white+ Transgene insertions presenting a dorsal/ventral pattern define a single cluster of homeobox genes that is silenced by the Polycomb-group proteins in Drosophila melanogaster

• Published in: Genetics (Austin) Vol. 149; no. 1; pp. 257 - 275
• Main Authors: Netter, S, Fauvarque, M.O, Diez del Corral, R, Dura, J.M, Coen, D
• Format: Journal Article
• Language: English
• Published: United States Genetics Soc America 01.05.1998; Genetics Society of America
• Subjects: ANIMAL TRANSGENIQUE; ANIMALES TRANSGENICOS; Animals; ATP-Binding Cassette Transporters; BETA GALACTOSIDASA; BETA GALACTOSIDASE; Body Patterning; Body Patterning - genetics; Cells, Cultured; CHROMATIN; CHROMATINE; CHROMOSOME; Chromosome Mapping; CHROMOSOMES; Cloning, Molecular; COLOR; COLOUR; COMPOUND EYES; COULEUR; CROMATINA; CROMOSOMAS; DNA Transposable Elements; DNA-Binding Proteins; DNA-Binding Proteins - genetics; DROSOPHILA MELANOGASTER; Drosophila melanogaster - genetics; Drosophila Proteins; EXPRESION GENICA; EXPRESSION DES GENES; Eye Color; Eye Color - genetics; Eye Proteins; Eye Proteins - genetics; EYES; FACTEUR DE TRANSCRIPTION; FACTORES DE TRANSCRIPCION; GEN HOMEOTICO; GENE; GENE EXPRESSION; GENE HOMEOTIQUE; GENES; Genes, Homeobox; GENETIC REGULATION; GENETICA; GENETICS; GENETIQUE; histochemistry; HISTOENZYMOLOGY; Homeodomain Proteins; Homeodomain Proteins - genetics; HOMEOTIC GENES; Insect Proteins; Insect Proteins - genetics; Insects; Models, Genetic; MOLECULAR MAPPING; MUTACION; MUTATION; OEIL; OJOS; PIGMENTACION; PIGMENTATION; Pigments; Polycomb Repressive Complex 1; POLYTENE CHROMOSOMES; Proteins; REPORTER GENES; Repressor Proteins; Repressor Proteins - genetics; TRANSCRIPTION FACTORS; Transgenes; TRANSGENIC ANIMALS
• ISSN: 0016-6731; 1943-2631; 1943-2631
• DOI: 10.1093/genetics/149.1.257

We used the white gene as an enhancer trap and reporter of chromatin structure. We collected white+ transgene insertions presenting a peculiar pigmentation pattern in the eye: white expression is restricted to the dorsal half of the eye, with a clear-cut dorsal/ventral (D/V) border. This D/V pattern is stable and heritable, indicating that phenotypic expression of the white reporter reflects positional information in the developing eye. Localization of these transgenes led us to identify a unique genomic region encompassing 140 kb in 69D1–3 subject to this D/V effect. This region contains at least three closely related homeobox-containing genes that are constituents of the iroquois complex (IRO-C). IRO-C genes are coordinately regulated and implicated in similar developmental processes. Expression of these genes in the eye is regulated by the products of the Polycomb -group (Pc-G) and trithorax-group (trx-G) genes but is not modified by classical modifiers of position-effect variegation. Our results, together with the report of a Pc -G binding site in 69D, suggest that we have identified a novel cluster of target genes for the Pc-G and trx-G products. We thus propose that ventral silencing of the whole IRO-C in the eye occurs at the level of chromatin structure in a manner similar to that of the homeotic gene complexes, perhaps by local compaction of the region into a heterochromatin-like structure involving the Pc-G products.