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An endogenous Suppressor of Hairy-wing insulator separates regulatory domains in Drosophila
Journal article   Open access   Peer reviewed

An endogenous Suppressor of Hairy-wing insulator separates regulatory domains in Drosophila

Timothy J Parnell, Michaela M Viering, Astrid Skjesol, Cecilia Helou, Emily J Kuhn and Pamela K Geyer
Proceedings of the National Academy of Sciences - PNAS, Vol.100(23), pp.13436-13441
11/11/2003
DOI: 10.1073/pnas.2333111100
PMCID: PMC263832
PMID: 14597701
url
https://doi.org/10.1073/pnas.2333111100View
Published (Version of record) Open Access

Abstract

Insulators define independent domains of gene function throughout the genome. The Drosophila gypsy insulator was isolated from the gypsy retrotransposon as a region that contains a cluster of binding sites for the Suppressor of Hairy-wing [Su(Hw)] protein. To study the effects of the gypsy insulator on gene expression within a single genomic domain, targeted gene replacement was used to exchange the endogenous yellow gene, located at cytological location 1A, with a set of gypsy -modified yellow genes. Replaced yellow genes carried a gypsy insulator positioned between the yellow promoter and either the upstream or the downstream tissue-specific enhancers. Whereas the gypsy insulator blocked the function of the upstream enhancers at the endogenous location, the downstream enhancers were not blocked. Investigation of the 1A region revealed two clustered Su(Hw)-binding sites downstream of the yellow gene, named 1A-2, that bind Su(Hw) in vivo and possess enhancer blocking function. We propose that interaction between 1A-2 and the gypsy insulator permits activation of yellow expression by enhancers in the neighboring achaete - scute complex, causing an apparent absence of the block of the downstream yellow enhancers. Based on these data, we suggest that 1A-2 is an endogenous Su(Hw) insulator that separates regulatory domains within the Drosophila genome.
gypsy Biological Sciences enhancers gene replacement chromatin

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