ABSTRACT
The segment-specific regulatory domains of the Bithorax complex (BX-C), which consists of three homeotic genes Ubx, abd-A and Abd-B, are separated by boundaries that function as insulators. Most of the boundaries contain binding sites for the architectural protein CTCF, which is conserved for higher eukaryotes. As was shown previously, the CTCF sites determine the insulator activity of the boundaries of the Abd-B regulatory region. In this study, it was shown that fragments of the Fab-3 and Fab-4 boundaries of the abd-A regulatory region, containing CTCF binding sites, are not effective insulators.
Subject(s)
CCCTC-Binding Factor , Drosophila Proteins , Drosophila melanogaster , Animals , Binding Sites , CCCTC-Binding Factor/genetics , CCCTC-Binding Factor/metabolism , Drosophila Proteins/genetics , Drosophila Proteins/metabolism , Drosophila melanogaster/genetics , Drosophila melanogaster/metabolism , Genes, Homeobox , Homeodomain Proteins/genetics , Homeodomain Proteins/metabolism , Insulator Elements , Transcription Factors/metabolismABSTRACT
Increasing evidence suggests that noncoding RNA transcribed from the enhancers play an important role in the regulation of gene transcription. Insulators are the regulatory elements that limit the activity of enhancers and form independent transcriptional domains. Using a transgenic lines, we show that the Fab-7 insulator of the bithorax complex and the MDG4 (gypsy) insulator are able to disrupt weak transcription derived from the enhancer regulating the white gene expression in the eyes. The ability of insulators to disrupt weak transcription may play a role in the enhancer-blocking activity.
