The gypsy insulator can act as a promoter-specific transcriptional stimulator.
Insulators define chromosomal domains such that an enhancer in one domain cannot activate a promoter in a different domain. We show that the Drosophila gypsy insulator behaves as a cis-stimulatory element in the larval fat body. Transcriptional stimulation by the insulator is distance dependent, as expected for a promoter element as opposed to an enhancer. Stimulation of a test alcohol dehydrogenase promoter requires a binding site for a GATA transcription factor, suggesting that the insulator may be facilitating access of this DNA binding protein to the promoter. Short-range stimulation requires both the Suppressor of Hairy-wing protein and the Mod(mdg4)-62.7 protein encoded by the trithorax group gene mod(mdg4). In the absence of interaction with Mod(mdg4)-62.7, the insulator is converted into a short-range transcriptional repressor but retains some cis-stimulatory activity over longer distances. These results indicate that insulator and promoter sequences share important characteristics and are not entirely distinct. We propose that the gypsy insulator can function as a promoter element and may be analogous to promoter-proximal regulatory modules that integrate input from multiple distal enhancer sequences.
Wei
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Department of Biochemistry and Molecular Biology, University of Louisville, Kentucky 40202, USA.
Brennan
M D
MD
D000426:Alcohol Dehydrogenase / Q000235:genetics; D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins; D005786:Gene Expression Regulation; D017344:Genes, Insect; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D018626:Retroelements; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D018626:Retroelements; D014157:Transcription Factors; C110987:mdg4 protein (gypsy); C083738:su(Hw) protein, Drosophila; D000426:Alcohol Dehydrogenase