title: Promoter-proximal tethering elements regulate enhancer-promoter specificity in the Drosophila Antennapedia complex.
abstract: Insulator DNAs and promoter competition regulate enhancer-promoter interactions within complex genetic loci. Here we provide evidence for a third mechanism: promoter-proximal tethering elements. The Scr-ftz region of the Antennapedia gene complex includes two known enhancers, AE1 and T1. AE1 selectively interacts with the ftz promoter to maintain pair-rule stripes of ftz expression during gastrulation and germ-band elongation. The T1 enhancer, located 3' of the ftz gene and approximately 25 kb 5' of the Scr promoter, selectively activates Scr expression in the prothorax and posterior head segments. A variety of P element minigenes were examined in transgenic embryos to determine the basis for specific AE1-ftz and T1-Scr interactions. A 450-bp DNA fragment located approximately 100 bp 5' of the Scr transcription start site is essential for T1-Scr interactions and can mediate long-range activation of a ftz/lacZ reporter gene when placed 5' of the ftz promoter. We suggest that the Scr450 fragment contains tethering elements that selectively recruit T1 to the Scr promoter. Tethering elements might regulate enhancer-promoter interactions at other complex genetic loci.
authors.affiliation: Department of Molecular and Cell Biology, Division of Genetics and Development, University of California, Berkeley, CA 94720, USA.
authors.forename: Vincent C
authors.initials: VC
authors.lastname: Calhoun
authors.forename: Angelike
authors.initials: A
authors.lastname: Stathopoulos
authors.forename: Michael
authors.initials: M
authors.lastname: Levine
mesh_terms: D000818:Animals; D051943:Antennapedia Homeodomain Protein; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D029721:Drosophila Proteins; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D017344:Genes, Insect; D018398:Homeodomain Proteins / Q000235:genetics*; D005810:Multigene Family; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D014157:Transcription Factors
chemical_list: D051943:Antennapedia Homeodomain Protein; C497974:Antp protein, Drosophila; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D004247:DNA