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TY - JOUR AU - Cai, Haini AU - Levine, Michael PY - 1995 DA - 1995/08/01 TI - Modulation of enhancerá¤-promoter interactions by insulators in the Drosophilaembryo JO - Nature SP - 533 EP - 536 VL - 376 IS - 6540 AB - INSULATOR DNAs, or boundary elements, functionally isolate neighbouring genes by blocking interactions between distal enhancers and inappropriate target promoters1á¤-5. The best-characterized insulators in Drosophila correspond to a 340-base-pair (bp) fragment from the gypsy retrotransposon3, and the scs and scs′ sequences flanking the 87A1 hsp70 locus1,2. Here we demonstrate that both insulators block the interaction of defined even-skipped (eve) stripe enhancers6,7 when positioned between the enhancer and the target promoter. The simultaneous use of two stripe enhancers (eve stripes 2 and 3) provides evidence that enhancers lying distal to the insulator are selectively blocked. The insertion of stripeá¤-insulatorá¤-stripe sequences between two divergently transcribed promoters indicates that enhancers barred from acting on one basal promoter are fully accessible to appropriate regulatory factors for activating the other promoter. These results suggest that insulators do not propagate changes in chromatin structure. Finally, we present evidence that the gypsy insulator does not block interactions between a silencer element and a basal promoter. Taken together, these results suggest that insulators might not be restricted to the functional isolation of neighbouring genetic loci. Rather, they might function as flexible regulatory elements that modulate enhancerá¤-promoter interactions within complex promoters and complex genetic loci. SN - 1476-4687 UR - https://doi.org/10.1038/376533a0 DO - 10.1038/376533a0 ID - Cai1995 ER -