Effective Blocking of the White Enhancer Requires Cooperation between Two Main Mechanisms Suggested for the Insulator Function

摘要: Chromatin insulators block the action of transcriptional enhancers when interposed between an enhancer and a promoter. In this study, we examined role chromatin loops formed by two unrelated insulators, gypsy Fab-7, in their enhancer-blocking activity. To test for activity, selected white reporter gene that is activated eye-specific enhancer. The results showed one copy or Fab-7 insulator failed to eye most genomic sites, whereas loop flanking either completely blocked stimulation However, strong blocking was achieved due not only formation but also direct interaction with enhancer, which confirmed 3C assay. particular, it observed Mod(mdg4)-67.2, component insulator, interacted Zeste protein, critical enhancer-white promoter communication. These suggest efficient depends on combination factors: paired generates physical constraints enhancer-promoter communication, proteins recruited pair.