title: Roles of DNA looping in enhancer-blocking activity.
abstract: Enhancer-promoter interactions in eukaryotic genomes are often controlled by sequence elements that block the actions of enhancers. Although the experimental evidence suggests that those sequence elements contribute to forming loops of chromatin, the molecular mechanism of how such looping affects the enhancer-blocking activity is still largely unknown. In this article, the roles of DNA looping in enhancer blocking are investigated by numerically simulating the DNA conformation of a prototypical model system of gene regulation. The simulated results show that the enhancer function is indeed blocked when the enhancer is looped out so that it is separated from the promoter, which explains experimental observations of gene expression in the model system. The local structural distortion of DNA caused by looping is important for blocking, so the ability of looping to block enhancers can be lost when the loop length is much larger than the persistence length of the chain.
authors.affiliation: Department of Computational Science and Engineering, Nagoya University, Nagoya, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Tokuda
authors.forename: Masaki
authors.initials: M
authors.lastname: Sasai
authors.forename: George
authors.initials: G
authors.lastname: Chikenji
mesh_terms: D020029:Base Pairing / Q000235:genetics; D001483:Base Sequence; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D019277:Entropy; D006367:HeLa Cells; D006801:Humans; D009010:Monte Carlo Method; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic
chemical_list: D004247:DNA