title: Disappearance of nucleosome positioning in mitotic chromatin in vivo.
abstract: During mitosis, transcription is silenced and most transcription factors are displaced from their recognition sequences. By in vivo footprinting analysis, we have confirmed and extended previous studies showing loss of transcription factors from an RNA polymerase II promoter (c-FOS) and, for the first time, an RNA polymerase III promoter (U6) in HeLa cells. Because little was known about nucleosomal organization in mitotic chromosomes, we performed footprinting analysis for nucleosomes on these promoters in interphase and mitotic cells. During interphase, each of the promoters had a positioned nucleosome in the region intervening between proximal promoter elements and distal enhancer elements, but the strong nucleosome positioning disappeared during mitosis. Thus, the nucleosomal organization that appears to facilitate transcription in interphase cells may be lost in mitotic cells, and nucleosome positioning during mitosis does not seem to be a major component of the epigenetic mechanisms to mark genes for rapid reactivation after this phase.
authors.affiliation: Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan. junkom@mail.tains.tohoku.ac.jp
authors.forename: Jun-ichiro
authors.initials: J
authors.lastname: Komura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ono
mesh_terms: D002843:Chromatin / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D017931:DNA Primers / Q000737:chemistry; D004742:Enhancer Elements, Genetic; D020868:Gene Silencing; D006367:HeLa Cells; D006657:Histones / Q000737:chemistry; D006801:Humans; D007399:Interphase; D046911:Macromolecular Substances / Q000737:chemistry; D008938:Mitosis; D008954:Models, Biological; D009707:Nucleosomes / Q000378:metabolism*; D017319:Photosensitizing Agents / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D014158:Transcription, Genetic; D014307:Trioxsalen / Q000494:pharmacology
chemical_list: D002843:Chromatin; D017931:DNA Primers; D006657:Histones; D046911:Macromolecular Substances; D009707:Nucleosomes; D017319:Photosensitizing Agents; D016760:Proto-Oncogene Proteins c-fos; D004247:DNA; D012319:RNA Polymerase II; D014307:Trioxsalen