title: Regulation of an inducible promoter by an HP1beta-HP1gamma switch.
abstract: The mammalian heterochromatin protein 1 (HP1) family of proteins was recently shown to be involved in transient repression of inducible promoters. One of these promoters is the HIV1 long terminal repeat, which, during viral latency, recruits a non-processive RNA polymerase II (RNAPII) that synthesizes a short regulatory transcript. Here, we have used this promoter to examine the interplay of HP1alpha, HP1beta and HP1gamma with RNAPII. We find that, in the absence of stimulation, HP1beta is present on the promoter together with the non-processive RNAPII and functions as a negative regulator. On activation, HP1beta bound to methylated H3K9 is rapidly released concurrent with histone H3 phospho-acetylation, and is replaced by HP1gamma. This isoform localizes to the promoter but also inside the coding region, together with the processive RNAPII. Our data show that HP1 recruitment-release is a sequential mechanism that is precisely regulated and highly dependent on transcription.
authors.affiliation: Institut Pasteur, Département de Biologie du Développement, URA2578 du CNRS, cedex 15, France.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Mateescu
authors.forename: Brigitte
authors.initials: B
authors.lastname: Bourachot
authors.forename: Christophe
authors.initials: C
authors.lastname: Rachez
authors.forename: Vasily
authors.initials: V
authors.lastname: Ogryzko
authors.forename: Christian
authors.initials: C
authors.lastname: Muchardt
mesh_terms: D002843:Chromatin / Q000378:metabolism; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D004789:Enzyme Activation; D015967:Gene Expression Regulation, Viral; D005812:Genes, Switch; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D011401:Promoter Regions, Genetic / Q000235:genetics*; D021381:Protein Transport; D012319:RNA Polymerase II / Q000378:metabolism; D020079:Terminal Repeat Sequences; D014158:Transcription, Genetic
chemical_list: C000715593:CBX1 protein, human; C518294:CBX3 protein, human; C000715594:CBX5 protein, human; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D000090266:Chromobox Protein Homolog 5; D012319:RNA Polymerase II