title: Truncated HP1 lacking a functional chromodomain induces heterochromatinization upon in vivo targeting.
abstract: Packaging of the eukaryotic genome into higher order chromatin structures is tightly related to gene expression. Pericentromeric heterochromatin is typified by accumulations of heterochromatin protein 1 (HP1), methylation of histone H3 at lysine 9 (MeH3K9) and global histone deacetylation. HP1 interacts with chromatin by binding to MeH3K9 through the chromodomain (CD). HP1 dimerizes with itself and binds a variety of proteins through its chromoshadow domain. We have analyzed at the single cell level whether HP1 lacking its functional CD is able to induce heterochromatinization in vivo. We used a lac-operator array-based system in mammalian cells to target EGFP-lac repressor tagged truncated HP1alpha and HP1beta to a lac operator containing gene-amplified chromosome region in living cells. After targeting truncated HP1alpha or HP1beta we observe enhanced tri-MeH3K9 and recruitment of endogenous HP1alpha and HP1beta to the chromosome region. We show that CD-less HP1alpha can induce chromatin condensation, whereas the effect of truncated HP1beta is less pronounced. Our results demonstrate that after lac repressor-mediated targeting, HP1alpha and HP1beta without a functional CD are able to induce heterochromatinization.
authors.affiliation: Swammerdam Institute for Life Sciences, BioCentrum Amsterdam, University of Amsterdam, Kruislaan 318, 1098 SM, Amsterdam, The Netherlands.
authors.forename: Maartje C
authors.initials: MC
authors.lastname: Brink
authors.forename: Yme
authors.initials: Y
authors.lastname: van der Velden
authors.forename: Wim
authors.initials: W
authors.lastname: de Leeuw
authors.forename: Julio
authors.initials: J
authors.lastname: Mateos-Langerak
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Belmont
authors.forename: Roel
authors.initials: R
authors.lastname: van Driel
authors.forename: Pernette J
authors.initials: PJ
authors.lastname: Verschure
mesh_terms: D000818:Animals; D016466:CHO Cells; D002843:Chromatin / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure*; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D006224:Cricetinae; D005455:Fluorescent Antibody Technique; D006570:Heterochromatin / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D018613:Microscopy, Confocal; D010957:Plasmids / Q000235:genetics
chemical_list: C000715593:CBX1 protein, human; C000715594:CBX5 protein, human; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D006570:Heterochromatin; D006657:Histones; D000090266:Chromobox Protein Homolog 5; D008239:Lysine