Article

Truncated HP1 lacking a functional chromodomain induces heterochromatinization upon in vivo targeting.

Swammerdam Institute for Life Sciences, BioCentrum Amsterdam, University of Amsterdam, Kruislaan 318, 1098 SM, Amsterdam, The Netherlands.
Histochemie (Impact Factor: 2.93). 02/2006; 125(1-2):53-61. DOI: 10.1007/s00418-005-0088-7
Source: PubMed

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.

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Available from: Maartje C Brink, Jul 12, 2015
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    • "Recently, we showed that in vivo targeting of HP1␣ or HP1␤ to an amplified chromosomal region causes local chromatin condensation , enhanced trimethylated H3K9me, and recruitment of histone methyltransferases (Verschure et al., 2005). Targeting of the HP1 lacking a functional CD also caused heterochromatinization of the amplified chromosome region (Brink et al., 2006). These results show that normal binding of HP1 through its CD domain, as well as artificial binding of HP1 without a CD through lac operator-lac Repressor interaction, is sufficient to trigger heterochromatin formation. "
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    • "We used the Argos system to analyze our data within the context of our research concerning chromatin structure and gene control. We focused on the effect of targeting a protein, Heterochromatin protein 1 (HP1) that is involved in gene regulation, to a defined chromosomal domain in the cell nucleus [26] [6]. We used a cell line containing a large 200 Mbp chromosome domain consisting of lac operator repeats. "
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    • "Hs-beta , or a CSD to reporter genes in mammalian cell culture studies caused H3K9me3, in this case by SETDB1 (BRINK et al. 2006; VERSCHURE et al. 2005). Likewise, targeting HP1 "
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