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High-resolution mapping reveals links of HP1 with active and inactive chromatin components.

de Wit E, Greil F, van Steensel B - PLoS Genet. (2007)

Bottom Line: Thus, H3.3 and HP1 are mutually exclusive marks on active chromatin.Additionally, we observed that HP1-chromatin and Polycomb-chromatin are nonoverlapping, but often closely juxtaposed, suggesting an interplay between both types of chromatin.These results demonstrate that HP1-chromatin is transcriptionally active and has extensive links with several other chromatin components.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Netherlands Cancer Institute, Amsterdam, The Netherlands.

ABSTRACT
Heterochromatin protein 1 (HP1) is commonly seen as a key factor of repressive heterochromatin, even though a few genes are known to require HP1-chromatin for their expression. To obtain insight into the targeting of HP1 and its interplay with other chromatin components, we have mapped HP1-binding sites on Chromosomes 2 and 4 in Drosophila Kc cells using high-density oligonucleotide arrays and the DNA adenine methyltransferase identification (DamID) technique. The resulting high-resolution maps show that HP1 forms large domains in pericentric regions, but is targeted to single genes on chromosome arms. Intriguingly, HP1 shows a striking preference for exon-dense genes on chromosome arms. Furthermore, HP1 binds along entire transcription units, except for 5' regions. Comparison with expression data shows that most of these genes are actively transcribed. HP1 target genes are also marked by the histone variant H3.3 and dimethylated histone 3 lysine 4 (H3K4me2), which are both typical of active chromatin. Interestingly, H3.3 deposition, which is usually observed along entire transcription units, is limited to the 5' ends of HP1-bound genes. Thus, H3.3 and HP1 are mutually exclusive marks on active chromatin. Additionally, we observed that HP1-chromatin and Polycomb-chromatin are nonoverlapping, but often closely juxtaposed, suggesting an interplay between both types of chromatin. These results demonstrate that HP1-chromatin is transcriptionally active and has extensive links with several other chromatin components.

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Related in: MedlinePlus

HP1 and Polycomb Form Two Distinct, Nonoverlapping Chromatin Domains That Are Often in Close Proximity to Each OtherRunning mean (window size 20 GATC fragments) of HP1-Dam/Dam–binding ratios (black) and Pc-Dam/Dam–binding ratios (red) of (A) Chromosome 4; (B and C) pericentric regions of Chromosome 2; and (D) a repeat-rich region on the right arm of Chromosome 2 (cytological region 42AB). Positions of genes are indicated below each graph.
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pgen-0030038-g005: HP1 and Polycomb Form Two Distinct, Nonoverlapping Chromatin Domains That Are Often in Close Proximity to Each OtherRunning mean (window size 20 GATC fragments) of HP1-Dam/Dam–binding ratios (black) and Pc-Dam/Dam–binding ratios (red) of (A) Chromosome 4; (B and C) pericentric regions of Chromosome 2; and (D) a repeat-rich region on the right arm of Chromosome 2 (cytological region 42AB). Positions of genes are indicated below each graph.

Mentions: We found that HP1 and Pc clearly bind to distinct regions (Figure 5A–5D, black and red lines, respectively). In fact, the Pc signal in HP1 domains is frequently lower than the general baseline of Pc levels in regions where neither of the two proteins is enriched (Figure 5A and 5B), suggesting that Pc may be actively excluded from HP1 domains.


High-resolution mapping reveals links of HP1 with active and inactive chromatin components.

de Wit E, Greil F, van Steensel B - PLoS Genet. (2007)

HP1 and Polycomb Form Two Distinct, Nonoverlapping Chromatin Domains That Are Often in Close Proximity to Each OtherRunning mean (window size 20 GATC fragments) of HP1-Dam/Dam–binding ratios (black) and Pc-Dam/Dam–binding ratios (red) of (A) Chromosome 4; (B and C) pericentric regions of Chromosome 2; and (D) a repeat-rich region on the right arm of Chromosome 2 (cytological region 42AB). Positions of genes are indicated below each graph.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1808074&req=5

pgen-0030038-g005: HP1 and Polycomb Form Two Distinct, Nonoverlapping Chromatin Domains That Are Often in Close Proximity to Each OtherRunning mean (window size 20 GATC fragments) of HP1-Dam/Dam–binding ratios (black) and Pc-Dam/Dam–binding ratios (red) of (A) Chromosome 4; (B and C) pericentric regions of Chromosome 2; and (D) a repeat-rich region on the right arm of Chromosome 2 (cytological region 42AB). Positions of genes are indicated below each graph.
Mentions: We found that HP1 and Pc clearly bind to distinct regions (Figure 5A–5D, black and red lines, respectively). In fact, the Pc signal in HP1 domains is frequently lower than the general baseline of Pc levels in regions where neither of the two proteins is enriched (Figure 5A and 5B), suggesting that Pc may be actively excluded from HP1 domains.

Bottom Line: Thus, H3.3 and HP1 are mutually exclusive marks on active chromatin.Additionally, we observed that HP1-chromatin and Polycomb-chromatin are nonoverlapping, but often closely juxtaposed, suggesting an interplay between both types of chromatin.These results demonstrate that HP1-chromatin is transcriptionally active and has extensive links with several other chromatin components.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Netherlands Cancer Institute, Amsterdam, The Netherlands.

ABSTRACT
Heterochromatin protein 1 (HP1) is commonly seen as a key factor of repressive heterochromatin, even though a few genes are known to require HP1-chromatin for their expression. To obtain insight into the targeting of HP1 and its interplay with other chromatin components, we have mapped HP1-binding sites on Chromosomes 2 and 4 in Drosophila Kc cells using high-density oligonucleotide arrays and the DNA adenine methyltransferase identification (DamID) technique. The resulting high-resolution maps show that HP1 forms large domains in pericentric regions, but is targeted to single genes on chromosome arms. Intriguingly, HP1 shows a striking preference for exon-dense genes on chromosome arms. Furthermore, HP1 binds along entire transcription units, except for 5' regions. Comparison with expression data shows that most of these genes are actively transcribed. HP1 target genes are also marked by the histone variant H3.3 and dimethylated histone 3 lysine 4 (H3K4me2), which are both typical of active chromatin. Interestingly, H3.3 deposition, which is usually observed along entire transcription units, is limited to the 5' ends of HP1-bound genes. Thus, H3.3 and HP1 are mutually exclusive marks on active chromatin. Additionally, we observed that HP1-chromatin and Polycomb-chromatin are nonoverlapping, but often closely juxtaposed, suggesting an interplay between both types of chromatin. These results demonstrate that HP1-chromatin is transcriptionally active and has extensive links with several other chromatin components.

Show MeSH
Related in: MedlinePlus