Insulator action. Top: In the absence of the insulator

CTCF induces histone variant incorporation, erases the H3K27me3 histone mark and opens chromatin. Weth O, Paprotka C, Günther K, Schulte A, Baierl M, Leers J, Galjart N, Renkawitz R - Nucleic Acids Res. (2014) Bottom Line: The insulator factor, CTCF, has been found to bind to boundaries and to mediate insulator function.This demonstrates the causal role for CTCF in generating the chromatin features found at insulators.Thereby, spreading of a histone modification from one domain through the insulator into the neighbouring domain is inhibited. View Article: PubMed Central - PubMed Affiliation: Institute for Genetics, Justus-Liebig-University, 35392 Giessen, Germany. Show MeSH Major Chromatin/chemistry/metabolism* Histones/metabolism* Insulator Elements* Repressor Proteins/chemistry/metabolism/physiology Minor* Cell Line DNA-Binding Proteins/metabolism HeLa Cells Humans Methylation Zinc Fingers Related in: MedlinePlus	© Copyright Policy - creative-commons Related In: Results - Collection License Show All Figures getmorefigures.php?uid=PMC4231773&req=5 Figure 9: Insulator action. Top: In the absence of the insulator factor CTCF a repressive chromatin modification, such as H3K27me3 (red octant-sphere) within nucleosomes (grey sphere), shows the tendency to spread from a repressed chromatin domain into an active chromatin domain devoid of this mark. Bottom: In the presence of CTCF, the variant histone H3.3 (green octant-sphere) replaces modified histone H3. H3.3, often in combination with H2A.Z, destabilizes nucleosomes, which may have to be continuously replaced. Such an activity would act antagonistically to a spreading of the H3K27me3 mark. Mentions: Together these results suggest that the rapid removal of the H3K27me3 mark, which precedes chromatin opening as tested with the LacO array model, is at least in part mediated by the transient incorporation of H3.3. This is supported by the analysis of endogenous CTCF/H3.3 sites, which show a reduced H3.3 incorporation upon CTCF depletion. Thus, it can be envisaged (Figure 9) that CTCF incorporates H3.3, which causes depletion of stable nucleosomes and thereby interferes with spreading of the repressive marks into the active domain.

CTCF induces histone variant incorporation, erases the H3K27me3 histone mark and opens chromatin.

Weth O, Paprotka C, Günther K, Schulte A, Baierl M, Leers J, Galjart N, Renkawitz R - Nucleic Acids Res. (2014)

Bottom Line: The insulator factor, CTCF, has been found to bind to boundaries and to mediate insulator function.This demonstrates the causal role for CTCF in generating the chromatin features found at insulators.Thereby, spreading of a histone modification from one domain through the insulator into the neighbouring domain is inhibited.

View Article: PubMed Central - PubMed

Affiliation: Institute for Genetics, Justus-Liebig-University, 35392 Giessen, Germany.

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Related in: MedlinePlus

Insulator action. Top: In the absence of the insulator factor CTCF a repressive chromatin modification, such as H3K27me3 (red octant-sphere) within nucleosomes (grey sphere), shows the tendency to spread from a repressed chromatin domain into an active chromatin domain devoid of this mark. Bottom: In the presence of CTCF, the variant histone H3.3 (green octant-sphere) replaces modified histone H3. H3.3, often in combination with H2A.Z, destabilizes nucleosomes, which may have to be continuously replaced. Such an activity would act antagonistically to a spreading of the H3K27me3 mark.

Related In: Results - Collection

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Figure 9: Insulator action. Top: In the absence of the insulator factor CTCF a repressive chromatin modification, such as H3K27me3 (red octant-sphere) within nucleosomes (grey sphere), shows the tendency to spread from a repressed chromatin domain into an active chromatin domain devoid of this mark. Bottom: In the presence of CTCF, the variant histone H3.3 (green octant-sphere) replaces modified histone H3. H3.3, often in combination with H2A.Z, destabilizes nucleosomes, which may have to be continuously replaced. Such an activity would act antagonistically to a spreading of the H3K27me3 mark.

Mentions: Together these results suggest that the rapid removal of the H3K27me3 mark, which precedes chromatin opening as tested with the LacO array model, is at least in part mediated by the transient incorporation of H3.3. This is supported by the analysis of endogenous CTCF/H3.3 sites, which show a reduced H3.3 incorporation upon CTCF depletion. Thus, it can be envisaged (Figure 9) that CTCF incorporates H3.3, which causes depletion of stable nucleosomes and thereby interferes with spreading of the repressive marks into the active domain.