In vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications.

BACKGROUND: The folding of genetic information into chromatin plays important regulatory roles in many nuclear processes and particularly in gene transcription. Post translational histone modifications are associated with specific chromatin condensation states and with distinct transcriptional activ...

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Main Authors: Caroline Kizilyaprak, Danièle Spehner, Didier Devys, Patrick Schultz
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2010-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC2882955?pdf=render
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author Caroline Kizilyaprak
Danièle Spehner
Didier Devys
Patrick Schultz
author_facet Caroline Kizilyaprak
Danièle Spehner
Didier Devys
Patrick Schultz
author_sort Caroline Kizilyaprak
collection DOAJ
description BACKGROUND: The folding of genetic information into chromatin plays important regulatory roles in many nuclear processes and particularly in gene transcription. Post translational histone modifications are associated with specific chromatin condensation states and with distinct transcriptional activities. The peculiar chromatin organization of rod photoreceptor nuclei, with a large central domain of condensed chromatin surrounded by a thin border of extended chromatin was used as a model to correlate in vivo chromatin structure, histone modifications and transcriptional activity. METHODOLOGY: We investigated the functional relationships between chromatin compaction, distribution of histone modifications and location of RNA polymerase II in intact murine rod photoreceptors using cryo-preparation methods, electron tomography and immunogold labeling. Our results show that the characteristic central heterochromatin of rod nuclei is organized into concentric domains characterized by a progressive loosening of the chromatin architecture from inside towards outside and by specific combinations of silencing histone marks. The peripheral heterochromatin is formed by closely packed 30 nm fibers as revealed by a characteristic optical diffraction signal. Unexpectedly, the still highly condensed most external heterochromatin domain contains acetylated histones, which are usually associated with active transcription and decondensed chromatin. Histone acetylation is thus not sufficient in vivo for complete chromatin decondensation. The euchromatin domain contains several degrees of chromatin compaction and the histone tails are hyperacetylated, enriched in H3K4 monomethylation and hypo trimethylated on H3K9, H3K27 and H4K20. The transcriptionally active RNA polymerases II molecules are confined in the euchromatin domain and are preferentially located at the vicinity of the interface with heterochromatin. CONCLUSIONS: Our results show that transcription is located in the most decondensed and highly acetylated chromatin regions, but since acetylation is found associated with compact chromatin it is not sufficient to decondense chromatin in vivo. We also show that a combination of histone marks defines distinct concentric heterochromatin domains.
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spelling doaj.art-ba58ac83ea6a4d3fb8fcd52ba07b666a2022-12-22T03:43:57ZengPublic Library of Science (PLoS)PLoS ONE1932-62032010-01-0156e1103910.1371/journal.pone.0011039In vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications.Caroline KizilyaprakDanièle SpehnerDidier DevysPatrick SchultzBACKGROUND: The folding of genetic information into chromatin plays important regulatory roles in many nuclear processes and particularly in gene transcription. Post translational histone modifications are associated with specific chromatin condensation states and with distinct transcriptional activities. The peculiar chromatin organization of rod photoreceptor nuclei, with a large central domain of condensed chromatin surrounded by a thin border of extended chromatin was used as a model to correlate in vivo chromatin structure, histone modifications and transcriptional activity. METHODOLOGY: We investigated the functional relationships between chromatin compaction, distribution of histone modifications and location of RNA polymerase II in intact murine rod photoreceptors using cryo-preparation methods, electron tomography and immunogold labeling. Our results show that the characteristic central heterochromatin of rod nuclei is organized into concentric domains characterized by a progressive loosening of the chromatin architecture from inside towards outside and by specific combinations of silencing histone marks. The peripheral heterochromatin is formed by closely packed 30 nm fibers as revealed by a characteristic optical diffraction signal. Unexpectedly, the still highly condensed most external heterochromatin domain contains acetylated histones, which are usually associated with active transcription and decondensed chromatin. Histone acetylation is thus not sufficient in vivo for complete chromatin decondensation. The euchromatin domain contains several degrees of chromatin compaction and the histone tails are hyperacetylated, enriched in H3K4 monomethylation and hypo trimethylated on H3K9, H3K27 and H4K20. The transcriptionally active RNA polymerases II molecules are confined in the euchromatin domain and are preferentially located at the vicinity of the interface with heterochromatin. CONCLUSIONS: Our results show that transcription is located in the most decondensed and highly acetylated chromatin regions, but since acetylation is found associated with compact chromatin it is not sufficient to decondense chromatin in vivo. We also show that a combination of histone marks defines distinct concentric heterochromatin domains.http://europepmc.org/articles/PMC2882955?pdf=render
spellingShingle Caroline Kizilyaprak
Danièle Spehner
Didier Devys
Patrick Schultz
In vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications.
PLoS ONE
title In vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications.
title_full In vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications.
title_fullStr In vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications.
title_full_unstemmed In vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications.
title_short In vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications.
title_sort in vivo chromatin organization of mouse rod photoreceptors correlates with histone modifications
url http://europepmc.org/articles/PMC2882955?pdf=render
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AT didierdevys invivochromatinorganizationofmouserodphotoreceptorscorrelateswithhistonemodifications
AT patrickschultz invivochromatinorganizationofmouserodphotoreceptorscorrelateswithhistonemodifications