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Chromatin organization changes during the establishment and maintenance of the postmitotic state

BACKGROUND: Genome organization changes during development as cells differentiate. Chromatin motion becomes increasingly constrained and heterochromatin clusters as cells become restricted in their developmental potential. These changes coincide with slowing of the cell cycle, which can also influen...

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Autores principales: Ma, Yiqin, Buttitta, Laura
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5681785/
https://www.ncbi.nlm.nih.gov/pubmed/29126440
http://dx.doi.org/10.1186/s13072-017-0159-8
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author Ma, Yiqin
Buttitta, Laura
author_facet Ma, Yiqin
Buttitta, Laura
author_sort Ma, Yiqin
collection PubMed
description BACKGROUND: Genome organization changes during development as cells differentiate. Chromatin motion becomes increasingly constrained and heterochromatin clusters as cells become restricted in their developmental potential. These changes coincide with slowing of the cell cycle, which can also influence chromatin organization and dynamics. Terminal differentiation is often coupled with permanent exit from the cell cycle, and existing data suggest a close relationship between a repressive chromatin structure and silencing of the cell cycle in postmitotic cells. Heterochromatin clustering could also contribute to stable gene repression to maintain terminal differentiation or cell cycle exit, but whether clustering is initiated by differentiation, cell cycle changes, or both is unclear. Here we examine the relationship between chromatin organization, terminal differentiation and cell cycle exit. RESULTS: We focused our studies on the Drosophila wing, where epithelial cells transition from active proliferation to a postmitotic state in a temporally controlled manner. We find there are two stages of G(0) in this tissue, a flexible G(0) period where cells can be induced to reenter the cell cycle under specific genetic manipulations and a state we call “robust,” where cells become strongly refractory to cell cycle reentry. Compromising the flexible G(0) by driving ectopic expression of cell cycle activators causes a global disruption of the clustering of heterochromatin-associated histone modifications such as H3K27 trimethylation and H3K9 trimethylation, as well as their associated repressors, Polycomb and heterochromatin protein 1 (HP1). However, this disruption is reversible. When cells enter a robust G(0) state, even in the presence of ectopic cell cycle activity, clustering of heterochromatin-associated modifications is restored. If cell cycle exit is bypassed, cells in the wing continue to terminally differentiate, but heterochromatin clustering is severely disrupted. Heterochromatin-dependent gene silencing does not appear to be required for cell cycle exit, as compromising the H3K27 methyltransferase Enhancer of zeste, and/or HP1 cannot prevent the robust cell cycle exit, even in the face of normally oncogenic cell cycle activities. CONCLUSIONS: Heterochromatin clustering during terminal differentiation is a consequence of cell cycle exit, rather than differentiation. Compromising heterochromatin-dependent gene silencing does not disrupt cell cycle exit. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13072-017-0159-8) contains supplementary material, which is available to authorized users.
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spelling pubmed-56817852017-11-17 Chromatin organization changes during the establishment and maintenance of the postmitotic state Ma, Yiqin Buttitta, Laura Epigenetics Chromatin Research BACKGROUND: Genome organization changes during development as cells differentiate. Chromatin motion becomes increasingly constrained and heterochromatin clusters as cells become restricted in their developmental potential. These changes coincide with slowing of the cell cycle, which can also influence chromatin organization and dynamics. Terminal differentiation is often coupled with permanent exit from the cell cycle, and existing data suggest a close relationship between a repressive chromatin structure and silencing of the cell cycle in postmitotic cells. Heterochromatin clustering could also contribute to stable gene repression to maintain terminal differentiation or cell cycle exit, but whether clustering is initiated by differentiation, cell cycle changes, or both is unclear. Here we examine the relationship between chromatin organization, terminal differentiation and cell cycle exit. RESULTS: We focused our studies on the Drosophila wing, where epithelial cells transition from active proliferation to a postmitotic state in a temporally controlled manner. We find there are two stages of G(0) in this tissue, a flexible G(0) period where cells can be induced to reenter the cell cycle under specific genetic manipulations and a state we call “robust,” where cells become strongly refractory to cell cycle reentry. Compromising the flexible G(0) by driving ectopic expression of cell cycle activators causes a global disruption of the clustering of heterochromatin-associated histone modifications such as H3K27 trimethylation and H3K9 trimethylation, as well as their associated repressors, Polycomb and heterochromatin protein 1 (HP1). However, this disruption is reversible. When cells enter a robust G(0) state, even in the presence of ectopic cell cycle activity, clustering of heterochromatin-associated modifications is restored. If cell cycle exit is bypassed, cells in the wing continue to terminally differentiate, but heterochromatin clustering is severely disrupted. Heterochromatin-dependent gene silencing does not appear to be required for cell cycle exit, as compromising the H3K27 methyltransferase Enhancer of zeste, and/or HP1 cannot prevent the robust cell cycle exit, even in the face of normally oncogenic cell cycle activities. CONCLUSIONS: Heterochromatin clustering during terminal differentiation is a consequence of cell cycle exit, rather than differentiation. Compromising heterochromatin-dependent gene silencing does not disrupt cell cycle exit. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13072-017-0159-8) contains supplementary material, which is available to authorized users. BioMed Central 2017-11-10 /pmc/articles/PMC5681785/ /pubmed/29126440 http://dx.doi.org/10.1186/s13072-017-0159-8 Text en © The Author(s) 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Ma, Yiqin
Buttitta, Laura
Chromatin organization changes during the establishment and maintenance of the postmitotic state
title Chromatin organization changes during the establishment and maintenance of the postmitotic state
title_full Chromatin organization changes during the establishment and maintenance of the postmitotic state
title_fullStr Chromatin organization changes during the establishment and maintenance of the postmitotic state
title_full_unstemmed Chromatin organization changes during the establishment and maintenance of the postmitotic state
title_short Chromatin organization changes during the establishment and maintenance of the postmitotic state
title_sort chromatin organization changes during the establishment and maintenance of the postmitotic state
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5681785/
https://www.ncbi.nlm.nih.gov/pubmed/29126440
http://dx.doi.org/10.1186/s13072-017-0159-8
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