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Vogelmann J, Le Gall A, Dejardin S, Allemand F, Gamot A, Labesse G, Cuvier O, Nègre N, Cohen-Gonsaud M, Margeat E, Nöllmann M. Chromatin insulator factors involved in long-range DNA interactions and their role in the folding of the Drosophila genome. PLoS Genet 2014; 10:e1004544. [PMID: 25165871 PMCID: PMC4148193 DOI: 10.1371/journal.pgen.1004544] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 06/17/2014] [Indexed: 11/18/2022] Open
Abstract
Chromatin insulators are genetic elements implicated in the organization of chromatin and the regulation of transcription. In Drosophila, different insulator types were characterized by their locus-specific composition of insulator proteins and co-factors. Insulators mediate specific long-range DNA contacts required for the three dimensional organization of the interphase nucleus and for transcription regulation, but the mechanisms underlying the formation of these contacts is currently unknown. Here, we investigate the molecular associations between different components of insulator complexes (BEAF32, CP190 and Chromator) by biochemical and biophysical means, and develop a novel single-molecule assay to determine what factors are necessary and essential for the formation of long-range DNA interactions. We show that BEAF32 is able to bind DNA specifically and with high affinity, but not to bridge long-range interactions (LRI). In contrast, we show that CP190 and Chromator are able to mediate LRI between specifically-bound BEAF32 nucleoprotein complexes in vitro. This ability of CP190 and Chromator to establish LRI requires specific contacts between BEAF32 and their C-terminal domains, and dimerization through their N-terminal domains. In particular, the BTB/POZ domains of CP190 form a strict homodimer, and its C-terminal domain interacts with several insulator binding proteins. We propose a general model for insulator function in which BEAF32/dCTCF/Su(HW) provide DNA specificity (first layer proteins) whereas CP190/Chromator are responsible for the physical interactions required for long-range contacts (second layer). This network of organized, multi-layer interactions could explain the different activities of insulators as chromatin barriers, enhancer blockers, and transcriptional regulators, and suggest a general mechanism for how insulators may shape the organization of higher-order chromatin during cell division.
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Affiliation(s)
- Jutta Vogelmann
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5048, Centre de Biochimie Structurale, Montpellier, France
- Institut National de la Santé et la Recherche Médicale, Unité 1054, Montpellier, France
- Universités Montpellier I et II, Montpellier, France
| | - Antoine Le Gall
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5048, Centre de Biochimie Structurale, Montpellier, France
- Institut National de la Santé et la Recherche Médicale, Unité 1054, Montpellier, France
- Universités Montpellier I et II, Montpellier, France
| | - Stephanie Dejardin
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5048, Centre de Biochimie Structurale, Montpellier, France
- Institut National de la Santé et la Recherche Médicale, Unité 1054, Montpellier, France
- Universités Montpellier I et II, Montpellier, France
| | - Frederic Allemand
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5048, Centre de Biochimie Structurale, Montpellier, France
- Institut National de la Santé et la Recherche Médicale, Unité 1054, Montpellier, France
- Universités Montpellier I et II, Montpellier, France
| | - Adrien Gamot
- Laboratoire de Biologie Moléculaire Eucaryote, CNRS and Université de Toulouse, Toulouse; France
| | - Gilles Labesse
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5048, Centre de Biochimie Structurale, Montpellier, France
- Institut National de la Santé et la Recherche Médicale, Unité 1054, Montpellier, France
- Universités Montpellier I et II, Montpellier, France
| | - Olivier Cuvier
- Laboratoire de Biologie Moléculaire Eucaryote, CNRS and Université de Toulouse, Toulouse; France
| | - Nicolas Nègre
- Laboratoire Diversité, Génomes & Interactions Microorganismes-Insectes, INRA UMR1333, Université de Montpellier 2, Montpellier, France
| | - Martin Cohen-Gonsaud
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5048, Centre de Biochimie Structurale, Montpellier, France
- Institut National de la Santé et la Recherche Médicale, Unité 1054, Montpellier, France
- Universités Montpellier I et II, Montpellier, France
| | - Emmanuel Margeat
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5048, Centre de Biochimie Structurale, Montpellier, France
- Institut National de la Santé et la Recherche Médicale, Unité 1054, Montpellier, France
- Universités Montpellier I et II, Montpellier, France
| | - Marcelo Nöllmann
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5048, Centre de Biochimie Structurale, Montpellier, France
- Institut National de la Santé et la Recherche Médicale, Unité 1054, Montpellier, France
- Universités Montpellier I et II, Montpellier, France
- * E-mail:
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Nativio R, Ito Y, Murrell A. Quantitative chromosome conformation capture. Methods Mol Biol 2012; 925:173-185. [PMID: 22907497 DOI: 10.1007/978-1-62703-011-3_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
It is becoming increasingly apparent that chromatin is not randomly folded into the nucleus, but instead is highly organized into specific conformations within the nucleus. One consequence of such higher order structure is that chromatin looping can bring together genomic elements which are separated by several hundreds of kilobases, such as enhancers and promoters, and functionally facilitate their interaction. The Chromosome Conformation Capture (3C) assay is a powerful technique to detect looping structures and assess the probability of interaction between distant genomic elements (1-3). Here we describe the 3C methodology, its power, and limitations, together with the controls and normalization steps required for an accurate analysis.
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Affiliation(s)
- Raffaella Nativio
- Department of Oncology, CRUK Cambridge Research Institute, University of Cambridge, Cambridge, UK
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Vogelmann J, Valeri A, Guillou E, Cuvier O, Nollmann M. Roles of chromatin insulator proteins in higher-order chromatin organization and transcription regulation. Nucleus 2011; 2:358-69. [PMID: 21983085 DOI: 10.4161/nucl.2.5.17860] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Eukaryotic chromosomes are condensed into several hierarchical levels of complexity: DNA is wrapped around core histones to form nucleosomes, nucleosomes form a higher-order structure called chromatin, and chromatin is subsequently compartmentalized in part by the combination of multiple specific or unspecific long-range contacts. The conformation of chromatin at these three levels greatly influences DNA metabolism and transcription. One class of chromatin regulatory proteins called insulator factors may organize chromatin both locally, by setting up barriers between heterochromatin and euchromatin, and globally by establishing platforms for long-range interactions. Here, we review recent data revealing a global role of insulator proteins in the regulation of transcription through the formation of clusters of long-range interactions that impact different levels of chromatin organization.
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Affiliation(s)
- Jutta Vogelmann
- Centre de Biochimie Structurale, Centre National de la Recherche Scientifique and Institut National de la Santé et la Recherche Médicale, 29 rue de Navacelles, 34090, Montpellier, France
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