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Das M, Semple JI, Haemmerli A, Volodkina V, Scotton J, Gitchev T, Annan A, Campos J, Statzer C, Dakhovnik A, Ewald CY, Mozziconacci J, Meister P. Condensin I folds the Caenorhabditis elegans genome. Nat Genet 2024:10.1038/s41588-024-01832-5. [PMID: 39039278 DOI: 10.1038/s41588-024-01832-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/13/2024] [Indexed: 07/24/2024]
Abstract
The structural maintenance of chromosome (SMC) complexes-cohesin and condensins-are crucial for chromosome separation and compaction during cell division. During the interphase, mammalian cohesins additionally fold the genome into loops and domains. Here we show that, in Caenorhabditis elegans, a species with holocentric chromosomes, condensin I is the primary, long-range loop extruder. The loss of condensin I and its X-specific variant, condensin IDC, leads to genome-wide decompaction, chromosome mixing and disappearance of X-specific topologically associating domains, while reinforcing fine-scale epigenomic compartments. In addition, condensin I/IDC inactivation led to the upregulation of X-linked genes and unveiled nuclear bodies grouping together binding sites for the X-targeting loading complex of condensin IDC. C. elegans condensin I/IDC thus uniquely organizes holocentric interphase chromosomes, akin to cohesin in mammals, as well as regulates X-chromosome gene expression.
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Affiliation(s)
- Moushumi Das
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Jennifer I Semple
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Anja Haemmerli
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Valeriia Volodkina
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Janik Scotton
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Todor Gitchev
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Ahrmad Annan
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Julie Campos
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Cyril Statzer
- Eidgenössische Technische Hochschule Zürich, Department of Health Sciences and Technology, Institute of Translational Medicine, Schwerzenbach, Switzerland
| | - Alexander Dakhovnik
- Eidgenössische Technische Hochschule Zürich, Department of Health Sciences and Technology, Institute of Translational Medicine, Schwerzenbach, Switzerland
| | - Collin Y Ewald
- Eidgenössische Technische Hochschule Zürich, Department of Health Sciences and Technology, Institute of Translational Medicine, Schwerzenbach, Switzerland
| | - Julien Mozziconacci
- Laboratoire Structure et Instabilité des Génomes UMR 7196, Muséum National d'Histoire Naturelle, Paris, France
| | - Peter Meister
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Bern, Switzerland.
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2
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Andrade Ruiz L, Kops GJPL, Sacristan C. Vertebrate centromere architecture: from chromatin threads to functional structures. Chromosoma 2024; 133:169-181. [PMID: 38856923 PMCID: PMC11266386 DOI: 10.1007/s00412-024-00823-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 05/21/2024] [Accepted: 05/27/2024] [Indexed: 06/11/2024]
Abstract
Centromeres are chromatin structures specialized in sister chromatid cohesion, kinetochore assembly, and microtubule attachment during chromosome segregation. The regional centromere of vertebrates consists of long regions of highly repetitive sequences occupied by the Histone H3 variant CENP-A, and which are flanked by pericentromeres. The three-dimensional organization of centromeric chromatin is paramount for its functionality and its ability to withstand spindle forces. Alongside CENP-A, key contributors to the folding of this structure include components of the Constitutive Centromere-Associated Network (CCAN), the protein CENP-B, and condensin and cohesin complexes. Despite its importance, the intricate architecture of the regional centromere of vertebrates remains largely unknown. Recent advancements in long-read sequencing, super-resolution and cryo-electron microscopy, and chromosome conformation capture techniques have significantly improved our understanding of this structure at various levels, from the linear arrangement of centromeric sequences and their epigenetic landscape to their higher-order compaction. In this review, we discuss the latest insights on centromere organization and place them in the context of recent findings describing a bipartite higher-order organization of the centromere.
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Affiliation(s)
- Lorena Andrade Ruiz
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands
- University Medical Center Utrecht, Utrecht, Netherlands
- Oncode Institute, Utrecht, Netherlands
| | - Geert J P L Kops
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands
- University Medical Center Utrecht, Utrecht, Netherlands
- Oncode Institute, Utrecht, Netherlands
| | - Carlos Sacristan
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands.
- University Medical Center Utrecht, Utrecht, Netherlands.
- Oncode Institute, Utrecht, Netherlands.
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3
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Prevo B, Earnshaw WC. DNA packaging by molecular motors: from bacteriophage to human chromosomes. Nat Rev Genet 2024:10.1038/s41576-024-00740-y. [PMID: 38886215 DOI: 10.1038/s41576-024-00740-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2024] [Indexed: 06/20/2024]
Abstract
Dense packaging of genomic DNA is crucial for organismal survival, as DNA length always far exceeds the dimensions of the cells that contain it. Organisms, therefore, use sophisticated machineries to package their genomes. These systems range across kingdoms from a single ultra-powerful rotary motor that spools the DNA into a bacteriophage head, to hundreds of thousands of relatively weak molecular motors that coordinate the compaction of mitotic chromosomes in eukaryotic cells. Recent technological advances, such as DNA proximity-based sequencing approaches, polymer modelling and in vitro reconstitution of DNA loop extrusion, have shed light on the biological mechanisms driving DNA organization in different systems. Here, we discuss DNA packaging in bacteriophage, bacteria and eukaryotic cells, which, despite their extreme variation in size, structure and genomic content, all rely on the action of molecular motors to package their genomes.
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Affiliation(s)
- Bram Prevo
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK.
| | - William C Earnshaw
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK.
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4
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Câmara AS, Kubalová I, Schubert V. Helical chromonema coiling is conserved in eukaryotes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:1284-1300. [PMID: 37840457 DOI: 10.1111/tpj.16484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 09/07/2023] [Accepted: 09/13/2023] [Indexed: 10/17/2023]
Abstract
Efficient chromatin condensation is required to transport chromosomes during mitosis and meiosis, forming daughter cells. While it is well accepted that these processes follow fundamental rules, there has been a controversial debate for more than 140 years on whether the higher-order chromatin organization in chromosomes is evolutionarily conserved. Here, we summarize historical and recent investigations based on classical and modern methods. In particular, classical light microscopy observations based on living, fixed, and treated chromosomes covering a wide range of plant and animal species, and even in single-cell eukaryotes suggest that the chromatids of large chromosomes are formed by a coiled chromatin thread, named the chromonema. More recently, these findings were confirmed by electron and super-resolution microscopy, oligo-FISH, molecular interaction data, and polymer simulation. Altogether, we describe common and divergent features of coiled chromonemata in different species. We hypothesize that chromonema coiling in large chromosomes is a fundamental feature established early during the evolution of eukaryotes to handle increasing genome sizes.
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Affiliation(s)
- Amanda Souza Câmara
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, D-06466, Seeland, Germany
| | - Ivona Kubalová
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, D-06466, Seeland, Germany
| | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, D-06466, Seeland, Germany
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5
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Zhao H, Lin Y, Lin E, Liu F, Shu L, Jing D, Wang B, Wang M, Shan F, Zhang L, Lam JC, Midla SC, Giardine BM, Keller CA, Hardison RC, Blobel GA, Zhang H. Genome folding principles uncovered in condensin-depleted mitotic chromosomes. Nat Genet 2024; 56:1213-1224. [PMID: 38802567 DOI: 10.1038/s41588-024-01759-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 04/18/2024] [Indexed: 05/29/2024]
Abstract
During mitosis, condensin activity is thought to interfere with interphase chromatin structures. To investigate genome folding principles in the absence of chromatin loop extrusion, we codepleted condensin I and condensin II, which triggered mitotic chromosome compartmentalization in ways similar to that in interphase. However, two distinct euchromatic compartments, indistinguishable in interphase, emerged upon condensin loss with different interaction preferences and dependencies on H3K27ac. Constitutive heterochromatin gradually self-aggregated and cocompartmentalized with facultative heterochromatin, contrasting with their separation during interphase. Notably, some cis-regulatory element contacts became apparent even in the absence of CTCF/cohesin-mediated structures. Heterochromatin protein 1 (HP1) proteins, which are thought to partition constitutive heterochromatin, were absent from mitotic chromosomes, suggesting, surprisingly, that constitutive heterochromatin can self-aggregate without HP1. Indeed, in cells traversing from M to G1 phase in the combined absence of HP1α, HP1β and HP1γ, constitutive heterochromatin compartments are normally re-established. In sum, condensin-deficient mitotic chromosomes illuminate forces of genome compartmentalization not identified in interphase cells.
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Affiliation(s)
- Han Zhao
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
| | - Yinzhi Lin
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
| | - En Lin
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
| | - Fuhai Liu
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
| | - Lirong Shu
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
| | - Dannan Jing
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
- Department of Biology, College of Science, Shantou University, Shantou, China
| | - Baiyue Wang
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
| | - Manzhu Wang
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
- School of Basic Medicine, Capital Medical University, Beijing, China
| | - Fengnian Shan
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
- School of Pharmacology, South China University of Technology, Guangzhou, China
| | - Lin Zhang
- School of Biological Science, Hongkong University, Hongkong, China
| | - Jessica C Lam
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Susannah C Midla
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Belinda M Giardine
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Cheryl A Keller
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Ross C Hardison
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Gerd A Blobel
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Haoyue Zhang
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China.
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6
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McDonald A, Murre C, Sedat J. Helical Coiled Nucleosome Chromosome Architectures during Cell Cycle Progression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.25.595892. [PMID: 38826250 PMCID: PMC11142257 DOI: 10.1101/2024.05.25.595892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Recent studies showed an interphase chromosome architecture, --- a specific coiled nucleosome structure, --- derived from cryo-preserved EM tomograms, and dispersed throughout the nucleus. The images were computationally processed to fill in the missing wedges of data caused by incomplete tomographic tilts. The resulting structures increased z-resolution enabling an extension of the proposed architecture to that of mitotic chromosomes. Here we provide additional insights and details into the coiled nucleosome chromosome architectures. We build on the defined chromosomes time-dependent structures in an effort to probe their dynamics. Variants of the coiled chromosome structures, possibly further defining specific regions, are discussed. We propose, based on generalized specific uncoiling of mitotic chromosomes in telophase, large-scale re-organization of interphase chromosomes. Chromosome territories, organized as micron-sized small patches, are constructed, satisfying complex volume considerations. Finally, we unveiled the structures of replicated coiled chromosomes, still attached to centromeres, as part of chromosome architecture. Significance Statement This study places all 46 sequenced human chromosomes, --- correctly filled with nucleosomes and in micron sized chromosome territories - into 10micron (average sized) nuclei. The chromosome architecture used a helical nucleosome coiled structure discerned from cryo-EM tomography, as was recently published ( https://doi.org/10.1073/pnas.2119101119 ). This chromosome architecture was further modeled to dynamic structures, structure variations and chromosome replication centromere complications. Finally, this chromosome architecture was modified to allow seamless transition through the cell cycle.
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Hildebrand EM, Polovnikov K, Dekker B, Liu Y, Lafontaine DL, Fox AN, Li Y, Venev SV, Mirny LA, Dekker J. Mitotic chromosomes are self-entangled and disentangle through a topoisomerase-II-dependent two-stage exit from mitosis. Mol Cell 2024; 84:1422-1441.e14. [PMID: 38521067 DOI: 10.1016/j.molcel.2024.02.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 10/23/2023] [Accepted: 02/24/2024] [Indexed: 03/25/2024]
Abstract
The topological state of chromosomes determines their mechanical properties, dynamics, and function. Recent work indicated that interphase chromosomes are largely free of entanglements. Here, we use Hi-C, polymer simulations, and multi-contact 3C and find that, by contrast, mitotic chromosomes are self-entangled. We explore how a mitotic self-entangled state is converted into an unentangled interphase state during mitotic exit. Most mitotic entanglements are removed during anaphase/telophase, with remaining ones removed during early G1, in a topoisomerase-II-dependent process. Polymer models suggest a two-stage disentanglement pathway: first, decondensation of mitotic chromosomes with remaining condensin loops produces entropic forces that bias topoisomerase II activity toward decatenation. At the second stage, the loops are released, and the formation of new entanglements is prevented by lower topoisomerase II activity, allowing the establishment of unentangled and territorial G1 chromosomes. When mitotic entanglements are not removed in experiments and models, a normal interphase state cannot be acquired.
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Affiliation(s)
- Erica M Hildebrand
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | | | - Bastiaan Dekker
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Yu Liu
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; Nuclear Dynamics and Cancer Program, Cancer Epigenetics Institute, Fox Chase Cancer Center, Temple Health, Philadelphia, PA 19111, USA
| | - Denis L Lafontaine
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - A Nicole Fox
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Ying Li
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Sergey V Venev
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Leonid A Mirny
- Institute for Medical Engineering and Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Job Dekker
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
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8
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Kuzminov A. Bacterial nucleoid is a riddle wrapped in a mystery inside an enigma. J Bacteriol 2024; 206:e0021123. [PMID: 38358278 PMCID: PMC10994824 DOI: 10.1128/jb.00211-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024] Open
Abstract
Bacterial chromosome, the nucleoid, is traditionally modeled as a rosette of DNA mega-loops, organized around proteinaceous central scaffold by nucleoid-associated proteins (NAPs), and mixed with the cytoplasm by transcription and translation. Electron microscopy of fixed cells confirms dispersal of the cloud-like nucleoid within the ribosome-filled cytoplasm. Here, I discuss evidence that the nucleoid in live cells forms DNA phase separate from riboprotein phase, the "riboid." I argue that the nucleoid-riboid interphase, where DNA interacts with NAPs, transcribing RNA polymerases, nascent transcripts, and ssRNA chaperones, forms the transcription zone. An active part of phase separation, transcription zone enforces segregation of the centrally positioned information phase (the nucleoid) from the surrounding action phase (the riboid), where translation happens, protein accumulates, and metabolism occurs. I speculate that HU NAP mostly tiles up the nucleoid periphery-facilitating DNA mobility but also supporting transcription in the interphase. Besides extruding plectonemically supercoiled DNA mega-loops, condensins could compact them into solenoids of uniform rings, while HU could support rigidity and rotation of these DNA rings. The two-phase cytoplasm arrangement allows the bacterial cell to organize the central dogma activities, where (from the cell center to its periphery) DNA replicates and segregates, DNA is transcribed, nascent mRNA is handed over to ribosomes, mRNA is translated into proteins, and finally, the used mRNA is recycled into nucleotides at the inner membrane. The resulting information-action conveyor, with one activity naturally leading to the next one, explains the efficiency of prokaryotic cell design-even though its main intracellular transportation mode is free diffusion.
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Affiliation(s)
- Andrei Kuzminov
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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9
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Yoshida MM, Kinoshita K, Shintomi K, Aizawa Y, Hirano T. Regulation of condensin II by self-suppression and release mechanisms. Mol Biol Cell 2024; 35:ar21. [PMID: 38088875 PMCID: PMC10881152 DOI: 10.1091/mbc.e23-10-0392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 01/14/2024] Open
Abstract
In vertebrates, two distinct condensin complexes, condensin I and condensin II, cooperate to drive mitotic chromosome assembly. It remains largely unknown how the two complexes differentially contribute to this process at a mechanistic level. We have previously dissected the role of individual subunits of condensin II by introducing recombinant complexes into Xenopus egg extracts. Here we extend these efforts by introducing a modified functional assay using extracts depleted of topoisomerase IIα (topo IIα), which allows us to further elucidate the functional similarities and differences between condensin I and condensin II. The intrinsically disordered C-terminal region of the CAP-D3 subunit (the D3 C-tail) is a major target of Cdk1 phosphorylation, and phosphorylation-deficient mutations in this region impair condensin II functions. We also identify a unique helical structure in CAP-D3 (the D3 HEAT docker) that is predicted to directly interact with CAP-G2. Deletion of the D3 HEAT docker, along with the D3 C-tail, enhances the ability of condensin II to assemble mitotic chromosomes. Taken together, we propose a self-suppression mechanism unique to condensin II that is released by mitotic phosphorylation. Evolutionary implications of our findings are also discussed.
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Affiliation(s)
- Makoto M. Yoshida
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | | | - Keishi Shintomi
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Yuuki Aizawa
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Tatsuya Hirano
- Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
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10
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Clement TVM, van der Smagt C, Wuite GJL. Probing Mitotic Chromosome Mechanics Using Optical Tweezers. Methods Mol Biol 2024; 2694:91-107. [PMID: 37824001 DOI: 10.1007/978-1-0716-3377-9_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
During mitosis, cells compact their DNA into rodlike shapes, four orders of magnitude shorter than the DNA backbone contour length. We describe an experimental protocol to isolate and study these intricate mitotic chromosomes using optical tweezers. We touch upon the technical details of the required optical tweezers and microfluidics setup, including advanced force calibration procedures to accurately measure the high forces the chromosomes withstand. The procedure used to isolate mitotic chromosomes, including biotinylation of the telomeric ends to facilitate trapping them in optical tweezers, is described in detail. Finally, we provide a protocol for carrying out optical tweezers experiments on the isolated mitotic chromosomes.
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Affiliation(s)
- Tinka V M Clement
- LaserLaB Amsterdam and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Constantijn van der Smagt
- LaserLaB Amsterdam and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Gijs J L Wuite
- LaserLaB Amsterdam and Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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11
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Forte G, Boteva L, Conforto F, Gilbert N, Cook PR, Marenduzzo D. Bridging condensins mediate compaction of mitotic chromosomes. J Cell Biol 2024; 223:e202209113. [PMID: 37976091 PMCID: PMC10655892 DOI: 10.1083/jcb.202209113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 07/08/2023] [Accepted: 11/01/2023] [Indexed: 11/19/2023] Open
Abstract
Eukaryotic chromosomes compact during mitosis into elongated cylinders-and not the spherical globules expected of self-attracting long flexible polymers. This process is mainly driven by condensin-like proteins. Here, we present Brownian-dynamic simulations involving two types of such proteins with different activities. One, which we refer to as looping condensins, anchors long-lived chromatin loops to create bottlebrush structures. The second, referred to as bridging condensins, forms multivalent bridges between distant parts of these loops. We show that binding of bridging condensins leads to the formation of shorter and stiffer mitotic-like cylinders without requiring any additional energy input. These cylinders have several features matching experimental observations. For instance, the axial condensin backbone breaks up into clusters as found by microscopy, and cylinder elasticity qualitatively matches that seen in chromosome pulling experiments. Additionally, simulating global condensin depletion or local faulty condensin loading gives phenotypes seen experimentally and points to a mechanistic basis for the structure of common fragile sites in mitotic chromosomes.
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Affiliation(s)
- Giada Forte
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - Lora Boteva
- MRC Human Genetics Unit, Western General Hospital, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, UK
| | - Filippo Conforto
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
| | - Nick Gilbert
- MRC Human Genetics Unit, Western General Hospital, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, UK
| | - Peter R. Cook
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Davide Marenduzzo
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
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12
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Abstract
The raison d'être of meiosis is shuffling of genetic information via Mendelian segregation and, within individual chromosomes, by DNA crossing-over. These outcomes are enabled by a complex cellular program in which interactions between homologous chromosomes play a central role. We first provide a background regarding the basic principles of this program. We then summarize the current understanding of the DNA events of recombination and of three processes that involve whole chromosomes: homolog pairing, crossover interference, and chiasma maturation. All of these processes are implemented by direct physical interaction of recombination complexes with underlying chromosome structures. Finally, we present convergent lines of evidence that the meiotic program may have evolved by coupling of this interaction to late-stage mitotic chromosome morphogenesis.
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Affiliation(s)
- Denise Zickler
- Institute for Integrative Biology of the Cell (I2BC), Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Nancy Kleckner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA;
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13
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Colin L, Reyes C, Berthezene J, Maestroni L, Modolo L, Toselli E, Chanard N, Schaak S, Cuvier O, Gachet Y, Coulon S, Bernard P, Tournier S. Condensin positioning at telomeres by shelterin proteins drives sister-telomere disjunction in anaphase. eLife 2023; 12:RP89812. [PMID: 37988290 PMCID: PMC10662949 DOI: 10.7554/elife.89812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2023] Open
Abstract
The localization of condensin along chromosomes is crucial for their accurate segregation in anaphase. Condensin is enriched at telomeres but how and for what purpose had remained elusive. Here, we show that fission yeast condensin accumulates at telomere repeats through the balancing acts of Taz1, a core component of the shelterin complex that ensures telomeric functions, and Mit1, a nucleosome remodeler associated with shelterin. We further show that condensin takes part in sister-telomere separation in anaphase, and that this event can be uncoupled from the prior separation of chromosome arms, implying a telomere-specific separation mechanism. Consistent with a cis-acting process, increasing or decreasing condensin occupancy specifically at telomeres modifies accordingly the efficiency of their separation in anaphase. Genetic evidence suggests that condensin promotes sister-telomere separation by counteracting cohesin. Thus, our results reveal a shelterin-based mechanism that enriches condensin at telomeres to drive in cis their separation during mitosis.
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Affiliation(s)
- Léonard Colin
- CNRS - Laboratory of Biology and Modelling of the CellLyonFrance
- ENS de Lyon, Université Lyon, site Jacques MonodLyonFrance
| | - Celine Reyes
- MCD, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPSToulouseFrance
| | - Julien Berthezene
- MCD, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPSToulouseFrance
| | - Laetitia Maestroni
- CNRS, INSERM, Aix Marseille Université, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le CancerMarseilleFrance
| | - Laurent Modolo
- CNRS - Laboratory of Biology and Modelling of the CellLyonFrance
- ENS de Lyon, Université Lyon, site Jacques MonodLyonFrance
| | - Esther Toselli
- CNRS - Laboratory of Biology and Modelling of the CellLyonFrance
- ENS de Lyon, Université Lyon, site Jacques MonodLyonFrance
| | - Nicolas Chanard
- MCD, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPSToulouseFrance
- CBI, MCD-UMR5077, CNRS, Chromatin Dynamics TeamToulouseFrance
| | - Stephane Schaak
- MCD, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPSToulouseFrance
- CBI, MCD-UMR5077, CNRS, Chromatin Dynamics TeamToulouseFrance
| | - Olivier Cuvier
- MCD, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPSToulouseFrance
- CBI, MCD-UMR5077, CNRS, Chromatin Dynamics TeamToulouseFrance
| | - Yannick Gachet
- MCD, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPSToulouseFrance
| | - Stephane Coulon
- CNRS, INSERM, Aix Marseille Université, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le CancerMarseilleFrance
| | - Pascal Bernard
- CNRS - Laboratory of Biology and Modelling of the CellLyonFrance
- ENS de Lyon, Université Lyon, site Jacques MonodLyonFrance
| | - Sylvie Tournier
- MCD, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPSToulouseFrance
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14
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Zhao H, Lin Y, Lin E, Liu F, Shu L, Jing D, Wang B, Wang M, Shan F, Zhang L, Lam JC, Midla SC, Giardine BM, Keller CA, Hardison RC, Blobel GA, Zhang H. Genome folding principles revealed in condensin-depleted mitotic chromosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.09.566494. [PMID: 38014261 PMCID: PMC10680603 DOI: 10.1101/2023.11.09.566494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
During mitosis, condensin activity interferes with interphase chromatin structures. Here, we generated condensin-free mitotic chromosomes to investigate genome folding principles. Co-depletion of condensin I and II, but neither alone, triggered mitotic chromosome compartmentalization in ways that differ from interphase. Two distinct euchromatic compartments, indistinguishable in interphase, rapidly emerged upon condensin loss with different interaction preferences and dependence on H3K27ac. Constitutive heterochromatin gradually self-aggregated and co-compartmentalized with the facultative heterochromatin, contrasting with their separation during interphase. While topologically associating domains (TADs) and CTCF/cohesin mediated structural loops remained undetectable, cis-regulatory element contacts became apparent, providing an explanation for their quick re-establishment during mitotic exit. HP1 proteins, which are thought to partition constitutive heterochromatin, were absent from mitotic chromosomes, suggesting, surprisingly, that constitutive heterochromatin can self-aggregate without HP1. Indeed, in cells traversing from M- to G1-phase in the combined absence of HP1α, HP1β and HP1γ, re-established constitutive heterochromatin compartments normally. In sum, "clean-slate" condensing-deficient mitotic chromosomes illuminate mechanisms of genome compartmentalization not revealed in interphase cells.
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Affiliation(s)
- Han Zhao
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
| | - Yinzhi Lin
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
| | - En Lin
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
| | - Fuhai Liu
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
| | - Lirong Shu
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
| | - Dannan Jing
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
- Department of Biology, College of Science, Shantou University, Shantou, China
| | - Baiyue Wang
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
| | - Manzhu Wang
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
- School of Basic medicine, Capital Medical University, Beijing, China
| | - Fengnian Shan
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
- School of Pharmacology, South China University of Technology, Guangzhou, Guangdong, China
| | - Lin Zhang
- School of Biological Science, Hongkong University, Hongkong, China
| | - Jessica C. Lam
- Division of Hematology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Susannah C. Midla
- Division of Hematology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Belinda M. Giardine
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Cheryl A. Keller
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Ross C. Hardison
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Gerd A. Blobel
- Division of Hematology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Haoyue Zhang
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong, China
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15
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Tang M, Pobegalov G, Tanizawa H, Chen ZA, Rappsilber J, Molodtsov M, Noma KI, Uhlmann F. Establishment of dsDNA-dsDNA interactions by the condensin complex. Mol Cell 2023; 83:3787-3800.e9. [PMID: 37820734 PMCID: PMC10842940 DOI: 10.1016/j.molcel.2023.09.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/13/2023] [Accepted: 09/13/2023] [Indexed: 10/13/2023]
Abstract
Condensin is a structural maintenance of chromosomes (SMC) complex family member thought to build mitotic chromosomes by DNA loop extrusion. However, condensin variants unable to extrude loops, yet proficient in chromosome formation, were recently described. Here, we explore how condensin might alternatively build chromosomes. Using bulk biochemical and single-molecule experiments with purified fission yeast condensin, we observe that individual condensins sequentially and topologically entrap two double-stranded DNAs (dsDNAs). Condensin loading transitions through a state requiring DNA bending, as proposed for the related cohesin complex. While cohesin then favors the capture of a second single-stranded DNA (ssDNA), second dsDNA capture emerges as a defining feature of condensin. We provide complementary in vivo evidence for DNA-DNA capture in the form of condensin-dependent chromatin contacts within, as well as between, chromosomes. Our results support a "diffusion capture" model in which condensin acts in mitotic chromosome formation by sequential dsDNA-dsDNA capture.
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Affiliation(s)
- Minzhe Tang
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Georgii Pobegalov
- Mechanobiology and Biophysics Laboratory, The Francis Crick Institute, London NW1 1AT, UK; Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - Hideki Tanizawa
- Division of Genome Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan
| | - Zhuo A Chen
- Bioanalytics Unit, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany
| | - Juri Rappsilber
- Bioanalytics Unit, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany; Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Maxim Molodtsov
- Mechanobiology and Biophysics Laboratory, The Francis Crick Institute, London NW1 1AT, UK; Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - Ken-Ichi Noma
- Division of Genome Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido 060-0815, Japan; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK; Cell Biology Centre, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa 226-0026, Japan.
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16
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Chu X, Wang J. Quantifying the large-scale chromosome structural dynamics during the mitosis-to-G1 phase transition of cell cycle. Open Biol 2023; 13:230175. [PMID: 37907089 PMCID: PMC10618054 DOI: 10.1098/rsob.230175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/27/2023] [Indexed: 11/02/2023] Open
Abstract
Cell cycle is known to be regulated by the underlying gene network. Chromosomes, which serve as the scaffold for gene expressions, undergo significant structural reorganizations during mitosis. Understanding the mechanism of the cell cycle from the chromosome structural perspective remains a grand challenge. In this study, we applied an integrated theoretical approach to investigate large-scale chromosome structural dynamics during the mitosis-to-G1 phase transition. We observed that the chromosome structural expansion and adaptation of the structural asphericity do not occur synchronously and attributed this behaviour to the unique unloading sequence of the two types of condensins. Furthermore, we observed that the coherent motions between the chromosomal loci are primarily enhanced within the topologically associating domains (TADs) as cells progress to the G1 phase, suggesting that TADs can be considered as both structural and dynamical units for organizing the three-dimensional chromosome. Our analysis also reveals that the quantified pathways of chromosome structural reorganization during the mitosis-to-G1 phase transition exhibit high stochasticity at the single-cell level and show nonlinear behaviours in changing TADs and contacts formed at the long-range regions. Our findings offer valuable insights into large-scale chromosome structural dynamics after mitosis.
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Affiliation(s)
- Xiakun Chu
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794, USA
| | - Jin Wang
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794, USA
- Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, NY 11794, USA
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17
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Abstract
Many cellular processes require large-scale rearrangements of chromatin structure. Structural maintenance of chromosomes (SMC) protein complexes are molecular machines that can provide structure to chromatin. These complexes can connect DNA elements in cis, walk along DNA, build and processively enlarge DNA loops and connect DNA molecules in trans to hold together the sister chromatids. These DNA-shaping abilities place SMC complexes at the heart of many DNA-based processes, including chromosome segregation in mitosis, transcription control and DNA replication, repair and recombination. In this Review, we discuss the latest insights into how SMC complexes such as cohesin, condensin and the SMC5-SMC6 complex shape DNA to direct these fundamental chromosomal processes. We also consider how SMC complexes, by building chromatin loops, can counteract the natural tendency of alike chromatin regions to cluster. SMC complexes thus control nuclear organization by participating in a molecular tug of war that determines the architecture of our genome.
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Affiliation(s)
- Claire Hoencamp
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Benjamin D Rowland
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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18
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Batty P, Langer CCH, Takács Z, Tang W, Blaukopf C, Peters J, Gerlich DW. Cohesin-mediated DNA loop extrusion resolves sister chromatids in G2 phase. EMBO J 2023; 42:e113475. [PMID: 37357575 PMCID: PMC10425840 DOI: 10.15252/embj.2023113475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 05/26/2023] [Accepted: 06/14/2023] [Indexed: 06/27/2023] Open
Abstract
Genetic information is stored in linear DNA molecules, which are highly folded inside cells. DNA replication along the folded template path yields two sister chromatids that initially occupy the same nuclear region in an intertwined arrangement. Dividing cells must disentangle and condense the sister chromatids into separate bodies such that a microtubule-based spindle can move them to opposite poles. While the spindle-mediated transport of sister chromatids has been studied in detail, the chromosome-intrinsic mechanics presegregating sister chromatids have remained elusive. Here, we show that human sister chromatids resolve extensively already during interphase, in a process dependent on the loop-extruding activity of cohesin, but not that of condensins. Increasing cohesin's looping capability increases sister DNA resolution in interphase nuclei to an extent normally seen only during mitosis, despite the presence of abundant arm cohesion. That cohesin can resolve sister chromatids so extensively in the absence of mitosis-specific activities indicates that DNA loop extrusion is a generic mechanism for segregating replicated genomes, shared across different Structural Maintenance of Chromosomes (SMC) protein complexes in all kingdoms of life.
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Affiliation(s)
- Paul Batty
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
- Vienna BioCenter PhD ProgramDoctoral School of the University of Vienna and Medical University of ViennaViennaAustria
| | - Christoph CH Langer
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
| | - Zsuzsanna Takács
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
| | - Wen Tang
- Research Institute of Molecular Pathology (IMP)Vienna BioCenter (VBC)ViennaAustria
| | - Claudia Blaukopf
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
| | - Jan‐Michael Peters
- Research Institute of Molecular Pathology (IMP)Vienna BioCenter (VBC)ViennaAustria
| | - Daniel W Gerlich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)Vienna BioCenter (VBC)ViennaAustria
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19
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Spicer MFD, Gerlich DW. The material properties of mitotic chromosomes. Curr Opin Struct Biol 2023; 81:102617. [PMID: 37279615 PMCID: PMC10448380 DOI: 10.1016/j.sbi.2023.102617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/28/2023] [Accepted: 05/04/2023] [Indexed: 06/08/2023]
Abstract
Chromosomes transform during the cell cycle, allowing transcription and replication during interphase and chromosome segregation during mitosis. Morphological changes are thought to be driven by the combined effects of DNA loop extrusion and a chromatin solubility phase transition. By extruding the chromatin fibre into loops, condensins enrich at an axial core and provide resistance to spindle pulling forces. Mitotic chromosomes are further compacted by deacetylation of histone tails, rendering chromatin insoluble and resistant to penetration by microtubules. Regulation of surface properties by Ki-67 allows independent chromosome movement in early mitosis and clustering during mitotic exit. Recent progress has provided insight into how the extraordinary material properties of chromatin emerge from these activities, and how these properties facilitate faithful chromosome segregation.
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Affiliation(s)
- Maximilian F D Spicer
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030, Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, A-1030, Vienna, Austria. https://twitter.com/Spicer__Max
| | - Daniel W Gerlich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030, Vienna, Austria.
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20
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Piemonte KM, Webb BM, Bobbitt JR, Majmudar PR, Cuellar-Vite L, Bryson BL, Latina NC, Seachrist DD, Keri RA. Disruption of CDK7 signaling leads to catastrophic chromosomal instability coupled with a loss of condensin-mediated chromatin compaction. J Biol Chem 2023; 299:104834. [PMID: 37201585 PMCID: PMC10300262 DOI: 10.1016/j.jbc.2023.104834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/11/2023] [Accepted: 05/12/2023] [Indexed: 05/20/2023] Open
Abstract
Chromatin organization is highly dynamic and modulates DNA replication, transcription, and chromosome segregation. Condensin is essential for chromosome assembly during mitosis and meiosis, as well as maintenance of chromosome structure during interphase. While it is well established that sustained condensin expression is necessary to ensure chromosome stability, the mechanisms that control its expression are not yet known. Herein, we report that disruption of cyclin-dependent kinase 7 (CDK7), the core catalytic subunit of CDK-activating kinase, leads to reduced transcription of several condensin subunits, including structural maintenance of chromosomes 2 (SMC2). Live and static microscopy revealed that inhibiting CDK7 signaling prolongs mitosis and induces chromatin bridge formation, DNA double-strand breaks, and abnormal nuclear features, all of which are indicative of mitotic catastrophe and chromosome instability. Affirming the importance of condensin regulation by CDK7, genetic suppression of the expression of SMC2, a core subunit of this complex, phenocopies CDK7 inhibition. Moreover, analysis of genome-wide chromatin conformation using Hi-C revealed that sustained activity of CDK7 is necessary to maintain chromatin sublooping, a function that is ascribed to condensin. Notably, the regulation of condensin subunit gene expression is independent of superenhancers. Together, these studies reveal a new role for CDK7 in sustaining chromatin configuration by ensuring the expression of condensin genes, including SMC2.
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Affiliation(s)
- Katrina M Piemonte
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Bryan M Webb
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Jessica R Bobbitt
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Parth R Majmudar
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Leslie Cuellar-Vite
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Benjamin L Bryson
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Nicholas C Latina
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Darcie D Seachrist
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Ruth A Keri
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA; Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA; Department of General Medical Sciences-Oncology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
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21
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Bartas M, Slychko K, Červeň J, Pečinka P, Arndt-Jovin DJ, Jovin TM. Extensive Bioinformatics Analyses Reveal a Phylogenetically Conserved Winged Helix (WH) Domain (Zτ) of Topoisomerase IIα, Elucidating Its Very High Affinity for Left-Handed Z-DNA and Suggesting Novel Putative Functions. Int J Mol Sci 2023; 24:10740. [PMID: 37445918 DOI: 10.3390/ijms241310740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/13/2023] [Accepted: 06/22/2023] [Indexed: 07/15/2023] Open
Abstract
The dynamic processes operating on genomic DNA, such as gene expression and cellular division, lead inexorably to topological challenges in the form of entanglements, catenanes, knots, "bubbles", R-loops, and other outcomes of supercoiling and helical disruption. The resolution of toxic topological stress is the function attributed to DNA topoisomerases. A prominent example is the negative supercoiling (nsc) trailing processive enzymes such as DNA and RNA polymerases. The multiple equilibrium states that nscDNA can adopt by redistribution of helical twist and writhe include the left-handed double-helical conformation known as Z-DNA. Thirty years ago, one of our labs isolated a protein from Drosophila cells and embryos with a 100-fold greater affinity for Z-DNA than for B-DNA, and identified it as topoisomerase II (gene Top2, orthologous to the human UniProt proteins TOP2A and TOP2B). GTP increased the affinity and selectivity for Z-DNA even further and also led to inhibition of the isomerase enzymatic activity. An allosteric mechanism was proposed, in which topoII acts as a Z-DNA-binding protein (ZBP) to stabilize given states of topological (sub)domains and associated multiprotein complexes. We have now explored this possibility by comprehensive bioinformatic analyses of the available protein sequences of topoII representing organisms covering the whole tree of life. Multiple alignment of these sequences revealed an extremely high level of evolutionary conservation, including a winged-helix protein segment, here denoted as Zτ, constituting the putative structural homolog of Zα, the canonical Z-DNA/Z-RNA binding domain previously identified in the interferon-inducible RNA Adenosine-to-Inosine-editing deaminase, ADAR1p150. In contrast to Zα, which is separate from the protein segment responsible for catalysis, Zτ encompasses the active site tyrosine of topoII; a GTP-binding site and a GxxG sequence motif are in close proximity. Quantitative Zτ-Zα similarity comparisons and molecular docking with interaction scoring further supported the "B-Z-topoII hypothesis" and has led to an expanded mechanism for topoII function incorporating the recognition of Z-DNA segments ("Z-flipons") as an inherent and essential element. We further propose that the two Zτ domains of the topoII homodimer exhibit a single-turnover "conformase" activity on given G(ate) B-DNA segments ("Z-flipins"), inducing their transition to the left-handed Z-conformation. Inasmuch as the topoII-Z-DNA complexes are isomerase inactive, we infer that they fulfill important structural roles in key processes such as mitosis. Topoisomerases are preeminent targets of anti-cancer drug discovery, and we anticipate that detailed elucidation of their structural-functional interactions with Z-DNA and GTP will facilitate the design of novel, more potent and selective anti-cancer chemotherapeutic agents.
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Affiliation(s)
- Martin Bartas
- Department of Biology and Ecology, University of Ostrava, 710 00 Ostrava, Czech Republic
| | - Kristyna Slychko
- Department of Biology and Ecology, University of Ostrava, 710 00 Ostrava, Czech Republic
| | - Jiří Červeň
- Department of Biology and Ecology, University of Ostrava, 710 00 Ostrava, Czech Republic
| | - Petr Pečinka
- Department of Biology and Ecology, University of Ostrava, 710 00 Ostrava, Czech Republic
| | - Donna J Arndt-Jovin
- Emeritus Laboratory of Cellular Dynamics, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Thomas M Jovin
- Emeritus Laboratory of Cellular Dynamics, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
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22
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Dey A, Shi G, Takaki R, Thirumalai D. Structural changes in chromosomes driven by multiple condensin motors during mitosis. Cell Rep 2023; 42:112348. [PMID: 37027299 DOI: 10.1016/j.celrep.2023.112348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 11/10/2022] [Accepted: 03/21/2023] [Indexed: 04/08/2023] Open
Abstract
We create a computational framework that utilizes loop extrusion (LE) by multiple condensin I/II motors to predict changes in chromosome organization during mitosis. The theory accurately reproduces the experimental contact probability profiles for the mitotic chromosomes in HeLa and DT40 cells. The LE rate is smaller at the start of mitosis and increases as the cells approach metaphase. Condensin II-mediated mean loop size is about six times larger than loops because of condensin I. The loops, which overlap each other, are stapled to a central dynamically changing helical scaffold formed by the motors during the LE process. A polymer physics-based data-driven method that uses the Hi-C contact map as the only input shows that the helix is characterized as random helix perversions (RHPs) in which the handedness changes randomly along the scaffold. The theoretical predictions, which are testable using imaging experiments, do not contain any parameters.
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Affiliation(s)
- Atreya Dey
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712, USA
| | - Guang Shi
- Department of Materials Science, University of Illinois, Urbana, IL 61801, USA
| | - Ryota Takaki
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str.38, 01187 Dresden, Saxony, Germany
| | - D Thirumalai
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712, USA; Department of Physics, The University of Texas at Austin, Austin, TX 78712, USA.
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23
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Super-resolution microscopy reveals the number and distribution of topoisomerase IIα and CENH3 molecules within barley metaphase chromosomes. Chromosoma 2023; 132:19-29. [PMID: 36719450 PMCID: PMC9981516 DOI: 10.1007/s00412-023-00785-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/25/2022] [Accepted: 12/13/2022] [Indexed: 02/01/2023]
Abstract
Topoisomerase IIα (Topo IIα) and the centromere-specific histone H3 variant CENH3 are key proteins involved in chromatin condensation and centromere determination, respectively. Consequently, they are required for proper chromosome segregation during cell divisions. We combined two super-resolution techniques, structured illumination microscopy (SIM) to co-localize Topo IIα and CENH3, and photoactivated localization microscopy (PALM) to determine their molecule numbers in barley metaphase chromosomes. We detected a dispersed Topo IIα distribution along chromosome arms but an accumulation at centromeres, telomeres, and nucleolus-organizing regions. With a precision of 10-50 nm, we counted ~ 20,000-40,000 Topo IIα molecules per chromosome, 28% of them within the (peri)centromere. With similar precision, we identified ~13,500 CENH3 molecules per centromere where Topo IIα proteins and CENH3-containing chromatin intermingle. In short, we demonstrate PALM as a useful method to count and localize single molecules with high precision within chromosomes. The ultrastructural distribution and the detected amount of Topo IIα and CENH3 are instrumental for a better understanding of their functions during chromatin condensation and centromere determination.
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24
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Kakui Y, Barrington C, Kusano Y, Thadani R, Fallesen T, Hirota T, Uhlmann F. Chromosome arm length, and a species-specific determinant, define chromosome arm width. Cell Rep 2022; 41:111753. [PMID: 36476849 DOI: 10.1016/j.celrep.2022.111753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 09/05/2022] [Accepted: 11/09/2022] [Indexed: 12/12/2022] Open
Abstract
Mitotic chromosomes in different organisms adopt various dimensions. What defines these dimensions is scarcely understood. Here, we compare mitotic chromosomes in budding and fission yeasts harboring similarly sized genomes distributed among 16 or 3 chromosomes, respectively. Hi-C analyses and superresolution microscopy reveal that budding yeast chromosomes are characterized by shorter-ranging mitotic chromatin contacts and are thinner compared with the thicker fission yeast chromosomes that contain longer-ranging mitotic contacts. These distinctions persist even after budding yeast chromosomes are fused to form three fission-yeast-length entities, revealing a species-specific organizing principle. Species-specific widths correlate with the known binding site intervals of the chromosomal condensin complex. Unexpectedly, within each species, we find that longer chromosome arms are always thicker and harbor longer-ranging contacts, a trend that we also observe with human chromosomes. Arm length as a chromosome width determinant informs mitotic chromosome formation models.
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Affiliation(s)
- Yasutaka Kakui
- Waseda Institute for Advanced Study, Waseda University, Tokyo 169-0051, Japan; Laboratory of Cytoskeletal Logistics, Center for Advanced Biomedical Sciences, Waseda University, Tokyo 162-8480, Japan; Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
| | - Christopher Barrington
- Bioinformatics & Biostatistics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Yoshiharu Kusano
- Division of Experimental Pathology, Cancer Institute of the Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Rahul Thadani
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Todd Fallesen
- Advanced Light Microscopy Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Toru Hirota
- Division of Experimental Pathology, Cancer Institute of the Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
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25
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Kim JH, Youn Y, Hwang JH. NCAPH Stabilizes GEN1 in Chromatin to Resolve Ultra-Fine DNA Bridges and Maintain Chromosome Stability. Mol Cells 2022; 45:792-805. [PMID: 36380731 PMCID: PMC9676985 DOI: 10.14348/molcells.2022.0048] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/11/2022] [Accepted: 11/11/2022] [Indexed: 11/18/2022] Open
Abstract
Repairing damaged DNA and removing all physical connections between sister chromosomes is important to ensure proper chromosomal segregation by contributing to chromosomal stability. Here, we show that the depletion of non-SMC condensin I complex subunit H (NCAPH) exacerbates chromosome segregation errors and cytokinesis failure owing to sister-chromatid intertwinement, which is distinct from the ultra-fine DNA bridges induced by DNA inter-strand crosslinks (DNA-ICLs). Importantly, we identified an interaction between NCAPH and GEN1 in the chromatin involving binding at the N-terminus of NCAPH. DNA-ICL activation, using ICL-inducing agents, increased the expression and interaction between NCAPH and GEN1 in the soluble nuclear and chromatin, indicating that the NCAPH-GEN1 interaction participates in repairing DNA damage. Moreover, NCAPH stabilizes GEN1 within chromatin at the G2/M-phase and is associated with DNA-ICL-induced damage repair. Therefore, NCAPH resolves DNA-ICL-induced ultra-fine DNA bridges by stabilizing GEN1 and ensures proper chromosome separation and chromosome structural stability.
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Affiliation(s)
- Jae Hyeong Kim
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Korea
| | - Yuna Youn
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Korea
| | - Jin-Hyeok Hwang
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Korea
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul 03080, Korea
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26
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Regulation of the mitotic chromosome folding machines. Biochem J 2022; 479:2153-2173. [PMID: 36268993 DOI: 10.1042/bcj20210140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 09/30/2022] [Accepted: 10/03/2022] [Indexed: 11/17/2022]
Abstract
Over the last several years enormous progress has been made in identifying the molecular machines, including condensins and topoisomerases that fold mitotic chromosomes. The discovery that condensins generate chromatin loops through loop extrusion has revolutionized, and energized, the field of chromosome folding. To understand how these machines fold chromosomes with the appropriate dimensions, while disentangling sister chromatids, it needs to be determined how they are regulated and deployed. Here, we outline the current understanding of how these machines and factors are regulated through cell cycle dependent expression, chromatin localization, activation and inactivation through post-translational modifications, and through associations with each other, with other factors and with the chromatin template itself. There are still many open questions about how condensins and topoisomerases are regulated but given the pace of progress in the chromosome folding field, it seems likely that many of these will be answered in the years ahead.
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27
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Ward JR, Khan A, Torres S, Crawford B, Nock S, Frisbie T, Moran J, Longworth M. Condensin I and condensin II proteins form a LINE-1 dependent super condensin complex and cooperate to repress LINE-1. Nucleic Acids Res 2022; 50:10680-10694. [PMID: 36169232 PMCID: PMC9561375 DOI: 10.1093/nar/gkac802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/31/2022] [Accepted: 09/06/2022] [Indexed: 11/17/2022] Open
Abstract
Condensin I and condensin II are multi-subunit complexes that are known for their individual roles in genome organization and preventing genomic instability. However, interactions between condensin I and condensin II subunits and cooperative roles for condensin I and condensin II, outside of their genome organizing functions, have not been reported. We previously discovered that condensin II cooperates with Gamma Interferon Activated Inhibitor of Translation (GAIT) proteins to associate with Long INterspersed Element-1 (LINE-1 or L1) RNA and repress L1 protein expression and the retrotransposition of engineered L1 retrotransposition in cultured human cells. Here, we report that the L1 3'UTR is required for condensin II and GAIT association with L1 RNA, and deletion of the L1 RNA 3'UTR results in increased L1 protein expression and retrotransposition. Interestingly, like condensin II, we report that condensin I also binds GAIT proteins, associates with the L1 RNA 3'UTR, and represses L1 retrotransposition. We provide evidence that the condensin I protein, NCAPD2, is required for condensin II and GAIT protein association with L1 RNA. Furthermore, condensin I and condensin II subunits interact to form a L1-dependent super condensin complex (SCC) which is located primarily within the cytoplasm of both transformed and primary epithelial cells. These data suggest that increases in L1 expression in epithelial cells promote cytoplasmic condensin protein associations that facilitate a feedback loop in which condensins may cooperate to mediate L1 repression.
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Affiliation(s)
- Jacqueline R Ward
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Afshin Khan
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Sabrina Torres
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Bert Crawford
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Sarah Nock
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44195, USA
| | - Trenton Frisbie
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - John V Moran
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
- Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Michelle S Longworth
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44195, USA
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28
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Ectopic expression of meiotic cohesin generates chromosome instability in cancer cell line. Proc Natl Acad Sci U S A 2022; 119:e2204071119. [PMID: 36179046 PMCID: PMC9549395 DOI: 10.1073/pnas.2204071119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
This work originated from mining of cancer genome data and proceeded to analyze the effects of ectopic expression of meiotic cohesins in mitotic cells in culture. In the process, apart from conclusively answering the question on mechanisms for RAD21L toxicity and its underrepresentation in tumor transcriptomes, we found an association of meiotic cohesin binding with BORIS/CTCFL sites in the normal testis. We also elucidated the patterns and outcomes of meiotic cohesin binding to chromosomes in model cell lines. Furthermore, we uncovered that RAD21L-based meiotic cohesin possesses a self-contained chromosome restructuring activity able to trigger sustainable but imperfect mitotic arrest leading to chromosomal instability. The discovered epigenomic and genetic mechanisms can be relevant to chromosome instability in cancer. Many tumors express meiotic genes that could potentially drive somatic chromosome instability. While germline cohesin subunits SMC1B, STAG3, and REC8 are widely expressed in many cancers, messenger RNA and protein for RAD21L subunit are expressed at very low levels. To elucidate the potential of meiotic cohesins to contribute to genome instability, their expression was investigated in human cell lines, predominately in DLD-1. While the induction of the REC8 complex resulted in a mild mitotic phenotype, the expression of the RAD21L complex produced an arrested but viable cell pool, thus providing a source of DNA damage, mitotic chromosome missegregation, sporadic polyteny, and altered gene expression. We also found that genomic binding profiles of ectopically expressed meiotic cohesin complexes were reminiscent of their corresponding specific binding patterns in testis. Furthermore, meiotic cohesins were found to localize to the same sites as BORIS/CTCFL, rather than CTCF sites normally associated with the somatic cohesin complex. These findings highlight the existence of a germline epigenomic memory that is conserved in cells that normally do not express meiotic genes. Our results reveal a mechanism of action by unduly expressed meiotic cohesins that potentially links them to aneuploidy and chromosomal mutations in affected cells.
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29
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Yoshida MM, Kinoshita K, Aizawa Y, Tane S, Yamashita D, Shintomi K, Hirano T. Molecular dissection of condensin II-mediated chromosome assembly using in vitro assays. eLife 2022; 11:78984. [PMID: 35983835 PMCID: PMC9433093 DOI: 10.7554/elife.78984] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 08/11/2022] [Indexed: 11/18/2022] Open
Abstract
In vertebrates, condensin I and condensin II cooperate to assemble rod-shaped chromosomes during mitosis. Although the mechanism of action and regulation of condensin I have been studied extensively, our corresponding knowledge of condensin II remains very limited. By introducing recombinant condensin II complexes into Xenopus egg extracts, we dissect the roles of its individual subunits in chromosome assembly. We find that one of two HEAT subunits, CAP-D3, plays a crucial role in condensin II-mediated assembly of chromosome axes, whereas the other HEAT subunit, CAP-G2, has a very strong negative impact on this process. The structural maintenance of chromosomes ATPase and the basic amino acid clusters of the kleisin subunit CAP-H2 are essential for this process. Deletion of the C-terminal tail of CAP-D3 increases the ability of condensin II to assemble chromosomes and further exposes a hidden function of CAP-G2 in the lateral compaction of chromosomes. Taken together, our results uncover a multilayered regulatory mechanism unique to condensin II, and provide profound implications for the evolution of condensin II.
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Affiliation(s)
| | | | - Yuuki Aizawa
- Chromosome Dynamics Laboratory, RIKEN, Wako, Japan
| | - Shoji Tane
- Chromosome Dynamics Laboratory, RIKEN, Wako, Japan
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30
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Increased Gene Targeting in Hyper-Recombinogenic LymphoBlastoid Cell Lines Leaves Unchanged DSB Processing by Homologous Recombination. Int J Mol Sci 2022; 23:ijms23169180. [PMID: 36012445 PMCID: PMC9409177 DOI: 10.3390/ijms23169180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 11/16/2022] Open
Abstract
In the cells of higher eukaryotes, sophisticated mechanisms have evolved to repair DNA double-strand breaks (DSBs). Classical nonhomologous end joining (c-NHEJ), homologous recombination (HR), alternative end joining (alt-EJ) and single-strand annealing (SSA) exploit distinct principles to repair DSBs throughout the cell cycle, resulting in repair outcomes of different fidelity. In addition to their functions in DSB repair, the same repair pathways determine how cells integrate foreign DNA or rearrange their genetic information. As a consequence, random integration of DNA fragments is dominant in somatic cells of higher eukaryotes and suppresses integration events at homologous genomic locations, leading to very low gene-targeting efficiencies. However, this response is not universal, and embryonic stem cells display increased targeting efficiency. Additionally, lymphoblastic chicken and human cell lines DT40 and NALM6 show up to a 1000-fold increased gene-targeting efficiency that is successfully harnessed to generate knockouts for a large number of genes. We inquired whether the increased gene-targeting efficiency of DT40 and NALM6 cells is linked to increased rates of HR-mediated DSB repair after exposure to ionizing radiation (IR). We analyzed IR-induced γ-H2AX foci as a marker for the total number of DSBs induced in a cell and RAD51 foci as a marker for the fraction of those DSBs undergoing repair by HR. We also evaluated RPA accretion on chromatin as evidence for ongoing DNA end resection, an important initial step for all pathways of DSB repair except c-NHEJ. We finally employed the DR-GFP reporter assay to evaluate DSB repair by HR in DT40 cells. Collectively, the results obtained, unexpectedly show that DT40 and NALM6 cells utilized HR for DSB repair at levels very similar to those of other somatic cells. These observations uncouple gene-targeting efficiency from HR contribution to DSB repair and suggest the function of additional mechanisms increasing gene-targeting efficiency. Indeed, our results show that analysis of the contribution of HR to DSB repair may not be used as a proxy for gene-targeting efficiency.
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31
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A mitotic chromatin phase transition prevents perforation by microtubules. Nature 2022; 609:183-190. [PMID: 35922507 PMCID: PMC9433320 DOI: 10.1038/s41586-022-05027-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 06/27/2022] [Indexed: 12/20/2022]
Abstract
Dividing eukaryotic cells package extremely long chromosomal DNA molecules into discrete bodies to enable microtubule-mediated transport of one genome copy to each of the newly forming daughter cells1–3. Assembly of mitotic chromosomes involves DNA looping by condensin4–8 and chromatin compaction by global histone deacetylation9–13. Although condensin confers mechanical resistance to spindle pulling forces14–16, it is not known how histone deacetylation affects material properties and, as a consequence, segregation mechanics of mitotic chromosomes. Here we show how global histone deacetylation at the onset of mitosis induces a chromatin-intrinsic phase transition that endows chromosomes with the physical characteristics necessary for their precise movement during cell division. Deacetylation-mediated compaction of chromatin forms a structure dense in negative charge and allows mitotic chromosomes to resist perforation by microtubules as they are pushed to the metaphase plate. By contrast, hyperacetylated mitotic chromosomes lack a defined surface boundary, are frequently perforated by microtubules and are prone to missegregation. Our study highlights the different contributions of DNA loop formation and chromatin phase separation to genome segregation in dividing cells. Histone deacetylation at the onset of mitosis induces a chromatin-intrinsic phase transition that endows chromosomes with the physical characteristics necessary for their precise movement during cell division.
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32
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Flashner S, Swift M, Sowash A, Fahmy AN, Azizkhan-Clifford J. Transcription factor Sp1 regulates mitotic chromosome assembly and segregation. Chromosoma 2022; 131:175-191. [PMID: 35916925 PMCID: PMC9470683 DOI: 10.1007/s00412-022-00778-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 06/14/2022] [Accepted: 07/14/2022] [Indexed: 11/30/2022]
Abstract
Aneuploidy is a pervasive feature of cancer cells that results from chromosome missegregation. Several transcription factors have been associated with aneuploidy; however, no studies to date have demonstrated that mammalian transcription factors directly regulate chromosome segregation during mitosis. Here, we demonstrate that the ubiquitously expressed transcription factor specificity protein 1 (Sp1), which we have previously linked to aneuploidy, has a mitosis-specific role regulating chromosome segregation. We find that Sp1 localizes to mitotic centromeres and auxin-induced rapid Sp1 degradation at mitotic onset results in chromosome segregation errors and aberrant mitotic progression. Furthermore, rapid Sp1 degradation results in anomalous mitotic chromosome assembly characterized by loss of condensin complex I localization to mitotic chromosomes and chromosome condensation defects. Consistent with these defects, Sp1 degradation results in reduced chromosome passenger complex activity and histone H3 serine 10 phosphorylation during mitosis, which is essential for condensin complex I recruitment and chromosome condensation. Together, these data provide the first evidence of a mammalian transcription factor acting specifically during mitosis to regulate chromosome segregation.
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Affiliation(s)
- Samuel Flashner
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N 15th Street, MS 497, Philadelphia, PA, 19102, USA
| | - Michelle Swift
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N 15th Street, MS 497, Philadelphia, PA, 19102, USA
| | - Aislinn Sowash
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N 15th Street, MS 497, Philadelphia, PA, 19102, USA
| | - Alexander N Fahmy
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N 15th Street, MS 497, Philadelphia, PA, 19102, USA
| | - Jane Azizkhan-Clifford
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N 15th Street, MS 497, Philadelphia, PA, 19102, USA.
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33
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Macdonald L, Taylor GC, Brisbane JM, Christodoulou E, Scott L, von Kriegsheim A, Rossant J, Gu B, Wood AJ. Rapid and specific degradation of endogenous proteins in mouse models using auxin-inducible degrons. eLife 2022; 11:e77987. [PMID: 35736539 PMCID: PMC9273210 DOI: 10.7554/elife.77987] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 05/19/2022] [Indexed: 11/13/2022] Open
Abstract
Auxin-inducible degrons are a chemical genetic tool for targeted protein degradation and are widely used to study protein function in cultured mammalian cells. Here, we develop CRISPR-engineered mouse lines that enable rapid and highly specific degradation of tagged endogenous proteins in vivo. Most but not all cell types are competent for degradation. By combining ligand titrations with genetic crosses to generate animals with different allelic combinations, we show that degradation kinetics depend upon the dose of the tagged protein, ligand, and the E3 ligase substrate receptor TIR1. Rapid degradation of condensin I and II - two essential regulators of mitotic chromosome structure - revealed that both complexes are individually required for cell division in precursor lymphocytes, but not in their differentiated peripheral lymphocyte derivatives. This generalisable approach provides unprecedented temporal control over the dose of endogenous proteins in mouse models, with implications for studying essential biological pathways and modelling drug activity in mammalian tissues.
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Affiliation(s)
- Lewis Macdonald
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Gillian C Taylor
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Jennifer Margaret Brisbane
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Ersi Christodoulou
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Lucy Scott
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Alex von Kriegsheim
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
| | - Janet Rossant
- Program in Developmental and Stem Cell Biology, Hospital for Sick ChildrenTorontoCanada
| | - Bin Gu
- Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State UniversityEast LansingUnited States
- Department of Biomedical Engineering; Michigan State UniversityEast LansingUnited States
- Institute for Quantitative Health Science and Engineering, Michigan State UniversityEast LansingUnited States
| | - Andrew J Wood
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of EdinburghEdinburghUnited Kingdom
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34
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Barbiero M, Cirillo L, Veerapathiran S, Coates C, Ruffilli C, Pines J. Cell cycle-dependent binding between Cyclin B1 and Cdk1 revealed by time-resolved fluorescence correlation spectroscopy. Open Biol 2022; 12:220057. [PMID: 35765818 PMCID: PMC9240681 DOI: 10.1098/rsob.220057] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 06/07/2022] [Indexed: 01/04/2023] Open
Abstract
Measuring the dynamics with which the regulatory complexes assemble and disassemble is a crucial barrier to our understanding of how the cell cycle is controlled that until now has been difficult to address. This considerable gap in our understanding is due to the difficulty of reconciling biochemical assays with single cell-based techniques, but recent advances in microscopy and gene editing techniques now enable the measurement of the kinetics of protein-protein interaction in living cells. Here, we apply fluorescence correlation spectroscopy and fluorescence cross-correlation spectroscopy to study the dynamics of the cell cycle machinery, beginning with Cyclin B1 and its binding to its partner kinase Cdk1 that together form the major mitotic kinase. Although Cyclin B1 and Cdk1 are known to bind with high affinity, our results reveal that in living cells there is a pool of Cyclin B1 that is not bound to Cdk1. Furthermore, we provide evidence that the affinity of Cyclin B1 for Cdk1 increases during the cell cycle, indicating that the assembly of the complex is a regulated step. Our work lays the groundwork for studying the kinetics of protein complex assembly and disassembly during the cell cycle in living cells.
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Affiliation(s)
- Martina Barbiero
- Cancer Biology, The Institute of Cancer Research Chester Beatty Laboratories, 237 Fulham Road, London, London SW3 6JB, UK
| | - Luca Cirillo
- Cancer Biology, The Institute of Cancer Research Chester Beatty Laboratories, 237 Fulham Road, London, London SW3 6JB, UK
| | - Sapthaswaran Veerapathiran
- Cancer Biology, The Institute of Cancer Research Chester Beatty Laboratories, 237 Fulham Road, London, London SW3 6JB, UK
| | - Catherine Coates
- Cancer Biology, The Institute of Cancer Research Chester Beatty Laboratories, 237 Fulham Road, London, London SW3 6JB, UK
| | - Camilla Ruffilli
- Cancer Biology, The Institute of Cancer Research Chester Beatty Laboratories, 237 Fulham Road, London, London SW3 6JB, UK
| | - Jonathon Pines
- Cancer Biology, The Institute of Cancer Research Chester Beatty Laboratories, 237 Fulham Road, London, London SW3 6JB, UK
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35
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Abstract
The significance of this proposed mitotic chromosome architecture is that a specific, sequenced chromosome, human chromosome 10, can be built into a specific architecture that accounts for the dimensional values and cytological descriptions. Since this molecular architecture is an extension of the interphase chromosome structure, a coiling of the 11-nm nucleosome fiber with further coiling, a unifying molecular structure motif is present throughout the entire mitotic cycle, interphase through mitosis. A molecular architecture is proposed for a representative mitotic chromosome, human chromosome 10. This architecture is built on an interphase chromosome structure based on cryo-electron microscopy (cryo-EM) cellular tomography [J. Sedat et al., Proc. Natl. Acad. Sci. U.S.A., in press], thus unifying chromosome structure throughout the complete mitotic cycle. The basic organizational principle for mitotic chromosomes is specific coiling of the 11-nm nucleosome fiber into large scale, ∼200-nm interphase structures, a Slinky [https://en.wikipedia.org/wiki/Slinky; motif cited in S. Bowerman et al., eLife 10, e65587 (2021)], then further modified with subsequent additional coiling for the final mitotic chromosome structure. The final mitotic chromosome architecture accounts for the dimensional values as well as the well-known cytological configurations. In addition, proof is experimentally provided by digital PCR technology that G1 T cell nuclei are diploid with one DNA molecule per chromosome. Many nucleosome linker DNA sequences, the promotors and enhancers, are suggestive of optimal exposure on the surfaces of the large-scale coils.
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36
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Meijering AEC, Sarlós K, Nielsen CF, Witt H, Harju J, Kerklingh E, Haasnoot GH, Bizard AH, Heller I, Broedersz CP, Liu Y, Peterman EJG, Hickson ID, Wuite GJL. Nonlinear mechanics of human mitotic chromosomes. Nature 2022; 605:545-550. [PMID: 35508652 PMCID: PMC9117150 DOI: 10.1038/s41586-022-04666-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 03/21/2022] [Indexed: 12/26/2022]
Abstract
In preparation for mitotic cell division, the nuclear DNA of human cells is compacted into individualized, X-shaped chromosomes1. This metamorphosis is driven mainly by the combined action of condensins and topoisomerase IIα (TOP2A)2,3, and has been observed using microscopy for over a century. Nevertheless, very little is known about the structural organization of a mitotic chromosome. Here we introduce a workflow to interrogate the organization of human chromosomes based on optical trapping and manipulation. This allows high-resolution force measurements and fluorescence visualization of native metaphase chromosomes to be conducted under tightly controlled experimental conditions. We have used this method to extensively characterize chromosome mechanics and structure. Notably, we find that under increasing mechanical load, chromosomes exhibit nonlinear stiffening behaviour, distinct from that predicted by classical polymer models4. To explain this anomalous stiffening, we introduce a hierarchical worm-like chain model that describes the chromosome as a heterogeneous assembly of nonlinear worm-like chains. Moreover, through inducible degradation of TOP2A5 specifically in mitosis, we provide evidence that TOP2A has a role in the preservation of chromosome compaction. The methods described here open the door to a wide array of investigations into the structure and dynamics of both normal and disease-associated chromosomes.
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Affiliation(s)
- Anna E C Meijering
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Kata Sarlós
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Christian F Nielsen
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Hannes Witt
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Janni Harju
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Emma Kerklingh
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Guus H Haasnoot
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Anna H Bizard
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Iddo Heller
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Chase P Broedersz
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
| | - Ying Liu
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Erwin J G Peterman
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Ian D Hickson
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.
| | - Gijs J L Wuite
- Department of Physics and Astronomy and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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37
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Brahmachari S, Contessoto VG, Di Pierro M, Onuchic JN. Shaping the genome via lengthwise compaction, phase separation, and lamina adhesion. Nucleic Acids Res 2022; 50:4258-4271. [PMID: 35420130 PMCID: PMC9071446 DOI: 10.1093/nar/gkac231] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/02/2022] [Accepted: 04/11/2022] [Indexed: 01/13/2023] Open
Abstract
The link between genomic structure and biological function is yet to be consolidated, it is, however, clear that physical manipulation of the genome, driven by the activity of a variety of proteins, is a crucial step. To understand the consequences of the physical forces underlying genome organization, we build a coarse-grained polymer model of the genome, featuring three fundamentally distinct classes of interactions: lengthwise compaction, i.e., compaction of chromosomes along its contour, self-adhesion among epigenetically similar genomic segments, and adhesion of chromosome segments to the nuclear envelope or lamina. We postulate that these three types of interactions sufficiently represent the concerted action of the different proteins organizing the genome architecture and show that an interplay among these interactions can recapitulate the architectural variants observed across the tree of life. The model elucidates how an interplay of forces arising from the three classes of genomic interactions can drive drastic, yet predictable, changes in the global genome architecture, and makes testable predictions. We posit that precise control over these interactions in vivo is key to the regulation of genome architecture.
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Affiliation(s)
| | | | - Michele Di Pierro
- Department of Physics, and Center for Theoretical Biological Physics, Northeastern University, Boston, MA 02115, USA
| | - José N Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA.,Department of Physics and Astronomy, Department of Chemistry, Department of BioSciences, Rice University, Houston TX 77005, USA
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38
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Haase J, Chen R, Parker WM, Bonner MK, Jenkins LM, Kelly AE. The TFIIH complex is required to establish and maintain mitotic chromosome structure. eLife 2022; 11:75475. [PMID: 35293859 PMCID: PMC8956287 DOI: 10.7554/elife.75475] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/15/2022] [Indexed: 11/13/2022] Open
Abstract
Condensins compact chromosomes to promote their equal segregation during mitosis, but the mechanism of condensin engagement with and action on chromatin is incompletely understood. Here, we show that the general transcription factor TFIIH complex is continuously required to establish and maintain a compacted chromosome structure in transcriptionally silent Xenopus egg extracts. Inhibiting the DNA-dependent ATPase activity of the TFIIH complex subunit XPB rapidly and reversibly induces a complete loss of chromosome structure and prevents the enrichment of condensins I and II, but not topoisomerase II, on chromatin. In addition, inhibiting TFIIH prevents condensation of both mouse and Xenopus nuclei in Xenopus egg extracts, which suggests an evolutionarily conserved mechanism of TFIIH action. Reducing nucleosome density through partial histone depletion restores chromosome structure and condensin enrichment in the absence of TFIIH activity. We propose that the TFIIH complex promotes mitotic chromosome condensation by dynamically altering the chromatin environment to facilitate condensin loading and condensin-dependent loop extrusion.
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Affiliation(s)
- Julian Haase
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| | - Richard Chen
- Graduate School of Biomedical Sciences, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Wesley M Parker
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| | - Mary Kate Bonner
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| | - Lisa M Jenkins
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
| | - Alexander E Kelly
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States
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39
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Higashi TL, Uhlmann F. SMC complexes: Lifting the lid on loop extrusion. Curr Opin Cell Biol 2022; 74:13-22. [PMID: 35016058 PMCID: PMC9089308 DOI: 10.1016/j.ceb.2021.12.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 01/02/2023]
Abstract
Loop extrusion has emerged as a prominent hypothesis for how SMC complexes shape chromosomes - single molecule in vitro observations have yielded fascinating images of this process. When not extruding loops, SMC complexes are known to topologically entrap one or more DNAs. Here, we review how structural insight into the SMC complex cohesin has led to a molecular framework for both activities: a Brownian ratchet motion, associated with topological DNA entry, might repeat itself to elicit loop extrusion. After contrasting alternative loop extrusion models, we explore whether topological loading or loop extrusion is more adept at explaining in vivo SMC complex function. SMC variants that experimentally separate topological loading from loop extrusion will in the future probe their respective contributions to chromosome biology.
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Affiliation(s)
- Torahiko L Higashi
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, NW1 1AT, UK; Department of Cellular Biochemistry, Kyushu University, Fukuoka, 812-8582, Japan
| | - Frank Uhlmann
- Chromosome Segregation Laboratory, The Francis Crick Institute, London, NW1 1AT, UK.
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40
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Breimann L, Morao AK, Kim J, Jimenez DS, Maryn N, Bikkasani K, Carrozza MJ, Albritton SE, Kramer M, Street LA, Cerimi K, Schumann VF, Bahry E, Preibisch S, Woehler A, Ercan S. The H4K20 demethylase DPY-21 regulates the dynamics of condensin DC binding. J Cell Sci 2021; 135:273768. [PMID: 34918745 PMCID: PMC8917352 DOI: 10.1242/jcs.258818] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 11/29/2021] [Indexed: 11/26/2022] Open
Abstract
Condensin is a multi-subunit structural maintenance of chromosomes (SMC) complex that binds to and compacts chromosomes. Here, we addressed the regulation of condensin binding dynamics using Caenorhabditis elegans condensin DC, which represses X chromosomes in hermaphrodites for dosage compensation. We established fluorescence recovery after photobleaching (FRAP) using the SMC4 homolog DPY-27 and showed that a well-characterized ATPase mutation abolishes DPY-27 binding to X chromosomes. Next, we performed FRAP in the background of several chromatin modifier mutants that cause varying degrees of X chromosome derepression. The greatest effect was in a null mutant of the H4K20me2 demethylase DPY-21, where the mobile fraction of condensin DC reduced from ∼30% to 10%. In contrast, a catalytic mutant of dpy-21 did not regulate condensin DC mobility. Hi-C sequencing data from the dpy-21 null mutant showed little change compared to wild-type data, uncoupling Hi-C-measured long-range DNA contacts from transcriptional repression of the X chromosomes. Taken together, our results indicate that DPY-21 has a non-catalytic role in regulating the dynamics of condensin DC binding, which is important for transcription repression. Summary: The histone demethylase DPY-21 has catalytic and non-catalytic roles in condensin DC-mediated X chromosome repression. The non-catalytic activity regulates dynamics of condensin DC binding to X chromosomes.
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Affiliation(s)
- Laura Breimann
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA.,Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Institute for Biology, Humboldt University of Berlin, Berlin, Germany
| | - Ana Karina Morao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Jun Kim
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - David Sebastian Jimenez
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Nina Maryn
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Krishna Bikkasani
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Michael J Carrozza
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Sarah E Albritton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Maxwell Kramer
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Lena Annika Street
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Kustrim Cerimi
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Vic-Fabienne Schumann
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ella Bahry
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Stephan Preibisch
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Andrew Woehler
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
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41
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Houlard M, Cutts EE, Shamim MS, Godwin J, Weisz D, Presser Aiden A, Lieberman Aiden E, Schermelleh L, Vannini A, Nasmyth K. MCPH1 inhibits Condensin II during interphase by regulating its SMC2-Kleisin interface. eLife 2021; 10:e73348. [PMID: 34850681 PMCID: PMC8673838 DOI: 10.7554/elife.73348] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 11/08/2021] [Indexed: 12/20/2022] Open
Abstract
Dramatic change in chromosomal DNA morphology between interphase and mitosis is a defining features of the eukaryotic cell cycle. Two types of enzymes, namely cohesin and condensin confer the topology of chromosomal DNA by extruding DNA loops. While condensin normally configures chromosomes exclusively during mitosis, cohesin does so during interphase. The processivity of cohesin's loop extrusion during interphase is limited by a regulatory factor called WAPL, which induces cohesin to dissociate from chromosomes via a mechanism that requires dissociation of its kleisin from the neck of SMC3. We show here that a related mechanism may be responsible for blocking condensin II from acting during interphase. Cells derived from patients affected by microcephaly caused by mutations in the MCPH1 gene undergo premature chromosome condensation. We show that deletion of Mcph1 in mouse embryonic stem cells unleashes an activity of condensin II that triggers formation of compact chromosomes in G1 and G2 phases, accompanied by enhanced mixing of A and B chromatin compartments, and this occurs even in the absence of CDK1 activity. Crucially, inhibition of condensin II by MCPH1 depends on the binding of a short linear motif within MCPH1 to condensin II's NCAPG2 subunit. MCPH1's ability to block condensin II's association with chromatin is abrogated by the fusion of SMC2 with NCAPH2, hence may work by a mechanism similar to cohesin. Remarkably, in the absence of both WAPL and MCPH1, cohesin and condensin II transform chromosomal DNAs of G2 cells into chromosomes with a solenoidal axis.
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Affiliation(s)
- Martin Houlard
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Erin E Cutts
- Division of Structural Biology, The Institute of Cancer ResearchLondonUnited Kingdom
| | - Muhammad S Shamim
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- Medical Scientist Training Program, Baylor College of Medicine, Department of Bioengineering, Rice UniversityHoustonUnited States
- Center for Theoretical Biological Physics, Rice UniversityHoustonUnited States
| | - Jonathan Godwin
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - David Weisz
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- Center for Theoretical Biological Physics, Rice UniversityHoustonUnited States
| | - Aviva Presser Aiden
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- Center for Theoretical Biological Physics, Rice UniversityHoustonUnited States
| | - Erez Lieberman Aiden
- The Center for Genome Architecture, Department of Molecular and Human Genetics, Baylor College of MedicineHoustonUnited States
- Center for Theoretical Biological Physics, Rice UniversityHoustonUnited States
| | | | - Alessandro Vannini
- Division of Structural Biology, The Institute of Cancer ResearchLondonUnited Kingdom
- Human TechnopoleMilanItaly
| | - Kim Nasmyth
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
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42
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Liu H, Zhang C, Xu J, Jin J, Cheng L, Miao X, Wu Q, Wei Z, Liu P, Lu H, van Zijl PCM, Ross CA, Hua J, Duan W. Huntingtin silencing delays onset and slows progression of Huntington's disease: a biomarker study. Brain 2021; 144:3101-3113. [PMID: 34043007 PMCID: PMC8634120 DOI: 10.1093/brain/awab190] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 04/19/2021] [Accepted: 04/29/2021] [Indexed: 01/29/2023] Open
Abstract
Huntington's disease is a dominantly inherited, fatal neurodegenerative disorder caused by a CAG expansion in the huntingtin (HTT) gene, coding for pathological mutant HTT protein (mHTT). Because of its gain-of-function mechanism and monogenic aetiology, strategies to lower HTT are being actively investigated as disease-modifying therapies. Most approaches are currently targeted at the manifest stage, where clinical outcomes are used to evaluate the effectiveness of therapy. However, as almost 50% of striatal volume has been lost at the time of onset of clinical manifest, it would be preferable to begin therapy in the premanifest period. An unmet challenge is how to evaluate therapeutic efficacy before the presence of clinical symptoms as outcome measures. To address this, we aim to develop non-invasive sensitive biomarkers that provide insight into therapeutic efficacy in the premanifest stage of Huntington's disease. In this study, we mapped the temporal trajectories of arteriolar cerebral blood volumes (CBVa) using inflow-based vascular-space-occupancy (iVASO) MRI in the heterozygous zQ175 mice, a full-length mHTT expressing and slowly progressing model with a premanifest period as in human Huntington's disease. Significantly elevated CBVa was evident in premanifest zQ175 mice prior to motor deficits and striatal atrophy, recapitulating altered CBVa in human premanifest Huntington's disease. CRISPR/Cas9-mediated non-allele-specific HTT silencing in striatal neurons restored altered CBVa in premanifest zQ175 mice, delayed onset of striatal atrophy, and slowed the progression of motor phenotype and brain pathology. This study-for the first time-shows that a non-invasive functional MRI measure detects therapeutic efficacy in the premanifest stage and demonstrates long-term benefits of a non-allele-selective HTT silencing treatment introduced in the premanifest Huntington's disease.
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Affiliation(s)
- Hongshuai Liu
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Chuangchuang Zhang
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jiadi Xu
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jing Jin
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Liam Cheng
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xinyuan Miao
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Qian Wu
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Zhiliang Wei
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Peiying Liu
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hanzhang Lu
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Peter C M van Zijl
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Christopher A Ross
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jun Hua
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
- The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Wenzhen Duan
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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43
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Roca J, Dyson S, Segura J, Valdés A, Martínez-García B. Keeping intracellular DNA untangled: A new role for condensin? Bioessays 2021; 44:e2100187. [PMID: 34761394 DOI: 10.1002/bies.202100187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/25/2022]
Abstract
The DNA-passage activity of topoisomerase II accidentally produces DNA knots and interlinks within and between chromatin fibers. Fortunately, these unwanted DNA entanglements are actively removed by some mechanism. Here we present an outline on DNA knot formation and discuss recent studies that have investigated how intracellular DNA knots are removed. First, although topoisomerase II is able to minimize DNA entanglements in vitro to below equilibrium values, it is unclear whether such capacity performs equally in vivo in chromatinized DNA. Second, DNA supercoiling could bias topoisomerase II to untangle the DNA. However, experimental evidence indicates that transcriptional supercoiling of intracellular DNA boosts knot formation. Last, cohesin and condensin could tighten DNA entanglements via DNA loop extrusion (LE) and force their dissolution by topoisomerase II. Recent observations indicate that condensin activity promotes the removal of DNA knots during interphase and mitosis. This activity might facilitate the spatial organization and dynamics of chromatin.
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Affiliation(s)
- Joaquim Roca
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona, Spain
| | - Silvia Dyson
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona, Spain
| | - Joana Segura
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona, Spain
| | - Antonio Valdés
- Julius Maximilian University of Würzburg, Würzburg, Germany
| | - Belén Martínez-García
- Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona, Spain
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44
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Schneider I, de Ruijter-Villani M, Hossain MJ, Stout TA, Ellenberg J. Dual spindles assemble in bovine zygotes despite the presence of paternal centrosomes. J Cell Biol 2021; 220:e202010106. [PMID: 34550316 PMCID: PMC8563290 DOI: 10.1083/jcb.202010106] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 07/05/2021] [Accepted: 09/02/2021] [Indexed: 11/30/2022] Open
Abstract
The first mitosis of the mammalian embryo must partition the parental genomes contained in two pronuclei. In rodent zygotes, sperm centrosomes are degraded, and instead, acentriolar microtubule organizing centers and microtubule self-organization guide the assembly of two separate spindles around the genomes. In nonrodent mammals, including human or bovine, centrosomes are inherited from the sperm and have been widely assumed to be active. Whether nonrodent zygotes assemble a single centrosomal spindle around both genomes or follow the dual spindle self-assembly pathway is unclear. To address this, we investigated spindle assembly in bovine zygotes by systematic immunofluorescence and real-time light-sheet microscopy. We show that two independent spindles form despite the presence of centrosomes, which had little effect on spindle structure and were only loosely connected to the two spindles. We conclude that the dual spindle assembly pathway is conserved in nonrodent mammals. This could explain whole parental genome loss frequently observed in blastomeres of human IVF embryos.
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Affiliation(s)
- Isabell Schneider
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Marta de Ruijter-Villani
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
- Division of Woman and Baby, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - M. Julius Hossain
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Tom A.E. Stout
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Jan Ellenberg
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
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45
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Takaki R, Dey A, Shi G, Thirumalai D. Theory and simulations of condensin mediated loop extrusion in DNA. Nat Commun 2021; 12:5865. [PMID: 34620869 PMCID: PMC8497514 DOI: 10.1038/s41467-021-26167-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 09/15/2021] [Indexed: 11/08/2022] Open
Abstract
Condensation of hundreds of mega-base-pair-long human chromosomes in a small nuclear volume is a spectacular biological phenomenon. This process is driven by the formation of chromosome loops. The ATP consuming motor, condensin, interacts with chromatin segments to actively extrude loops. Motivated by real-time imaging of loop extrusion (LE), we created an analytically solvable model, predicting the LE velocity and step size distribution as a function of external load. The theory fits the available experimental data quantitatively, and suggests that condensin must undergo a large conformational change, induced by ATP binding, bringing distant parts of the motor to proximity. Simulations using a simple model confirm that the motor transitions between an open and a closed state in order to extrude loops by a scrunching mechanism, similar to that proposed in DNA bubble formation during bacterial transcription. Changes in the orientation of the motor domains are transmitted over ~50 nm, connecting the motor head and the hinge, thus providing an allosteric basis for LE.
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Affiliation(s)
- Ryota Takaki
- Department of Physics, The University of Texas at Austin, Austin, 78712, USA
| | - Atreya Dey
- Department of Chemistry, The University of Texas at Austin, Austin, 78712, USA
| | - Guang Shi
- Department of Chemistry, The University of Texas at Austin, Austin, 78712, USA
| | - D Thirumalai
- Department of Chemistry, The University of Texas at Austin, Austin, 78712, USA.
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46
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Abstract
Condensation and faithful separation of the genome are crucial for the cellular life cycle. During chromosome segregation, mechanical forces generated by the mitotic spindle pull apart the sister chromatids. The mechanical nature of this process has motivated a lot of research interest into the mechanical properties of mitotic chromosomes. Although their fundamental mechanical characteristics are known, it still remains unclear how these characteristics emerge from the structure of the mitotic chromosome. Recent advances in genomics, computational and super-resolution microscopy techniques have greatly promoted our understanding of the chromosomal structure and have motivated us to review the mechanical characteristics of chromosomes in light of the current structural insights. In this review, we will first introduce the current understanding of the chromosomal structure, before reviewing characteristic mechanical properties such as the Young's modulus and the bending modulus of mitotic chromosomes. Then we will address the approaches used to relate mechanical properties to the structure of chromosomes and we will also discuss how mechanical characterization can aid in elucidating their structure. Finally, future challenges, recent developments and emergent questions in this research field will be discussed.
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47
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Choppakatla P, Dekker B, Cutts EE, Vannini A, Dekker J, Funabiki H. Linker histone H1.8 inhibits chromatin binding of condensins and DNA topoisomerase II to tune chromosome length and individualization. eLife 2021; 10:e68918. [PMID: 34406118 PMCID: PMC8416026 DOI: 10.7554/elife.68918] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 08/13/2021] [Indexed: 12/14/2022] Open
Abstract
DNA loop extrusion by condensins and decatenation by DNA topoisomerase II (topo II) are thought to drive mitotic chromosome compaction and individualization. Here, we reveal that the linker histone H1.8 antagonizes condensins and topo II to shape mitotic chromosome organization. In vitro chromatin reconstitution experiments demonstrate that H1.8 inhibits binding of condensins and topo II to nucleosome arrays. Accordingly, H1.8 depletion in Xenopus egg extracts increased condensins and topo II levels on mitotic chromatin. Chromosome morphology and Hi-C analyses suggest that H1.8 depletion makes chromosomes thinner and longer through shortening the average loop size and reducing the DNA amount in each layer of mitotic loops. Furthermore, excess loading of condensins and topo II to chromosomes by H1.8 depletion causes hyper-chromosome individualization and dispersion. We propose that condensins and topo II are essential for chromosome individualization, but their functions are tuned by the linker histone to keep chromosomes together until anaphase.
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Affiliation(s)
- Pavan Choppakatla
- Laboratory of Chromosome and Cell Biology, The Rockefeller UniversityNew YorkUnited States
| | - Bastiaan Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical SchoolWorcesterUnited States
| | - Erin E Cutts
- Division of Structural Biology, The Institute of Cancer ResearchLondonUnited Kingdom
| | - Alessandro Vannini
- Division of Structural Biology, The Institute of Cancer ResearchLondonUnited Kingdom
- Fondazione Human Technopole, Structural Biology Research Centre, 20157MilanItaly
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical SchoolWorcesterUnited States
- Howard Hughes Medical InstituteChevy ChaseUnited States
| | - Hironori Funabiki
- Laboratory of Chromosome and Cell Biology, The Rockefeller UniversityNew YorkUnited States
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48
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Davidson IF, Peters JM. Genome folding through loop extrusion by SMC complexes. Nat Rev Mol Cell Biol 2021; 22:445-464. [PMID: 33767413 DOI: 10.1038/s41580-021-00349-7] [Citation(s) in RCA: 206] [Impact Index Per Article: 68.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2021] [Indexed: 02/02/2023]
Abstract
Genomic DNA is folded into loops and topologically associating domains (TADs), which serve important structural and regulatory roles. It has been proposed that these genomic structures are formed by a loop extrusion process, which is mediated by structural maintenance of chromosomes (SMC) protein complexes. Recent single-molecule studies have shown that the SMC complexes condensin and cohesin are indeed able to extrude DNA into loops. In this Review, we discuss how the loop extrusion hypothesis can explain key features of genome architecture; cellular functions of loop extrusion, such as separation of replicated DNA molecules, facilitation of enhancer-promoter interactions and immunoglobulin gene recombination; and what is known about the mechanism of loop extrusion and its regulation, for example, by chromatin boundaries that depend on the DNA binding protein CTCF. We also discuss how the loop extrusion hypothesis has led to a paradigm shift in our understanding of both genome architecture and the functions of SMC complexes.
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Affiliation(s)
- Iain F Davidson
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Jan-Michael Peters
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria.
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49
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Municio C, Antosz W, Grasser KD, Kornobis E, Van Bel M, Eguinoa I, Coppens F, Bräutigam A, Lermontova I, Bruckmann A, Zelkowska K, Houben A, Schubert V. The Arabidopsis condensin CAP-D subunits arrange interphase chromatin. THE NEW PHYTOLOGIST 2021; 230:972-987. [PMID: 33475158 DOI: 10.1111/nph.17221] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 01/11/2021] [Indexed: 06/12/2023]
Abstract
Condensins are best known for their role in shaping chromosomes. Other functions such as organizing interphase chromatin and transcriptional control have been reported in yeasts and animals, but little is known about their function in plants. To elucidate the specific composition of condensin complexes and the expression of CAP-D2 (condensin I) and CAP-D3 (condensin II), we performed biochemical analyses in Arabidopsis. The role of CAP-D3 in interphase chromatin organization and function was evaluated using cytogenetic and transcriptome analysis in cap-d3 T-DNA insertion mutants. CAP-D2 and CAP-D3 are highly expressed in mitotically active tissues. In silico and pull-down experiments indicate that both CAP-D proteins interact with the other condensin I and II subunits. In cap-d3 mutants, an association of heterochromatic sequences occurs, but the nuclear size and the general histone and DNA methylation patterns remain unchanged. Also, CAP-D3 influences the expression of genes affecting the response to water, chemicals, and stress. The expression and composition of the condensin complexes in Arabidopsis are similar to those in other higher eukaryotes. We propose a model for the CAP-D3 function during interphase in which CAP-D3 localizes in euchromatin loops to stiffen them and consequently separates centromeric regions and 45S rDNA repeats.
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Affiliation(s)
- Celia Municio
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, D-06466, Seeland, Germany
| | - Wojciech Antosz
- Cell Biology and Plant Biochemistry, Biochemistry Center, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Klaus D Grasser
- Cell Biology and Plant Biochemistry, Biochemistry Center, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Etienne Kornobis
- Plate-forme Technologique Biomics - Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, 75015, Paris, France
- Hub de Bioinformatique et Biostatistique -Département Biologie Computationnelle, Institut Pasteur, 75015, Paris, France
| | - Michiel Van Bel
- VIB-UGent Center for Plant Systems Biology, Technologiepark 71, 9052, Gent, Belgium
| | - Ignacio Eguinoa
- VIB-UGent Center for Plant Systems Biology, Technologiepark 71, 9052, Gent, Belgium
| | - Frederik Coppens
- VIB-UGent Center for Plant Systems Biology, Technologiepark 71, 9052, Gent, Belgium
| | - Andrea Bräutigam
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, D-06466, Seeland, Germany
| | - Inna Lermontova
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, D-06466, Seeland, Germany
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
| | - Astrid Bruckmann
- Department for Biochemistry I, Biochemistry Center, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Katarzyna Zelkowska
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, D-06466, Seeland, Germany
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, D-06466, Seeland, Germany
| | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstraße 3, D-06466, Seeland, Germany
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Paulson JR, Hudson DF, Cisneros-Soberanis F, Earnshaw WC. Mitotic chromosomes. Semin Cell Dev Biol 2021; 117:7-29. [PMID: 33836947 PMCID: PMC8406421 DOI: 10.1016/j.semcdb.2021.03.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 03/23/2021] [Accepted: 03/23/2021] [Indexed: 01/25/2023]
Abstract
Our understanding of the structure and function of mitotic chromosomes has come a long way since these iconic objects were first recognized more than 140 years ago, though many details remain to be elucidated. In this chapter, we start with the early history of chromosome studies and then describe the path that led to our current understanding of the formation and structure of mitotic chromosomes. We also discuss some of the remaining questions. It is now well established that each mitotic chromatid consists of a central organizing region containing a so-called "chromosome scaffold" from which loops of DNA project radially. Only a few key non-histone proteins and protein complexes are required to form the chromosome: topoisomerase IIα, cohesin, condensin I and condensin II, and the chromokinesin KIF4A. These proteins are concentrated along the axis of the chromatid. Condensins I and II are primarily responsible for shaping the chromosome and the scaffold, and they produce the loops of DNA by an ATP-dependent process known as loop extrusion. Modelling of Hi-C data suggests that condensin II adopts a spiral staircase arrangement with an extruded loop extending out from each step in a roughly helical pattern. Condensin I then forms loops nested within these larger condensin II loops, thereby giving rise to the final compaction of the mitotic chromosome in a process that requires Topo IIα.
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Affiliation(s)
- James R Paulson
- Department of Chemistry, University of Wisconsin Oshkosh, 800 Algoma Boulevard, Oshkosh, WI 54901, USA.
| | - Damien F Hudson
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC 3052, Australia
| | - Fernanda Cisneros-Soberanis
- Wellcome Trust Centre for Cell Biology, ICB, University of Edinburgh, Michael Swann Building, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, ICB, University of Edinburgh, Michael Swann Building, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK.
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