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Booth DG, Kozar N, Bradley S, Meijer D. Characterizing the molecular etiology of arthrogryposis multiplex congenita in patients with LGI4 mutations. Glia 2021; 69:2605-2617. [PMID: 34288120 DOI: 10.1002/glia.24061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/07/2021] [Accepted: 07/09/2021] [Indexed: 11/05/2022]
Abstract
Disruption of axon-glia interactions in the peripheral nervous system has emerged as a major cause of arthrogryposis multiplex congenita (AMC), a condition characterized by multiple congenital postural abnormalities involving the major joints. Several genes crucially important to the biology of Schwann cells have now been implicated with AMC. One such gene is LGI4 which encodes a secreted glycoprotein. LGI4 is expressed and secreted by Schwann cells and binds its receptor ADAM22 on the axonal membrane to drive myelination. Homozygous mutations in LGI4 or ADAM22 results in severe congenital hypomyelination and joint contractures in mice. Recently bi-allelic LGI4 loss of function mutations has been described in three unrelated families with severe AMC. Two individuals in a fourth, non-consanguineous family were found to be compound heterozygous for two LGI4 missense mutations. It is not known how these missense mutations affect the biology of LGI4. Here we investigated whether these missense mutations affected the secretion of the protein, its ADAM22 binding capacity, or its myelination-promoting function. We demonstrate that the mutations largely affect the progression of the mutant protein through the endomembrane system resulting in severely reduced expression. Importantly, binding to ADAM22 and myelination-promoting activity appear largely unaffected, suggesting that treatment with chemical chaperones to improve secretion of the mutant proteins might prove beneficial.
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Affiliation(s)
- Daniel G Booth
- Centre for Discovery Brain Sciences and MS Society Edinburgh Centre for MS Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Nina Kozar
- Centre for Discovery Brain Sciences and MS Society Edinburgh Centre for MS Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Stephen Bradley
- Centre for Discovery Brain Sciences and MS Society Edinburgh Centre for MS Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Dies Meijer
- Centre for Discovery Brain Sciences and MS Society Edinburgh Centre for MS Research, University of Edinburgh, Edinburgh, United Kingdom
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2
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Malavasi EL, Ghosh A, Booth DG, Zagnoni M, Sherman DL, Brophy PJ. Dynamic early clusters of nodal proteins contribute to node of Ranvier assembly during myelination of peripheral neurons. eLife 2021; 10:68089. [PMID: 34240706 PMCID: PMC8289411 DOI: 10.7554/elife.68089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 07/07/2021] [Indexed: 12/31/2022] Open
Abstract
Voltage-gated sodium channels cluster in macromolecular complexes at nodes of Ranvier to promote rapid nerve impulse conduction in vertebrate nerves. Node assembly in peripheral nerves is thought to be initiated at heminodes at the extremities of myelinating Schwann cells, and fusion of heminodes results in the establishment of nodes. Here we show that assembly of 'early clusters' of nodal proteins in the murine axonal membrane precedes heminode formation. The neurofascin (Nfasc) proteins are essential for node assembly, and the formation of early clusters also requires neuronal Nfasc. Early clusters are mobile and their proteins are dynamically recruited by lateral diffusion. They can undergo fusion not only with each other but also with heminodes, thus contributing to the development of nodes in peripheral axons. The formation of early clusters constitutes the earliest stage in peripheral node assembly and expands the repertoire of strategies that have evolved to establish these essential structures.
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Affiliation(s)
- Elise Lv Malavasi
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Aniket Ghosh
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Daniel G Booth
- Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Michele Zagnoni
- Centre for Microsystems & Photonics, Dept. Electronic and Electrical Engineering, University of Strathclyde, Strathclyde, United Kingdom
| | - Diane L Sherman
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter J Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
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3
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Booth DG, Beckett AJ, Prior IA, Meijer D. SuperCLEM: an accessible correlative light and electron microscopy approach for investigation of neurons and glia in vitro. Biol Open 2019; 8:bio.042085. [PMID: 31110056 PMCID: PMC6550067 DOI: 10.1242/bio.042085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The rapid evolution of super-resolution light microscopy has narrowed the gap between light and electron microscopy, allowing the imaging of molecules and cellular structures at high resolution within their normal cellular and tissue context. Multimodal imaging approaches such as correlative light electron microscopy (CLEM) combine these techniques to create a tool with unique imaging capacity. However, these approaches are typically reserved for specialists, and their application to the analysis of neural tissue is challenging. Here we present SuperCLEM, a relatively simple approach that combines super-resolution fluorescence light microscopy (FLM), 3D electron microscopy (3D-EM) and rendering into 3D models. We demonstrate our workflow using neuron-glia cultures from which we first acquire high-resolution fluorescent light images of myelinated axons. After resin embedding and re-identification of the region of interest, serially aligned EM sections are acquired and imaged using a serial block face scanning electron microscope (SBF-SEM). The FLM and 3D-EM datasets are then combined to render 3D models of the myelinated axons. Thus, the SuperCLEM imaging pipeline is a useful new tool for researchers pursuing similar questions in neuronal and other complex tissue culture systems. Summary: We developed an advanced, accessible and adaptable correlative light and electron microscopy pipeline for study of neuron-glia cultures and demonstrate its power by deriving accurate 3D models of myelinated axons.
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Affiliation(s)
- Daniel G Booth
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Alison J Beckett
- Biomedical Electron Microscopy Unit, Department of Molecular and Cellular Biology, University of Liverpool, Crown Street, Liverpool L69 3BX, UK
| | - Ian A Prior
- Biomedical Electron Microscopy Unit, Department of Molecular and Cellular Biology, University of Liverpool, Crown Street, Liverpool L69 3BX, UK
| | - Dies Meijer
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
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Remnant L, Booth DG, Vargiu G, Spanos C, Kerr ARW, Earnshaw WC. In vitro BioID: mapping the CENP-A microenvironment with high temporal and spatial resolution. Mol Biol Cell 2019; 30:1314-1325. [PMID: 30892990 PMCID: PMC6724601 DOI: 10.1091/mbc.e18-12-0799] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The centromere is located at the primary constriction of condensed chromosomes where it acts as a platform regulating chromosome segregation. The histone H3 variant CENP-A is the foundation for kinetochore formation. CENP-A directs the formation of a highly dynamic molecular neighborhood whose temporal characterization during mitosis remains a challenge due to limitations in available techniques. BioID is a method that exploits a “promiscuous” biotin ligase (BirA118R or BirA*) to identify proteins within close proximity to a fusion protein of interest. As originally described, cells expressing BirA* fusions were exposed to high biotin concentrations for 24 h during which the ligase transferred activated biotin (BioAmp) to other proteins within the immediate vicinity. The protein neighborhood could then be characterized by streptavidin-based purification and mass spectrometry. Here we describe a further development to this technique, allowing CENP-A interactors to be characterized within only a few minutes, in an in vitro reaction in lysed cells whose physiological progression is “frozen.” This approach, termed in vitro BioID (ivBioID), has the potential to study the molecular neighborhood of any structural protein whose interactions change either during the cell cycle or in response to other changes in cell physiology.
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Affiliation(s)
- Lucy Remnant
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology and
| | - Daniel G Booth
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology and.,Centre for Brain Discovery Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Giulia Vargiu
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology and
| | - Christos Spanos
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology and
| | - Alastair R W Kerr
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology and
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Samejima K, Booth DG, Ogawa H, Paulson JR, Xie L, Watson CA, Platani M, Kanemaki MT, Earnshaw WC. Functional analysis after rapid degradation of condensins and 3D-EM reveals chromatin volume is uncoupled from chromosome architecture in mitosis. J Cell Sci 2018; 131:jcs.210187. [PMID: 29361541 PMCID: PMC5868952 DOI: 10.1242/jcs.210187] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/15/2018] [Indexed: 01/01/2023] Open
Abstract
The requirement for condensin in chromosome formation in somatic cells remains unclear, as imperfectly condensed chromosomes do form in cells depleted of condensin by conventional methodologies. In order to dissect the roles of condensin at different stages of vertebrate mitosis, we have established a versatile cellular system that combines auxin-mediated rapid degradation with chemical genetics to obtain near-synchronous mitotic entry of chicken DT40 cells in the presence and absence of condensin. We analyzed the outcome by live- and fixed-cell microscopy methods, including serial block face scanning electron microscopy with digital reconstruction. Following rapid depletion of condensin, chromosomal defects were much more obvious than those seen after a slow depletion of condensin. The total mitotic chromatin volume was similar to that in control cells, but a single mass of mitotic chromosomes was clustered at one side of a bent mitotic spindle. Cultures arrest at prometaphase, eventually exiting mitosis without segregating chromosomes. Experiments where the auxin concentration was titrated showed that different condensin levels are required for anaphase chromosome segregation and formation of a normal chromosome architecture. This article has an associated First Person interview with the first author of the paper. Summary: Rapid condensin depletion reveals that different condensin levels are required for mitotic chromosome architecture and segregation. Condensin is not required for chromatin volume compaction during mitosis.
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Affiliation(s)
- Kumiko Samejima
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Daniel G Booth
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Hiromi Ogawa
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - James R Paulson
- Department of Chemistry, University of Wisconsin-Oshkosh, 800 Algoma Blvd, Oshkosh, WI 54901, USA
| | - Linfeng Xie
- Department of Chemistry, University of Wisconsin-Oshkosh, 800 Algoma Blvd, Oshkosh, WI 54901, USA
| | - Cara A Watson
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Melpomeni Platani
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Masato T Kanemaki
- Division of Molecular Cell Engineering, National Institute of Genetics, ROIS, and Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - William C Earnshaw
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
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Booth DG, Earnshaw WC. Ki-67 and the Chromosome Periphery Compartment in Mitosis. Trends Cell Biol 2017; 27:906-916. [PMID: 28838621 DOI: 10.1016/j.tcb.2017.08.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 12/12/2022]
Abstract
The chromosome periphery is a complex network of proteins and RNA molecules (many derived from nucleoli) that covers the outer surface of chromosomes and whose function remains mysterious. Although it was first described over 130 years ago, technological advances and the recent discovery that Ki-67 acts as an organiser of this region have allowed the chromosome periphery to be dissected in previously unattainable detail, leading to a revival of interest in this obscure chromosomal compartment. Here, we review the most recent advances into the composition, structure and function of the chromosome periphery, discuss possible roles of Ki-67 during mitosis and consider why this structure is likely to remain the focus of ongoing attention in the future.
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Affiliation(s)
- Daniel G Booth
- Centre For Neuroregeneration, Chancellor's Building, University of Edinburgh, Edinburgh, EH16 4SB, UK.
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK.
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Booth DG, Beckett AJ, Molina O, Samejima I, Masumoto H, Kouprina N, Larionov V, Prior IA, Earnshaw WC. 3D-CLEM Reveals that a Major Portion of Mitotic Chromosomes Is Not Chromatin. Mol Cell 2016; 64:790-802. [PMID: 27840028 PMCID: PMC5128728 DOI: 10.1016/j.molcel.2016.10.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 08/24/2016] [Accepted: 10/05/2016] [Indexed: 11/20/2022]
Abstract
Recent studies have revealed the importance of Ki-67 and the chromosome periphery in chromosome structure and segregation, but little is known about this elusive chromosome compartment. Here we used correlative light and serial block-face scanning electron microscopy, which we term 3D-CLEM, to model the entire mitotic chromosome complement at ultra-structural resolution. Prophase chromosomes exhibit a highly irregular surface appearance with a volume smaller than metaphase chromosomes. This may be because of the absence of the periphery, which associates with chromosomes only after nucleolar disassembly later in prophase. Indeed, the nucleolar volume almost entirely accounts for the extra volume found in metaphase chromosomes. Analysis of wild-type and Ki-67-depleted chromosomes reveals that the periphery comprises 30%–47% of the entire chromosome volume and more than 33% of the protein mass of isolated mitotic chromosomes determined by quantitative proteomics. Thus, chromatin makes up a surprisingly small percentage of the total mass of metaphase chromosomes. 3D-CLEM combines light and serial block-face scanning electron microscopy The complete architecture of all 46 human chromosomes has been defined A large portion of mitotic chromosomes is not composed of chromatin Chromosome volumes determined by light and electron microscopy differ dramatically
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Affiliation(s)
- Daniel G Booth
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, EH9 3BF Edinburgh, UK.
| | - Alison J Beckett
- Biomedical Electron Microscopy Unit, Division of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, L69 3BX Liverpool, UK
| | - Oscar Molina
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, EH9 3BF Edinburgh, UK
| | - Itaru Samejima
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, EH9 3BF Edinburgh, UK
| | - Hiroshi Masumoto
- Department of Frontier Research, Laboratory of Cell Engineering, Kazusa DNA Research Institute, Kisarazu, 292-0818 Chiba, Japan
| | - Natalay Kouprina
- Developmental Therapeutics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4264, USA
| | - Vladimir Larionov
- Developmental Therapeutics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4264, USA
| | - Ian A Prior
- Biomedical Electron Microscopy Unit, Division of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, L69 3BX Liverpool, UK
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, EH9 3BF Edinburgh, UK.
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8
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Wood L, Booth DG, Vargiu G, Ohta S, deLima Alves F, Samejima K, Fukagawa T, Rappsilber J, Earnshaw WC. Auxin/AID versus conventional knockouts: distinguishing the roles of CENP-T/W in mitotic kinetochore assembly and stability. Open Biol 2016; 6:150230. [PMID: 26791246 PMCID: PMC4736828 DOI: 10.1098/rsob.150230] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Most studies using knockout technologies to examine protein function have relied either on shutting off transcription (conventional conditional knockouts with tetracycline-regulated gene expression or gene disruption) or destroying the mature mRNA (RNAi technology). In both cases, the target protein is lost at a rate determined by its intrinsic half-life. Thus, protein levels typically fall over at least 1-3 days, and cells continue to cycle while exposed to a decreasing concentration of the protein. Here we characterise the kinetochore proteome of mitotic chromosomes isolated from a cell line in which the essential kinetochore protein CENP-T is present as an auxin-inducible degron (AID) fusion protein that is fully functional and able to support the viability of the cells. Stripping of the protein from chromosomes in early mitosis via targeted proteasomal degradation reveals the dependency of other proteins on CENP-T for their maintenance in kinetochores. We compare these results with the kinetochore proteome of conventional CENP-T/W knockouts. As the cell cycle is mostly formed from G1, S and G2 phases a gradual loss of CENP-T/W levels is more likely to reflect dependencies associated with kinetochore assembly pre-mitosis and upon entry into mitosis. Interestingly, a putative super-complex involving Rod-Zw10-zwilch (RZZ complex), Spindly, Mad1/Mad2 and CENP-E requires the function of CENP-T/W during kinetochore assembly for its stable association with the outer kinetochore, but once assembled remains associated with chromosomes after stripping of CENP-T during mitosis. This study highlights the different roles core kinetochore components may play in the assembly of kinetochores (upon entry into mitosis) versus the maintenance of specific components (during mitosis).
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Affiliation(s)
- Laura Wood
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Daniel G Booth
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Giulia Vargiu
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Shinya Ohta
- Center for Innovative and Translational Medicine, Kochi University, Kochi, Japan
| | - Flavia deLima Alves
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Kumiko Samejima
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Suita 565-0871, Japan
| | - Juri Rappsilber
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK Institute of Bioanalytics, Department of Biotechnology, Technische Universität Berlin, Berlin 13353, Germany
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
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Robson MI, de Las Heras JI, Czapiewski R, Lê Thành P, Booth DG, Kelly DA, Webb S, Kerr ARW, Schirmer EC. Tissue-Specific Gene Repositioning by Muscle Nuclear Membrane Proteins Enhances Repression of Critical Developmental Genes during Myogenesis. Mol Cell 2016; 62:834-847. [PMID: 27264872 PMCID: PMC4914829 DOI: 10.1016/j.molcel.2016.04.035] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 12/21/2015] [Accepted: 04/28/2016] [Indexed: 12/28/2022]
Abstract
Whether gene repositioning to the nuclear periphery during differentiation adds another layer of regulation to gene expression remains controversial. Here, we resolve this by manipulating gene positions through targeting the nuclear envelope transmembrane proteins (NETs) that direct their normal repositioning during myogenesis. Combining transcriptomics with high-resolution DamID mapping of nuclear envelope-genome contacts, we show that three muscle-specific NETs, NET39, Tmem38A, and WFS1, direct specific myogenic genes to the nuclear periphery to facilitate their repression. Retargeting a NET39 fragment to nucleoli correspondingly repositioned a target gene, indicating a direct tethering mechanism. Being able to manipulate gene position independently of other changes in differentiation revealed that repositioning contributes ⅓ to ⅔ of a gene’s normal repression in myogenesis. Together, these NETs affect 37% of all genes changing expression during myogenesis, and their combined knockdown almost completely blocks myotube formation. This unequivocally demonstrates that NET-directed gene repositioning is critical for developmental gene regulation. Tissue-specific NETs direct repositioning of critical muscle genes during myogenesis Expression changes for NET-repositioned genes depend on cell differentiation state Isolating position from differentiation reveals its contribution to gene expression Three NETs together affect 37% of all genes normally changing in myogenesis
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Affiliation(s)
- Michael I Robson
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Jose I de Las Heras
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Rafal Czapiewski
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Phú Lê Thành
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Daniel G Booth
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - David A Kelly
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Shaun Webb
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Alastair R W Kerr
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Eric C Schirmer
- The Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK.
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Nixon FM, Gutiérrez-Caballero C, Hood FE, Booth DG, Prior IA, Royle SJ. The mesh is a network of microtubule connectors that stabilizes individual kinetochore fibers of the mitotic spindle. eLife 2015; 4. [PMID: 26090906 PMCID: PMC4495718 DOI: 10.7554/elife.07635] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 06/18/2015] [Indexed: 12/11/2022] Open
Abstract
Kinetochore fibers (K-fibers) of the mitotic spindle are force-generating units that power chromosome movement during mitosis. K-fibers are composed of many microtubules that are held together throughout their length. Here, we show, using 3D electron microscopy, that K-fiber microtubules (MTs) are connected by a network of MT connectors. We term this network ‘the mesh’. The K-fiber mesh is made of linked multipolar connectors. Each connector has up to four struts, so that a single connector can link up to four MTs. Molecular manipulation of the mesh by overexpression of TACC3 causes disorganization of the K-fiber MTs. Optimal stabilization of K-fibers by the mesh is required for normal progression through mitosis. We propose that the mesh stabilizes K-fibers by pulling MTs together and thereby maintaining the integrity of the fiber. Our work thus identifies the K-fiber meshwork of linked multipolar connectors as a key integrator and determinant of K-fiber structure and function. DOI:http://dx.doi.org/10.7554/eLife.07635.001 Before a cell divides, its genetic material must be copied and then equally distributed between the newly formed daughter cells. In the cells of plants, animals, and fungi, a structure known as the spindle pulls the two copies of the chromosomes apart. The spindle is made up of a network of long, protein filaments called microtubules, and the bundles of microtubules that attach to the chromosomes are referred to as ‘K-fibers’. K-fibers are organized in a way that provides strength. These bundles of microtubules are held together throughout their entire length and, in 2011, it was suggested that a group of proteins including one called TACC3 could cross-link adjacent microtubules within K-fibers. However, it remained unclear how these proteins achieved this. Now, Nixon et al.—including several of the researchers involved in the 2011 work—have used a technique called 3D electron tomography to analyze what holds the K-fibers together in human cells. This analysis revealed struts or connectors that hold together adjacent microtubules within K-fibers. These connectors can vary in size and a single connector can link up to four microtubules. This means that, in a three-dimensional view, the connectors appear as a ‘mesh’ between the microtubules in the bundle. Nixon et al. then increased the levels of the TACC3 protein and found that the K-fibers became disorganized. The spacing of the microtubules with the K-fibers was reduced so that they were more tightly packed than normal. These observations suggest that ‘the mesh’ influences the microtubule spacing within a K-fiber. Nixon et al. analyzed how disorganized K-fibers affected dividing cells and found that it took longer for the chromosomes to move to the newly forming daughter cells. This suggests that cells must maintain optimal levels of TACC3 to ensure that the K-fibers can effectively separate the chromosomes. Further work is needed to identify the other proteins and molecules that make up the mesh. DOI:http://dx.doi.org/10.7554/eLife.07635.002
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Affiliation(s)
- Faye M Nixon
- Division of Biomedical Cell Biology, Warwick Medical School, Coventry, United Kingdom
| | | | - Fiona E Hood
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Daniel G Booth
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Ian A Prior
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Stephen J Royle
- Division of Biomedical Cell Biology, Warwick Medical School, Coventry, United Kingdom
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11
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Cheeseman LP, Booth DG, Hood FE, Prior IA, Royle SJ. Aurora A kinase activity is required for localization of TACC3/ch-TOG/clathrin inter-microtubule bridges. Commun Integr Biol 2014. [DOI: 10.4161/cib.15250] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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12
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Booth DG, Takagi M, Sanchez-Pulido L, Petfalski E, Vargiu G, Samejima K, Imamoto N, Ponting CP, Tollervey D, Earnshaw WC, Vagnarelli P. Ki-67 is a PP1-interacting protein that organises the mitotic chromosome periphery. eLife 2014; 3:e01641. [PMID: 24867636 PMCID: PMC4032110 DOI: 10.7554/elife.01641] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 04/27/2014] [Indexed: 12/23/2022] Open
Abstract
When the nucleolus disassembles during open mitosis, many nucleolar proteins and RNAs associate with chromosomes, establishing a perichromosomal compartment coating the chromosome periphery. At present nothing is known about the function of this poorly characterised compartment. In this study, we report that the nucleolar protein Ki-67 is required for the assembly of the perichromosomal compartment in human cells. Ki-67 is a cell-cycle regulated protein phosphatase 1-binding protein that is involved in phospho-regulation of the nucleolar protein B23/nucleophosmin. Following siRNA depletion of Ki-67, NIFK, B23, nucleolin, and four novel chromosome periphery proteins all fail to associate with the periphery of human chromosomes. Correlative light and electron microscopy (CLEM) images suggest a near-complete loss of the entire perichromosomal compartment. Mitotic chromosome condensation and intrinsic structure appear normal in the absence of the perichromosomal compartment but significant differences in nucleolar reassembly and nuclear organisation are observed in post-mitotic cells.DOI: http://dx.doi.org/10.7554/eLife.01641.001.
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Affiliation(s)
- Daniel G Booth
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Masatoshi Takagi
- Cellular Dynamics Laboratory, Riken Advanced Science Institute, Wako Saitama, Japan
| | - Luis Sanchez-Pulido
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Elizabeth Petfalski
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Giulia Vargiu
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Kumiko Samejima
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Naoko Imamoto
- Cellular Dynamics Laboratory, Riken Advanced Science Institute, Wako Saitama, Japan
| | - Chris P Ponting
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
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Abstract
Electron microscopy (EM) has dominated high-resolution cellular imaging for over 50 years, thanks to its ability to resolve on nanometer-scale intracellular structures such as the microtubules of the mitotic spindle. It is advantageous to view the cell of interest prior to processing the sample for EM. Correlative light-electron microscopy (CLEM) is a technique that allows one to visualize cells of interest by light microscopy (LM) before being transferred to EM for ultrastructural examination. Here, we describe how CLEM can be applied as an effective tool to study the spindle apparatus of mitotic cells. This approach allows transfected cells of interest, in desirable stages of mitosis, to be followed from LM to EM. CLEM has often been considered as a technically challenging and laborious technique. In this chapter, we provide step-by-step pictorial guides that allow successful CLEM to be achieved. In addition, we explain how it is possible to vary the sectioning plane, allowing spindles and microtubules to be analyzed from different angles, and the outputs that can be obtained from these methods when applied to the study of kinetochore fiber ultrastructure.
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Affiliation(s)
- Daniel G. Booth
- Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, King’s Building, Mayfield Road, Edinburgh EH9 3JR, U.K
| | - Liam P. Cheeseman
- Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Ian A. Prior
- Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
| | - Stephen J. Royle
- Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool L69 3BX, U.K
- Centre for Mechanochemical Cell Biology, Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
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Cheeseman LP, Booth DG, Hood FE, Prior IA, Royle SJ. Aurora A kinase activity is required for localization of TACC3/ch-TOG/clathrin inter-microtubule bridges. Commun Integr Biol 2011; 4:409-12. [PMID: 21966557 DOI: 10.4161/cib.4.4.15250] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Accepted: 02/19/2011] [Indexed: 12/18/2022] Open
Abstract
Accurate chromosome segregation during mitosis is achieved by the kinetochore fibers (K-fibers) of the spindle apparatus. These fibers are bundles of microtubules (MTs) connected by non-motor bridges. We recently identified a TACC3/ch-TOG/clathrin complex that constitutes the shortest class of inter-MT bridge in K-fibers. TACC3 anchors the complex to MTs and this is dependent on phosphorylation by Aurora A kinase. Here we show that inhibition of Aurora A kinase using MLN8237 results in (1) loss of clathrin and TACC3 from spindles, (2) destabilization of K-fibers and (3) loss of inter-MT bridges. These results are similar to those in cells depleted of clathrin or TACC3; suggesting that TACC3/ch-TOG/clathrin bridges are the major class of bridge that is regulated by this kinase.
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Affiliation(s)
- Liam P Cheeseman
- The Physiological Laboratory; University of Liverpool; Liverpool, UK
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Honohan T, Fitzpatrick FA, Booth DG, McGrath JP, Morton DR, Nishizawa E. Hydrolysis of an orally active platelet inhibitory prostanoid amide in the plasma of several species. Prostaglandins 1980; 19:123-36. [PMID: 6770417 DOI: 10.1016/0090-6980(80)90160-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The prostanoid 3-oxa-4,5,6-trinor-3,7-inter-m-phenylene-PGE1-amide (OI-PGE1-amide) has a prolonged duration of oral platelet aggregation inhibitory activity when compared to the parent free acid (OI-PGE1) in the rat. When incubated in rat plasma at 1 microgram/ml for 30 seconds prior to addition of ADP, OI-PGE1-amide inhibits in vitro rat platelet aggregation approximately 50%. OI-PGE1 inhibits at 1 ng/ml. Inhibition of platelet aggregation by plasma incubated with OI-PGE1-amide (1 microgram/ml) increases with time and the rate of this increase differs with species. Incubation of OI-PGE1 in plasma does not result in an increase of platelet inhibitory activity with time. The increase of platelet inhibitory activity was assumed to indicate hydrolysis of OI-PGE1-amide to the more active OI-PGE1. A compound, different from OI-PGE1-amide, was isolated by an ion exchange/silica gel separation sequence from an incubation of OI-PGE1-amide in rat plasma. It had potent platelet aggregation inhibitory activity. This material was shown to be OI-PGE1 by thin-layer chromatography, gas chromatography and mass spectral analysis. Studies with [3H]-OI-PGE1-amide confirmed the formation of OI-PGE1 in plasma incubations. Amide hydrolytic activity was significantly different between species, the rank order being: rat greater than guine pig greater than monkey = human greater than dog. This relationship corresponded with that determined by measuring the increase in platelet inhibitory activity with time in plasma incubations of OI-PGE1-amide reported above. Present data indicate that (a) OI-PGE1-amide is hydrolyzed to the parent acid by plasma enzymes of several species and (b) hydrolytic activity of plasma varies widely between species.
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