1
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Kroll J, Hauschild R, Kuznetcov A, Stefanowski K, Hermann MD, Merrin J, Shafeek L, Müller‐Taubenberger A, Renkawitz J. Adaptive pathfinding by nucleokinesis during amoeboid migration. EMBO J 2023; 42:e114557. [PMID: 37987147 PMCID: PMC10711653 DOI: 10.15252/embj.2023114557] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 10/31/2023] [Accepted: 11/03/2023] [Indexed: 11/22/2023] Open
Abstract
Motile cells encounter microenvironments with locally heterogeneous mechanochemical composition. Individual compositional parameters, such as chemokines and extracellular matrix pore sizes, are well known to provide guidance cues for pathfinding. However, motile cells face diverse cues at the same time, raising the question of how they respond to multiple and potentially competing signals on their paths. Here, we reveal that amoeboid cells require nuclear repositioning, termed nucleokinesis, for adaptive pathfinding in heterogeneous mechanochemical micro-environments. Using mammalian immune cells and the amoeba Dictyostelium discoideum, we discover that frequent, rapid and long-distance nucleokinesis is a basic component of amoeboid pathfinding, enabling cells to reorientate quickly between locally competing cues. Amoeboid nucleokinesis comprises a two-step polarity switch and is driven by myosin-II forces that readjust the nuclear to the cellular path. Impaired nucleokinesis distorts path adaptions and causes cellular arrest in the microenvironment. Our findings establish that nucleokinesis is required for amoeboid cell navigation. Given that many immune cells, amoebae, and some cancer cells utilize an amoeboid migration strategy, these results suggest that nucleokinesis underlies cellular navigation during unicellular biology, immunity, and disease.
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Affiliation(s)
- Janina Kroll
- Biomedical Center Munich (BMC), Walter Brendel Center of Experimental Medicine, Institute of Cardiovascular Physiology and Pathophysiology, University HospitalLudwig Maximilians University MunichMunichGermany
| | - Robert Hauschild
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Artur Kuznetcov
- Biomedical Center Munich (BMC), Walter Brendel Center of Experimental Medicine, Institute of Cardiovascular Physiology and Pathophysiology, University HospitalLudwig Maximilians University MunichMunichGermany
| | - Kasia Stefanowski
- Biomedical Center Munich (BMC), Walter Brendel Center of Experimental Medicine, Institute of Cardiovascular Physiology and Pathophysiology, University HospitalLudwig Maximilians University MunichMunichGermany
| | - Monika D Hermann
- Biomedical Center Munich (BMC), Walter Brendel Center of Experimental Medicine, Institute of Cardiovascular Physiology and Pathophysiology, University HospitalLudwig Maximilians University MunichMunichGermany
| | - Jack Merrin
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Lubuna Shafeek
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Annette Müller‐Taubenberger
- Biomedical Center Munich (BMC), Department of Cell Biology (Anatomy III)Ludwig Maximilians University MunichMunichGermany
| | - Jörg Renkawitz
- Biomedical Center Munich (BMC), Walter Brendel Center of Experimental Medicine, Institute of Cardiovascular Physiology and Pathophysiology, University HospitalLudwig Maximilians University MunichMunichGermany
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2
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Gibson JM, Zhao X, Ali MY, Solmaz SR, Wang C. A Structural Model for the Core Nup358-BicD2 Interface. Biomolecules 2023; 13:1445. [PMID: 37892127 PMCID: PMC10604712 DOI: 10.3390/biom13101445] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/08/2023] [Accepted: 09/19/2023] [Indexed: 10/29/2023] Open
Abstract
Dynein motors facilitate the majority of minus-end-directed transport events on microtubules. The dynein adaptor Bicaudal D2 (BicD2) recruits the dynein machinery to several cellular cargo for transport, including Nup358, which facilitates a nuclear positioning pathway that is essential for the differentiation of distinct brain progenitor cells. Previously, we showed that Nup358 forms a "cargo recognition α-helix" upon binding to BicD2; however, the specifics of the BicD2-Nup358 interface are still not well understood. Here, we used AlphaFold2, complemented by two additional docking programs (HADDOCK and ClusPro) as well as mutagenesis, to show that the Nup358 cargo-recognition α-helix binds to BicD2 between residues 747 and 774 in an anti-parallel manner, forming a helical bundle. We identified two intermolecular salt bridges that are important to stabilize the interface. In addition, we uncovered a secondary interface mediated by an intrinsically disordered region of Nup358 that is directly N-terminal to the cargo-recognition α-helix and binds to BicD2 between residues 774 and 800. This is the same BicD2 domain that binds to the competing cargo adapter Rab6, which is important for the transport of Golgi-derived and secretory vesicles. Our results establish a structural basis for cargo recognition and selection by the dynein adapter BicD2, which facilitates transport pathways that are important for brain development.
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Affiliation(s)
- James M. Gibson
- Department of Biological Sciences, Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA
| | - Xiaoxin Zhao
- Department of Chemistry, Binghamton University, P.O. Box 6000, Binghamton, NY 13902, USA;
| | - M. Yusuf Ali
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405, USA;
| | - Sozanne R. Solmaz
- Department of Chemistry, Binghamton University, P.O. Box 6000, Binghamton, NY 13902, USA;
| | - Chunyu Wang
- Department of Biological Sciences, Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA
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3
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Jun M, Lee YL, Zhou T, Maric M, Burke B, Park S, Low BC, Chiam KH. Subcellular Force Imbalance in Actin Bundles Induces Nuclear Repositioning and Durotaxis. ACS Appl Mater Interfaces 2023; 15:43387-43402. [PMID: 37674326 DOI: 10.1021/acsami.3c07546] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Durotaxis is a phenomenon in which cells migrate toward substrates of increasing stiffness. However, how cells assimilate substrate stiffness as a directional cue remains poorly understood. In this study, we experimentally show that mouse embryonic fibroblasts can discriminate between different substrate stiffnesses and develop higher traction forces at regions of the cell adhering to the stiffer pillars. In this way, the cells generate a force imbalance between adhesion sites. It is this traction force imbalance that drives durotaxis by providing directionality for cell migration. Significantly, we found that traction forces are transmitted via LINC complexes to the cell nucleus, which serves to maintain the global force imbalance. In this way, LINC complexes play an essential role in anterograde nuclear movement and durotaxis. This conclusion is supported by the fact that LINC complex-deficient cells are incapable of durotaxis and instead migrate randomly on substrates featuring a stiffness gradient.
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Affiliation(s)
- Myeongjun Jun
- Bioinformatics institute, A*STAR, Singapore 138671, Singapore
- Department of Biological Science, National University of Singapore, Singapore 117558, Singapore
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea
| | - Yin Loon Lee
- A*STAR Skin Research Laboratories, A*STAR, Singapore 138648, Singapore
| | - Tianxun Zhou
- Bioinformatics institute, A*STAR, Singapore 138671, Singapore
| | - Martina Maric
- A*STAR Skin Research Laboratories, A*STAR, Singapore 138648, Singapore
| | - Brian Burke
- A*STAR Skin Research Laboratories, A*STAR, Singapore 138648, Singapore
| | - Sungsu Park
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea
- Institute of Quantum Biophysics, Sungkyunkwan University, Suwon 16419, Korea
| | - Boon Chuan Low
- Department of Biological Science, National University of Singapore, Singapore 117558, Singapore
- Mechanobiology Institute, National University of Singapore, Singapore 117558, Singapore
- NUS college, National University of Singapore, Singapore 117558, Singapore
| | - Keng-Hwee Chiam
- Bioinformatics institute, A*STAR, Singapore 138671, Singapore
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4
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De Silva S, Fan Z, Kang B, Shanahan CM, Zhang Q. Nesprin-1: novel regulator of striated muscle nuclear positioning and mechanotransduction. Biochem Soc Trans 2023; 51:1331-1345. [PMID: 37171063 PMCID: PMC10317153 DOI: 10.1042/bst20221541] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 04/20/2023] [Accepted: 04/20/2023] [Indexed: 05/13/2023]
Abstract
Nesprins (nuclear envelope spectrin repeat proteins) are multi-isomeric scaffolding proteins. Giant nesprin-1 and -2 localise to the outer nuclear membrane, interact with SUN (Sad1p/UNC-84) domain-containing proteins at the inner nuclear membrane to form the LInker of Nucleoskeleton and Cytoskeleton (LINC) complex, which, in association with lamin A/C and emerin, mechanically couples the nucleus to the cytoskeleton. Despite ubiquitous expression of nesprin giant isoforms, pathogenic mutations in nesprin-1 and -2 are associated with tissue-specific disorders, particularly related to striated muscle such as dilated cardiomyopathy and Emery-Dreifuss muscular dystrophy. Recent evidence suggests this muscle-specificity might be attributable in part, to the small muscle specific isoform, nesprin-1α2, which has a novel role in striated muscle function. Our current understanding of muscle-specific functions of nesprin-1 and its isoforms will be summarised in this review to provide insight into potential pathological mechanisms of nesprin-related muscle disease and may inform potential targets of therapeutic modulation.
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Affiliation(s)
- Shanelle De Silva
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
| | - Zhijuan Fan
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
- Clinical Laboratory, Tianjin Third Central Hospital, Tianjin 300170, China
| | - Baoqiang Kang
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
| | - Catherine M. Shanahan
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
| | - Qiuping Zhang
- King's College London British Heart Foundation Centre of Research Excellence, School of Cardiovascular and Metabolic Medicine & Sciences, London SE5 9NU, U.K
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5
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Hayden L, Chao A, Deneke VE, Vergassola M, Puliafito A, Di Talia S. Cullin-5 mutants reveal collective sensing of the nucleocytoplasmic ratio in Drosophila embryogenesis. Curr Biol 2022; 32:2084-2092.e4. [PMID: 35334230 PMCID: PMC9090985 DOI: 10.1016/j.cub.2022.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 01/21/2022] [Revised: 02/27/2022] [Accepted: 03/01/2022] [Indexed: 11/28/2022]
Abstract
In most metazoans, early embryonic development is characterized by rapid division cycles that pause before gastrulation at the midblastula transition (MBT).1 These cleavage divisions are accompanied by cytoskeletal rearrangements that ensure proper nuclear positioning. However, the molecular mechanisms controlling nuclear positioning are not fully elucidated. In Drosophila, early embryogenesis unfolds in a multinucleated syncytium. Nuclei rapidly move across the anterior-posterior (AP) axis at cell cycles 4-6 in a process driven by actomyosin contractility and cytoplasmic flows.2,3 In shackleton (shkl) mutants, this axial spreading is impaired.4 Here, we show that shkl mutants carry mutations in the cullin-5 (cul-5) gene. Live imaging experiments show that Cul-5 is downstream of the cell cycle but is required for cortical actomyosin contractility. The nuclear spreading phenotype of cul-5 mutants can be rescued by reducing Src activity, suggesting that a major target of cul-5 is Src kinase. cul-5 mutants display gradients of nuclear density across the AP axis that we exploit to study cell-cycle control as a function of the N/C ratio. We found that the N/C ratio is sensed collectively in neighborhoods of about 100 μm, and such collective sensing is required for a precise MBT, in which all the nuclei in the embryo pause their division cycle. Moreover, we found that the response to the N/C ratio is slightly graded along the AP axis. These two features can be linked to Cdk1 dynamics. Collectively, we reveal a new pathway controlling nuclear positioning and provide a dissection of how nuclear cycles respond to the N/C ratio.
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Affiliation(s)
- Luke Hayden
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Anna Chao
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Victoria E Deneke
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Massimo Vergassola
- Laboratoire de physique de l'École Normale Supérieure, CNRS, PSL Research University, Sorbonne Université, Paris, France; Department of Physics, University of California, San Diego, La Jolla, CA, USA
| | - Alberto Puliafito
- Candiolo Cancer Institute, FPO-IRCCS, Laboratory of Cell Migration, 10060 Candiolo, Italy; Department of Oncology, Università di Torino, 10060 Candiolo, Italy
| | - Stefano Di Talia
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA.
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6
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Ulm P, Jantsch V. Putting organelles in their place. eLife 2021; 10:69422. [PMID: 34018487 PMCID: PMC8139855 DOI: 10.7554/elife.69422] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 11/13/2022] Open
Abstract
Experiments in C. elegans reveal new insights into how the ANC-1 protein helps to anchor the nucleus and other organelles in place.
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Affiliation(s)
- Patricia Ulm
- Department of Chromosome Biology, Max Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Verena Jantsch
- Department of Chromosome Biology, Max Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
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7
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Maggi L, Mavroidis M, Psarras S, Capetanaki Y, Lattanzi G. Skeletal and Cardiac Muscle Disorders Caused by Mutations in Genes Encoding Intermediate Filament Proteins. Int J Mol Sci 2021; 22:4256. [PMID: 33923914 DOI: 10.3390/ijms22084256] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/12/2021] [Accepted: 04/15/2021] [Indexed: 02/08/2023] Open
Abstract
Intermediate filaments are major components of the cytoskeleton. Desmin and synemin, cytoplasmic intermediate filament proteins and A-type lamins, nuclear intermediate filament proteins, play key roles in skeletal and cardiac muscle. Desmin, encoded by the DES gene (OMIM *125660) and A-type lamins by the LMNA gene (OMIM *150330), have been involved in striated muscle disorders. Diseases include desmin-related myopathy and cardiomyopathy (desminopathy), which can be manifested with dilated, restrictive, hypertrophic, arrhythmogenic, or even left ventricular non-compaction cardiomyopathy, Emery–Dreifuss Muscular Dystrophy (EDMD2 and EDMD3, due to LMNA mutations), LMNA-related congenital Muscular Dystrophy (L-CMD) and LMNA-linked dilated cardiomyopathy with conduction system defects (CMD1A). Recently, mutations in synemin (SYNM gene, OMIM *606087) have been linked to cardiomyopathy. This review will summarize clinical and molecular aspects of desmin-, lamin- and synemin-related striated muscle disorders with focus on LMNA and DES-associated clinical entities and will suggest pathogenetic hypotheses based on the interplay of desmin and lamin A/C. In healthy muscle, such interplay is responsible for the involvement of this network in mechanosignaling, nuclear positioning and mitochondrial homeostasis, while in disease it is disturbed, leading to myocyte death and activation of inflammation and the associated secretome alterations.
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8
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Hao H, Kalra S, Jameson LE, Guerrero LA, Cain NE, Bolivar J, Starr DA. The Nesprin-1/-2 ortholog ANC-1 regulates organelle positioning in C. elegans independently from its KASH or actin-binding domains. eLife 2021; 10:e61069. [PMID: 33860766 PMCID: PMC8139857 DOI: 10.7554/elife.61069] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [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: 07/14/2020] [Accepted: 04/11/2021] [Indexed: 12/15/2022] Open
Abstract
KASH proteins in the outer nuclear membrane comprise the cytoplasmic half of linker of nucleoskeleton and cytoskeleton (LINC) complexes that connect nuclei to the cytoskeleton. Caenorhabditis elegans ANC-1, an ortholog of Nesprin-1/2, contains actin-binding and KASH domains at opposite ends of a long spectrin-like region. Deletion of either the KASH or calponin homology (CH) domains does not completely disrupt nuclear positioning, suggesting neither KASH nor CH domains are essential. Deletions in the spectrin-like region of ANC-1 led to significant defects, but only recapitulated the null phenotype in combination with mutations in the transmembrane (TM) span. In anc-1 mutants, the endoplasmic reticulum ER, mitochondria, and lipid droplets were unanchored, moving throughout the cytoplasm. The data presented here support a cytoplasmic integrity model where ANC-1 localizes to the ER membrane and extends into the cytoplasm to position nuclei, ER, mitochondria, and other organelles in place.
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Affiliation(s)
- Hongyan Hao
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Shilpi Kalra
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Laura E Jameson
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Leslie A Guerrero
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Natalie E Cain
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Jessica Bolivar
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
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9
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Calero-Cuenca FJ, Osorio DS, Carvalho-Marques S, Sridhara SC, Oliveira LM, Jiao Y, Diaz J, Janota CS, Cadot B, Gomes ER. Ctdnep1 and Eps8L2 regulate dorsal actin cables for nuclear positioning during cell migration. Curr Biol 2021; 31:1521-1530.e8. [PMID: 33567288 PMCID: PMC8043254 DOI: 10.1016/j.cub.2021.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [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: 08/29/2019] [Revised: 11/12/2020] [Accepted: 01/06/2021] [Indexed: 11/30/2022]
Abstract
Cells actively position their nuclei within the cytoplasm for multiple cellular and physiological functions.1, 2, 3 Consequently, nuclear mispositioning is usually associated with cell dysfunction and disease, from muscular disorders to cancer metastasis.4, 5, 6, 7 Different cell types position their nuclei away from the leading edge during cell migration.8, 9, 10, 11 In migrating fibroblasts, nuclear positioning is driven by an actin retrograde flow originated at the leading edge that drives dorsal actin cables away from the leading edge. The dorsal actin cables connect to the nuclear envelope by the linker of nucleoskeleton and cytoskeleton (LINC) complex on transmembrane actin-associated nuclear (TAN) lines.12, 13, 14 Dorsal actin cables are required for the formation of TAN lines. How dorsal actin cables are organized to promote TAN lines formation is unknown. Here, we report a role for Ctdnep1/Dullard, a nuclear envelope phosphatase,15, 16, 17, 18, 19, 20, 21, 22 and the actin regulator Eps8L223, 24, 25 on nuclear positioning and cell migration. We demonstrate that Ctdnep1 and Eps8L2 directly interact, and this interaction is important for nuclear positioning and cell migration. We also show that Ctdnep1 and Eps8L2 are involved in the formation and thickness of dorsal actin cables required for TAN lines engagement during nuclear movement. We propose that Ctdnep1-Eps8L2 interaction regulates dorsal actin cables for nuclear movement during cell migration. Ctdnep1 and Eps8L2 are required for nuclear positioning and TAN lines formation Ctdnep1 directly interacts with Eps8L2 for nuclear movement and cell migration Ctdnep1-Eps8L2 interaction regulates dorsal actin organization
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Affiliation(s)
- Francisco J Calero-Cuenca
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Daniel S Osorio
- Center for Research in Myology, INSERM U974, CNRS FRE3617, Université Pierre et Marie Curie, Sorbonne Universités, GH Pitié Salpêtrière, 75013 Paris, France
| | - Sofia Carvalho-Marques
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Sreerama Chaitanya Sridhara
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Luis M Oliveira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Yue Jiao
- Center for Research in Myology, INSERM U974, CNRS FRE3617, Université Pierre et Marie Curie, Sorbonne Universités, GH Pitié Salpêtrière, 75013 Paris, France
| | - Jheimmy Diaz
- Center for Research in Myology, INSERM U974, CNRS FRE3617, Université Pierre et Marie Curie, Sorbonne Universités, GH Pitié Salpêtrière, 75013 Paris, France
| | - Cátia S Janota
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Bruno Cadot
- Center for Research in Myology, INSERM U974, CNRS FRE3617, Université Pierre et Marie Curie, Sorbonne Universités, GH Pitié Salpêtrière, 75013 Paris, France
| | - Edgar R Gomes
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal; Center for Research in Myology, INSERM U974, CNRS FRE3617, Université Pierre et Marie Curie, Sorbonne Universités, GH Pitié Salpêtrière, 75013 Paris, France; Instituto de Histologia e Biologia do Desenvolvimento, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal.
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10
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Cui H, Ali MY, Goyal P, Zhang K, Loh JY, Trybus KM, Solmaz SR. Coiled-coil registry shifts in the F684I mutant of Bicaudal D result in cargo-independent activation of dynein motility. Traffic 2021; 21:463-478. [PMID: 32378283 DOI: 10.1111/tra.12734] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 02/01/2020] [Revised: 04/29/2020] [Accepted: 05/01/2020] [Indexed: 11/28/2022]
Abstract
The dynein adaptor Drosophila Bicaudal D (BicD) is auto-inhibited and activates dynein motility only after cargo is bound, but the underlying mechanism is elusive. In contrast, we show that the full-length BicD/F684I mutant activates dynein processivity even in the absence of cargo. Our X-ray structure of the C-terminal domain of the BicD/F684I mutant reveals a coiled-coil registry shift; in the N-terminal region, the two helices of the homodimer are aligned, whereas they are vertically shifted in the wild-type. One chain is partially disordered and this structural flexibility is confirmed by computations, which reveal that the mutant transitions back and forth between the two registries. We propose that a coiled-coil registry shift upon cargo-binding activates BicD for dynein recruitment. Moreover, the human homolog BicD2/F743I exhibits diminished binding of cargo adaptor Nup358, implying that a coiled-coil registry shift may be a mechanism to modulate cargo selection for BicD2-dependent transport pathways.
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Affiliation(s)
- Heying Cui
- Department of Chemistry, State University of New York at Binghamton, Binghamton, New York, USA
| | - M Yusuf Ali
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont, USA
| | - Puja Goyal
- Department of Chemistry, State University of New York at Binghamton, Binghamton, New York, USA
| | - Kaiqi Zhang
- Department of Chemistry, State University of New York at Binghamton, Binghamton, New York, USA
| | - Jia Ying Loh
- Department of Chemistry, State University of New York at Binghamton, Binghamton, New York, USA
| | - Kathleen M Trybus
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont, USA
| | - Sozanne R Solmaz
- Department of Chemistry, State University of New York at Binghamton, Binghamton, New York, USA
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11
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Alexander KA, Coté A, Nguyen SC, Zhang L, Gholamalamdari O, Agudelo-Garcia P, Lin-Shiao E, Tanim KMA, Lim J, Biddle N, Dunagin MC, Good CR, Mendoza MR, Little SC, Belmont A, Joyce EF, Raj A, Berger SL. p53 mediates target gene association with nuclear speckles for amplified RNA expression. Mol Cell 2021; 81:1666-1681.e6. [PMID: 33823140 DOI: 10.1016/j.molcel.2021.03.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/05/2021] [Accepted: 03/03/2021] [Indexed: 01/01/2023]
Abstract
Nuclear speckles are prominent nuclear bodies that contain proteins and RNA involved in gene expression. Although links between nuclear speckles and gene activation are emerging, the mechanisms regulating association of genes with speckles are unclear. We find that speckle association of p53 target genes is driven by the p53 transcription factor. Focusing on p21, a key p53 target, we demonstrate that speckle association boosts expression by elevating nascent RNA amounts. p53-regulated speckle association did not depend on p53 transactivation functions but required an intact proline-rich domain and direct DNA binding, providing mechanisms within p53 for regulating gene-speckle association. Beyond p21, a substantial subset of p53 targets have p53-regulated speckle association. Strikingly, speckle-associating p53 targets are more robustly activated and occupy a distinct niche of p53 biology compared with non-speckle-associating p53 targets. Together, our findings illuminate regulated speckle association as a mechanism used by a transcription factor to boost gene expression.
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12
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Liu J, Huang ZP, Nie M, Wang G, Silva WJ, Yang Q, Freire PP, Hu X, Chen H, Deng Z, Pu WT, Wang DZ. Regulation of myo nuclear positioning and muscle function by the skeletal muscle-specific CIP protein. Proc Natl Acad Sci U S A 2020; 117:19254-19265. [PMID: 32719146 PMCID: PMC7430979 DOI: 10.1073/pnas.1922911117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [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] [Indexed: 01/29/2023] Open
Abstract
The appropriate arrangement of myonuclei within skeletal muscle myofibers is of critical importance for normal muscle function, and improper myonuclear localization has been linked to a variety of skeletal muscle diseases, such as centronuclear myopathy and muscular dystrophies. However, the molecules that govern myonuclear positioning remain elusive. Here, we report that skeletal muscle-specific CIP (sk-CIP) is a regulator of nuclear positioning. Genetic deletion of sk-CIP in mice results in misalignment of myonuclei along the myofibers and at specialized structures such as neuromuscular junctions (NMJs) and myotendinous junctions (MTJs) in vivo, impairing myonuclear positioning after muscle regeneration, leading to severe muscle dystrophy in mdx mice, a mouse model of Duchenne muscular dystrophy. sk-CIP is localized to the centrosome in myoblasts and relocates to the outer nuclear envelope in myotubes upon differentiation. Mechanistically, we found that sk-CIP interacts with the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex and the centriole Microtubule Organizing Center (MTOC) proteins to coordinately modulate myonuclear positioning and alignment. These findings indicate that sk-CIP may function as a muscle-specific anchoring protein to regulate nuclear position in multinucleated muscle cells.
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MESH Headings
- Animals
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Co-Repressor Proteins
- Humans
- Mice
- Mice, Inbred mdx
- Mice, Knockout
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiopathology
- Myoblasts/metabolism
- Myopathies, Structural, Congenital/genetics
- Myopathies, Structural, Congenital/metabolism
- Myopathies, Structural, Congenital/physiopathology
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Organ Specificity
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Affiliation(s)
- Jianming Liu
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
| | - Zhan-Peng Huang
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Center for Translational Medicine, National Health Commission (NHC) Key Laboratory of Assisted Circulation, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510275, China
| | - Mao Nie
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Department of Orthopaedic Surgery, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, 400010, China
| | - Gang Wang
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
| | - William J Silva
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Laboratório de Biologia Celular e Molecular do Músculo Estriado, University of São Paulo, CEP 05508-000 Cidade Universitária, São Paulo, Brazil
| | - Qiumei Yang
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Department of Animal Sciences, Sichuan Agriculture University, Chengdu, 611130, China
| | - Paula P Freire
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Department of Morphology, Institute of Biosciences, São Paulo State University, CEP 18618-000, Botucatu, São Paulo, Brazil
| | - Xiaoyun Hu
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
| | - Huaqun Chen
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Department of Biology, Nanjing Normal University, Nanjing, 225300, China
| | - Zhongliang Deng
- Department of Orthopaedic Surgery, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, 400010, China
| | - William T Pu
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138
| | - Da-Zhi Wang
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115;
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138
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13
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Antoku S, Wu W, Joseph LC, Morrow JP, Worman HJ, Gundersen GG. ERK1/2 Phosphorylation of FHOD Connects Signaling and Nuclear Positioning Alternations in Cardiac Laminopathy. Dev Cell 2020; 51:602-616.e12. [PMID: 31794718 DOI: 10.1016/j.devcel.2019.10.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 08/06/2019] [Accepted: 10/24/2019] [Indexed: 12/13/2022]
Abstract
Mutations in the lamin A/C gene (LMNA) cause cardiomyopathy and also disrupt nuclear positioning in fibroblasts. LMNA mutations causing cardiomyopathy elevate ERK1/2 activity in the heart, and inhibition of the ERK1/2 kinase activity ameliorates pathology, but the downstream effectors remain largely unknown. We now show that cardiomyocytes from mice with an Lmna mutation and elevated cardiac ERK1/2 activity have altered nuclear positioning. In fibroblasts, ERK1/2 activation negatively regulated nuclear movement by phosphorylating S498 of FHOD1. Expression of an unphosphorylatable FHOD1 variant rescued the nuclear movement defect in fibroblasts expressing a cardiomyopathy-causing lamin A mutant. In hearts of mice with LMNA mutation-induced cardiomyopathy, ERK1/2 mediated phosphorylation of FHOD3, an isoform highly expressed in cardiac tissue. Phosphorylation of FHOD1 and FHOD3 inhibited their actin bundling activity. These results show that phosphorylation of FHOD proteins by ERK1/2 is a critical switch for nuclear positioning and may play a role in the pathogenesis of cardiomyopathy caused by LMNA mutations.
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Affiliation(s)
- Susumu Antoku
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Wei Wu
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA; Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Leroy C Joseph
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - John P Morrow
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Howard J Worman
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA; Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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14
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Abstract
LINC complexes (Linker of Nucleoskeleton and Cytoskeleton), consisting of inner nuclear membrane SUN (Sad1, UNC-84) proteins and outer nuclear membrane KASH (Klarsicht, ANC-1, and Syne Homology) proteins, are essential for nuclear positioning, cell migration and chromosome dynamics. To test the in vivo functions of conserved interfaces revealed by crystal structures, Cain et al used a combination of Caenorhabditis elegans genetics, imaging in cultured NIH 3T3 fibroblasts, and Molecular Dynamic simulations, to study SUN-KASH interactions. Conserved aromatic residues at the -7 position of the C-termini of KASH proteins and conserved disulfide bonds in LINC complexes play important roles in force transmission across the nuclear envelope. Other properties of LINC complexes, such as the helices preceding the SUN domain, the longer coiled-coils spanning the perinuclear space and higher-order organization may also function to transmit mechanical forces generated by the cytoskeleton across the nuclear envelope.
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Affiliation(s)
- Hongyan Hao
- a Department of Molecular and Cellular Biology , University of California , Davis , CA USA
| | - Daniel A Starr
- a Department of Molecular and Cellular Biology , University of California , Davis , CA USA
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15
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Azevedo M, Baylies MK. Getting into Position: Nuclear Movement in Muscle Cells. Trends Cell Biol 2020; 30:303-316. [PMID: 32008895 DOI: 10.1016/j.tcb.2020.01.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [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: 11/18/2019] [Revised: 01/04/2020] [Accepted: 01/06/2020] [Indexed: 12/26/2022]
Abstract
The positioning of nuclei within the cell is a dynamic process that depends on the cell's fate and developmental stage and that is adjusted for optimal cell function. This is especially true in skeletal muscle cells, which contain hundreds of myonuclei distributed evenly along the periphery of the muscle cell. Mispositioned myonuclei are often associated with muscle dysfunction and disease. Different mechanisms governing myonuclear positioning are now emerging, with several of the new genes implicated in nuclear movement linked to human muscle disease. Here we discuss the recent advances in myonuclear positioning and its implications for muscle size and function from the view of Drosophila. Additionally, we highlight similarities and differences to mammalian systems and provide connections to human muscle disease.
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Affiliation(s)
- Mafalda Azevedo
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA; Graduate Program in Areas of Basic and Applied Biology (GABBA), Abel Salazar Biomedical Sciences Institute, University of Porto, Porto, Portugal
| | - Mary K Baylies
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA; Cell and Developmental Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY, USA.
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16
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Starr DA. A network of nuclear envelope proteins and cytoskeletal force generators mediates movements of and within nuclei throughout Caenorhabditis elegans development. Exp Biol Med (Maywood) 2019; 244:1323-1332. [PMID: 31495194 PMCID: PMC6880151 DOI: 10.1177/1535370219871965] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nuclear migration and anchorage, together referred to as nuclear positioning, are central to many cellular and developmental events. Nuclear positioning is mediated by a conserved network of nuclear envelope proteins that interacts with force generators in the cytoskeleton. At the heart of this network are li nker of n ucleoskeleton and c ytoskeleton (LINC) complexes made of S ad1 and UN C-84 (SUN) proteins at the inner nuclear membrane and K larsicht, A NC-1, and S yne homology (KASH) proteins in the outer nuclear membrane. LINC complexes span the nuclear envelope, maintain nuclear envelope architecture, designate the surface of nuclei distinctly from the contiguous endoplasmic reticulum, and were instrumental in the early evolution of eukaryotes. LINC complexes interact with lamins in the nucleus and with various cytoplasmic KASH effectors from the surface of nuclei. These effectors regulate the cytoskeleton, leading to a variety of cellular outputs including pronuclear migration, nuclear migration through constricted spaces, nuclear anchorage, centrosome attachment to nuclei, meiotic chromosome movements, and DNA damage repair. How LINC complexes are regulated and how they function are reviewed here. The focus is on recent studies elucidating the best-understood network of LINC complexes, those used throughout Caenorhabditis elegans development.
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Affiliation(s)
- Daniel A Starr
- Department of Molecular and Cellular Biology,
University of California, Davis, CA 95616, USA
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17
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Deneke VE, Puliafito A, Krueger D, Narla AV, De Simone A, Primo L, Vergassola M, De Renzis S, Di Talia S. Self-Organized Nuclear Positioning Synchronizes the Cell Cycle in Drosophila Embryos. Cell 2019; 177:925-941.e17. [PMID: 30982601 DOI: 10.1016/j.cell.2019.03.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 12/16/2018] [Accepted: 03/04/2019] [Indexed: 11/22/2022]
Abstract
The synchronous cleavage divisions of early embryogenesis require coordination of the cell-cycle oscillator, the dynamics of the cytoskeleton, and the cytoplasm. Yet, it remains unclear how spatially restricted biochemical signals are integrated with physical properties of the embryo to generate collective dynamics. Here, we show that synchronization of the cell cycle in Drosophila embryos requires accurate nuclear positioning, which is regulated by the cell-cycle oscillator through cortical contractility and cytoplasmic flows. We demonstrate that biochemical oscillations are initiated by local Cdk1 inactivation and spread through the activity of phosphatase PP1 to generate cortical myosin II gradients. These gradients cause cortical and cytoplasmic flows that control proper nuclear positioning. Perturbations of PP1 activity and optogenetic manipulations of cortical actomyosin disrupt nuclear spreading, resulting in loss of cell-cycle synchrony. We conclude that mitotic synchrony is established by a self-organized mechanism that integrates the cell-cycle oscillator and embryo mechanics.
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18
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Windner SE, Manhart A, Brown A, Mogilner A, Baylies MK. Nuclear Scaling Is Coordinated among Individual Nuclei in Multinucleated Muscle Fibers. Dev Cell 2019; 49:48-62.e3. [PMID: 30905770 DOI: 10.1016/j.devcel.2019.02.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 11/28/2018] [Accepted: 02/22/2019] [Indexed: 12/22/2022]
Abstract
Optimal cell performance depends on cell size and the appropriate relative size, i.e., scaling, of the nucleus. How nuclear scaling is regulated and contributes to cell function is poorly understood, especially in skeletal muscle fibers, which are among the largest cells, containing hundreds of nuclei. Here, we present a Drosophila in vivo system to analyze nuclear scaling in whole multinucleated muscle fibers, genetically manipulate individual components, and assess muscle function. Despite precise global coordination, we find that individual nuclei within a myofiber establish different local scaling relationships by adjusting their size and synthetic activity in correlation with positional or spatial cues. While myonuclei exhibit compensatory potential, even minor changes in global nuclear size scaling correlate with reduced muscle function. Our study provides the first comprehensive approach to unraveling the intrinsic regulation of size in multinucleated muscle fibers. These insights to muscle cell biology will accelerate the development of interventions for muscle diseases.
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19
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Meyer GA. Evidence of induced muscle regeneration persists for years in the mouse. Muscle Nerve 2018; 58:858-862. [PMID: 30159908 DOI: 10.1002/mus.26329] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [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: 04/30/2018] [Revised: 08/21/2018] [Accepted: 08/26/2018] [Indexed: 11/09/2022]
Abstract
INTRODUCTION Efficient repositioning of centralized nuclei after injury has long been assumed, with centralized nuclei frequently cited as indicators of ongoing regeneration. However, reports of centralized nuclei that persist after full recovery of fiber area and muscle force production call into question the time course of nuclear repositioning. METHODS We evaluated regeneration after cardiotoxin-induced damage in 10-week-old mice by quantifying intracellular and extracellular pathology at 2 and 94 weeks post-injection. RESULTS Centrally nucleated fibers were still prevalent at 94 weeks post-injection, representing > 25% of muscle fibers. Areas with > 90% centrally nucleated fibers could still be identified. Extra-myocellular indicators of regeneration (e.g., fibrosis and fatty infiltration) also remained significantly elevated at the 94-week time-point. DISCUSSION These findings indicate that not all nuclei are repositioned at the conclusion of induced muscle regeneration. Muscle Nerve 58:858-862, 2018.
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Affiliation(s)
- Gretchen A Meyer
- Program in Physical Therapy, Washington University in St. Louis, 4444 Forest Park Avenue, Suite 1101, St. Louis, Missouri, 63108, USA
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20
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Cain NE, Jahed Z, Schoenhofen A, Valdez VA, Elkin B, Hao H, Harris NJ, Herrera LA, Woolums BM, Mofrad MRK, Luxton GWG, Starr DA. Conserved SUN-KASH Interfaces Mediate LINC Complex-Dependent Nuclear Movement and Positioning. Curr Biol 2018; 28:3086-3097.e4. [PMID: 30245107 DOI: 10.1016/j.cub.2018.08.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [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: 12/27/2017] [Revised: 06/18/2018] [Accepted: 08/01/2018] [Indexed: 12/20/2022]
Abstract
Many nuclear positioning events involve linker of nucleoskeleton and cytoskeleton (LINC) complexes, which transmit forces generated by the cytoskeleton across the nuclear envelope. LINC complexes are formed by trans-luminal interactions between inner nuclear membrane SUN proteins and outer nuclear membrane KASH proteins, but how these interactions are regulated is poorly understood. We combine in vivo C. elegans genetics, in vitro wounded fibroblast polarization, and in silico molecular dynamics simulations to elucidate mechanisms of LINC complexes. The extension of the KASH domain by a single alanine residue or the mutation of the conserved tyrosine at -7 completely blocked the nuclear migration function of C. elegans UNC-83. Analogous mutations at -7 of mouse nesprin-2 disrupted rearward nuclear movements in NIH 3T3 cells, but did not disrupt ANC-1 in nuclear anchorage. Furthermore, conserved cysteines predicted to form a disulfide bond between SUN and KASH proteins are important for the function of certain LINC complexes, and might promote a developmental switch between nuclear migration and nuclear anchorage. Mutations of conserved cysteines in SUN or KASH disrupted ANC-1-dependent nuclear anchorage in C. elegans and Nesprin-2G-dependent nuclear movements in polarizing fibroblasts. However, the SUN cysteine mutation did not disrupt nuclear migration. Moreover, molecular dynamics simulations showed that a disulfide bond is necessary for the maximal transmission of cytoskeleton-generated forces by LINC complexes in silico. Thus, we have demonstrated functions for SUN-KASH binding interfaces, including a predicted intermolecular disulfide bond, as mechanistic determinants of nuclear positioning that may represent targets for regulation.
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Affiliation(s)
- Natalie E Cain
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA
| | - Zeinab Jahed
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, 208A Stanley Hall, Berkeley, CA 94720, USA
| | - Amy Schoenhofen
- Department of Genetics, Cell Biology, and Development, University of Minnesota, 420 Washington Avenue SE, Minneapolis, MN 55455, USA
| | - Venecia A Valdez
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA
| | - Baila Elkin
- Department of Genetics, Cell Biology, and Development, University of Minnesota, 420 Washington Avenue SE, Minneapolis, MN 55455, USA
| | - Hongyan Hao
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA
| | - Nathan J Harris
- Department of Genetics, Cell Biology, and Development, University of Minnesota, 420 Washington Avenue SE, Minneapolis, MN 55455, USA
| | - Leslie A Herrera
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA
| | - Brian M Woolums
- Department of Genetics, Cell Biology, and Development, University of Minnesota, 420 Washington Avenue SE, Minneapolis, MN 55455, USA
| | - Mohammad R K Mofrad
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, 208A Stanley Hall, Berkeley, CA 94720, USA
| | - G W Gant Luxton
- Department of Genetics, Cell Biology, and Development, University of Minnesota, 420 Washington Avenue SE, Minneapolis, MN 55455, USA
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA.
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21
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Zhao T, Li R, Tan X, Zhang J, Fan C, Zhao Q, Deng Y, Xu A, Lukong KE, Genth H, Xiang J. Simulated Microgravity Reduces Focal Adhesions and Alters Cytoskeleton and Nuclear Positioning Leading to Enhanced Apoptosis via Suppressing FAK/RhoA-Mediated mTORC1/NF-κB and ERK1/2 Pathways. Int J Mol Sci 2018; 19:ijms19071994. [PMID: 29986550 PMCID: PMC6073227 DOI: 10.3390/ijms19071994] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/04/2018] [Accepted: 07/06/2018] [Indexed: 12/16/2022] Open
Abstract
Simulated-microgravity (SMG) promotes cell-apoptosis. We demonstrated that SMG inhibited cell proliferation/metastasis via FAK/RhoA-regulated mTORC1 pathway. Since mTORC1, NF-κB, and ERK1/2 signaling are important in cell apoptosis, we examined whether SMG-enhanced apoptosis is regulated via these signals controlled by FAK/RhoA in BL6-10 melanoma cells under clinostat-modelled SMG-condition. We show that SMG promotes cell-apoptosis, alters cytoskeleton, reduces focal adhesions (FAs), and suppresses FAK/RhoA signaling. SMG down-regulates expression of mTORC1-related Raptor, pS6K, pEIF4E, pNF-κB, and pNF-κB-regulated Bcl2, and induces relocalization of pNF-κB from the nucleus to the cytoplasm. In addition, SMG also inhibits expression of nuclear envelope proteins (NEPs) lamin-A, emerin, sun1, and nesprin-3, which control nuclear positioning, and suppresses nuclear positioning-regulated pERK1/2 signaling. Moreover, rapamycin, the mTORC1 inhibitor, also enhances apoptosis in cells under 1 g condition via suppressing the mTORC1/NF-κB pathway. Furthermore, the FAK/RhoA activator, toxin cytotoxic necrotizing factor-1 (CNF1), reduces cell apoptosis, restores the cytoskeleton, FAs, NEPs, and nuclear positioning, and converts all of the above SMG-induced changes in molecular signaling in cells under SMG. Therefore, our data demonstrate that SMG reduces FAs and alters the cytoskeleton and nuclear positioning, leading to enhanced cell apoptosis via suppressing the FAK/RhoA-regulated mTORC1/NF-κB and ERK1/2 pathways. The FAK/RhoA regulatory network may, thus, become a new target for the development of novel therapeutics for humans under spaceflight conditions with stressed physiological challenges, and for other human diseases.
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Affiliation(s)
- Tuo Zhao
- School of Life Sciences, Beijing Institute of Technology, Beijing 10081, China.
| | - Rong Li
- Cancer Research, Saskatchewan Cancer Agency, Saskatoon, SK S7N 4H4, Canada.
- Department of Oncology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Xin Tan
- School of Life Sciences, Beijing Institute of Technology, Beijing 10081, China.
| | - Jun Zhang
- School of Life Sciences, Beijing Institute of Technology, Beijing 10081, China.
| | - Cuihong Fan
- School of Life Sciences, Beijing Institute of Technology, Beijing 10081, China.
| | - Qin Zhao
- School of Life Sciences, Beijing Institute of Technology, Beijing 10081, China.
| | - Yulin Deng
- School of Life Sciences, Beijing Institute of Technology, Beijing 10081, China.
| | - Aizhang Xu
- Cancer Research, Saskatchewan Cancer Agency, Saskatoon, SK S7N 4H4, Canada.
- Department of Oncology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Kiven Erique Lukong
- Department of Biochemistry, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
| | - Harald Genth
- Institute of Toxicology, Hannover Medical School, D-30625 Hannover, Germany.
| | - Jim Xiang
- Cancer Research, Saskatchewan Cancer Agency, Saskatoon, SK S7N 4H4, Canada.
- Department of Oncology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
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22
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Le Noir S, Laffleur B, Carrion C, Garot A, Lecardeur S, Pinaud E, Denizot Y, Skok J, Cogné M. The IgH locus 3' cis-regulatory super-enhancer co-opts AID for allelic transvection. Oncotarget 2017; 8:12929-12940. [PMID: 28088785 PMCID: PMC5355067 DOI: 10.18632/oncotarget.14585] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [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: 12/20/2016] [Accepted: 01/01/2017] [Indexed: 11/25/2022] Open
Abstract
Immunoglobulin heavy chain (IgH) alleles have ambivalent relationships: they feature both allelic exclusion, ensuring monoallelic expression of a single immunoglobulin (Ig) allele, and frequent inter-allelic class-switch recombination (CSR) reassembling genes from both alleles. The IgH locus 3' regulatory region (3'RR) includes several transcriptional cis-enhancers promoting activation-induced cytidine deaminase (AID)-dependent somatic hypermutation (SHM) and CSR, and altogether behaves as a strong super-enhancer. It can also promote deregulated expression of translocated oncogenes during lymphomagenesis. Besides these rare, illegitimate and pathogenic interactions, we now show that under physiological conditions, the 3'RR super-enhancer supports not only legitimate cis- , but also trans-recruitment of AID, contributing to IgH inter-allelic proximity and enabling the super-enhancer on one allele to stimulate biallelic SHM and CSR. Such inter-allelic activating interactions define transvection, a phenomenon well-known in drosophila but rarely observed in mammalian cells, now appearing as a unique feature of the IgH 3'RR super-enhancer.
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Affiliation(s)
- Sandrine Le Noir
- UMR 7276 CNRS and Université de Limoges: Contrôle de la Réponse Immune B et Lymphoprolifération, Limoges, France
| | - Brice Laffleur
- UMR 7276 CNRS and Université de Limoges: Contrôle de la Réponse Immune B et Lymphoprolifération, Limoges, France
| | - Claire Carrion
- UMR 7276 CNRS and Université de Limoges: Contrôle de la Réponse Immune B et Lymphoprolifération, Limoges, France
| | - Armand Garot
- UMR 7276 CNRS and Université de Limoges: Contrôle de la Réponse Immune B et Lymphoprolifération, Limoges, France
| | - Sandrine Lecardeur
- UMR 7276 CNRS and Université de Limoges: Contrôle de la Réponse Immune B et Lymphoprolifération, Limoges, France
| | - Eric Pinaud
- UMR 7276 CNRS and Université de Limoges: Contrôle de la Réponse Immune B et Lymphoprolifération, Limoges, France
| | - Yves Denizot
- UMR 7276 CNRS and Université de Limoges: Contrôle de la Réponse Immune B et Lymphoprolifération, Limoges, France
| | - Jane Skok
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Michel Cogné
- UMR 7276 CNRS and Université de Limoges: Contrôle de la Réponse Immune B et Lymphoprolifération, Limoges, France
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23
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Gimpel P, Lee YL, Sobota RM, Calvi A, Koullourou V, Patel R, Mamchaoui K, Nédélec F, Shackleton S, Schmoranzer J, Burke B, Cadot B, Gomes ER. Nesprin-1α-Dependent Microtubule Nucleation from the Nuclear Envelope via Akap450 Is Necessary for Nuclear Positioning in Muscle Cells. Curr Biol 2017; 27:2999-3009.e9. [PMID: 28966089 DOI: 10.1016/j.cub.2017.08.031] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/08/2017] [Accepted: 08/15/2017] [Indexed: 11/20/2022]
Abstract
The nucleus is the main microtubule-organizing center (MTOC) in muscle cells due to the accumulation of centrosomal proteins and microtubule (MT) nucleation activity at the nuclear envelope (NE) [1, 2, 3, 4]. The relocalization of centrosomal proteins, including Pericentrin, Pcm1, and γ-tubulin, depends on Nesprin-1, an outer nuclear membrane (ONM) protein that connects the nucleus to the cytoskeleton via its N-terminal region [5, 6, 7]. Nesprins are also involved in the recruitment of kinesin to the NE and play a role in nuclear positioning in skeletal muscle cells [8, 9, 10, 11, 12]. However, a function for MT nucleation from the NE in nuclear positioning has not been established. Using the proximity-dependent biotin identification (BioID) method [13, 14], we found several centrosomal proteins, including Akap450, Pcm1, and Pericentrin, whose association with Nesprin-1α is increased in differentiated myotubes. We show that Nesprin-1α recruits Akap450 to the NE independently of kinesin and that Akap450, but not other centrosomal proteins, is required for MT nucleation from the NE. Furthermore, we demonstrate that this mechanism is disrupted in congenital muscular dystrophy patient myotubes carrying a nonsense mutation within the SYNE1 gene (23560 G>T) encoding Nesprin-1 [15, 16]. Finally, using computer simulation and cell culture systems, we provide evidence for a role of MT nucleation from the NE on nuclear spreading in myotubes. Our data thus reveal a novel function for Nesprin-1α/Nesprin-1 in nuclear positioning through recruitment of Akap450-mediated MT nucleation activity to the NE. BioID of Nesprin-1α identifies centrosomal proteins at myotube nuclear envelope Nesprin-1α-containing LINC complexes recruit Akap450 to myotube nuclear envelope Akap450 is required for microtubule nucleation at the nuclear envelope Microtubule nucleation at the nuclear envelope is involved in nuclear positioning
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Wan ZY, Zhang Y, Li S. Protein S-acyl transferase 4 controls nucleus position during root hair tip growth. Plant Signal Behav 2017; 12:e1311438. [PMID: 28368733 PMCID: PMC5437833 DOI: 10.1080/15592324.2017.1311438] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 03/16/2017] [Accepted: 03/20/2017] [Indexed: 05/29/2023]
Abstract
Protein S-acyl transferases (PATs) play critical roles in plant developmental and environmental responses by catalyzing S-acylation of substrate proteins, most of which are involved in cellular signaling. However, only few plant PATs have been functionally characterized. We recently demonstrated that Arabidopsis PAT4 mediates root hair elongation by positively regulating the membrane association of ROP2 and actin microfilament organization. Here, we show that apex-associated re-positioning of nucleus during root hair elongation was impaired by PAT4 loss-of-function. Results presented here pose a significant question concerning the molecular machinery mediating nuclear migration during root hair growth.
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Affiliation(s)
- Zhi-Yuan Wan
- Stage Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Tai'an, Shandong, China
| | - Yan Zhang
- Stage Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Tai'an, Shandong, China
| | - Sha Li
- Stage Key Laboratory of Crop Biology, College of Life Science, Shandong Agricultural University, Tai'an, Shandong, China
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Quintin S, Gally C, Labouesse M. Noncentrosomal microtubules in C. elegans epithelia. Genesis 2016; 54:229-42. [PMID: 26789944 DOI: 10.1002/dvg.22921] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 12/08/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 11/12/2022]
Abstract
The microtubule cytoskeleton has a dual contribution to cell organization. First, microtubules help displace chromosomes and provide tracks for organelle transport. Second, microtubule rigidity confers specific mechanical properties to cells, which are crucial in cilia or mechanosensory structures. Here we review the recently uncovered organization and functions of noncentrosomal microtubules in C. elegans epithelia, focusing on how they contribute to nuclear positioning and protein transport. In addition, we describe recent data illustrating how the microtubule and actin cytoskeletons interact to achieve those functions.
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Affiliation(s)
- Sophie Quintin
- Development and Stem Cells Department, IGBMC - CNRS UMR 7104/INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, Illkirch, 67400, France
| | - Christelle Gally
- Development and Stem Cells Department, IGBMC - CNRS UMR 7104/INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, Illkirch, 67400, France
| | - Michel Labouesse
- Université Pierre Et Marie Curie, IBPS, CNRS UMR7622, 7 Quai St-Bernard, Paris, 75005, France
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Chang W, Antoku S, Östlund C, Worman HJ, Gundersen GG. Linker of nucleoskeleton and cytoskeleton (LINC) complex-mediated actin-dependent nuclear positioning orients centrosomes in migrating myoblasts. Nucleus 2015; 6:77-88. [PMID: 25587885 DOI: 10.1080/19491034.2015.1004947] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Myoblast migration is essential for muscle development and repair; however, the factors that contribute to the polarity of migrating myoblasts are relatively unknown. We find that randomly migrating C2C12 myoblasts orient their centrosomes in the direction of migration. Using wounded monolayers, we further show that centrosome orientation is stimulated by the serum factor lysophosphatidic acid (LPA) and involves the rearward movement of the nucleus while the centrosome is maintained at the cell centroid. The rate of nuclear movement correlated with that of actin retrograde flow and both cytochalasin D and blebbistatin prevented nuclear movement and centrosome orientation. Actin-dependent rearward nuclear movement in fibroblasts is mediated by assembly of nuclear membrane nesprin-2G and SUN2 LINC complexes into transmembrane actin-associated nuclear (TAN) lines anchored by A-type lamins and emerin. In C2C12 myoblasts, depletion of nesprin-2G, SUN2 or lamin A/C prevented nuclear movement and endogenous nesprin-2G and a chimeric GFP-mini-nesprin-2G formed TAN lines during nuclear movement. Depleting nesprin-2G strongly interfered with directed cell migration and reduced the efficiency of myoblast fusion into multinucleated myotubes. Our results show that nuclear movement contributes to centrosome orientation and polarity for efficient migration and fusion of myoblasts. Given that mutations in the genes encoding A-type lamins, nesprin-2 and SUN2 cause Emery-Dreifuss muscular dystrophy and related myopathies, our results have implications for understanding the mechanism of disease pathogenesis.
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Affiliation(s)
- Wakam Chang
- a Department of Pathology and Cell Biology ; College of Physicians and Surgeons; Columbia University ; New York , NY USA
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Neelam S, Chancellor TJ, Li Y, Nickerson JA, Roux KJ, Dickinson RB, Lele TP. Direct force probe reveals the mechanics of nuclear homeostasis in the mammalian cell. Proc Natl Acad Sci U S A 2015; 112:5720-5. [PMID: 25901323 DOI: 10.1073/pnas.1502111112] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
How cells maintain nuclear shape and position against various intracellular and extracellular forces is not well understood, although defects in nuclear mechanical homeostasis are associated with a variety of human diseases. We estimated the force required to displace and deform the nucleus in adherent living cells with a technique to locally pull the nuclear surface. A minimum pulling force of a few nanonewtons--far greater than typical intracellular motor forces--was required to significantly displace and deform the nucleus. Upon force removal, the original shape and position were restored quickly within a few seconds. This stiff, elastic response required the presence of vimentin, lamin A/C, and SUN (Sad1p, UNC-84)-domain protein linkages, but not F-actin or microtubules. Although F-actin and microtubules are known to exert mechanical forces on the nuclear surface through molecular motor activity, we conclude that the intermediate filament networks maintain nuclear mechanical homeostasis against localized forces.
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Abstract
The nuclear envelope (NE) is a double membrane system enclosing the genome of eukaryotes. Besides nuclear pore proteins, which form channels at the NE, nuclear membranes are populated by a collection of NE proteins that perform various cellular functions. However, in contrast to well-conserved nuclear pore proteins, known NE proteins share little homology between opisthokonts and plants. Recent studies on NE protein complexes formed by Sad1/UNC-84 (SUN) and Klarsicht/ANC-1/Syne-1 Homology (KASH) proteins have advanced our understanding of plant NE proteins and revealed their function in anchoring other proteins at the NE, nuclear shape determination, nuclear positioning, anti-pathogen defence, root development, and meiotic chromosome organization. In this review, we discuss the current understanding of plant SUN, KASH, and other related NE proteins, and compare their function with the opisthokont counterparts.
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Affiliation(s)
- Xiao Zhou
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Katja Graumann
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Headington Campus, Oxford OX3 OBP, UK
| | - Iris Meier
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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Abstract
Nuclear positioning is an important process during development and homeostasis. Depending on the affected tissue, mislocalized nuclei can alter cellular processes such as polarization, differentiation, or migration and lead ultimately to diseases. Many cells actively control the position of their nucleus using their cytoskeleton and motor proteins. We have recently shown that during Drosophila oogenesis, nurse cells employ cytoplasmic actin cables in association with perinuclear actin to position their nucleus. Here, we briefly summarize our work and discuss why nuclear positioning in nurse cells is specialized but the molecular mechanisms are likely to be more generally used.
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Affiliation(s)
- Sven Huelsmann
- The Gurdon Institute and Department of Physiology, Development, and Neuroscience; University of Cambridge; Cambridge, UK; Department of Biological and Environmental Science; University of Jyväskylä; Jyväskylä, Finland
| | - Nicholas H Brown
- The Gurdon Institute and Department of Physiology, Development, and Neuroscience; University of Cambridge; Cambridge, UK
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Shinar T, Mana M, Piano F, Shelley MJ. A model of cytoplasmically driven microtubule-based motion in the single-celled Caenorhabditis elegans embryo. Proc Natl Acad Sci U S A 2011; 108:10508-13. [PMID: 21670261 PMCID: PMC3127902 DOI: 10.1073/pnas.1017369108] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
We present a model of cytoplasmically driven microtubule-based pronuclear motion in the single-celled Caenorhabditis elegans embryo. In this model, a centrosome pair at the male pronucleus initiates stochastic microtubule (MT) growth. These MTs encounter motor proteins, distributed throughout the cytoplasm, that attach and exert a pulling force. The consequent MT-length-dependent pulling forces drag the pronucleus through the cytoplasm. On physical grounds, we assume that the motor proteins also exert equal and opposite forces on the surrounding viscous cytoplasm, here modeled as an incompressible Newtonian fluid constrained within an ellipsoidal eggshell. This naturally leads to streaming flows along the MTs. Our computational method is based on an immersed boundary formulation that allows for the simultaneous treatment of fluid flow and the dynamics of structures immersed within. Our simulations demonstrate that the balance of MT pulling forces and viscous nuclear drag is sufficient to move the pronucleus, while simultaneously generating minus-end directed flows along MTs that are similar to the observed movement of yolk granules toward the center of asters. Our simulations show pronuclear migration, and moreover, a robust pronuclear centration and rotation very similar to that observed in vivo. We find also that the confinement provided by the eggshell significantly affects the internal dynamics of the cytoplasm, increasing by an order of magnitude the forces necessary to translocate and center the pronucleus.
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Affiliation(s)
- Tamar Shinar
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA.
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Iwabuchi K, Takagi S. Actin-based mechanisms for light-dependent intracellular positioning of nuclei and chloroplasts in Arabidopsis. Plant Signal Behav 2010; 5:1010-3. [PMID: 20724834 PMCID: PMC3115182 DOI: 10.4161/psb.5.8.12233] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Accepted: 05/02/2010] [Indexed: 05/19/2023]
Abstract
The plant organelles, chloroplast and nucleus, change their position in response to light. In Arabidopsis thaliana leaf cells, chloroplasts and nuclei are distributed along the inner periclinal wall in darkness. In strong blue light, they become positioned along the anticlinal wall, while in weak blue light, only chloroplasts are accumulated along the inner and outer periclinal walls. Blue-light dependent positioning of both organelles is mediated by the blue-light receptor phototropin and controlled by the actin cytoskeleton. Interestingly, however, it seems that chloroplast movement requires short, fine actin filaments organized at the chloroplast edge, whereas nuclear movement does cytoplasmic, thick actin bundles intimately associated with the nucleus. Although there are many similarities between photo-relocation movements of chloroplasts and nuclei, plant cells appear to have evolved distinct mechanisms to regulate actin organization required for driving the movements of these organelles.
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Frey N, Klotz J, Nick P. A kinesin with calponin-homology domain is involved in premitotic nuclear migration. J Exp Bot 2010; 61:3423-37. [PMID: 20566563 PMCID: PMC2905203 DOI: 10.1093/jxb/erq164] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 05/15/2010] [Accepted: 05/18/2010] [Indexed: 05/17/2023]
Abstract
Interaction and cross-talk between microtubules and actin microfilaments are important for numerous processes during plant growth and development, including the control of cell elongation and tissue expansion, but little is known about the molecular components of this interaction. Plant kinesins with the calponin-homology domain (KCH) were recently identified and associated with a putative role in microtubule-microfilament cross-linking. The putative biological role of the rice KCH member OsKCH1 is addressed here using a combined approach with Tos17 kch1 knock-out mutants on the one hand, and a KCH1 overexpression line generated in tobacco BY-2 cells. It is shown that OsKCH1 is expressed in a development and tissue-specific manner in rice and antagonistic cell elongation and division phenotypes as a result of knock-down and overexpression are reported. Further, the dynamic repartitioning of OsKCH1 during the cell cycle is described and it is demonstrated that KCH overexpression delays nuclear positioning and mitosis in BY-2 cells. These findings are discussed with respect to a putative role of KCHs as linkers between actin filaments and microtubules during nuclear positioning.
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Affiliation(s)
- Nicole Frey
- Institute of Botany 1 and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Kaiserstrasse 2, D-76131 Karlsruhe, Germany.
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Iwabuchi K, Takagi S. How and why do plant nuclei move in response to light? Plant Signal Behav 2008; 3:266-268. [PMID: 19704650 PMCID: PMC2634198 DOI: 10.4161/psb.3.4.5213] [Citation(s) in RCA: 5] [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] [Subscribe] [Scholar Register] [Received: 10/25/2008] [Accepted: 10/28/2007] [Indexed: 05/28/2023]
Abstract
We recently found that nuclei take different intracellular positions depending upon dark and light conditions in Arabidopsis thaliana leaf cells. Under dark conditions, nuclei in both epidermal and mesophyll cells are distributed baso-centrally within the cell (dark position). Under light conditions, in contrast, nuclei are distributed along the anticlinal walls (light position). Nuclear repositioning from the dark to light positions is induced specifically by blue light at >50 micromol m(-2) s(-1) in a reversible manner. Using analysis of mutant plants, it was demonstrated that the response is mediated by the blue-light photoreceptor phototropin2. Intriguingly, phototropin2 also seems to play an important role in the proper positioning of nuclei and chloroplasts under dark conditions. Light-dependent nuclear positioning is one of the organelle movements regulated by phototropin2. However, the mechanisms of organelle motility, physiological significance, and generality of the phenomenon are poorly understood. In this addendum, we discussed how and why nuclei move depending on light, together with future perspectives.
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Affiliation(s)
- Kosei Iwabuchi
- Department of Biological Sciences; Graduate School of Science; Osaka University; Toyonaka, Osaka, Japan
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Abstract
The correct positioning of the nucleus is often important in defining the spatial organization of the cell, for example, in determining the cell division plane. In interphase Schizosaccharomyces pombe cells, the nucleus is positioned in the middle of the cylindrical cell in an active microtubule (MT)-dependent process. Here, we used green fluorescent protein markers to examine the dynamics of MTs, spindle pole body, and the nuclear envelope in living cells. We find that interphase MTs are organized in three to four antiparallel MT bundles arranged along the long axis of the cell, with MT plus ends facing both the cell tips and minus ends near the middle of the cell. The MT bundles are organized from medial MT-organizing centers that may function as nuclear attachment sites. When MTs grow to the cell tips, they exert transient forces produced by plus end MT polymerization that push the nucleus. After an average of 1.5 min of growth at the cell tip, MT plus ends exhibit catastrophe and shrink back to the nuclear region before growing back to the cell tip. Computer modeling suggests that a balance of these pushing MT forces can provide a mechanism to position the nucleus at the middle of the cell.
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Affiliation(s)
- P T Tran
- Department of Microbiology, Columbia University, New York, New York 10032, USA.
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