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Walsh ME, King GA, Ünal E. Not just binary: embracing the complexity of nuclear division dynamics. Nucleus 2024; 15:2360601. [PMID: 38842147 PMCID: PMC11164224 DOI: 10.1080/19491034.2024.2360601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 05/22/2024] [Indexed: 06/07/2024] Open
Abstract
Cell division presents a challenge for eukaryotic cells: how can chromosomes effectively segregate within the confines of a membranous nuclear compartment? Different organisms have evolved diverse solutions by modulating the degree of nuclear compartmentalization, ranging from complete nuclear envelope breakdown to complete maintenance of nuclear compartmentalization via nuclear envelope expansion. Many intermediate forms exist between these extremes, suggesting that nuclear dynamics during cell division are surprisingly plastic. In this review, we highlight the evolutionary diversity of nuclear divisions, focusing on two defining characteristics: (1) chromosome compartmentalization and (2) nucleocytoplasmic transport. Further, we highlight recent evidence that nuclear behavior during division can vary within different cellular contexts in the same organism. The variation observed within and between organisms underscores the dynamic evolution of nuclear divisions tailored to specific contexts and cellular requirements. In-depth investigation of diverse nuclear divisions will enhance our understanding of the nucleus, both in physiological and pathological states.
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Affiliation(s)
- Madison E. Walsh
- Department of Molecular and Cell Biology, Barker Hall, University of California, Berkeley, CA, USA
| | - Grant A. King
- Department of Molecular and Cell Biology, Barker Hall, University of California, Berkeley, CA, USA
| | - Elçin Ünal
- Department of Molecular and Cell Biology, Barker Hall, University of California, Berkeley, CA, USA
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2
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La Torre M, Burla R, Saggio I. Preserving Genome Integrity: Unveiling the Roles of ESCRT Machinery. Cells 2024; 13:1307. [PMID: 39120335 PMCID: PMC11311930 DOI: 10.3390/cells13151307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2024] [Revised: 08/02/2024] [Accepted: 08/02/2024] [Indexed: 08/10/2024] Open
Abstract
The endosomal sorting complex required for transport (ESCRT) machinery is composed of an articulated architecture of proteins that assemble at multiple cellular sites. The ESCRT machinery is involved in pathways that are pivotal for the physiology of the cell, including vesicle transport, cell division, and membrane repair. The subunits of the ESCRT I complex are mainly responsible for anchoring the machinery to the action site. The ESCRT II subunits function to bridge and recruit the ESCRT III subunits. The latter are responsible for finalizing operations that, independently of the action site, involve the repair and fusion of membrane edges. In this review, we report on the data related to the activity of the ESCRT machinery at two sites: the nuclear membrane and the midbody and the bridge linking cells in the final stages of cytokinesis. In these contexts, the machinery plays a significant role for the protection of genome integrity by contributing to the control of the abscission checkpoint and to nuclear envelope reorganization and correlated resilience. Consistently, several studies show how the dysfunction of the ESCRT machinery causes genome damage and is a codriver of pathologies, such as laminopathies and cancer.
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Affiliation(s)
- Mattia La Torre
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, 00185 Rome, Italy; (M.L.T.); (R.B.)
| | - Romina Burla
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, 00185 Rome, Italy; (M.L.T.); (R.B.)
- CNR Institute of Molecular Biology and Pathology, 00185 Rome, Italy
| | - Isabella Saggio
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, 00185 Rome, Italy; (M.L.T.); (R.B.)
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3
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Acs-Szabo L, Papp LA, Miklos I. Understanding the molecular mechanisms of human diseases: the benefits of fission yeasts. MICROBIAL CELL (GRAZ, AUSTRIA) 2024; 11:288-311. [PMID: 39104724 PMCID: PMC11299203 DOI: 10.15698/mic2024.08.833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 07/04/2024] [Accepted: 07/10/2024] [Indexed: 08/07/2024]
Abstract
The role of model organisms such as yeasts in life science research is crucial. Although the baker's yeast (Saccharomyces cerevisiae) is the most popular model among yeasts, the contribution of the fission yeasts (Schizosaccharomyces) to life science is also indisputable. Since both types of yeasts share several thousands of common orthologous genes with humans, they provide a simple research platform to investigate many fundamental molecular mechanisms and functions, thereby contributing to the understanding of the background of human diseases. In this review, we would like to highlight the many advantages of fission yeasts over budding yeasts. The usefulness of fission yeasts in virus research is shown as an example, presenting the most important research results related to the Human Immunodeficiency Virus Type 1 (HIV-1) Vpr protein. Besides, the potential role of fission yeasts in the study of prion biology is also discussed. Furthermore, we are keen to promote the uprising model yeast Schizosaccharomyces japonicus, which is a dimorphic species in the fission yeast genus. We propose the hyphal growth of S. japonicus as an unusual opportunity as a model to study the invadopodia of human cancer cells since the two seemingly different cell types can be compared along fundamental features. Here we also collect the latest laboratory protocols and bioinformatics tools for the fission yeasts to highlight the many possibilities available to the research community. In addition, we present several limiting factors that everyone should be aware of when working with yeast models.
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Affiliation(s)
- Lajos Acs-Szabo
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
| | - Laszlo Attila Papp
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
| | - Ida Miklos
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
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4
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Yan B, Liao P, Liu Y, Han Z, Wang C, Chen F, Lei P. Therapeutic potential of microglia-derived extracellular vesicles in ischemic stroke. Int Immunopharmacol 2024; 139:112712. [PMID: 39032476 DOI: 10.1016/j.intimp.2024.112712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 07/06/2024] [Accepted: 07/15/2024] [Indexed: 07/23/2024]
Abstract
Ischemic stroke (IS) is a debilitating neurological disorder with limited treatment options. Extracellular vesicles (EVs) have emerged as crucial lipid bilayer particles derived from various cell types that facilitate intercellular communication and enable the exchange of proteins, lipids, and genetic material. Microglia are resident brain cells that play a crucial role in brain development, maintenance of neuronal networks, and injury repair. They secrete numerous extracellular vesicles in different states. Recent evidence indicates that microglia-derived extracellular vesicles (M-EVs) actively participate in mediating various biological processes, such as neuroprotection and neurorepair, in stroke, making them an excellent therapeutic approach for treating this condition. This review comprehensively summarizes the latest research on M-EVs in stroke and explores their potential as novel therapeutic targets for this disorder. Additionally, it provides an overview of the effects and functions of M-EVs on stroke recovery to facilitate the development of clinically relevant therapies for IS.
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Affiliation(s)
- Bo Yan
- Department of Geriatrics, Tianjin Medical University General Hospital, Anshan Road No. 154, Tianjin 300052, China; Key Laboratory of Post-Trauma Neuro-Repair and Regeneration in Central Nervous System, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin Neurological Institute, Ministry of Education, Tianjin 300052, China
| | - Pan Liao
- Key Laboratory of Post-Trauma Neuro-Repair and Regeneration in Central Nervous System, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin Neurological Institute, Ministry of Education, Tianjin 300052, China; School of Medicine, Nankai University, Tianjin 300192, China
| | - Yaru Liu
- Department of Geriatrics, Tianjin Medical University General Hospital, Anshan Road No. 154, Tianjin 300052, China; Key Laboratory of Post-Trauma Neuro-Repair and Regeneration in Central Nervous System, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin Neurological Institute, Ministry of Education, Tianjin 300052, China
| | - Zhaoli Han
- Department of Geriatrics, Tianjin Medical University General Hospital, Anshan Road No. 154, Tianjin 300052, China; Key Laboratory of Post-Trauma Neuro-Repair and Regeneration in Central Nervous System, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin Neurological Institute, Ministry of Education, Tianjin 300052, China
| | - Conglin Wang
- Department of Geriatrics, Tianjin Medical University General Hospital, Anshan Road No. 154, Tianjin 300052, China; Key Laboratory of Post-Trauma Neuro-Repair and Regeneration in Central Nervous System, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin Neurological Institute, Ministry of Education, Tianjin 300052, China
| | - Fanglian Chen
- Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, China.
| | - Ping Lei
- Department of Geriatrics, Tianjin Medical University General Hospital, Anshan Road No. 154, Tianjin 300052, China; Key Laboratory of Post-Trauma Neuro-Repair and Regeneration in Central Nervous System, Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin Neurological Institute, Ministry of Education, Tianjin 300052, China; School of Medicine, Nankai University, Tianjin 300192, China.
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5
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Hirano Y, Sato T, Miura A, Kubota Y, Shindo T, Fukase K, Fukagawa T, Kabayama K, Haraguchi T, Hiraoka Y. Disordered region of nuclear membrane protein Bqt4 recruits phosphatidic acid to the nuclear envelope to maintain its structural integrity. J Biol Chem 2024; 300:107430. [PMID: 38825008 PMCID: PMC11253665 DOI: 10.1016/j.jbc.2024.107430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 05/09/2024] [Accepted: 05/18/2024] [Indexed: 06/04/2024] Open
Abstract
The nuclear envelope (NE) is a permeable barrier that maintains nuclear-cytoplasmic compartmentalization and ensures nuclear function; however, it ruptures in various situations such as mechanical stress and mitosis. Although the protein components for sealing a ruptured NE have been identified, the mechanism by which lipid components are involved in this process remains to be elucidated. Here, we found that an inner nuclear membrane (INM) protein Bqt4 directly interacts with phosphatidic acid (PA) and serves as a platform for NE maintenance in the fission yeast Schizosaccharomyces pombe. The intrinsically disordered region (IDR) of Bqt4, proximal to the transmembrane domain, binds to PA and forms a solid aggregate in vitro. Excessive accumulation of Bqt4 IDR in INM results in membrane overproliferation and lipid droplet formation in the nucleus, leading to centromere dissociation from the NE and chromosome missegregation. Our findings suggest that Bqt4 IDR controls nuclear membrane homeostasis by recruiting PA to the INM, thereby maintaining the structural integrity of the NE.
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Affiliation(s)
- Yasuhiro Hirano
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.
| | - Tsukino Sato
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Ayane Miura
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Yoshino Kubota
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | | | - Koichi Fukase
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Kazuya Kabayama
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.
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6
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Dupouy G, Dong Y, Herzog E, Chabouté ME, Berr A. Nuclear envelope dynamics in connection to chromatin remodeling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:963-981. [PMID: 37067011 DOI: 10.1111/tpj.16246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/29/2023] [Accepted: 04/12/2023] [Indexed: 05/11/2023]
Abstract
The nucleus is a central organelle of eukaryotic cells undergoing dynamic structural changes during cellular fundamental processes such as proliferation and differentiation. These changes rely on the integration of developmental and stress signals at the nuclear envelope (NE), orchestrating responses at the nucleo-cytoplasmic interface for efficient genomic functions such as DNA transcription, replication and repair. While in animals, correlation has already been established between NE dynamics and chromatin remodeling using last-generation tools and cutting-edge technologies, this topic is just emerging in plants, especially in response to mechanical cues. This review summarizes recent data obtained in this field with more emphasis on the mechanical stress response. It also highlights similarities/differences between animal and plant cells at multiples scales, from the structural organization of the nucleo-cytoplasmic continuum to the functional impacts of NE dynamics.
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Affiliation(s)
- Gilles Dupouy
- Institut de Biologie Moléculaire des Plantes du CNRS- Université de Strasbourg, 12 rue du Général Zimmer,, F-67084, Strasbourg, France
| | - Yihan Dong
- Institut de Biologie Moléculaire des Plantes du CNRS- Université de Strasbourg, 12 rue du Général Zimmer,, F-67084, Strasbourg, France
| | - Etienne Herzog
- Institut de Biologie Moléculaire des Plantes du CNRS- Université de Strasbourg, 12 rue du Général Zimmer,, F-67084, Strasbourg, France
| | - Marie-Edith Chabouté
- Institut de Biologie Moléculaire des Plantes du CNRS- Université de Strasbourg, 12 rue du Général Zimmer,, F-67084, Strasbourg, France
| | - Alexandre Berr
- Institut de Biologie Moléculaire des Plantes du CNRS- Université de Strasbourg, 12 rue du Général Zimmer,, F-67084, Strasbourg, France
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7
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Dvilansky I, Altaras Y, Kamenetsky N, Nachmias D, Elia N. The human AAA-ATPase VPS4A isoform and its co-factor VTA1 have a unique function in regulating mammalian cytokinesis abscission. PLoS Biol 2024; 22:e3002327. [PMID: 38687820 PMCID: PMC11086821 DOI: 10.1371/journal.pbio.3002327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 05/10/2024] [Accepted: 04/04/2024] [Indexed: 05/02/2024] Open
Abstract
Mutations in the human AAA-ATPase VPS4 isoform, VPS4A, cause severe neurodevelopmental defects and congenital dyserythropoietic anemia (CDA). VPS4 is a crucial component of the endosomal sorting complex required for transport (ESCRT) system, which drives membrane remodeling in numerous cellular processes, including receptor degradation, cell division, and neural pruning. Notably, while most organisms encode for a single VPS4 gene, human cells have 2 VPS4 paralogs, namely VPS4A and VPS4B, but the functional differences between these paralogs is mostly unknown. Here, we set out to investigate the role of the human VPS4 paralogs in cytokinetic abscission using a series of knockout cell lines. We found that VPS4A and VPS4B hold both overlapping and distinct roles in abscission. VPS4A depletion resulted in a more severe abscission delay than VPS4B and was found to be involved in earlier stages of abscission. Moreover, VPS4A and a monomeric-locked VPS4A mutant bound the abscission checkpoint proteins CHMP4C and ANCHR, while VPS4B did not, indicating a regulatory role for the VPS4A isoform in abscission. Depletion of VTA1, a co-factor of VPS4, disrupted VPS4A-ANCHR interactions and accelerated abscission, suggesting that VTA1 is also involved in the abscission regulation. Our findings reveal a dual role for VPS4A in abscission, one that is canonical and can be compensated by VPS4B, and another that is regulatory and may be delivered by its monomeric form. These observations provide a potential mechanistic explanation for the neurodevelopmental defects and other related disorders reported in VPS4A-mutated patients with a fully functional VPS4B paralog.
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Affiliation(s)
- Inbar Dvilansky
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
- National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Yarin Altaras
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
- National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Nikita Kamenetsky
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
- National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dikla Nachmias
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
- National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Natalie Elia
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
- National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, Beer Sheva, Israel
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8
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Etherington GJ, Wu PS, Oliferenko S, Uhlmann F, Nieduszynski CA. Telomere-to-telomere Schizosaccharomyces japonicus genome assembly reveals hitherto unknown genome features. Yeast 2024; 41:73-86. [PMID: 38451028 DOI: 10.1002/yea.3912] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/27/2023] [Accepted: 11/10/2023] [Indexed: 03/08/2024] Open
Abstract
Schizosaccharomyces japonicus belongs to the single-genus class Schizosaccharomycetes, otherwise known as "fission yeasts." As part of a composite model system with its widely studied S. pombe sister species, S. japonicus has provided critical insights into the workings and the evolution of cell biological mechanisms. Furthermore, its divergent biology makes S. japonicus a valuable model organism in its own right. However, the currently available genome assembly contains gaps and has been unable to resolve centromeres and other repeat-rich chromosomal regions. Here we present a telomere-to-telomere long-read genome assembly of the S. japonicus genome. This includes the three megabase-length chromosomes, with centromeres hundreds of kilobases long, rich in 5S ribosomal RNA genes, transfer RNA genes, long terminal repeats, and short repeats. We identify a gene-sparse region on chromosome 2 that resembles a 331 kb centromeric duplication. We revise the genome size of S. japonicus to at least 16.6 Mb and possibly up to 18.12 Mb, at least 30% larger than previous estimates. Our whole genome assembly will support the growing S. japonicus research community and facilitate research in new directions, including centromere and DNA repeat evolution, and yeast comparative genomics.
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Affiliation(s)
| | | | - Snezhana Oliferenko
- The Francis Crick Institute, London, UK
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, UK
| | - Frank Uhlmann
- The Francis Crick Institute, London, UK
- Cell Biology Centre, Institute of Innovative Research, Tokyo Institute of Technology, Kanagawa, Japan
| | - Conrad A Nieduszynski
- The Earlham Institute, Norwich, UK
- School of Biological Sciences, University of East Anglia, Norwich, UK
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9
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Etherington GJ, Gil EG, Haerty W, Oliferenko S, Nieduszynski CA. Schizosaccharomyces versatilis represents a distinct evolutionary lineage of fission yeast. Yeast 2024; 41:95-107. [PMID: 38146786 DOI: 10.1002/yea.3919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 11/28/2023] [Accepted: 12/01/2023] [Indexed: 12/27/2023] Open
Abstract
The fission yeast species Schizosaccharomyces japonicus is currently divided into two varieties-S. japonicus var. japonicus and S. japonicus var. versatilis. Here we examine the var. versatilis isolate CBS5679. The CBS5679 genome shows 88% identity to the reference genome of S. japonicus var. japonicus at the coding sequence level, with phylogenetic analyses suggesting that it has split from the S. japonicus lineage 25 million years ago. The CBS5679 genome contains a reciprocal translocation between chromosomes 1 and 2, together with several large inversions. The products of genes linked to the major translocation are associated with 'metabolism' and 'cellular assembly' ontology terms. We further show that CBS5679 does not generate viable progeny with the reference strain of S. japonicus. Although CBS5679 shares closer similarity to the 'type' strain of var. versatilis as compared to S. japonicus, it is not identical to the type strain, suggesting population structure within var. versatilis. We recommend that the taxonomic status of S. japonicus var. versatilis is raised, with it being treated as a separate species, Schizosaccharomyces versatilis.
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Affiliation(s)
| | - Elisa Gomez Gil
- Oliferenko Lab, The Francis Crick Institute, London, UK
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, UK
| | - Wilfried Haerty
- Research Faculty, The Earlham Institute, Norwich Research Park, Norwich, UK
| | - Snezhana Oliferenko
- Oliferenko Lab, The Francis Crick Institute, London, UK
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, UK
| | - Conrad A Nieduszynski
- Research Faculty, The Earlham Institute, Norwich Research Park, Norwich, UK
- School of Biological Sciences, University of East Anglia, Norwich, UK
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10
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Strachan J, Leidecker O, Spanos C, Le Coz C, Chapman E, Arsenijevic A, Zhang H, Zhao N, Spoel SH, Bayne EH. SUMOylation regulates Lem2 function in centromere clustering and silencing. J Cell Sci 2023; 136:jcs260868. [PMID: 37970674 PMCID: PMC10730020 DOI: 10.1242/jcs.260868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 11/07/2023] [Indexed: 11/17/2023] Open
Abstract
Regulation by the small modifier SUMO is heavily dependent on spatial control of enzymes that mediate the attachment and removal of SUMO on substrate proteins. Here, we show that in the fission yeast Schizosaccharomyces pombe, delocalisation of the SUMO protease Ulp1 from the nuclear envelope results in centromeric defects that can be attributed to hyper-SUMOylation at the nuclear periphery. Unexpectedly, we find that although this localised hyper-SUMOylation impairs centromeric silencing, it can also enhance centromere clustering. Moreover, both effects are at least partially dependent on SUMOylation of the inner nuclear membrane protein Lem2. Lem2 has previously been implicated in diverse biological processes, including the promotion of both centromere clustering and silencing, but how these distinct activities are coordinated was unclear; our observations suggest a model whereby SUMOylation serves as a regulatory switch, modulating Lem2 interactions with competing partner proteins to balance its roles in alternative pathways. Our findings also reveal a previously unappreciated role for SUMOylation in promoting centromere clustering.
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Affiliation(s)
- Joanna Strachan
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Orsolya Leidecker
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, Cologne 50931, Germany
| | - Christos Spanos
- Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Clementine Le Coz
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Elliott Chapman
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Ana Arsenijevic
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Haidao Zhang
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Ning Zhao
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Steven H. Spoel
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Elizabeth H. Bayne
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, UK
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11
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London N, Medina-Pritchard B, Spanos C, Rappsilber J, Jeyaprakash AA, Allshire RC. Direct recruitment of Mis18 to interphase spindle pole bodies promotes CENP-A chromatin assembly. Curr Biol 2023; 33:4187-4201.e6. [PMID: 37714149 DOI: 10.1016/j.cub.2023.08.063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/04/2023] [Accepted: 08/22/2023] [Indexed: 09/17/2023]
Abstract
CENP-A chromatin specifies mammalian centromere identity, and its chaperone HJURP replenishes CENP-A when recruited by the Mis18 complex (Mis18C) via M18BP1/KNL2 to CENP-C at kinetochores during interphase. However, the Mis18C recruitment mechanism remains unresolved in species lacking M18BP1, such as fission yeast. Fission yeast centromeres cluster at G2 spindle pole bodies (SPBs) when CENP-ACnp1 is replenished and where Mis18C also localizes. We show that SPBs play an unexpected role in concentrating Mis18C near centromeres through the recruitment of Mis18 by direct binding to the major SPB linker of nucleoskeleton and cytoskeleton (LINC) component Sad1. Mis18C recruitment by Sad1 is important for CENP-ACnp1 chromatin establishment and acts in parallel with a CENP-C-mediated Mis18C recruitment pathway to maintain centromeric CENP-ACnp1 but operates independently of Sad1-mediated centromere clustering. SPBs therefore provide a non-chromosomal scaffold for both Mis18C recruitment and centromere clustering during G2. This centromere-independent Mis18-SPB recruitment provides a mechanism that governs de novo CENP-ACnp1 chromatin assembly by the proximity of appropriate sequences to SPBs and highlights how nuclear spatial organization influences centromere identity.
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Affiliation(s)
- Nitobe London
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Bethan Medina-Pritchard
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Christos Spanos
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Juri Rappsilber
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK; Institute of Biotechnology, Technische Universität, 13355 Berlin, Germany
| | - A Arockia Jeyaprakash
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK; Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Robin C Allshire
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK.
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12
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Shah H, Dey G. A diffusion barrier limits nuclear leaks. Nat Cell Biol 2023; 25:1411-1412. [PMID: 37783793 DOI: 10.1038/s41556-023-01243-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Affiliation(s)
- Hiral Shah
- Cell Biology and Biophysics, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Gautam Dey
- Cell Biology and Biophysics, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
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13
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Gu Y, Alam S, Oliferenko S. Peroxisomal compartmentalization of amino acid biosynthesis reactions imposes an upper limit on compartment size. Nat Commun 2023; 14:5544. [PMID: 37684233 PMCID: PMC10491753 DOI: 10.1038/s41467-023-41347-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023] Open
Abstract
Cellular metabolism relies on just a few redox cofactors. Selective compartmentalization may prevent competition between metabolic reactions requiring the same cofactor. Is such compartmentalization necessary for optimal cell function? Is there an optimal compartment size? Here we probe these fundamental questions using peroxisomal compartmentalization of the last steps of lysine and histidine biosynthesis in the fission yeast Schizosaccharomyces japonicus. We show that compartmentalization of these NAD+ dependent reactions together with a dedicated NADH/NAD+ recycling enzyme supports optimal growth when an increased demand for anabolic reactions taxes cellular redox balance. In turn, compartmentalization constrains the size of individual organelles, with larger peroxisomes accumulating all the required enzymes but unable to support both biosynthetic reactions at the same time. Our reengineering and physiological experiments indicate that compartmentalized biosynthetic reactions are sensitive to the size of the compartment, likely due to scaling-dependent changes within the system, such as enzyme packing density.
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Affiliation(s)
- Ying Gu
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK.
| | - Sara Alam
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK
- Medical Research Council London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK
| | - Snezhana Oliferenko
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK.
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14
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van der Zanden SY, Jongsma MLM, Neefjes ACM, Berlin I, Neefjes J. Maintaining soluble protein homeostasis between nuclear and cytoplasmic compartments across mitosis. Trends Cell Biol 2023; 33:18-29. [PMID: 35778326 DOI: 10.1016/j.tcb.2022.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 05/23/2022] [Accepted: 06/06/2022] [Indexed: 12/27/2022]
Abstract
The nuclear envelope (NE) is central to the architecture of eukaryotic cells, both as a physical barrier separating the nucleus from the cytoplasm and as gatekeeper of selective transport between them. However, in open mitosis, the NE fragments to allow for spindle formation and segregation of chromosomes, resulting in intermixing of nuclear and cytoplasmic soluble fractions. Recent studies have shed new light on the mechanisms driving reinstatement of soluble proteome homeostasis following NE reformation in daughter cells. Here, we provide an overview of how mitotic cells confront this challenge to ensure continuity of basic cellular functions across generations and elaborate on the implications for the proteasome - a macromolecular machine that functions in both cytoplasmic and nuclear compartments.
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Affiliation(s)
- Sabina Y van der Zanden
- Department of Cell and Chemical Biology, ONCODE Institute, Leiden University Medical Center LUMC, 2333, ZC, Leiden, The Netherlands
| | - Marlieke L M Jongsma
- Department of Cell and Chemical Biology, ONCODE Institute, Leiden University Medical Center LUMC, 2333, ZC, Leiden, The Netherlands
| | - Anna C M Neefjes
- Department of Cell and Chemical Biology, ONCODE Institute, Leiden University Medical Center LUMC, 2333, ZC, Leiden, The Netherlands
| | - Ilana Berlin
- Department of Cell and Chemical Biology, ONCODE Institute, Leiden University Medical Center LUMC, 2333, ZC, Leiden, The Netherlands.
| | - Jacques Neefjes
- Department of Cell and Chemical Biology, ONCODE Institute, Leiden University Medical Center LUMC, 2333, ZC, Leiden, The Netherlands.
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15
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Borah S, Dhanasekaran K, Kumar S. The LEM-ESCRT toolkit: Repair and maintenance of the nucleus. Front Cell Dev Biol 2022; 10:989217. [PMID: 36172278 PMCID: PMC9512039 DOI: 10.3389/fcell.2022.989217] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/24/2022] [Indexed: 12/04/2022] Open
Abstract
The eukaryotic genome is enclosed in a nuclear envelope that protects it from potentially damaging cellular activities and physically segregates transcription and translation.Transport across the NE is highly regulated and occurs primarily via the macromolecular nuclear pore complexes.Loss of nuclear compartmentalization due to defects in NPC function and NE integrity are tied to neurological and ageing disorders like Alzheimer’s, viral pathogenesis, immune disorders, and cancer progression.Recent work implicates inner-nuclear membrane proteins of the conserved LEM domain family and the ESCRT machinery in NE reformation during cell division and NE repair upon rupture in migrating cancer cells, and generating seals over defective NPCs. In this review, we discuss the recent in-roads made into defining the molecular mechanisms and biochemical networks engaged by LEM and many other integral inner nuclear membrane proteins to preserve the nuclear barrier.
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Affiliation(s)
- Sapan Borah
- National Institute of Immunohaematology, Mumbai, Maharashtra, India
- *Correspondence: Sapan Borah, ; Karthigeyan Dhanasekaran, ; Santosh Kumar,
| | - Karthigeyan Dhanasekaran
- Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, Haryana, India
- *Correspondence: Sapan Borah, ; Karthigeyan Dhanasekaran, ; Santosh Kumar,
| | - Santosh Kumar
- National Centre for Cell Science, Pune, Maharashtra, India
- *Correspondence: Sapan Borah, ; Karthigeyan Dhanasekaran, ; Santosh Kumar,
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16
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Martín Caballero L, Capella M, Barrales RR, Dobrev N, van Emden T, Hirano Y, Suma Sreechakram VN, Fischer-Burkart S, Kinugasa Y, Nevers A, Rougemaille M, Sinning I, Fischer T, Hiraoka Y, Braun S. The inner nuclear membrane protein Lem2 coordinates RNA degradation at the nuclear periphery. Nat Struct Mol Biol 2022; 29:910-921. [PMID: 36123402 PMCID: PMC9507967 DOI: 10.1038/s41594-022-00831-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 08/02/2022] [Indexed: 11/21/2022]
Abstract
Transcriptionally silent chromatin often localizes to the nuclear periphery. However, whether the nuclear envelope (NE) is a site for post-transcriptional gene repression is not well understood. Here we demonstrate that Schizosaccharomycespombe Lem2, an NE protein, regulates nuclear-exosome-mediated RNA degradation. Lem2 deletion causes accumulation of RNA precursors and meiotic transcripts and de-localization of an engineered exosome substrate from the nuclear periphery. Lem2 does not directly bind RNA but instead interacts with the exosome-targeting MTREC complex and its human homolog PAXT to promote RNA recruitment. This pathway acts largely independently of nuclear bodies where exosome factors assemble. Nutrient availability modulates Lem2 regulation of meiotic transcripts, implying that this pathway is environmentally responsive. Our work reveals that multiple spatially distinct degradation pathways exist. Among these, Lem2 coordinates RNA surveillance of meiotic transcripts and non-coding RNAs by recruiting exosome co-factors to the nuclear periphery. The Braun lab shows that the conserved nuclear membrane protein Lem2 interacts with the MTREC complex of the nuclear-exosome pathway to promote recruitment and degradation of ncRNAs and meiotic transcripts at the nuclear periphery in Schizosaccharomycespombe.
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Affiliation(s)
- Lucía Martín Caballero
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany
| | - Matías Capella
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Ramón Ramos Barrales
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,Centro Andaluz de Biología del Desarrollo (CABD), Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucía, Seville, Spain
| | - Nikolay Dobrev
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany.,European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Thomas van Emden
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany
| | - Yasuhiro Hirano
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Vishnu N Suma Sreechakram
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,Institute for Genetics, Justus-Liebig-University Giessen, Giessen, Germany
| | - Sabine Fischer-Burkart
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
| | - Yasuha Kinugasa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.,Regulation for intractable Infectious Diseases, National Institutes of Biomedical Innovation, Health and Nutrition, Ibaraki, Japan
| | - Alicia Nevers
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France.,University Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Mathieu Rougemaille
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Tamás Fischer
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany.,The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Sigurd Braun
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany. .,International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany. .,Institute for Genetics, Justus-Liebig-University Giessen, Giessen, Germany.
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17
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The ESCRT Machinery: Remodeling, Repairing, and Sealing Membranes. MEMBRANES 2022; 12:membranes12060633. [PMID: 35736340 PMCID: PMC9229795 DOI: 10.3390/membranes12060633] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/16/2022] [Accepted: 06/17/2022] [Indexed: 01/27/2023]
Abstract
The ESCRT machinery is an evolutionarily conserved membrane remodeling complex that is used by the cell to perform reverse membrane scission in essential processes like protein degradation, cell division, and release of enveloped retroviruses. ESCRT-III, together with the AAA ATPase VPS4, harbors the main remodeling and scission function of the ESCRT machinery, whereas early-acting ESCRTs mainly contribute to protein sorting and ESCRT-III recruitment through association with upstream targeting factors. Here, we review recent advances in our understanding of the molecular mechanisms that underlie membrane constriction and scission by ESCRT-III and describe the involvement of this machinery in the sealing and repairing of damaged cellular membranes, a key function to preserve cellular viability and organellar function.
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18
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Hummel G, Liu C. Organization and epigenomic control of RNA polymerase III-transcribed genes in plants. CURRENT OPINION IN PLANT BIOLOGY 2022; 67:102199. [PMID: 35364484 DOI: 10.1016/j.pbi.2022.102199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 01/24/2022] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
The genetic information linearly scripted in chromosomes is wrapped in a ribonucleoprotein complex called chromatin. The adaptation of its compaction level and spatiotemporal organization refines gene expression in response to developmental and environmental cues. RNA polymerase III (RNAPIII) is responsible for the biogenesis of elementary non-coding RNAs. Their genes are subjected to high duplication and mutational rates, and invade nuclear genomes. Their insertion into different epigenomic environments raises the question of how chromatin packing affects their individual transcription. In this review, we provide a unique perspective to this issue in plants. In addition, we discuss how the genomic organization of RNAPIII-transcribed loci, combined with epigenetic differences, might participate to plant trait variations.
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Affiliation(s)
- Guillaume Hummel
- Institute of Biology, University of Hohenheim, Garbenstraße 30, 70599, Stuttgart, Germany.
| | - Chang Liu
- Institute of Biology, University of Hohenheim, Garbenstraße 30, 70599, Stuttgart, Germany.
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19
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Schweigel U, Batsios P, Müller-Taubenberger A, Gräf R, Grafe M. Dictyostelium spastin is involved in nuclear envelope dynamics during semi-closed mitosis. Nucleus 2022; 13:144-154. [PMID: 35298348 PMCID: PMC8932920 DOI: 10.1080/19491034.2022.2047289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Dictyostelium amoebae perform a semi-closed mitosis, in which the nuclear envelope is fenestrated at the insertion sites of the mitotic centrosomes and around the central spindle during karyokinesis. During late telophase the centrosome relocates to the cytoplasmic side of the nucleus, the central spindle disassembles and the nuclear fenestrae become closed. Our data indicate that Dictyostelium spastin (DdSpastin) is a microtubule-binding and severing type I membrane protein that plays a role in this process. Its mitotic localization is in agreement with a requirement for the removal of microtubules that would hinder closure of the fenestrae. Furthermore, DdSpastin interacts with the HeH/ LEM-family protein Src1 in BioID analyses as well as the inner nuclear membrane protein Sun1, and shows subcellular co-localizations with Src1, Sun1, the ESCRT component CHMP7 and the IST1-like protein filactin, suggesting that the principal pathway of mitotic nuclear envelope remodeling is conserved between animals and Dictyostelium amoebae.
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Affiliation(s)
- Ulrike Schweigel
- Department of Cell Biology, University of Potsdam, Institute for Biochemistry and Biology, Potsdam-Golm, Germany
| | - Petros Batsios
- Department of Cell Biology, University of Potsdam, Institute for Biochemistry and Biology, Potsdam-Golm, Germany
| | | | - Ralph Gräf
- Department of Cell Biology, University of Potsdam, Institute for Biochemistry and Biology, Potsdam-Golm, Germany
| | - Marianne Grafe
- Department of Cell Biology, University of Potsdam, Institute for Biochemistry and Biology, Potsdam-Golm, Germany
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20
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Separable roles for RNAi in regulation of transposable elements and viability in the fission yeast Schizosaccharomyces japonicus. PLoS Genet 2022; 18:e1010100. [PMID: 35226668 PMCID: PMC8912903 DOI: 10.1371/journal.pgen.1010100] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/10/2022] [Accepted: 02/14/2022] [Indexed: 11/30/2022] Open
Abstract
RNA interference (RNAi) is a conserved mechanism of small RNA-mediated genome regulation commonly involved in suppression of transposable elements (TEs) through both post-transcriptional silencing, and transcriptional repression via heterochromatin assembly. The fission yeast Schizosaccharomyces pombe has been extensively utilised as a model for studying RNAi pathways. However, this species is somewhat atypical in that TEs are not major targets of RNAi, and instead small RNAs correspond primarily to non-coding pericentromeric repeat sequences, reflecting a specialised role for the pathway in promoting heterochromatin assembly in these regions. In contrast, in the related fission yeast Schizosaccharomyces japonicus, sequenced small RNAs correspond primarily to TEs. This suggests there may be fundamental differences in the operation of RNAi pathways in these two related species. To investigate these differences, we probed RNAi function in S. japonicus. Unexpectedly, and in contrast to S. pombe, we found that RNAi is essential in this species. Moreover, viability of RNAi mutants can be rescued by mutations implicated in enhancing RNAi-independent heterochromatin propagation. These rescued strains retain heterochromatic marks on TE sequences, but exhibit derepression of TEs at the post-transcriptional level. Our findings indicate that S. japonicus retains the ancestral role of RNAi in facilitating suppression of TEs via both post-transcriptional silencing and heterochromatin assembly, with specifically the heterochromatin pathway being essential for viability, likely due to a function in genome maintenance. The specialised role of RNAi in heterochromatin assembly in S. pombe appears to be a derived state that emerged after the divergence of S. japonicus. The chromosomes of many species are populated by repetitive transposable elements that are able to “jump” throughout the genome. The consequences of these mobilisations can be catastrophic, resulting in disruption of genes or chromosomal rearrangements, thus organisms usually employ defence mechanisms to keep these elements inactivated. The most widespread of these systems is RNA interference, which utilises small RNA molecules to direct either packaging of transposable element DNA into repressive heterochromatin, or degradation of RNA transcripts. Many fundamental discoveries about RNAi function have been made in the model fission yeast Schizosaccharomyces pombe; however, this species is unusual as it does not generally employ RNAi to control its transposable elements. We found that in a lesser studied relative, Schizosaccharomyces japonicus, small RNAs are required to silence transposable elements, and that this silencing occurs via both formation of heterochromatin and degradation of transcripts. This dual function RNAi pathway targeting transposable elements that appear to cluster at centromeres is very similar to systems seen in complex multicellular organisms, thus our findings reveal S. japonicus to be an exciting emergent model in which to study RNAi and centromere function.
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21
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Shankar R, Lettman MM, Whisler W, Frankel EB, Audhya A. The ESCRT machinery directs quality control over inner nuclear membrane architecture. Cell Rep 2022; 38:110263. [PMID: 35045304 PMCID: PMC8801257 DOI: 10.1016/j.celrep.2021.110263] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 11/21/2021] [Accepted: 12/21/2021] [Indexed: 11/20/2022] Open
Abstract
The late-acting endosomal sorting complex required for transport (ESCRT) machinery has been implicated in facilitating the resealing of the nuclear envelope (NE) after mitosis, enabling compartmentalization of the genome away from the cytoplasm. Here, we leverage the stereotypic first division of the C. elegans embryo to identify additional functions of the ESCRT machinery in maintaining the structure of the inner nuclear membrane. Specifically, impaired ESCRT function results in a defect in the pruning of inner nuclear membrane invaginations, which arise normally during NE reformation and expansion. Additionally, in combination with a hypomorphic mutation that interferes with assembly of the underlying nuclear lamina, inhibition of ESCRT function significantly perturbs NE architecture and increases chromosome segregation defects, resulting in penetrant embryonic lethality. Our findings highlight links between ESCRT-mediated inner nuclear membrane remodeling, maintenance of nuclear envelope morphology, and the preservation of the genome during early development. In this study, Shankar et al. demonstrate that defects in ESCRT machinery functions impair pruning of inner nuclear membrane invaginations that form normally after mitotic exit as the nuclear envelope undergoes expansion. These findings highlight a critical role for the ESCRT machinery in the maintenance of inner nuclear membrane morphology.
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Affiliation(s)
- Raakhee Shankar
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Molly M Lettman
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - William Whisler
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Elisa B Frankel
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Anjon Audhya
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
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22
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Rutherford KM, Harris MA, Oliferenko S, Wood V. JaponicusDB: rapid deployment of a model organism database for an emerging model species. Genetics 2021; 220:6481558. [PMID: 35380656 PMCID: PMC9209809 DOI: 10.1093/genetics/iyab223] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/09/2021] [Indexed: 02/03/2023] Open
Abstract
The fission yeast Schizosaccharomyces japonicus has recently emerged as a powerful system for studying the evolution of essential cellular processes, drawing on similarities as well as key differences between S. japonicus and the related, well-established model Schizosaccharomyces pombe. We have deployed the open-source, modular code and tools originally developed for PomBase, the S. pombe model organism database (MOD), to create JaponicusDB (www.japonicusdb.org), a new MOD dedicated to S. japonicus. By providing a central resource with ready access to a growing body of experimental data, ontology-based curation, seamless browsing and querying, and the ability to integrate new data with existing knowledge, JaponicusDB supports fission yeast biologists to a far greater extent than any other source of S. japonicus data. JaponicusDB thus enables S. japonicus researchers to realize the full potential of studying a newly emerging model species and illustrates the widely applicable power and utility of harnessing reusable PomBase code to build a comprehensive, community-maintainable repository of species-relevant knowledge.
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Affiliation(s)
- Kim M Rutherford
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Midori A Harris
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Snezhana Oliferenko
- The Francis Crick Institute, London NW1 1AT, UK,Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King’s College London, London SE1 1UL, UK,Corresponding author: (S.O.); (V.W.)
| | - Valerie Wood
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK,Corresponding author: (S.O.); (V.W.)
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23
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Zhu X, Yang H, Zhang M, Wu X, Jiang L, Liu X, Lv K. YTHDC1-mediated VPS25 regulates cell cycle by targeting JAK-STAT signaling in human glioma cells. Cancer Cell Int 2021; 21:645. [PMID: 34863175 PMCID: PMC8642909 DOI: 10.1186/s12935-021-02304-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 10/28/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Glioma is a common type of malignant brain tumor with a high mortality and relapse rate. The endosomal sorting complex required for transport (ESCRT) has been reported to be involved in tumorigenesis. However, the molecular mechanisms have not been clarified. METHODS Bioinformatics was used to screen the ESCRT subunits highly expressed in glioma tissues from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The function of the ESCRT subunits in glioma cells was examined in vitro. Transcriptome sequencing analyzed the target genes and signaling pathways affected by the ESCRT subunit. Finally, the relationship between m6A (N6-methyladenosine) modification and high expression of the ESCRT subunit was studied. RESULTS VPS25 was upregulated in glioma tissues, which was correlated with poor prognosis in glioma patients. Furthermore, VPS25 knockdown inhibited the proliferation, blocked the cell cycle, and promoted apoptosis in glioma cells. Meanwhile, VPS25 induced a G0/G1 phase arrest of the cell cycle in glioma cells by directly mediating p21, CDK2, and cyclin E expression, and JAK-signal transducer and activator of transcription (STAT) activation. Finally, YTHDC1 inhibited glioma proliferation by reducing the expression of VPS25. CONCLUSION These results suggest that VPS25 is a promising prognostic indicator and a potential therapeutic target for glioma.
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Affiliation(s)
- Xiaolong Zhu
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241001, People's Republic of China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, 241001, People's Republic of China.,Non-Coding RNA Research Center of Wannan Medical College, Wuhu, 241001, China
| | - Hui Yang
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241001, People's Republic of China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, 241001, People's Republic of China.,Non-Coding RNA Research Center of Wannan Medical College, Wuhu, 241001, China
| | - Mengying Zhang
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241001, People's Republic of China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, 241001, People's Republic of China.,Non-Coding RNA Research Center of Wannan Medical College, Wuhu, 241001, China
| | - Xingwei Wu
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241001, People's Republic of China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, 241001, People's Republic of China.,Non-Coding RNA Research Center of Wannan Medical College, Wuhu, 241001, China
| | - Lan Jiang
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241001, People's Republic of China.,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, 241001, People's Republic of China.,Non-Coding RNA Research Center of Wannan Medical College, Wuhu, 241001, China
| | - Xiaocen Liu
- Department of Nuclear Medicine, The First Affiliated Hospital of Wannan Medical College, Wuhu, 241001, Anhui, People's Republic of China
| | - Kun Lv
- Central Laboratory, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241001, People's Republic of China. .,Key Laboratory of Non-Coding RNA Transformation Research of Anhui Higher Education Institutes (Wannan Medical College), Wuhu, 241001, People's Republic of China. .,Non-Coding RNA Research Center of Wannan Medical College, Wuhu, 241001, China.
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24
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Isono E. ESCRT Is a Great Sealer: Non-Endosomal Function of the ESCRT Machinery in Membrane Repair and Autophagy. PLANT & CELL PHYSIOLOGY 2021; 62:766-774. [PMID: 33768242 DOI: 10.1093/pcp/pcab045] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/18/2021] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
Components of the endosomal sorting complex required for transport (ESCRTs) were first identified in a genetic screen in budding yeast as factors interfering with vacuolar protein sorting. In the last three decades, intensive studies have revealed the subunit composition of ESCRT-0, ESCRT-I, ESCRT-II, ESCRT-III, their structure, the assembling mechanisms and their molecular and physiological functions. In plants, ESCRTs are essential for development, growth and stress responses. ESCRTs are best known for their function in endosomal trafficking, during which they are required for sorting ubiquitylated membrane proteins into intraluminal vesicles (ILVs) of multivesicular endosomes (MVEs). The formation of ILVs requires the function of ESCRT-III, which has been shown to mediate the membrane scission. Although the function of plant ESCRTs has been predominantly discussed in the context of endosomal trafficking, recent studies in other model organisms revealed a versatile role of ESCRTs in diverse cellular events with broad physiological implications. The non-endosomal functions of ESCRTs include cytokinesis, viral budding, autophagy, nuclear envelope reformation and membrane repair, although many of these have not yet been studied in plants. In this review, recent findings on non-endosomal ESCRT functions in plant, yeast and animals are highlighted and discussed.
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Affiliation(s)
- Erika Isono
- Department of Biology, University of Konstanz, Universitätsstrasse 10, Konstanz 78464, Germany
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25
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Pawar S, Kutay U. The Diverse Cellular Functions of Inner Nuclear Membrane Proteins. Cold Spring Harb Perspect Biol 2021; 13:a040477. [PMID: 33753404 PMCID: PMC8411953 DOI: 10.1101/cshperspect.a040477] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The nuclear compartment is delimited by a specialized expanded sheet of the endoplasmic reticulum (ER) known as the nuclear envelope (NE). Compared to the outer nuclear membrane and the contiguous peripheral ER, the inner nuclear membrane (INM) houses a unique set of transmembrane proteins that serve a staggering range of functions. Many of these functions reflect the exceptional position of INM proteins at the membrane-chromatin interface. Recent research revealed that numerous INM proteins perform crucial roles in chromatin organization, regulation of gene expression, genome stability, and mediation of signaling pathways into the nucleus. Other INM proteins establish mechanical links between chromatin and the cytoskeleton, help NE remodeling, or contribute to the surveillance of NE integrity and homeostasis. As INM proteins continue to gain prominence, we review these advancements and give an overview on the functional versatility of the INM proteome.
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Affiliation(s)
- Sumit Pawar
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Ulrike Kutay
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
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26
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Nucleolar release of rDNA repeats for repair involves SUMO-mediated untethering by the Cdc48/p97 segregase. Nat Commun 2021; 12:4918. [PMID: 34389719 PMCID: PMC8363623 DOI: 10.1038/s41467-021-25205-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 07/20/2021] [Indexed: 12/12/2022] Open
Abstract
Ribosomal RNA genes (rDNA) are highly unstable and susceptible to rearrangement due to their repetitive nature and active transcriptional status. Sequestration of rDNA in the nucleolus suppresses uncontrolled recombination. However, broken repeats must be first released to the nucleoplasm to allow repair by homologous recombination. Nucleolar release of broken rDNA repeats is conserved from yeast to humans, but the underlying molecular mechanisms are currently unknown. Here we show that DNA damage induces phosphorylation of the CLIP-cohibin complex, releasing membrane-tethered rDNA from the nucleolus in Saccharomyces cerevisiae. Downstream of phosphorylation, SUMOylation of CLIP-cohibin is recognized by Ufd1 via its SUMO-interacting motif, which targets the complex for disassembly through the Cdc48/p97 chaperone. Consistent with a conserved mechanism, UFD1L depletion in human cells impairs rDNA release. The dynamic and regulated assembly and disassembly of the rDNA-tethering complex is therefore a key determinant of nucleolar rDNA release and genome integrity.
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27
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Gatta AT, Olmos Y, Stoten CL, Chen Q, Rosenthal PB, Carlton JG. CDK1 controls CHMP7-dependent nuclear envelope reformation. eLife 2021; 10:59999. [PMID: 34286694 PMCID: PMC8324300 DOI: 10.7554/elife.59999] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 07/09/2021] [Indexed: 12/21/2022] Open
Abstract
Through membrane sealing and disassembly of spindle microtubules, the Endosomal Sorting Complex Required for Transport-III (ESCRT-III) machinery has emerged as a key player in the regeneration of a sealed nuclear envelope (NE) during mitotic exit, and in the repair of this organelle during interphase rupture. ESCRT-III assembly at the NE occurs transiently during mitotic (M) exit and is initiated when CHMP7, an ER-localised ESCRT-II/ESCRT-III hybrid protein, interacts with the Inner Nuclear Membrane (INM) protein LEM2. Whilst classical nucleocytoplasmic transport mechanisms have been proposed to separate LEM2 and CHMP7 during interphase, it is unclear how CHMP7 assembly is suppressed in mitosis when NE and ER identities are mixed. Here, we use live cell imaging and protein biochemistry to examine the biology of these proteins during M-exit. Firstly, we show that CHMP7 plays an important role in the dissolution of LEM2 clusters that form at the NE during M-exit. Secondly, we show that CDK1 phosphorylates CHMP7 upon M-entry at Ser3 and Ser441 and that this phosphorylation reduces CHMP7's interaction with LEM2, limiting its assembly during M-phase. We show that spatiotemporal differences in the dephosphorylation of CHMP7 license its assembly at the NE during telophase, but restrict its assembly on the ER at this time. Without CDK1 phosphorylation, CHMP7 undergoes inappropriate assembly in the peripheral ER during M-exit, capturing LEM2 and downstream ESCRT-III components. Lastly, we establish that a microtubule network is dispensable for ESCRT-III assembly at the reforming nuclear envelope. These data identify a key cell-cycle control programme allowing ESCRT-III-dependent nuclear regeneration.
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Affiliation(s)
- Alberto T Gatta
- School of Cancer and Pharmaceutical Sciences, King's College, London, United Kingdom.,Organelle Dynamics Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Yolanda Olmos
- School of Cancer and Pharmaceutical Sciences, King's College, London, United Kingdom.,Organelle Dynamics Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Caroline L Stoten
- School of Cancer and Pharmaceutical Sciences, King's College, London, United Kingdom.,Organelle Dynamics Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Qu Chen
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Peter B Rosenthal
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Jeremy G Carlton
- School of Cancer and Pharmaceutical Sciences, King's College, London, United Kingdom.,Organelle Dynamics Laboratory, The Francis Crick Institute, London, United Kingdom
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28
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Zhen Y, Radulovic M, Vietri M, Stenmark H. Sealing holes in cellular membranes. EMBO J 2021; 40:e106922. [PMID: 33644904 PMCID: PMC8013788 DOI: 10.15252/embj.2020106922] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/29/2020] [Accepted: 11/04/2020] [Indexed: 12/11/2022] Open
Abstract
The compartmentalization of eukaryotic cells, which is essential for their viability and functions, is ensured by single or double bilayer membranes that separate the cell from the exterior and form boundaries between the cell’s organelles and the cytosol. Nascent nuclear envelopes and autophagosomes, which both are enveloped by double membranes, need to be sealed during the late stage of their biogenesis. On the other hand, the integrity of cellular membranes such as the plasma membrane, lysosomes and the nuclear envelope can be compromised by pathogens, chemicals, radiation, inflammatory responses and mechanical stress. There are cellular programmes that restore membrane integrity after injury. Here, we review cellular mechanisms that have evolved to maintain membrane integrity during organelle biogenesis and after injury, including membrane scission mediated by the endosomal sorting complex required for transport (ESCRT), vesicle patching and endocytosis.
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Affiliation(s)
- Yan Zhen
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Maja Radulovic
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Marina Vietri
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Harald Stenmark
- Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.,Faculty of Medicine and Health Sciences, Centre of Molecular Inflammation Research, Norwegian University of Science and Technology, Trondheim, Norway
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29
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Thaller DJ, Tong D, Marklew CJ, Ader NR, Mannino PJ, Borah S, King MC, Ciani B, Lusk CP. Direct binding of ESCRT protein Chm7 to phosphatidic acid-rich membranes at nuclear envelope herniations. J Cell Biol 2021; 220:e202004222. [PMID: 33464310 PMCID: PMC7816628 DOI: 10.1083/jcb.202004222] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 11/04/2020] [Accepted: 12/11/2020] [Indexed: 12/03/2022] Open
Abstract
Mechanisms that control nuclear membrane remodeling are essential to maintain the integrity of the nucleus but remain to be fully defined. Here, we identify a phosphatidic acid (PA)-binding capacity in the nuclear envelope (NE)-specific ESCRT, Chm7, in budding yeast. Chm7's interaction with PA-rich membranes is mediated through a conserved hydrophobic stretch of amino acids, which confers recruitment to the NE in a manner that is independent of but required for Chm7's interaction with the LAP2-emerin-MAN1 (LEM) domain protein Heh1 (LEM2). Consistent with the functional importance of PA binding, mutation of this region abrogates recruitment of Chm7 to membranes and abolishes Chm7 function in the context of NE herniations that form during defective nuclear pore complex (NPC) biogenesis. In fact, we show that a PA sensor specifically accumulates within these NE herniations. We suggest that local control of PA metabolism is important for ensuring productive NE remodeling and that its dysregulation may contribute to pathologies associated with defective NPC assembly.
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Affiliation(s)
- David J. Thaller
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
| | - Danqing Tong
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
| | - Christopher J. Marklew
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Brook Hill, Sheffield, UK
| | - Nicholas R. Ader
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
| | | | - Sapan Borah
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
| | - Megan C. King
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
| | - Barbara Ciani
- Centre for Chemical Biology, Department of Chemistry, Krebs Institute, University of Sheffield, Brook Hill, Sheffield, UK
| | - C. Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, New Haven, CT
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30
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Why Cells and Viruses Cannot Survive without an ESCRT. Cells 2021; 10:cells10030483. [PMID: 33668191 PMCID: PMC7995964 DOI: 10.3390/cells10030483] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 02/19/2021] [Accepted: 02/21/2021] [Indexed: 12/15/2022] Open
Abstract
Intracellular organelles enwrapped in membranes along with a complex network of vesicles trafficking in, out and inside the cellular environment are one of the main features of eukaryotic cells. Given their central role in cell life, compartmentalization and mechanisms allowing their maintenance despite continuous crosstalk among different organelles have been deeply investigated over the past years. Here, we review the multiple functions exerted by the endosomal sorting complex required for transport (ESCRT) machinery in driving membrane remodeling and fission, as well as in repairing physiological and pathological membrane damages. In this way, ESCRT machinery enables different fundamental cellular processes, such as cell cytokinesis, biogenesis of organelles and vesicles, maintenance of nuclear–cytoplasmic compartmentalization, endolysosomal activity. Furthermore, we discuss some examples of how viruses, as obligate intracellular parasites, have evolved to hijack the ESCRT machinery or part of it to execute/optimize their replication cycle/infection. A special emphasis is given to the herpes simplex virus type 1 (HSV-1) interaction with the ESCRT proteins, considering the peculiarities of this interplay and the need for HSV-1 to cross both the nuclear-cytoplasmic and the cytoplasmic-extracellular environment compartmentalization to egress from infected cells.
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31
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Feurle P, Abentung A, Cera I, Wahl N, Ablinger C, Bucher M, Stefan E, Sprenger S, Teis D, Fischer A, Laighneach A, Whitton L, Morris DW, Apostolova G, Dechant G. SATB2-LEMD2 interaction links nuclear shape plasticity to regulation of cognition-related genes. EMBO J 2021; 40:e103701. [PMID: 33319920 PMCID: PMC7849313 DOI: 10.15252/embj.2019103701] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 10/22/2020] [Accepted: 11/06/2020] [Indexed: 01/22/2023] Open
Abstract
SATB2 is a schizophrenia risk gene and is genetically associated with human intelligence. How it affects cognition at molecular level is currently unknown. Here, we show that interactions between SATB2, a chromosomal scaffolding protein, and the inner nuclear membrane protein LEMD2 orchestrate the response of pyramidal neurons to neuronal activation. Exposure to novel environment in vivo causes changes in nuclear shape of CA1 hippocampal neurons via a SATB2-dependent mechanism. The activity-driven plasticity of the nuclear envelope requires not only SATB2, but also its protein interactor LEMD2 and the ESCRT-III/VPS4 membrane-remodeling complex. Furthermore, LEMD2 depletion in cortical neurons, similar to SATB2 ablation, affects neuronal activity-dependent regulation of multiple rapid and delayed primary response genes. In human genetic data, LEMD2-regulated genes are enriched for de novo mutations reported in intellectual disability and schizophrenia and are, like SATB2-regulated genes, enriched for common variants associated with schizophrenia and cognitive function. Hence, interactions between SATB2 and the inner nuclear membrane protein LEMD2 influence gene expression programs in pyramidal neurons that are linked to cognitive ability and psychiatric disorder etiology.
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Affiliation(s)
- Patrick Feurle
- Institute for NeuroscienceMedical University of InnsbruckInnsbruckAustria
| | - Andreas Abentung
- Institute for NeuroscienceMedical University of InnsbruckInnsbruckAustria
| | - Isabella Cera
- Institute for NeuroscienceMedical University of InnsbruckInnsbruckAustria
| | - Nico Wahl
- Institute for NeuroscienceMedical University of InnsbruckInnsbruckAustria
| | - Cornelia Ablinger
- Institute for NeuroscienceMedical University of InnsbruckInnsbruckAustria
| | - Michael Bucher
- Institute of Biochemistry and Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | - Eduard Stefan
- Institute of Biochemistry and Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | - Simon Sprenger
- Institute for Cell BiologyMedical University of InnsbruckInnsbruckAustria
| | - David Teis
- Institute for Cell BiologyMedical University of InnsbruckInnsbruckAustria
| | - Andre Fischer
- Department of Systems Medicine and EpigeneticsGerman Center for Neurodegenerative Diseases (DZNE)GoettingenGermany
- Department of Psychiatry and PsychotherapyUniversity Medical CenterGoettingenGermany
| | - Aodán Laighneach
- Neuroimaging, Cognition & Genomics (NICOG) CentreSchool of Psychology and Discipline of BiochemistryNational University of Ireland GalwayGalwayIreland
| | - Laura Whitton
- Neuroimaging, Cognition & Genomics (NICOG) CentreSchool of Psychology and Discipline of BiochemistryNational University of Ireland GalwayGalwayIreland
| | - Derek W Morris
- Neuroimaging, Cognition & Genomics (NICOG) CentreSchool of Psychology and Discipline of BiochemistryNational University of Ireland GalwayGalwayIreland
| | - Galina Apostolova
- Institute for NeuroscienceMedical University of InnsbruckInnsbruckAustria
| | - Georg Dechant
- Institute for NeuroscienceMedical University of InnsbruckInnsbruckAustria
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32
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Dey G, Baum B. Nuclear envelope remodelling during mitosis. Curr Opin Cell Biol 2021; 70:67-74. [PMID: 33421755 PMCID: PMC8129912 DOI: 10.1016/j.ceb.2020.12.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/07/2020] [Accepted: 12/09/2020] [Indexed: 12/20/2022]
Abstract
The defining feature of the eukaryotic cell, the nucleus, is bounded by a double envelope. This envelope and the nuclear pores within it play a critical role in separating the genome from the cytoplasm. It also presents cells with a challenge. How are cells to remodel the nuclear compartment boundary during mitosis without compromising nuclear function? In the two billion years since the emergence of the first cells with a nucleus, eukaryotes have evolved a range of strategies to do this. At one extreme, the nucleus is disassembled upon entry into mitosis and then reassembled anew in the two daughter cells. At the other, cells maintain an intact nuclear compartment boundary throughout the division process. In this review, we discuss common features of the division process that underpin remodelling mechanisms, the topological challenges involved and speculate on the selective pressures that may drive the evolution of distinct modes of division.
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Affiliation(s)
- Gautam Dey
- Cell Biology and Biophysics, European Molecular Biology Laboratory, 69117, Heidelberg, Germany.
| | - Buzz Baum
- Lab of Molecular Biology, Cambridge, CB2 0QH, United Kingdom; Lab for Molecular Cell Biology, UCL, London, WC1E 6BT, United Kingdom.
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33
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Capella M, Martín Caballero L, Pfander B, Braun S, Jentsch S. ESCRT recruitment by the S. cerevisiae inner nuclear membrane protein Heh1 is regulated by Hub1-mediated alternative splicing. J Cell Sci 2020; 133:jcs250688. [PMID: 33262311 DOI: 10.1242/jcs.250688] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 11/17/2020] [Indexed: 12/28/2022] Open
Abstract
Misassembled nuclear pore complexes (NPCs) are removed by sealing off the surrounding nuclear envelope (NE), which is conducted by the endosomal sorting complexes required for transport (ESCRT) machinery. Recruitment of ESCRT proteins to the NE is mediated by the interaction between the ESCRT member Chm7 and the inner nuclear membrane protein Heh1, which belongs to the conserved LEM family. Increased ESCRT recruitment results in excessive membrane scission at damage sites but its regulation remains poorly understood. Here, we show that Hub1-mediated alternative splicing of HEH1 pre-mRNA, resulting in production of its shorter form Heh1-S, is critical for the integrity of the NE in Saccharomyces cerevisiae ESCRT-III mutants lacking Hub1 or Heh1-S display severe growth defects and accumulate improperly assembled NPCs. This depends on the interaction of Chm7 with the conserved MSC domain, which is only present in the longer variant Heh1-L. Heh1 variants assemble into heterodimers, and we demonstrate that a unique splice segment in Heh1-S suppresses growth defects associated with the uncontrolled interaction between Heh1-L and Chm7. Together, our findings reveal that Hub1-mediated splicing generates Heh1-S to regulate ESCRT recruitment to the NE.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Matías Capella
- Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
- Department of Physiological Chemistry, Biomedical Center (BMC), Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
| | - Lucía Martín Caballero
- Department of Physiological Chemistry, Biomedical Center (BMC), Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
| | - Boris Pfander
- International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
- DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Sigurd Braun
- Department of Physiological Chemistry, Biomedical Center (BMC), Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
| | - Stefan Jentsch
- Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
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34
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High-Throughput Identification of Nuclear Envelope Protein Interactions in Schizosaccharomyces pombe Using an Arrayed Membrane Yeast-Two Hybrid Library. G3-GENES GENOMES GENETICS 2020; 10:4649-4663. [PMID: 33109728 PMCID: PMC7718735 DOI: 10.1534/g3.120.401880] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The nuclear envelope (NE) contains a specialized set of integral membrane proteins that maintain nuclear shape and integrity and influence chromatin organization and gene expression. Advances in proteomics techniques and studies in model organisms have identified hundreds of proteins that localize to the NE. However, the function of many of these proteins at the NE remains unclear, in part due to a lack of understanding of the interactions that these proteins participate in at the NE membrane. To assist in the characterization of NE transmembrane protein interactions we developed an arrayed library of integral and peripheral membrane proteins from the fission yeast Schizosaccharomyces pombe for high-throughput screening using the split-ubiquitin based membrane yeast two -hybrid system. We used this approach to characterize protein interactions for three conserved proteins that localize to the inner nuclear membrane: Cut11/Ndc1, Lem2 and Ima1/Samp1/Net5. Additionally, we determined how the interaction network for Cut11 is altered in canonical temperature-sensitive cut11-ts mutants. This library and screening approach is readily applicable to characterizing the interactomes of integral membrane proteins localizing to various subcellular compartments.
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35
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Mirza AN, Gonzalez F, Ha SK, Oro AE. The Sky's the LEMit: New insights into nuclear structure regulation of transcription factor activity. Curr Opin Cell Biol 2020; 68:173-180. [PMID: 33227657 DOI: 10.1016/j.ceb.2020.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/24/2020] [Accepted: 10/08/2020] [Indexed: 12/31/2022]
Abstract
The nucleoskeleton has been associated with partitioning the genome into active and inactive compartments that dictate local transcription factor (TF) activity. However, recent data indicate that the nucleoskeleton and TFs reciprocally influence each other in dynamic TF trafficking pathways through the functions of LEM proteins. While the conserved peripheral recruitment of TFs by LEM proteins has been viewed as a mechanism of repressing transcription, a diversity of release mechanisms from the lamina suggest this compartment serves as a refuge for nuclear TF accumulation for rapid mobilization and signal stability. Detailed mechanisms suggest that TFs toggle between nuclear lamina refuge and nuclear matrix lamin-LEM protein complexes at sites of active transcription. In this review we will highlight emerging LEM functions acting at the interface of chromatin and nucleoskeleton to create TF trafficking networks.
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Affiliation(s)
- Amar N Mirza
- Program in Epithelial Biology, Stanford University School of Medicine Stanford, CA, 94305, USA
| | - Fernanda Gonzalez
- Program in Epithelial Biology, Stanford University School of Medicine Stanford, CA, 94305, USA
| | - Sierra K Ha
- Program in Epithelial Biology, Stanford University School of Medicine Stanford, CA, 94305, USA
| | - Anthony E Oro
- Program in Epithelial Biology, Stanford University School of Medicine Stanford, CA, 94305, USA.
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36
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Capella M, Braun S. ESCRTing Heterochromatin Out of the Nuclear Periphery. Dev Cell 2020; 53:3-5. [PMID: 32259492 DOI: 10.1016/j.devcel.2020.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
ESCRT proteins fulfill an important function in membrane remodeling and scission. In this issue of Developmental Cell, Pieper et al. reveal that the ESCRT machinery releases the inner nuclear membrane protein Lem2 from heterochromatin, thus ensuring its function in nuclear envelope resealing after mitosis.
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Affiliation(s)
- Matías Capella
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Sigurd Braun
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.
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37
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Marcelot A, Worman HJ, Zinn-Justin S. Protein structural and mechanistic basis of progeroid laminopathies. FEBS J 2020; 288:2757-2772. [PMID: 32799420 DOI: 10.1111/febs.15526] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 07/30/2020] [Indexed: 12/14/2022]
Abstract
Progeroid laminopathies are characterized by the premature appearance of certain signs of physiological aging in a subset of tissues. They are caused by mutations in genes coding for A-type lamins or lamin-binding proteins. Here, we review how different mutations causing progeroid laminopathies alter protein structure or protein-protein interactions and how these impact on mechanisms that protect cell viability and function. One group of progeroid laminopathies, which includes Hutchinson-Gilford progeria syndrome, is characterized by accumulation of unprocessed prelamin A or variants. These are caused by mutations in the A-type lamin gene (LMNA), altering prelamin A itself, or in ZMPSTE24, encoding an endoprotease involved in its processing. The abnormally expressed farnesylated proteins impact on various cellular processes that may contribute to progeroid phenotypes. Other LMNA mutations lead to the production of nonfarnesylated A-type lamin variants with amino acid substitutions in solvent-exposed hot spots located mainly in coil 1B and the immunoglobulin fold domain. Dominant missense mutations might reinforce interactions between lamin domains, thus giving rise to excessively stabilized filament networks. Recessive missense mutations in A-type lamins and barrier-to-autointegration factor (BAF) causing progeroid disorders are found at the interface between these interacting proteins. The amino acid changes decrease the binding affinity of A-type lamins for BAF, which may contribute to lamina disorganization, as well as defective repair of mechanically induced nuclear envelope rupture. Targeting these molecular alterations in A-type lamins and associated proteins identified through structural biology studies could facilitate the design of therapeutic strategies to treat patients with rare but severe progeroid laminopathies.
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Affiliation(s)
- Agathe Marcelot
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Uni Paris-Sud, Uni Paris-Saclay, Gif-sur-Yvette Cedex, France
| | - Howard J Worman
- Department of Medicine and Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Sophie Zinn-Justin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Uni Paris-Sud, Uni Paris-Saclay, Gif-sur-Yvette Cedex, France
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38
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Dey G, Culley S, Curran S, Schmidt U, Henriques R, Kukulski W, Baum B. Closed mitosis requires local disassembly of the nuclear envelope. Nature 2020; 585:119-123. [PMID: 32848252 PMCID: PMC7610560 DOI: 10.1038/s41586-020-2648-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 05/21/2020] [Indexed: 01/15/2023]
Abstract
At the end of mitosis, eukaryotic cells must segregate the two copies of their replicated genome into two new nuclear compartments1. They do this either by first dismantling and later reassembling the nuclear envelope in an 'open mitosis' or by reshaping an intact nucleus and then dividing it into two in a 'closed mitosis'2,3. Mitosis has been studied in a wide variety of eukaryotes for more than a century4, but how the double membrane of the nuclear envelope is split into two at the end of a closed mitosis without compromising the impermeability of the nuclear compartment remains unknown5. Here, using the fission yeast Schizosaccharomyces pombe (a classical model for closed mitosis5), genetics, live-cell imaging and electron tomography, we show that nuclear fission is achieved via local disassembly of nuclear pores within the narrow bridge that links segregating daughter nuclei. In doing so, we identify the protein Les1, which is localized to the inner nuclear envelope and restricts the process of local nuclear envelope breakdown to the bridge midzone to prevent the leakage of material from daughter nuclei. The mechanism of local nuclear envelope breakdown in a closed mitosis therefore closely mirrors nuclear envelope breakdown in open mitosis3, revealing an unexpectedly high conservation of nuclear remodelling mechanisms across diverse eukaryotes.
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Affiliation(s)
- Gautam Dey
- MRC Laboratory for Molecular Cell Biology, London, UK.
| | - Siân Culley
- MRC Laboratory for Molecular Cell Biology, London, UK
| | | | - Uwe Schmidt
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Center for Systems Biology Dresden, Dresden, Germany
| | | | | | - Buzz Baum
- MRC Laboratory for Molecular Cell Biology, London, UK.
- Institute for the Physics of Living Systems, University College London, London, UK.
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Mori R, Oliferenko S. Cell Biology: An Open Solution for Closed Mitosis. Curr Biol 2020; 30:R942-R944. [PMID: 32810455 DOI: 10.1016/j.cub.2020.06.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
At the end of mitosis, cells must remodel their nuclear envelope to produce two identical daughter nuclei. Two new studies using Schizosaccharomyces pombe provide insight into how compartmentalized nuclear pore complex disassembly allows cells that undergo closed mitosis to achieve nuclear division.
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Affiliation(s)
- Risa Mori
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, UK
| | - Snezhana Oliferenko
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, UK.
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40
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Nuclear Envelope Proteins Modulating the Heterochromatin Formation and Functions in Fission Yeast. Cells 2020; 9:cells9081908. [PMID: 32824370 PMCID: PMC7464478 DOI: 10.3390/cells9081908] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/14/2020] [Accepted: 08/15/2020] [Indexed: 12/16/2022] Open
Abstract
The nuclear envelope (NE) consists of the inner and outer nuclear membranes (INM and ONM), and the nuclear pore complex (NPC), which penetrates the double membrane. ONM continues with the endoplasmic reticulum (ER). INM and NPC can interact with chromatin to regulate the genetic activities of the chromosome. Studies in the fission yeast Schizosaccharomyces pombe have contributed to understanding the molecular mechanisms underlying heterochromatin formation by the RNAi-mediated and histone deacetylase machineries. Recent studies have demonstrated that NE proteins modulate heterochromatin formation and functions through interactions with heterochromatic regions, including the pericentromeric and the sub-telomeric regions. In this review, we first introduce the molecular mechanisms underlying the heterochromatin formation and functions in fission yeast, and then summarize the NE proteins that play a role in anchoring heterochromatic regions and in modulating heterochromatin formation and functions, highlighting roles for a conserved INM protein, Lem2.
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Expósito-Serrano M, Sánchez-Molina A, Gallardo P, Salas-Pino S, Daga RR. Selective Nuclear Pore Complex Removal Drives Nuclear Envelope Division in Fission Yeast. Curr Biol 2020; 30:3212-3222.e2. [DOI: 10.1016/j.cub.2020.05.066] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/24/2020] [Accepted: 05/20/2020] [Indexed: 01/09/2023]
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42
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Guo X, Dai X, Wu X, Zhou T, Ni J, Xue J, Wang X. Understanding the birth of rupture-prone and irreparable micronuclei. Chromosoma 2020; 129:181-200. [PMID: 32671520 DOI: 10.1007/s00412-020-00741-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/30/2020] [Accepted: 07/02/2020] [Indexed: 12/17/2022]
Abstract
Micronuclei are extra-nuclear bodies mainly derived from ana-telophase lagging chromosomes/chromatins (LCs) that are not incorporated into primary nuclei at mitotic exit. Unlike primary nuclei, most micronuclei are enclosed by nuclear envelope (NE) that is highly susceptible to spontaneous and irreparable rupture. Ruptured micronuclei act as triggers of chromothripsis-like chaotic chromosomal rearrangements and cGAS-mediated innate immunity and inflammation, raising the view that micronuclei play active roles in human aging and tumorigenesis. Thus, understanding the ways in which micronuclear envelope (mNE) goes awry acquires increased importance. Here, we review the data to present a general framework for this question. We firstly describe NE reassembly after mitosis and NE repair during interphase. Simultaneously, we briefly discuss how mNE is organized and how mNE rupture controls the fate of micronuclei and micronucleated cells. As a focus of this review, we highlight current knowledge about why mNE is rupture-prone and irreparable. For this, we survey observations from a series of elegant studies to provide a systematic overview. We conclude that the birth of rupture-prone and irreparable micronuclei may be the cumulative effects of their intracellular geographic origins, biophysical properties, and specific mNE features. We propose that DNA damage and immunogenicity in micronuclei increase stepwise from altered mNE components, mNE rupture, and refractory to repair. Throughout our discussion, we note interesting issues in mNE fragility that have yet to be resolved.
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Affiliation(s)
- Xihan Guo
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, 650500, Yunnan, China
| | - Xueqin Dai
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650204, Yunnan, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Xue Wu
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, 650500, Yunnan, China
| | - Tao Zhou
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, 650500, Yunnan, China
| | - Juan Ni
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, 650500, Yunnan, China
| | - Jinglun Xue
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Xu Wang
- School of Life Sciences, The Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Yunnan Normal University, Kunming, 650500, Yunnan, China.
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Hirano Y, Kinugasa Y, Osakada H, Shindo T, Kubota Y, Shibata S, Haraguchi T, Hiraoka Y. Lem2 and Lnp1 maintain the membrane boundary between the nuclear envelope and endoplasmic reticulum. Commun Biol 2020; 3:276. [PMID: 32483293 PMCID: PMC7264229 DOI: 10.1038/s42003-020-0999-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 05/11/2020] [Indexed: 01/09/2023] Open
Abstract
The nuclear envelope (NE) continues to the endoplasmic reticulum (ER). Proper partitioning of NE and ER is crucial for cellular activity, but the key factors maintaining the boundary between NE and ER remain to be elucidated. Here we show that the conserved membrane proteins Lem2 and Lnp1 cooperatively play a crucial role in maintaining the NE-ER membrane boundary in fission yeast Schizosaccharomyces pombe. Cells lacking both Lem2 and Lnp1 caused severe growth defects associated with aberrant expansion of the NE/ER membranes, abnormal leakage of nuclear proteins, and abnormal formation of vacuolar-like structures in the nucleus. Overexpression of the ER membrane protein Apq12 rescued the growth defect associated with membrane disorder caused by the loss of Lem2 and Lnp1. Genetic analysis showed that Apq12 had overlapping functions with Lnp1. We propose that a membrane protein network with Lem2 and Lnp1 acts as a critical factor to maintain the NE-ER boundary.
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Affiliation(s)
- Yasuhiro Hirano
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.
| | - Yasuha Kinugasa
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
- Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8553, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan
| | - Tomoko Shindo
- Electron Microscope Laboratory, Keio University School of Medicine, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Yoshino Kubota
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
| | - Shinsuke Shibata
- Electron Microscope Laboratory, Keio University School of Medicine, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan.
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44
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Lusk CP, Ader NR. CHMPions of repair: Emerging perspectives on sensing and repairing the nuclear envelope barrier. Curr Opin Cell Biol 2020; 64:25-33. [PMID: 32105978 PMCID: PMC7371540 DOI: 10.1016/j.ceb.2020.01.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 12/20/2022]
Abstract
Understanding how the integrity of the nuclear membranes is protected against internal and external stresses is an emergent challenge. Work reviewed here investigated the mechanisms by which losses of nuclear-cytoplasmic compartmentalization are sensed and ameliorated. Fundamental to these is spatial control over interactions between the endosomal sorting complexes required for transport machinery and LAP2-emerin-MAN1 family inner nuclear membrane proteins, which together promote nuclear envelope sealing in interphase and at the end of mitosis. We suggest that the size of the nuclear envelope hole dictates the mechanism of its repair, with larger holes requiring barrier-to-autointegration factor and the potential triggering of a postmitotic nuclear envelope reassembly pathway in interphase. We also consider why these mechanisms fail at ruptured micronuclei. Together, this work re-emphasizes the need to understand how membrane flow and local lipid metabolism help ensure that the nuclear envelope is refractory to mechanical rupture yet fluid enough to allow its essential dynamics.
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Affiliation(s)
- C Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, 295 Congress Avenue, New Haven, CT, 06520, USA.
| | - Nicholas R Ader
- Department of Cell Biology, Yale School of Medicine, 295 Congress Avenue, New Haven, CT, 06520, USA
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45
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von Appen A, LaJoie D, Johnson IE, Trnka MJ, Pick SM, Burlingame AL, Ullman KS, Frost A. LEM2 phase separation promotes ESCRT-mediated nuclear envelope reformation. Nature 2020; 582:115-118. [PMID: 32494070 PMCID: PMC7321842 DOI: 10.1038/s41586-020-2232-x] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 02/26/2020] [Indexed: 01/01/2023]
Abstract
During cell division, remodelling of the nuclear envelope enables chromosome segregation by the mitotic spindle1. The reformation of sealed nuclei requires ESCRTs (endosomal sorting complexes required for transport) and LEM2, a transmembrane ESCRT adaptor2-4. Here we show how the ability of LEM2 to condense on microtubules governs the activation of ESCRTs and coordinated spindle disassembly. The LEM motif of LEM2 binds BAF, conferring on LEM2 an affinity for chromatin5,6, while an adjacent low-complexity domain (LCD) promotes LEM2 phase separation. A proline-arginine-rich sequence within the LCD binds to microtubules and targets condensation of LEM2 to spindle microtubules that traverse the nascent nuclear envelope. Furthermore, the winged-helix domain of LEM2 activates the ESCRT-II/ESCRT-III hybrid protein CHMP7 to form co-oligomeric rings. Disruption of these events in human cells prevented the recruitment of downstream ESCRTs, compromised spindle disassembly, and led to defects in nuclear integrity and DNA damage. We propose that during nuclear reassembly LEM2 condenses into a liquid-like phase and coassembles with CHMP7 to form a macromolecular O-ring seal at the confluence between membranes, chromatin and the spindle. The properties of LEM2 described here, and the homologous architectures of related inner nuclear membrane proteins7,8, suggest that phase separation may contribute to other critical envelope functions, including interphase repair8-13 and chromatin organization14-17.
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Affiliation(s)
- Alexander von Appen
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | - Dollie LaJoie
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Isabel E Johnson
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | - Michael J Trnka
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Sarah M Pick
- Faculty of Chemistry and Pharmacy, University of Freiburg, Freiburg, Germany
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Katharine S Ullman
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA.
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
- Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA, USA.
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46
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Lee IJ, Stokasimov E, Dempsey N, Varberg JM, Jacob E, Jaspersen SL, Pellman D. Factors promoting nuclear envelope assembly independent of the canonical ESCRT pathway. J Cell Biol 2020; 219:e201908232. [PMID: 32243490 PMCID: PMC7265314 DOI: 10.1083/jcb.201908232] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 01/11/2020] [Accepted: 03/03/2020] [Indexed: 01/15/2023] Open
Abstract
The nuclear envelope (NE) undergoes dynamic remodeling to maintain NE integrity, a process involving the inner nuclear membrane protein LEM2 recruiting CHMP7/Cmp7 and then ESCRT-III. However, prior work has hinted at CHMP7/ESCRT-independent mechanisms. To identify such mechanisms, we studied NE assembly in Schizosaccharomyces japonicus, a fission yeast that undergoes partial mitotic NE breakdown and reassembly. S. japonicus cells lacking Cmp7 have compromised NE sealing after mitosis but are viable. A genetic screen identified mutations that promote NE integrity in cmp7Δ cells. Unexpectedly, loss of Lem2 or its interacting partner Nur1 suppressed cmp7Δ defects. In the absence of Cmp7, Lem2 formed aggregates that appear to interfere with ESCRT-independent NE sealing. A gain-of-function mutation implicated a membrane and ESCRT-III regulator, Alx1, in this alternate pathway. Additional results suggest a potentially general role for unsaturated fatty acids in NE integrity. These findings establish the existence of mechanisms for NE sealing independent of the canonical ESCRT pathway.
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Affiliation(s)
- I-Ju Lee
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Ema Stokasimov
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Nathaniel Dempsey
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | | | - Etai Jacob
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
| | - Sue L. Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS
| | - David Pellman
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA
- Department of Cell Biology, Harvard Medical School, Boston, MA
- Howard Hughes Medical Institute, Chevy Chase, MD
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