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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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Rose M, Burgess JT, Cheong CM, Adams MN, Shahrouzi P, O’Byrne KJ, Richard DJ, Bolderson E. The expression and role of the Lem-D proteins Ankle2, Emerin, Lemd2, and TMPO in triple-negative breast cancer cell growth. Front Oncol 2024; 14:1222698. [PMID: 38720803 PMCID: PMC11076778 DOI: 10.3389/fonc.2024.1222698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 02/28/2024] [Indexed: 05/12/2024] Open
Abstract
Background Triple-negative breast cancer (TNBC) is a sub-classification of breast carcinomas, which leads to poor survival outcomes for patients. TNBCs do not possess the hormone receptors that are frequently targeted as a therapeutic in other cancer subtypes and, therefore, chemotherapy remains the standard treatment for TNBC. Nuclear envelope proteins are frequently dysregulated in cancer cells, supporting their potential as novel cancer therapy targets. The Lem-domain (Lem-D) (LAP2, Emerin, MAN1 domain, and Lem-D) proteins are a family of inner nuclear membrane proteins, which share a ~45-residue Lem-D. The Lem-D proteins, including Ankle2, Lemd2, TMPO, and Emerin, have been shown to be associated with many of the hallmarks of cancer. This study aimed to define the association between the Lem-D proteins and TNBC and determine whether these proteins could be promising therapeutic targets. Methods GENT2, TCGA, and KM plotter were utilized to investigate the expression and prognostic implications of several Lem-D proteins: Ankle2, TMPO, Emerin, and Lemd2 in publicly available breast cancer patient data. Immunoblotting and immunofluorescent analysis of immortalized non-cancerous breast cells and a panel of TNBC cells were utilized to establish whether protein expression of the Lem-D proteins was significantly altered in TNBC. SiRNA was used to decrease individual Lem-D protein expression, and functional assays, including proliferation assays and apoptosis assays, were conducted. Results The Lem-D proteins were generally overexpressed in TNBC patient samples at the mRNA level and showed variable expression at the protein level in TNBC cell lysates. Similarly, protein levels were generally negatively correlated with patient survival outcomes. siRNA-mediated depletion of the individual Lem-D proteins in TNBC cells induced aberrant nuclear morphology, decreased proliferation, and induced cell death. However, minimal effects on nuclear morphology or cell viability were observed following Lem-D depletion in non-cancerous MCF10A cells. Conclusion There is evidence to suggest that Ankle2, TMPO, Emerin, and Lemd2 expressions are correlated with breast cancer patient outcomes, but larger patient sample numbers are required to confirm this. siRNA-mediated depletion of these proteins was shown to specifically impair TNBC cell growth, suggesting that the Lem-D proteins may be a specific anti-cancer target.
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Affiliation(s)
- Maddison Rose
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology, Brisbane, QLD, Australia
| | - Joshua T. Burgess
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology, Brisbane, QLD, Australia
| | - Chee Man Cheong
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology, Brisbane, QLD, Australia
| | - Mark N. Adams
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology, Brisbane, QLD, Australia
| | - Parastoo Shahrouzi
- Department of Medical Genetics, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Kenneth J. O’Byrne
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology, Brisbane, QLD, Australia
- Cancer Services, Princess Alexandra Hospital, Brisbane, QLD, Australia
| | - Derek J. Richard
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology, Brisbane, QLD, Australia
| | - Emma Bolderson
- Cancer and Ageing Research Program, Centre for Genomics and Personalised Health, School of Biomedical Sciences, Translational Research Institute, Queensland University of Technology, Brisbane, QLD, Australia
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Kapoor S, Adhikary K, Kotak S. PP2A-B55 SUR-6 promotes nuclear envelope breakdown in C. elegans embryos. Cell Rep 2023; 42:113495. [PMID: 37995185 DOI: 10.1016/j.celrep.2023.113495] [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: 05/31/2023] [Revised: 09/25/2023] [Accepted: 11/09/2023] [Indexed: 11/25/2023] Open
Abstract
Nuclear envelope (NE) disassembly during mitosis is critical to ensure faithful segregation of the genetic material. NE disassembly is a phosphorylation-dependent process wherein mitotic kinases hyper-phosphorylate lamina and nucleoporins to initiate nuclear envelope breakdown (NEBD). In this study, we uncover an unexpected role of the PP2A phosphatase B55SUR-6 in NEBD during the first embryonic division of Caenorhabditis elegans embryo. B55SUR-6 depletion delays NE permeabilization and stabilizes lamina and nucleoporins. As a result, the merging of parental genomes and chromosome segregation is impaired. NEBD defect upon B55SUR-6 depletion is not due to delayed mitotic onset or mislocalization of mitotic kinases. Importantly, we demonstrate that microtubule-dependent mechanical forces synergize with B55SUR-6 for efficient NEBD. Finally, our data suggest that the lamin LMN-1 is likely a bona fide target of PP2A-B55SUR-6. These findings establish a model highlighting biochemical crosstalk between kinases, PP2A-B55SUR-6 phosphatase, and microtubule-generated mechanical forces in timely NE dissolution.
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Affiliation(s)
- Sukriti Kapoor
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science (IISc), Bangalore 560012, India
| | - Kuheli Adhikary
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science (IISc), Bangalore 560012, India
| | - Sachin Kotak
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science (IISc), Bangalore 560012, India.
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4
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Barger SR, Penfield L, Bahmanyar S. Nuclear envelope assembly relies on CHMP-7 in the absence of BAF-LEM-mediated hole closure. J Cell Sci 2023; 136:jcs261385. [PMID: 37795681 PMCID: PMC10668030 DOI: 10.1242/jcs.261385] [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: 06/04/2023] [Accepted: 09/21/2023] [Indexed: 10/06/2023] Open
Abstract
Barrier-to-autointegration factor (BAF) protein is a DNA-binding protein that crosslinks chromatin to allow mitotic nuclear envelope (NE) assembly. The LAP2-emerin-MAN1 (LEM)-domain protein LEMD2 and ESCRT-II/III hybrid protein CHMP7 close NE holes surrounding spindle microtubules (MTs). BAF binds LEM-domain family proteins to repair NE ruptures in interphase, but whether BAF-LEM binding participates in NE hole closure around spindle MTs is not known. Here, we took advantage of the stereotypical event of NE formation in fertilized Caenorhabditis elegans oocytes to show that BAF-LEM binding and LEM-2-CHMP-7 have distinct roles in NE closure around spindle MTs. LEM-2 and EMR-1 (homologs of LEMD2 and emerin) function redundantly with BAF-1 (the C. elegans BAF protein) in NE closure. Compromising BAF-LEM binding revealed an additional role for EMR-1 in the maintenance of the NE permeability barrier. In the absence of BAF-LEM binding, LEM-2-CHMP-7 was required for NE assembly and embryo survival. The winged helix domain of LEM-2 recruits CHMP-7 to the NE in C. elegans and a LEM-2-independent nucleoplasmic pool of CHMP-7 also contributes to NE stability. Thus, NE hole closure surrounding spindle MTs requires redundant mechanisms that safeguard against failure in NE assembly to support embryogenesis.
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Affiliation(s)
- Sarah R. Barger
- Yale University, Department of Molecular, Cellular, Developmental Biology, 266 Whitney Ave., New Haven, CT 06511, USA
| | - Lauren Penfield
- Yale University, Department of Molecular, Cellular, Developmental Biology, 266 Whitney Ave., New Haven, CT 06511, USA
| | - Shirin Bahmanyar
- Yale University, Department of Molecular, Cellular, Developmental Biology, 266 Whitney Ave., New Haven, CT 06511, USA
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5
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Nkombo Nkoula S, Velez-Aguilera G, Ossareh-Nazari B, Van Hove L, Ayuso C, Legros V, Chevreux G, Thomas L, Seydoux G, Askjaer P, Pintard L. Mechanisms of nuclear pore complex disassembly by the mitotic Polo-like kinase 1 (PLK-1) in C. elegans embryos. SCIENCE ADVANCES 2023; 9:eadf7826. [PMID: 37467327 PMCID: PMC10355831 DOI: 10.1126/sciadv.adf7826] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 06/16/2023] [Indexed: 07/21/2023]
Abstract
The nuclear envelope, which protects and organizes the genome, is dismantled during mitosis. In the Caenorhabditis elegans zygote, nuclear envelope breakdown (NEBD) of the parental pronuclei is spatially and temporally regulated during mitosis to promote the unification of the maternal and paternal genomes. Nuclear pore complex (NPC) disassembly is a decisive step of NEBD, essential for nuclear permeabilization. By combining live imaging, biochemistry, and phosphoproteomics, we show that NPC disassembly is a stepwise process that involves Polo-like kinase 1 (PLK-1)-dependent and -independent steps. PLK-1 targets multiple NPC subcomplexes, including the cytoplasmic filaments, central channel, and inner ring. PLK-1 is recruited to and phosphorylates intrinsically disordered regions (IDRs) of several multivalent linker nucleoporins. Notably, although the phosphosites are not conserved between human and C. elegans nucleoporins, they are located in IDRs in both species. Our results suggest that targeting IDRs of multivalent linker nucleoporins is an evolutionarily conserved driver of NPC disassembly during mitosis.
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Affiliation(s)
- Sylvia Nkombo Nkoula
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Programme Équipe Labellisée Ligue contre le Cancer, Paris, France
| | - Griselda Velez-Aguilera
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Programme Équipe Labellisée Ligue contre le Cancer, Paris, France
| | - Batool Ossareh-Nazari
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Programme Équipe Labellisée Ligue contre le Cancer, Paris, France
| | - Lucie Van Hove
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Programme Équipe Labellisée Ligue contre le Cancer, Paris, France
| | - Cristina Ayuso
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, Seville, Spain
| | - Véronique Legros
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Guillaume Chevreux
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | - Laura Thomas
- HHMI and Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Géraldine Seydoux
- HHMI and Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Peter Askjaer
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, Seville, Spain
| | - Lionel Pintard
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Programme Équipe Labellisée Ligue contre le Cancer, Paris, France
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Barger SR, Penfield L, Bahmanyar S. Nuclear envelope assembly relies on CHMP-7 in the absence of BAF-LEM-mediated hole closure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.06.547980. [PMID: 37461528 PMCID: PMC10350047 DOI: 10.1101/2023.07.06.547980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Barrier-to-autointegration factor (BAF) is a DNA binding protein that crosslinks chromatin to assemble the nuclear envelope (NE) after mitosis. BAF also binds the Lap2b-Emerin-Man1 (LEM) domain family of NE proteins to repair interphase ruptures. The NE adaptors to ESCRTs, LEMD2-CHMP7, seal NE holes surrounding mitotic spindle microtubules (MTs), but whether NE hole closure in mitosis involves BAF-LEM binding is not known. Here, we analyze NE sealing after meiosis II in C. elegans oocytes to show that BAF-LEM binding and LEM-2 LEMD2 -CHMP-7 have distinct roles in hole closure around spindle MTs. LEM-2/EMR-1 emerin function redundantly with BAF-1 to seal the NE. Compromising BAF-LEM binding revealed an additional role for EMR-1 in maintenance of the NE permeability barrier and an essential role for LEM-2-CHMP-7 in preventing NE assembly failure. The WH domain of LEM-2 recruits the majority of CHMP-7 to the NE in C. elegans and a LEM-2 -independent pool of CHMP-7, which is mostly enriched in the nucleoplasm, also contributes to NE stability. Thus, NE hole closure surrounding spindle MTs requires redundant mechanisms that safeguard against failure in NE assembly to support embryogenesis.
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Affiliation(s)
- Sarah R. Barger
- Yale University, Department of Molecular, Cellular, Developmental Biology, 266 Whitney Ave., New Haven, CT 06511
| | - Lauren Penfield
- Current address: Department of Molecular, Cellular, and Developmental Biology at University of California, Santa Barbara, CA
| | - Shirin Bahmanyar
- Yale University, Department of Molecular, Cellular, Developmental Biology, 266 Whitney Ave., New Haven, CT 06511
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7
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Fan Q, Li XM, Zhai C, Li B, Li ST, Dong MQ. Somatic nuclear blebbing in Caenorhabditis elegans is not a feature of organismal aging but a potential indicator of germline proliferation in early adulthood. G3 (BETHESDA, MD.) 2023; 13:jkad029. [PMID: 36735812 PMCID: PMC10085788 DOI: 10.1093/g3journal/jkad029] [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: 09/13/2022] [Revised: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023]
Abstract
Abnormal nuclear morphology is suggested to be a hallmark of aging and one such abnormality is nuclear blebbing. However, little is known about whether and how nuclear blebbing participates in animal aging, and what regulates it. In this study, we show that the frequency of nuclear blebbing in the hypodermis increases during aging in wild-type C. elegans. These nuclear blebs are enveloped by the nuclear lamina, the inner and the outer nuclear membrane, and 42% of them contain chromatin. Although nuclear blebbing could lead to DNA loss if chromatin-containing blebs detach and fuse with lysosomes, we find by time-lapse imaging that nuclear blebs rarely detach, and the estimated lifetime of a nuclear bleb is 772 h or 32 days. The amount of DNA lost through nuclear blebbing is estimated to be about 0.1% of the total DNA loss by adult Day 11. Furthermore, the frequency of nuclear blebbing does not correlate with the rate of aging in C. elegans. Old age does not necessarily induce nuclear blebbing, neither does starvation, heat stress, or oxidative stress. Intriguingly, we find that proliferation of germ cells promotes nuclear blebbing.
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Affiliation(s)
- Qiang Fan
- Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
- National Institute of Biological Sciences (NIBS), Beijing 102206, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Xue-Mei Li
- National Institute of Biological Sciences (NIBS), Beijing 102206, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Chao Zhai
- National Institute of Biological Sciences (NIBS), Beijing 102206, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Bin Li
- National Institute of Biological Sciences (NIBS), Beijing 102206, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Shang-Tong Li
- National Institute of Biological Sciences (NIBS), Beijing 102206, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Meng-Qiu Dong
- Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
- National Institute of Biological Sciences (NIBS), Beijing 102206, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
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8
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Nkoula SN, Velez-Aguilera G, Ossareh-Nazari B, Hove LV, Ayuso C, Legros V, Chevreux G, Thomas L, Seydoux G, Askjaer P, Pintard L. Mechanisms of Nuclear Pore Complex disassembly by the mitotic Polo-Like Kinase 1 (PLK-1) in C. elegans embryos. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.21.528438. [PMID: 36865292 PMCID: PMC9980100 DOI: 10.1101/2023.02.21.528438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The nuclear envelope, which protects and organizes the interphase genome, is dismantled during mitosis. In the C. elegans zygote, nuclear envelope breakdown (NEBD) of the parental pronuclei is spatially and temporally regulated during mitosis to promote the unification of the parental genomes. During NEBD, Nuclear Pore Complex (NPC) disassembly is critical for rupturing the nuclear permeability barrier and removing the NPCs from the membranes near the centrosomes and between the juxtaposed pronuclei. By combining live imaging, biochemistry, and phosphoproteomics, we characterized NPC disassembly and unveiled the exact role of the mitotic kinase PLK-1 in this process. We show that PLK-1 disassembles the NPC by targeting multiple NPC sub-complexes, including the cytoplasmic filaments, the central channel, and the inner ring. Notably, PLK-1 is recruited to and phosphorylates intrinsically disordered regions of several multivalent linker nucleoporins, a mechanism that appears to be an evolutionarily conserved driver of NPC disassembly during mitosis. (149/150 words). One-Sentence Summary PLK-1 targets intrinsically disordered regions of multiple multivalent nucleoporins to dismantle the nuclear pore complexes in the C. elegans zygote.
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von der Heyde EL, Hallmann A. Molecular and cellular dynamics of early embryonic cell divisions in Volvox carteri. THE PLANT CELL 2022; 34:1326-1353. [PMID: 35018470 PMCID: PMC9026201 DOI: 10.1093/plcell/koac004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 01/03/2022] [Indexed: 06/14/2023]
Abstract
Cell division is fundamental to all organisms and the green alga used here exhibits both key animal and plant functions. Specifically, we analyzed the molecular and cellular dynamics of early embryonic divisions of the multicellular green alga Volvox carteri (Chlamydomonadales). Relevant proteins related to mitosis and cytokinesis were identified in silico, the corresponding genes were cloned, fused to yfp, and stably expressed in Volvox, and the tagged proteins were studied by live-cell imaging. We reveal rearrangements of the microtubule cytoskeleton during centrosome separation, spindle formation, establishment of the phycoplast, and generation of previously unknown structures. The centrosomes participate in initiation of spindle formation and determination of spindle orientation. Although the nuclear envelope does not break down during early mitosis, intermixing of cytoplasm and nucleoplasm results in loss of nuclear identity. Finally, we present a model for mitosis in Volvox. Our study reveals enormous dynamics, clarifies spatio-temporal relationships of subcellular structures, and provides insight into the evolution of cell division.
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Affiliation(s)
- Eva Laura von der Heyde
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany
| | - Armin Hallmann
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany
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Velez-Aguilera G, Ossareh-Nazari B, Van Hove L, Joly N, Pintard L. Cortical microtubule pulling forces contribute to the union of the parental genomes in the C. elegans zygote. eLife 2022; 11:75382. [PMID: 35259092 PMCID: PMC8956289 DOI: 10.7554/elife.75382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 03/04/2022] [Indexed: 11/23/2022] Open
Abstract
Previously, we reported that the Polo-like kinase PLK-1 phosphorylates the single Caenorhabditis elegans lamin (LMN-1) to trigger lamina depolymerization during mitosis. We showed that this event is required to form a pronuclear envelope scission event that removes membranes on the juxtaposed oocyte and sperm pronuclear envelopes in the zygote, allowing the parental chromosomes to merge in a single nucleus after segregation (Velez-Aguilera et al., 2020). Here, we show that cortical microtubule pulling forces contribute to pronuclear envelopes scission by promoting mitotic spindle elongation, and conversely, nuclear envelopes remodeling facilitates spindle elongation. We also demonstrate that weakening the pronuclear envelopes via PLK-1-mediated lamina depolymerization, is a prerequisite for the astral microtubule pulling forces to trigger pronuclear membranes scission. Finally, we provide evidence that PLK-1 mainly acts via lamina depolymerization in this process. These observations thus indicate that temporal coordination between lamina depolymerization and mitotic spindle elongation facilitates pronuclear envelopes scission and parental genomes unification.
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Affiliation(s)
| | | | - Lucie Van Hove
- Cell Cycle and Development, Institut Jacques Monod, Paris, France
| | - Nicolas Joly
- Cell Cycle and Development, Institut Jacques Monod, Paris, France
| | - Lionel Pintard
- Cell Cycle and Development, Institut Jacques Monod, Paris, France
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11
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Lancaster C, Zavagno G, Groombridge J, Raimundo A, Weinkove D, Hawkins T, Robson J, Goldberg MW. Imaging Fluorescent Nuclear Pore Complex Proteins in C. elegans. Methods Mol Biol 2022; 2502:373-393. [PMID: 35412251 DOI: 10.1007/978-1-0716-2337-4_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
C. elegans is a well-characterized and relatively simple model organism, making it attractive for studying nuclear pore complex proteins in cell and developmental biology. C. elegans is transparent and highly amendable to genetic manipulation. Therefore, it is possible to generate fluorescently tagged proteins and combine this with various light microscopy techniques to study protein behavior in space and time. Here, we provide protocols to prepare both fixed and live C. elegans for confocal and light sheet microscopy. This enables the analysis of nuclear pore complex proteins from embryonic stages to the aging adult.
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Affiliation(s)
- Courtney Lancaster
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Giulia Zavagno
- Department of Biosciences, Durham University, Durham, UK
| | | | | | - David Weinkove
- Department of Biosciences, Durham University, Durham, UK
| | - Tim Hawkins
- Department of Biosciences, Durham University, Durham, UK
| | - Joanne Robson
- Department of Biosciences, Durham University, Durham, UK
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12
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Maheshwari R, Rahman MM, Joseph-Strauss D, Cohen-Fix O. An RNAi screen for genes that affect nuclear morphology in Caenorhabditis elegans reveals the involvement of unexpected processes. G3 (BETHESDA, MD.) 2021; 11:jkab264. [PMID: 34849797 PMCID: PMC8527477 DOI: 10.1093/g3journal/jkab264] [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: 06/30/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
Aberration in nuclear morphology is one of the hallmarks of cellular transformation. However, the processes that, when mis-regulated, result aberrant nuclear morphology are poorly understood. In this study, we carried out a systematic, high-throughput RNAi screen for genes that affect nuclear morphology in Caenorhabditis elegans embryos. The screen employed over 1700 RNAi constructs against genes required for embryonic viability. Nuclei of early embryos are typically spherical, and their NPCs are evenly distributed. The screen was performed on early embryos expressing a fluorescently tagged component of the nuclear pore complex (NPC), allowing visualization of nuclear shape as well as the distribution of NPCs around the nuclear envelope. Our screen uncovered 182 genes whose downregulation resulted in one or more abnormal nuclear phenotypes, including multiple nuclei, micronuclei, abnormal nuclear shape, anaphase bridges, and abnormal NPC distribution. Many of these genes fall into common functional groups, including some that were not previously known to affect nuclear morphology, such as genes involved in mitochondrial function, the vacuolar ATPase, and the CCT chaperonin complex. The results of this screen add to our growing knowledge of processes that affect nuclear morphology and that may be altered in cancer cells that exhibit abnormal nuclear shape.
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Affiliation(s)
- Richa Maheshwari
- The Laboratory of Biochemistry and Genetics, The National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD 20892, USA
| | - Mohammad M Rahman
- The Laboratory of Biochemistry and Genetics, The National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD 20892, USA
| | - Daphna Joseph-Strauss
- The Laboratory of Biochemistry and Genetics, The National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD 20892, USA
| | - Orna Cohen-Fix
- The Laboratory of Biochemistry and Genetics, The National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD 20892, USA
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Roubinet C, White IJ, Baum B. Asymmetric nuclear division in neural stem cells generates sibling nuclei that differ in size, envelope composition, and chromatin organization. Curr Biol 2021; 31:3973-3983.e4. [PMID: 34297912 PMCID: PMC8491657 DOI: 10.1016/j.cub.2021.06.063] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 05/12/2021] [Accepted: 06/23/2021] [Indexed: 01/08/2023]
Abstract
Although nuclei are the defining features of eukaryotes, we still do not fully understand how the nuclear compartment is duplicated and partitioned during division. This is especially the case for organisms that do not completely disassemble their nuclear envelope upon entry into mitosis. In studying this process in Drosophila neural stem cells, which undergo asymmetric divisions, we find that the nuclear compartment boundary persists during mitosis thanks to the maintenance of a supporting nuclear lamina. This mitotic nuclear envelope is then asymmetrically remodeled and partitioned to give rise to two daughter nuclei that differ in envelope composition and exhibit a >30-fold difference in volume. The striking difference in nuclear size was found to depend on two consecutive processes: asymmetric nuclear envelope resealing at mitotic exit at sites defined by the central spindle, and differential nuclear growth that appears to depend on the available local reservoir of ER/nuclear membranes, which is asymmetrically partitioned between the two daughter cells. Importantly, these asymmetries in size and composition of the daughter nuclei, and the associated asymmetries in chromatin organization, all become apparent long before the cortical release and the nuclear import of cell fates determinants. Thus, asymmetric nuclear remodeling during stem cell divisions may contribute to the generation of cellular diversity by initiating distinct transcriptional programs in sibling nuclei that contribute to later changes in daughter cell identity and fate.
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Affiliation(s)
- Chantal Roubinet
- MRC Laboratory for Molecular Biology, University College London, London, UK; MRC Laboratory of Molecular Cell Biology, Cambridge, UK.
| | - Ian J White
- MRC Laboratory for Molecular Biology, University College London, London, UK
| | - Buzz Baum
- MRC Laboratory for Molecular Biology, University College London, London, UK; Institute for the Physics of Living Systems, University College London, London, UK; MRC Laboratory of Molecular Cell Biology, Cambridge, UK.
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14
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Charar C, Metsuyanim-Cohen S, Bar DZ. Lamin regulates the dietary restriction response via the mTOR pathway in Caenorhabditis elegans. J Cell Sci 2021; 134:272061. [PMID: 34383046 PMCID: PMC8445603 DOI: 10.1242/jcs.258428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 07/30/2021] [Indexed: 11/30/2022] Open
Abstract
Animals subjected to dietary restriction (DR) have reduced body size, low fecundity, slower development, lower fat content and longer life span. We identified lamin as a regulator of multiple dietary restriction phenotypes. Downregulation of lmn-1, the single Caenorhabditis elegans lamin gene, increased animal size and fat content specifically in DR animals. The LMN-1 protein acts in the mTOR pathway, upstream of RAPTOR and S6 kinase β1 (S6K), a key component of and target of the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1), respectively. DR excludes the mTORC1 activator RAGC-1 from the nucleus. Downregulation of lmn-1 restores RAGC-1 to the nucleus, a necessary step for the activation of the mTOR pathway. These findings further link lamin to metabolic regulation. Summary: Downregulation of the single C. elegans lamin gene increases animal size and fat content specifically in dietary restricted animals. The lamin protein acts in the mTOR pathway to regulate these phenotypes.
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Affiliation(s)
- Chayki Charar
- The School of Dental Medicine, The Faculty of Medicine, Tel Aviv University, Israel.,The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Israel
| | | | - Daniel Z Bar
- The School of Dental Medicine, The Faculty of Medicine, Tel Aviv University, Israel
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15
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Velez-Aguilera G, Nkombo Nkoula S, Ossareh-Nazari B, Link J, Paouneskou D, Van Hove L, Joly N, Tavernier N, Verbavatz JM, Jantsch V, Pintard L. PLK-1 promotes the merger of the parental genome into a single nucleus by triggering lamina disassembly. eLife 2020; 9:59510. [PMID: 33030429 PMCID: PMC7544505 DOI: 10.7554/elife.59510] [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: 05/30/2020] [Accepted: 09/17/2020] [Indexed: 12/15/2022] Open
Abstract
Life of sexually reproducing organisms starts with the fusion of the haploid egg and sperm gametes to form the genome of a new diploid organism. Using the newly fertilized Caenorhabditis elegans zygote, we show that the mitotic Polo-like kinase PLK-1 phosphorylates the lamin LMN-1 to promote timely lamina disassembly and subsequent merging of the parental genomes into a single nucleus after mitosis. Expression of non-phosphorylatable versions of LMN-1, which affect lamina depolymerization during mitosis, is sufficient to prevent the mixing of the parental chromosomes into a single nucleus in daughter cells. Finally, we recapitulate lamina depolymerization by PLK-1 in vitro demonstrating that LMN-1 is a direct PLK-1 target. Our findings indicate that the timely removal of lamin is essential for the merging of parental chromosomes at the beginning of life in C. elegans and possibly also in humans, where a defect in this process might be fatal for embryo development.
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Affiliation(s)
- Griselda Velez-Aguilera
- Programme Equipe Labéllisée Ligue Contre le Cancer - Team Cell Cycle & Development - Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Sylvia Nkombo Nkoula
- Programme Equipe Labéllisée Ligue Contre le Cancer - Team Cell Cycle & Development - Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Batool Ossareh-Nazari
- Programme Equipe Labéllisée Ligue Contre le Cancer - Team Cell Cycle & Development - Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Jana Link
- Department of Chromosome Biology, Max Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Dimitra Paouneskou
- Department of Chromosome Biology, Max Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Lucie Van Hove
- Programme Equipe Labéllisée Ligue Contre le Cancer - Team Cell Cycle & Development - Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Nicolas Joly
- Programme Equipe Labéllisée Ligue Contre le Cancer - Team Cell Cycle & Development - Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Nicolas Tavernier
- Programme Equipe Labéllisée Ligue Contre le Cancer - Team Cell Cycle & Development - Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | | | - Verena Jantsch
- Department of Chromosome Biology, Max Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Lionel Pintard
- Programme Equipe Labéllisée Ligue Contre le Cancer - Team Cell Cycle & Development - Université de Paris, CNRS, Institut Jacques Monod, Paris, France
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16
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AlKhaleefa A, Snider FL, Duff HJ, McGhee JD. -Using the C. elegans lem-2 Gene to Reconstruct the Human LEMD2 Mutation Associated with Hutterite-type Cataract/Cardiomyopathy. MICROPUBLICATION BIOLOGY 2020; 2020. [PMID: 32666044 PMCID: PMC7351585 DOI: 10.17912/micropub.biology.000273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ayaa AlKhaleefa
- 1. Department of Biochemistry and Molecular Biology, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta CANADA
| | - Frances L Snider
- 1. Department of Biochemistry and Molecular Biology, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta CANADA
| | - Henry J Duff
- Cardiac Sciences, Libin Cardiology Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta CANADA
| | - James D McGhee
- 1. Department of Biochemistry and Molecular Biology, Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta CANADA
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17
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In vivo analysis of FANCD2 recruitment at meiotic DNA breaks in Caenorhabditis elegans. Sci Rep 2020; 10:103. [PMID: 31919410 PMCID: PMC6952437 DOI: 10.1038/s41598-019-57096-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/19/2019] [Indexed: 12/28/2022] Open
Abstract
Fanconi Anemia is a rare genetic disease associated with DNA repair defects, congenital abnormalities and infertility. Most of FA pathway is evolutionary conserved, allowing dissection and mechanistic studies in simpler model systems such as Caenorhabditis elegans. In the present study, we employed C. elegans to better understand the role of FA group D2 (FANCD2) protein in vivo, a key player in promoting genome stability. We report that localization of FCD-2/FANCD2 is dynamic during meiotic prophase I and requires its heterodimeric partner FNCI-1/FANCI. Strikingly, we found that FCD-2 recruitment depends on SPO-11-induced double-strand breaks (DSBs) but not RAD-51-mediated strand invasion. Furthermore, exposure to DNA damage-inducing agents boosts FCD-2 recruitment on the chromatin. Finally, analysis of genetic interaction between FCD-2 and BRC-1 (the C. elegans orthologue of mammalian BRCA1) supports a role for these proteins in different DSB repair pathways. Collectively, we showed a direct involvement of FCD-2 at DSBs and speculate on its function in driving meiotic DNA repair.
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18
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Iwamoto M, Fukuda Y, Osakada H, Mori C, Hiraoka Y, Haraguchi T. Identification of the evolutionarily conserved nuclear envelope proteins Lem2 and MicLem2 in Tetrahymena thermophila. Gene 2019; 721S:100006. [PMID: 32550543 PMCID: PMC7285967 DOI: 10.1016/j.gene.2019.100006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/18/2018] [Accepted: 01/11/2019] [Indexed: 11/26/2022]
Abstract
Lem2 family proteins, i.e. the LAP2-Emerin-MAN1 (LEM) domain-containing nuclear envelope proteins, are well-conserved from yeasts to humans, both of which belong to the Opisthokonta supergroup. However, whether their homologs are present in other eukaryotic phylogenies remains unclear. In this study, we identified two Lem2 homolog proteins, which we named as Lem2 and MicLem2, in a ciliate Tetrahymena thermophila belonging to the SAR supergroup. Lem2 was localized to the nuclear envelope of the macronucleus (MAC) and micronucleus (MIC), while MicLem2 was exclusively localized to the nuclear envelope of the MIC. Immunoelectron microscopy revealed that Lem2 in T. thermophila was localized to both the inner and outer nuclear envelopes of the MAC and MIC, while MicLem2 was mostly localized to the nuclear pores of the MIC. Molecular domain analysis using GFP-fused protein showed that the N-terminal and luminal domains, including the transmembrane segments, are responsible for nuclear envelope localization. During sexual reproduction, enrichment of Lem2 occurred in the nuclear envelopes of the MAC and MIC to be degraded, while MicLem2 was enriched in the nuclear envelope of the MIC that escaped degradation. These findings suggest the unique characteristics of Tetrahymena Lem2 proteins. Our findings provide insight into the evolutionary divergence of nuclear envelope proteins. Conserved nuclear envelope proteins Lem2 and MicLem2 are identified in Tetrahymena. Lem2 is localized to the nuclear envelope of the macronucleus and the micronucleus. MicLem2 is localized to the nuclear pore complex of the micronucleus. In sexual reproduction, Lem2 is enriched to the nuclei assigned to degradation. MicLem2 is enriched to the micronuclei that are escaped from degradation.
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Key Words
- BAF, barrier-to-autointegration factor
- DAPI, 4′,6‑diamidino‑2‑phenylindole
- DDW, double distilled water
- EDTA, ethylenediaminetetraacetic acid
- ER, endoplasmic reticulum
- GA, glutaraldehyde
- HeH domain
- HeH, helix-extension-helix
- LAP2, lamina associated polypeptide 2
- LEM domain
- LEM, LAP2-Emerin-MAN1
- MAC, macronucleus
- MIC, micronucleus
- MSC domain
- MSC, Man1-Src1p-C-terminal
- Man1
- Man1-Src1p-C-terminal domain
- NE, nuclear envelope
- NLS, nuclear localization signal
- NPC, nuclear pore complex
- Nuclear dimorphism
- Nuclear envelope
- ONM and INM, outer and inner nuclear membranes
- PB, phosphate buffer
- PBS, phosphate buffered saline
- Protist
- RRM, RNA recognition motif
- TM, transmembrane
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Affiliation(s)
- Masaaki Iwamoto
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Yasuhiro Fukuda
- Graduate School of Agricultural Science, Tohoku University, Osaki, 989-6711, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Chie Mori
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
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19
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Pintard L, Bowerman B. Mitotic Cell Division in Caenorhabditis elegans. Genetics 2019; 211:35-73. [PMID: 30626640 PMCID: PMC6325691 DOI: 10.1534/genetics.118.301367] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/24/2018] [Indexed: 11/18/2022] Open
Abstract
Mitotic cell divisions increase cell number while faithfully distributing the replicated genome at each division. The Caenorhabditis elegans embryo is a powerful model for eukaryotic cell division. Nearly all of the genes that regulate cell division in C. elegans are conserved across metazoan species, including humans. The C. elegans pathways tend to be streamlined, facilitating dissection of the more redundant human pathways. Here, we summarize the virtues of C. elegans as a model system and review our current understanding of centriole duplication, the acquisition of pericentriolar material by centrioles to form centrosomes, the assembly of kinetochores and the mitotic spindle, chromosome segregation, and cytokinesis.
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Affiliation(s)
- Lionel Pintard
- Equipe labellisée Ligue contre le Cancer, Institut Jacques Monod, Team Cell Cycle and Development UMR7592, Centre National de la Recherche Scientifique - Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
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20
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Augustine B, Chin CF, Yeong FM. Role of Kip2 during early mitosis - impact on spindle pole body separation and chromosome capture. J Cell Sci 2018; 131:jcs.211425. [PMID: 29739877 DOI: 10.1242/jcs.211425] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 04/30/2018] [Indexed: 11/20/2022] Open
Abstract
Mitotic spindle dynamics are regulated during the cell cycle by microtubule motor proteins. In Saccharomyces cerevisiae, one such protein is Kip2p, a plus-end motor that regulates the polymerization and stability of cytoplasmic microtubules (cMTs). Kip2p levels are regulated during the cell cycle, and its overexpression leads to the formation of hyper-elongated cMTs. To investigate the significance of varying Kip2p levels during the cell cycle and the hyper-elongated cMTs, we overexpressed KIP2 in the G1 phase and examined the effects on the separation of spindle pole bodies (SPBs) and chromosome segregation. Our results show that failure to regulate the cMT lengths during G1-S phase prevents the separation of SPBs. This, in turn, affects chromosome capture and leads to the activation of spindle assembly checkpoint (SAC) and causes mitotic arrest. These defects could be rescued by either the inactivation of checkpoint components or by co-overexpression of CIN8, which encodes a motor protein that elongates inter-polar microtubules (ipMTs). Hence, we propose that the maintenance of Kip2p level and cMT lengths during early cell division is important to ensure coordination between SPB separation and chromosome capture by kinetochore microtubules (kMTs).
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Affiliation(s)
- Beryl Augustine
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, MD4, 5 Science Drive 2, Singapore 117545
| | - Cheen Fei Chin
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, MD4, 5 Science Drive 2, Singapore 117545
| | - Foong May Yeong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, MD4, 5 Science Drive 2, Singapore 117545
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21
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Penfield L, Wysolmerski B, Mauro M, Farhadifar R, Martinez MA, Biggs R, Wu HY, Broberg C, Needleman D, Bahmanyar S. Dynein pulling forces counteract lamin-mediated nuclear stability during nuclear envelope repair. Mol Biol Cell 2018; 29:852-868. [PMID: 29386297 PMCID: PMC5905298 DOI: 10.1091/mbc.e17-06-0374] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transient nuclear envelope (NE) ruptures in the Caenorhabditis elegans zygote are caused by a weakened nuclear lamina during nuclear positioning. Dynein-pulling forces enhance the severity of ruptures, while lamin restricts nucleocytoplasmic mixing and allows stable NE repair. This work is the first mechanistic analysis of NE rupture and repair in an organism. Recent work done exclusively in tissue culture cells revealed that the nuclear envelope (NE) ruptures and repairs in interphase. The duration of NE ruptures depends on lamins; however, the underlying mechanisms and relevance to in vivo events are not known. Here, we use the Caenorhabditis elegans zygote to analyze lamin’s role in NE rupture and repair in vivo. Transient NE ruptures and subsequent NE collapse are induced by weaknesses in the nuclear lamina caused by expression of an engineered hypomorphic C. elegans lamin allele. Dynein-generated forces that position nuclei enhance the severity of transient NE ruptures and cause NE collapse. Reduction of dynein forces allows the weakened lamin network to restrict nucleo–cytoplasmic mixing and support stable NE recovery. Surprisingly, the high incidence of transient NE ruptures does not contribute to embryonic lethality, which is instead correlated with stochastic chromosome scattering resulting from premature NE collapse, suggesting that C. elegans tolerates transient losses of NE compartmentalization during early embryogenesis. In sum, we demonstrate that lamin counteracts dynein forces to promote stable NE repair and prevent catastrophic NE collapse, and thus provide the first mechanistic analysis of NE rupture and repair in an organismal context.
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Affiliation(s)
- Lauren Penfield
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520
| | - Brian Wysolmerski
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520
| | - Michael Mauro
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520
| | - Reza Farhadifar
- Department of Molecular and Cellular Biology, School of Engineering and Applied Sciences, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138
| | - Michael A Martinez
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520
| | - Ronald Biggs
- Department of Cellular & Molecular Medicine, Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, CA 92093
| | - Hai-Yin Wu
- Department of Molecular and Cellular Biology, School of Engineering and Applied Sciences, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138
| | - Curtis Broberg
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520
| | - Daniel Needleman
- Department of Molecular and Cellular Biology, School of Engineering and Applied Sciences, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138
| | - Shirin Bahmanyar
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520
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22
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Martino L, Morchoisne-Bolhy S, Cheerambathur DK, Van Hove L, Dumont J, Joly N, Desai A, Doye V, Pintard L. Channel Nucleoporins Recruit PLK-1 to Nuclear Pore Complexes to Direct Nuclear Envelope Breakdown in C. elegans. Dev Cell 2017; 43:157-171.e7. [PMID: 29065307 PMCID: PMC8184135 DOI: 10.1016/j.devcel.2017.09.019] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 08/02/2017] [Accepted: 09/22/2017] [Indexed: 01/24/2023]
Abstract
In animal cells, nuclear envelope breakdown (NEBD) is required for proper chromosome segregation. Whereas mitotic kinases have been implicated in NEBD, how they coordinate their activity to trigger this event is unclear. Here, we show that both in human cells and Caenorhabditis elegans, the Polo-like kinase 1 (PLK-1) is recruited to the nuclear pore complexes, just prior to NEBD, through its Polo-box domain (PBD). We provide evidence that PLK-1 localization to the nuclear envelope (NE) is required for efficient NEBD. We identify the central channel nucleoporins NPP-1/Nup58, NPP-4/Nup54, and NPP-11/Nup62 as the critical factors anchoring PLK-1 to the NE in C. elegans. In particular, NPP-1, NPP-4, and NPP-11 primed at multiple Polo-docking sites by Cdk1 and PLK-1 itself physically interact with the PLK-1 PBD. We conclude that nucleoporins play an unanticipated regulatory role in NEBD, by recruiting PLK-1 to the NE thereby facilitating phosphorylation of critical downstream targets.
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Affiliation(s)
- Lisa Martino
- Cell Cycle and Development, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Stéphanie Morchoisne-Bolhy
- Non-conventional Functions of Nuclear Pore, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Dhanya K Cheerambathur
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Lucie Van Hove
- Cell Cycle and Development, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Julien Dumont
- Cell Division and Reproduction, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Nicolas Joly
- Cell Cycle and Development, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Arshad Desai
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Valérie Doye
- Non-conventional Functions of Nuclear Pore, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Lionel Pintard
- Cell Cycle and Development, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
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23
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Abstract
The eukaryotic nucleus is enclosed by the nuclear envelope, which is perforated by the nuclear pores, the gateways of macromolecular exchange between the nucleoplasm and cytoplasm. The nucleoplasm is organized in a complex three-dimensional fashion that changes over time and in response to stimuli. Within the cell, the nucleus must be viewed as an organelle (albeit a gigantic one) that is a recipient of cytoplasmic forces and capable of morphological and positional dynamics. The most dramatic reorganization of this organelle occurs during mitosis and meiosis. Although many of these aspects are less well understood for the nuclei of plants than for those of animals or fungi, several recent discoveries have begun to place our understanding of plant nuclei firmly into this broader cell-biological context.
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Affiliation(s)
- Iris Meier
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210;
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
| | | | - David E Evans
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
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24
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Cohen-Fix O, Askjaer P. Cell Biology of the Caenorhabditis elegans Nucleus. Genetics 2017; 205:25-59. [PMID: 28049702 PMCID: PMC5216270 DOI: 10.1534/genetics.116.197160] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/09/2016] [Indexed: 12/25/2022] Open
Abstract
Studies on the Caenorhabditis elegans nucleus have provided fascinating insight to the organization and activities of eukaryotic cells. Being the organelle that holds the genetic blueprint of the cell, the nucleus is critical for basically every aspect of cell biology. The stereotypical development of C. elegans from a one cell-stage embryo to a fertile hermaphrodite with 959 somatic nuclei has allowed the identification of mutants with specific alterations in gene expression programs, nuclear morphology, or nuclear positioning. Moreover, the early C. elegans embryo is an excellent model to dissect the mitotic processes of nuclear disassembly and reformation with high spatiotemporal resolution. We review here several features of the C. elegans nucleus, including its composition, structure, and dynamics. We also discuss the spatial organization of chromatin and regulation of gene expression and how this depends on tight control of nucleocytoplasmic transport. Finally, the extensive connections of the nucleus with the cytoskeleton and their implications during development are described. Most processes of the C. elegans nucleus are evolutionarily conserved, highlighting the relevance of this powerful and versatile model organism to human biology.
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Affiliation(s)
- Orna Cohen-Fix
- Laboratory of Molecular and Cellular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Peter Askjaer
- Andalusian Center for Developmental Biology, Consejo Superior de Investigaciones Científicas/Junta de Andalucia/Universidad Pablo de Olavide, 41013 Seville, Spain
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25
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Fernández-Álvarez A, Cooper JP. Chromosomes Orchestrate Their Own Liberation: Nuclear Envelope Disassembly. Trends Cell Biol 2016; 27:255-265. [PMID: 28024902 DOI: 10.1016/j.tcb.2016.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/08/2016] [Accepted: 11/10/2016] [Indexed: 12/13/2022]
Abstract
The mammalian nuclear division cycle is coordinated with nuclear envelope breakdown (NEBD), in which the entire nuclear envelope (NE) is dissolved to allow chromosomes to access their segregation vehicle, the spindle. In other eukaryotes, complete NEBD is replaced by localized disassembly or remodeling of the NE. Although the molecular mechanisms controlling NE disassembly are incompletely understood, coordinated cycles of modification of specific NE components drive breakdown. Here, we review the current state of knowledge regarding NE disassembly and argue for a role of chromosome-NE contacts in triggering initiation of NE disassembly and thereby, cell division.
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Affiliation(s)
- Alfonso Fernández-Álvarez
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Julia Promisel Cooper
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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26
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Makarova M, Oliferenko S. Mixing and matching nuclear envelope remodeling and spindle assembly strategies in the evolution of mitosis. Curr Opin Cell Biol 2016; 41:43-50. [PMID: 27062548 PMCID: PMC7100904 DOI: 10.1016/j.ceb.2016.03.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/20/2016] [Accepted: 03/23/2016] [Indexed: 12/11/2022]
Abstract
In eukaryotes, cellular genome is enclosed inside a membrane-bound organelle called the nucleus. The nucleus compartmentalizes genome replication, repair and expression, keeping these activities separated from protein synthesis and other metabolic processes. Each proliferative division, the duplicated chromosomes must be equipartitioned between the daughter cells and this requires precise coordination between assembly of the microtubule-based mitotic spindle and nuclear remodeling. Here we review a surprising variety of strategies used by modern eukaryotes to manage these processes and discuss possible mechanisms that might have led to the emergence of this diversity in evolution.
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Affiliation(s)
- Maria Makarova
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Snezhana Oliferenko
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK.
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Complex Commingling: Nucleoporins and the Spindle Assembly Checkpoint. Cells 2015; 4:706-25. [PMID: 26540075 PMCID: PMC4695854 DOI: 10.3390/cells4040706] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 10/12/2015] [Accepted: 10/28/2015] [Indexed: 12/14/2022] Open
Abstract
The segregation of the chromosomes during mitosis is an important process, in which the replicated DNA content is properly allocated into two daughter cells. To ensure their genomic integrity, cells present an essential surveillance mechanism known as the spindle assembly checkpoint (SAC), which monitors the bipolar attachment of the mitotic spindle to chromosomes to prevent errors that would result in chromosome mis-segregation and aneuploidy. Multiple components of the nuclear pore complex (NPC), a gigantic protein complex that forms a channel through the nuclear envelope to allow nucleocytoplasmic exchange of macromolecules, were shown to be critical for faithful cell division and implicated in the regulation of different steps of the mitotic process, including kinetochore and spindle assembly as well as the SAC. In this review, we will describe current knowledge about the interconnection between the NPC and the SAC in an evolutional perspective, which primarily relies on the two mitotic checkpoint regulators, Mad1 and Mad2. We will further discuss the role of NPC constituents, the nucleoporins, in kinetochore and spindle assembly and the formation of the mitotic checkpoint complex during mitosis and interphase.
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Rahman MM, Munzig M, Kaneshiro K, Lee B, Strome S, Müller-Reichert T, Cohen-Fix O. Caenorhabditis elegans polo-like kinase PLK-1 is required for merging parental genomes into a single nucleus. Mol Biol Cell 2015; 26:4718-35. [PMID: 26490119 PMCID: PMC4678026 DOI: 10.1091/mbc.e15-04-0244] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 10/13/2015] [Indexed: 11/11/2022] Open
Abstract
Before the first zygotic division, the nuclear envelopes of the maternal and paternal pronuclei disassemble, allowing both sets of chromosomes to be incorporated into a single nucleus in daughter cells after mitosis. We found that in Caenorhabditis elegans, partial inactivation of the polo-like kinase PLK-1 causes the formation of two nuclei, containing either the maternal or paternal chromosomes, in each daughter cell. These two nuclei gave rise to paired nuclei in all subsequent cell divisions. The paired-nuclei phenotype was caused by a defect in forming a gap in the nuclear envelopes at the interface between the two pronuclei during the first mitotic division. This was accompanied by defects in chromosome congression and alignment of the maternal and paternal metaphase plates relative to each other. Perturbing chromosome congression by other means also resulted in failure to disassemble the nuclear envelope between the two pronuclei. Our data further show that PLK-1 is needed for nuclear envelope breakdown during early embryogenesis. We propose that during the first zygotic division, PLK-1-dependent chromosome congression and metaphase plate alignment are necessary for the disassembly of the nuclear envelope between the two pronuclei, ultimately allowing intermingling of the maternal and paternal chromosomes.
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Affiliation(s)
- Mohammad M Rahman
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Mandy Munzig
- Structural Cell Biology Group, Experimental Center, Medical Faculty Carl Gustav Carus, University of Technology Dresden, 01307 Dresden, Germany
| | - Kiyomi Kaneshiro
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Brandon Lee
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Susan Strome
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Thomas Müller-Reichert
- Structural Cell Biology Group, Experimental Center, Medical Faculty Carl Gustav Carus, University of Technology Dresden, 01307 Dresden, Germany
| | - Orna Cohen-Fix
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
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Morales-Martínez A, Dobrzynska A, Askjaer P. Inner nuclear membrane protein LEM-2 is required for proper nuclear separation and morphology. J Cell Sci 2015; 128:1090-6. [DOI: 10.1242/jcs.164202] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The inner nuclear membrane proteins emerin and LEMD2 have both overlapping and separate functions in regulation of nuclear organization, gene expression and cell differentiation. We report here that emerin/EMR-1 and LEMD2/LEM-2 are expressed in all tissues throughout Caenorhaditis elegans development but their relative distribution differs between cell types. The ratio between EMR-1 and LEM-2 is particularly high in contractile tissues, intermediate in neurons and hypodermis and lowest in intestine and germ line. We find that LEM-2 is recruited earlier than EMR-1 to reforming nuclear envelopes, suggesting the presence of separate mitotic membrane compartments and specific functions of each protein. Concordantly, we observe that nuclei of lem-2 mutant embryos, but not of emr-1 mutants, have reduced nuclear circularity. Finally, we uncover a novel role of LEM-2 in nuclear separation and anchoring of microtubule organizing centers.
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Mandrioli M, Bandinelli S, Manicardi GC. Occurrence of Rabl-like telomere clustering in the holocentric chromosomes of the peach potato aphid Myzus persicae (Hemiptera; Aphididae). Cytogenet Genome Res 2014; 144:68-75. [PMID: 25277538 DOI: 10.1159/000366049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2014] [Indexed: 11/19/2022] Open
Abstract
Several studies demonstrated that chromosome anchoring to nuclear structures is involved in the organization of the interphase nucleus. The Rabl configuration, a well-studied chromosome organization in the interphase nucleus, has been deeply studied in organisms with monocentric chromosomes but just slightly touched in species with holocentric chromosomes. In the present paper, by means of the isolation and chromosomal mapping of the C0t DNA fraction and chromatin immunoprecipitation with anti-LEM-2 antibodies, we evidenced the presence of few foci where telomeres and subtelomeric regions cluster in the aphid interphase nuclei, suggesting the occurrence of a Rabl-like chromosome configuration. The same experimental approaches also evidenced that most of the repetitive DNA of the 2 X chromosomes is located at the periphery of the nucleus, whereas the ribosomal genes, located at 1 telomere of each X chromosome, are present towards the inner portion of the nucleus, favoring their transcriptional activity.
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Affiliation(s)
- Mauro Mandrioli
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Modena, Italy
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Kanteti R, El-Hashani E, Dhanasingh I, Tretiakova M, Husain AN, Sharma S, Sharma J, Vokes EE, Salgia R. Role of PAX8 in the regulation of MET and RON receptor tyrosine kinases in non-small cell lung cancer. BMC Cancer 2014; 14:185. [PMID: 24628993 PMCID: PMC3995599 DOI: 10.1186/1471-2407-14-185] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 02/28/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Non-small cell lung cancers (NSCLC) are highly heterogeneous at the molecular level and comprise 75% of all lung tumors. We have previously shown that the receptor tyrosine kinase (RTK) MET frequently suffers gain-of-function mutations that significantly promote lung tumorigenesis. Subsequent studies from our lab also revealed that PAX5 transcription factor is preferentially expressed in small cell lung cancer (SCLC) and promotes MET transcription. PAX8, however, is also expressed in NSCLC cell lines. We therefore investigated the role of PAX8 in NSCLC. METHODS Using IHC analysis, PAX8 protein expression was determined in archival NSCLC tumor tissues (n = 254). In order to study the effects of PAX8 knockdown on NSCLC cellular functions such as apoptosis and motility, siRNA against PAX8 was used. Confocal fluorescence microscopy was used to monitor the localization of MET, RON and PAX8. The combinatorial effect of PAX8 knockdown and MET inhibition using SU11274 was investigated in NSCLC cell viability assay. RESULTS Relative levels of PAX8 protein were elevated (≥ + 2 on a scale of 0-3) in adenocarcinoma (58/94), large cell carcinoma (50/85), squamous cell carcinoma (28/47), and metastatic NSCLC (17/28; lymph node). Utilizing early progenitors isolated from NSCLC cell lines and fresh tumor tissues, we observed robust overexpression of PAX8, MET, and RON. PAX8 knockdown A549 cells revealed abrogated PAX8 expression with a concomitant loss in MET and the related RON kinase expression. A dramatic colocalization between the active form of MET (also RON) and PAX8 upon challenging A549 cells with HGF was visualized. A similar colocalization of MET and EGL5 (PAX8 ortholog) proteins was found in embryos of C. elegans. Most importantly, knockdown of PAX8 in A549 cells resulted in enhanced apoptosis (~6 fold) and decreased cell motility (~45%), thereby making PAX8 a potential therapeutic target. However, the combinatorial approach of PAX8 knockdown and treatment with MET inhibitor, SU11274, had marginal additive effect on loss of NSCLC cell viability. CONCLUSION PAX8 provides signals for growth and motility of NSCLC cells and is necessary for MET and RON expression. Further investigations are necessary to investigate the therapeutic potential of PA8 in NSCLC.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Ravi Salgia
- Department of Hematology/Oncology, University of Chicago Medical Center, Chicago, IL, USA.
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Nuclear Envelope Regulation of Signaling Cascades. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:187-206. [DOI: 10.1007/978-1-4899-8032-8_9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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33
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Lyakhovetsky R, Gruenbaum Y. Studying lamins in invertebrate models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:245-62. [PMID: 24563351 DOI: 10.1007/978-1-4899-8032-8_11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lamins are nuclear intermediate filament proteins that are conserved in all multicellular animals. Proteins that resemble lamins are also found in unicellular organisms and in plants. Lamins form a proteinaceous meshwork that outlines the nucleoplasmic side of the inner nuclear membrane, while a small fraction of lamin molecules is also present in the nucleoplasm. They provide structural support for the nucleus and help regulate many other nuclear activities. Much of our knowledge on the function of nuclear lamins and their associated proteins comes from studies in invertebrate organisms and specifically in the nematode Caenorhabditis elegans and the fruit fly Drosophila melanogaster. The simpler lamin system and the powerful genetic tools offered by these model organisms greatly promote such studies. Here we provide an overview of recent advances in the biology of invertebrate nuclear lamins, with special emphasis on their assembly, cellular functions and as models for studying the molecular basis underlying the pathology of human heritable diseases caused by mutations in lamins A/C.
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Affiliation(s)
- Roman Lyakhovetsky
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, 91904, Israel
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Askjaer P, Galy V, Meister P. Modern Tools to Study Nuclear Pore Complexes and Nucleocytoplasmic Transport in Caenorhabditis elegans. Methods Cell Biol 2014; 122:277-310. [DOI: 10.1016/b978-0-12-417160-2.00013-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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35
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Simultaneous expression of multiple proteins under a single promoter in Caenorhabditis elegans via a versatile 2A-based toolkit. Genetics 2013; 196:605-13. [PMID: 24361941 DOI: 10.1534/genetics.113.160846] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Caenorhabditis elegans is a powerful in vivo model in which transgenesis is highly developed. However, while the analysis of biological phenomena often require the expression of more than one protein of interest, no reliable tool exists to ensure efficient concomitant and equivalent expression of more than two polypeptides from a single promoter. We report the use of viral 2A peptides, which trigger a "ribosomal-skip" or "STOP&GO" mechanism during translation, to express multiple proteins from a single vector in C. elegans. Although none of the viruses known to infect C. elegans contain 2A-like sequences, our results show that 2A peptides allow the production of separate functional proteins in all cell types and at all developmental stages tested in the worm. In addition, we constructed a toolkit including a 2A-based polycistronic plasmid and reagents to generate 2A-tagged fosmids. 2A peptides constitute an important tool to ensure the delivery of multiple polypeptides in specific cells, enabling several novel applications such as the reconstitution of multi-subunit complexes.
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36
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Reil M, Dabauvalle MC. Essential roles of LEM-domain protein MAN1 during organogenesis in Xenopus laevis and overlapping functions of emerin. Eur J Cell Biol 2013; 92:280-94. [PMID: 24252515 DOI: 10.1016/j.ejcb.2013.10.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 10/23/2013] [Accepted: 10/25/2013] [Indexed: 11/26/2022] Open
Abstract
Mutations in nuclear envelope proteins are linked to an increasing number of human diseases, called envelopathies. Mutations in the inner nuclear membrane protein emerin lead to X-linked Emery-Dreifuss muscular dystrophy, characterized by muscle weakness or wasting. Conversely, mutations in nuclear envelope protein MAN1 are linked to bone and skin disorders. Both proteins share a highly conserved domain, called LEM-domain. LEM proteins are known to interact with Barrier-to-autointegration factor and several transcription factors. Most envelopathies are tissue-specific, but knowledge on the physiological roles of related LEM proteins is still unclear. For this reason, we investigated the roles of MAN1 and emerin during Xenopus laevis organogenesis. Morpholino-mediated knockdown of MAN1 revealed that MAN1 is essential for the formation of eye, skeletal and cardiac muscle tissues. The MAN1 knockdown could be compensated by ectopic expression of emerin, leading to a proper organ development. Further investigations revealed that MAN1 is involved in regulation of genes essential for organ development and tissue homeostasis. Thereby our work supports that LEM proteins might be involved in signalling essential for organ development during early embryogenesis and suggests that loss of MAN1 may cause muscle and retina specific diseases.
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Affiliation(s)
- Michael Reil
- Division of Electron Microscopy, Biocenter, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany.
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37
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Abstract
Emerin, a conserved LEM-domain protein, is among the few nuclear membrane proteins for which extensive basic knowledge—biochemistry, partners, functions, localizations, posttranslational regulation, roles in development and links to human disease—is available. This review summarizes emerin and its emerging roles in nuclear “lamina” structure, chromatin tethering, gene regulation, mitosis, nuclear assembly, development, signaling and mechano-transduction. We also highlight many open questions, exploration of which will be critical to understand how this intriguing nuclear membrane protein and its “family” influence the genome.
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Affiliation(s)
- Jason M Berk
- Department of Cell Biology; Johns Hopkins University School of Medicine; Baltimore, MD USA
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38
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Abstract
Mitosis is the process of one cell dividing into two daughters, such that each inherits a single and complete copy of the genome of their mother. This is achieved through the equal segregation of the sister chromatids between the daughter cells. However, beyond this simple principle, the partitioning of other cellular components between daughter cells appears to follow a large variety of patterns. We discuss here how the organization of the nuclear envelope during mitosis influences cell division and, subsequently, cellular identity.
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Affiliation(s)
- Barbara Boettcher
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich, Zürich, Switzerland
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39
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Abstract
The emergence of eukaryotes around two billion years ago provided new challenges for the chromosome segregation machineries: the physical separation of multiple large and linear chromosomes from the microtubule-organizing centres by the nuclear envelope. In this review, we set out the diverse solutions that eukaryotic cells use to solve this problem, and show how stepping away from ‘mainstream’ mitosis can teach us much about the mechanisms and mechanics that can drive chromosome segregation. We discuss the evidence for a close functional and physical relationship between membranes, nuclear pores and kinetochores in generating the forces necessary for chromosome segregation during mitosis.
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Affiliation(s)
- Hauke Drechsler
- Centre for Mechanochemical Cell Biology, Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
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40
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Bae YK, Sung JY, Kim YN, Kim S, Hong KM, Kim HT, Choi MS, Kwon JY, Shim J. An in vivo C. elegans model system for screening EGFR-inhibiting anti-cancer drugs. PLoS One 2012; 7:e42441. [PMID: 22957020 PMCID: PMC3434183 DOI: 10.1371/journal.pone.0042441] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 07/09/2012] [Indexed: 11/20/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) is a well-established target for cancer treatment. EGFR tyrosine kinase (TK) inhibitors, such as gefinitib and erlotinib, have been developed as anti-cancer drugs. Although non-small cell lung carcinoma with an activating EGFR mutation, L858R, responds well to gefinitib and erlotinib, tumors with a doubly mutated EGFR, T790M-L858R, acquire resistance to these drugs. The C. elegans EGFR homolog LET-23 and its downstream signaling pathway have been studied extensively to provide insight into regulatory mechanisms conserved from C. elegans to humans. To develop an in vivo screening system for potential cancer drugs targeting specific EGFR mutants, we expressed three LET-23 chimeras in which the TK domain was replaced with either the human wild-type TK domain (LET-23::hEGFR-TK), a TK domain with the L858R mutation (LET-23::hEGFR-TK[L858R]), or a TK domain with the T790M-L858R mutations (LET-23::hEGFR-TK[T790M-L858R]) in C. elegans vulval cells using the let-23 promoter. The wild-type hEGFR-TK chimeric protein rescued the let-23 mutant phenotype, and the activating mutant hEGFR-TK chimeras induced a multivulva (Muv) phenotype in a wild-type C. elegans background. The anti-cancer drugs gefitinib and erlotinib suppressed the Muv phenotype in LET-23::hEGFR-TK[L858R]-expressing transgenic animals, but not in LET-23::hEGFR-TK[T790M-L858R] transgenic animals. As a pilot screen, 8,960 small chemicals were tested for Muv suppression, and AG1478 (an EGFR-TK inhibitor) and U0126 (a MEK inhibitor) were identified as potential inhibitors of EGFR-mediated biological function. In conclusion, transgenic C. elegans expressing chimeric LET-23::hEGFR-TK proteins are a model system that can be used in mutation-specific screens for new anti-cancer drugs.
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Affiliation(s)
- Young-Ki Bae
- Comparative Biomedicine Research Branch, National Cancer Center, Ilsandong-gu, Goyang-si, Gyeonggi-do, Korea
| | - Jee Young Sung
- Pediatric Oncology Research Branch, National Cancer Center, Ilsandong-gu, Goyang-si, Gyeonggi-do, Korea
| | - Yong-Nyun Kim
- Comparative Biomedicine Research Branch, National Cancer Center, Ilsandong-gu, Goyang-si, Gyeonggi-do, Korea
| | - Sunshin Kim
- New Experimental Therapeutics Branch, National Cancer Center, Ilsandong-gu, Goyang-si, Gyeonggi-do, Korea
| | - Kyeong Man Hong
- Cancer Cell and Molecular Biology Branch, National Cancer Center, Ilsandong-gu, Goyang-si, Gyeonggi-do, Korea
| | - Heung Tae Kim
- Center for Lung Cancer, National Cancer Center, Ilsandong-gu, Goyang-si, Gyeonggi-do, Korea
| | - Min Sung Choi
- Department of Biological Sciences, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea
| | - Jae Young Kwon
- Department of Biological Sciences, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea
| | - Jaegal Shim
- Comparative Biomedicine Research Branch, National Cancer Center, Ilsandong-gu, Goyang-si, Gyeonggi-do, Korea
- * E-mail:
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Hachet V, Busso C, Toya M, Sugimoto A, Askjaer P, Gönczy P. The nucleoporin Nup205/NPP-3 is lost near centrosomes at mitotic onset and can modulate the timing of this process in Caenorhabditis elegans embryos. Mol Biol Cell 2012; 23:3111-21. [PMID: 22740626 PMCID: PMC3418306 DOI: 10.1091/mbc.e12-03-0204] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Through an RNAi-based modifier screen, we identified the nucleoporin Nup205/NPP-3 as a negative regulator of mitotic onset in Caenorhabditis elegans. Strikingly, NPP-3 is lost from the nuclear envelope at mitotic onset in an AIR-1– and centrosome-dependent manner. We propose a model whereby centrosomes and AIR-1 promote timely mitosis by locally removing NPP-3. Regulation of mitosis in time and space is critical for proper cell division. We conducted an RNA interference–based modifier screen to identify novel regulators of mitosis in Caenorhabditis elegans embryos. Of particular interest, this screen revealed that the Nup205 nucleoporin NPP-3 can negatively modulate the timing of mitotic onset. Furthermore, we discovered that NPP-3 and nucleoporins that are associated with it are lost from the nuclear envelope (NE) in the vicinity of centrosomes at the onset of mitosis. We demonstrate that centrosomes are both necessary and sufficient for NPP-3 local loss, which also requires the activity of the Aurora-A kinase AIR-1. Our findings taken together support a model in which centrosomes and AIR-1 promote timely onset of mitosis by locally removing NPP-3 and associated nucleoporins from the NE.
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Affiliation(s)
- Virginie Hachet
- Swiss Institute for Experimental Cancer Research, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
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Kim HJ, Hwang SH, Han ME, Baek S, Sim HE, Yoon S, Baek SY, Kim BS, Kim JH, Kim SY, Oh SO. LAP2 is widely overexpressed in diverse digestive tract cancers and regulates motility of cancer cells. PLoS One 2012; 7:e39482. [PMID: 22745766 PMCID: PMC3380024 DOI: 10.1371/journal.pone.0039482] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 05/24/2012] [Indexed: 11/21/2022] Open
Abstract
Background Lamina-associated polypeptides 2 (LAP2) is a nuclear protein that connects the nuclear lamina with chromatin. Although its critical roles in genetic disorders and hematopoietic malignancies have been described, its expression and roles in digestive tract cancers have been poorly characterized. Methods To examine the expression of LAP2 in patient tissues, we performed immunohistochemistry and real-time PCR. To examine motility of cancer cells, we employed Boyden chamber, wound healing and Matrigel invasion assays. To reveal its roles in metastasis in vivo, we used a liver metastasis xenograft model. To investigate the underlying mechanism, a cDNA microarray was conducted. Results Immunohistochemistry in patient tissues showed widespread expression of LAP2 in diverse digestive tract cancers including stomach, pancreas, liver, and bile duct cancers. Real-time PCR confirmed that LAP2β is over-expressed in gastric cancer tissues. Knockdown of LAP2β did not affect proliferation of most digestive tract cancer cells except pancreatic cancer cells. However, knockdown of LAP2β decreased motility of all tested cancer cells. Moreover, overexpression of LAP2β increased motility of gastric and pancreatic cancer cells. In the liver metastasis xenograft model, LAP2β increased metastatic efficacy of gastric cancer cells and mortality in tested mice. cDNA microarrays showed the possibility that myristoylated alanine-rich C kinase substrate (MARCKS) and interleukin6 (IL6) may mediate LAP2β-regulated motility of cancer cells. Conclusions From the above results, we conclude that LAP2 is widely overexpressed in diverse digestive tract cancers and LAP2β regulates motility of cancer cells and suggest that LAP2β may have utility for diagnostics and therapeutics in digestive tract cancers.
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Affiliation(s)
- Hyun-Jung Kim
- Department of Anatomy, School of Medicine, Pusan National University, Pusan, Republic of Korea
- Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Pusan, Republic of Korea
| | - Sun-Hwi Hwang
- Department of Surgery, School of Medicine, Pusan National University, Pusan, Republic of Korea
| | - Myoung-Eun Han
- Department of Anatomy, School of Medicine, Pusan National University, Pusan, Republic of Korea
- Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Pusan, Republic of Korea
| | - Sungmin Baek
- Department of Anatomy, School of Medicine, Pusan National University, Pusan, Republic of Korea
- Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Pusan, Republic of Korea
| | - Hey-Eun Sim
- Department of Anatomy, School of Medicine, Pusan National University, Pusan, Republic of Korea
- Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Pusan, Republic of Korea
| | - Sik Yoon
- Department of Anatomy, School of Medicine, Pusan National University, Pusan, Republic of Korea
| | - Sun-Yong Baek
- Department of Anatomy, School of Medicine, Pusan National University, Pusan, Republic of Korea
| | - Bong-Seon Kim
- Department of Anatomy, School of Medicine, Pusan National University, Pusan, Republic of Korea
| | - Jeong-Hwan Kim
- Medical Genomics Research Center, KRIBB, Daejeon, Republic of Korea
| | - Seon-Young Kim
- Medical Genomics Research Center, KRIBB, Daejeon, Republic of Korea
| | - Sae-Ock Oh
- Department of Anatomy, School of Medicine, Pusan National University, Pusan, Republic of Korea
- Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Pusan, Republic of Korea
- * E-mail:
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43
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Abstract
Several membrane trafficking proteins have been shown to participate in spindle assembly and stability during mitosis. Despite the fact that the role of some of them has been clarified, the requirement for these molecules in mitosis is still poorly understood.
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Affiliation(s)
- Letizia Lanzetti
- Department of Oncological Sciences, University of Turin, Candiolo, Turin, Italy.
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44
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Abstract
The aim of mitosis is to produce two daughter nuclei, each containing a chromosome complement identical to that of the mother nucleus. This can be accomplished through a variety of strategies, with "open" and "closed" modes of mitosis positioned at the opposite ends of the spectrum and a range of intermediate patterns in between. In the "closed" mitosis, the nuclear envelope remains intact throughout the nuclear division. In the "open" division type, the envelope of the original nucleus breaks down early in mitosis and reassembles around the segregated daughter genomes. In any case, the nuclear membrane has to remodel to accommodate the mitotic spindle assembly, chromosome segregation and formation of the daughter nuclei. We have recently shown that within the fission yeast clade, the mitotic control of the nuclear surface area may determine the choice between the nuclear envelope breakdown and a fully "closed" division. Here we discuss our data and argue that comparative cell biology studies using two fission yeast species, Schizosaccharomyces pombe and Schizosaccharomyces japonicus, could provide unprecedented insights into physiology and evolution of mitosis.
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Affiliation(s)
- Ying Gu
- Temasek Life Sciences Laboratory, Singapore
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45
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Joseph-Strauss D, Gorjánácz M, Santarella-Mellwig R, Voronina E, Audhya A, Cohen-Fix O. Sm protein down-regulation leads to defects in nuclear pore complex disassembly and distribution in C. elegans embryos. Dev Biol 2012; 365:445-57. [PMID: 22426005 DOI: 10.1016/j.ydbio.2012.02.036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 01/24/2012] [Accepted: 02/29/2012] [Indexed: 10/28/2022]
Abstract
Nuclear pore complexes (NPCs) are large macromolecular structures embedded in the nuclear envelope (NE), where they facilitate exchange of molecules between the cytoplasm and the nucleoplasm. In most cell types, NPCs are evenly distributed around the NE. However, the mechanisms dictating NPC distribution are largely unknown. Here, we used the model organism Caenorhabditis elegans to identify genes that affect NPC distribution during early embryonic divisions. We found that down-regulation of the Sm proteins, which are core components of the spliceosome, but not down-regulation of other splicing factors, led to clustering of NPCs. Down-regulation of Sm proteins also led to incomplete disassembly of NPCs during mitosis, but had no effect on lamina disassembly, suggesting that the defect in NPC disassembly was not due to a general defect in nuclear envelope breakdown. We further found that these mitotic NPC remnants persisted on an ER membrane that juxtaposes the mitotic spindle. At the end of mitosis, the remnant NPCs moved toward the chromatin and the reforming NE, where they ultimately clustered by forming membrane stacks perforated by NPCs. Our results suggest a novel, splicing-independent, role for Sm proteins in NPC disassembly, and point to a possible link between NPC disassembly in mitosis and NPC distribution in the subsequent interphase.
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Affiliation(s)
- Daphna Joseph-Strauss
- The Laboratory of Molecular and Cellular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, 8 Center Drive, Bethesda MD 20892, USA
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46
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Hayashi H, Kimura K, Kimura A. Localized accumulation of tubulin during semi-open mitosis in the Caenorhabditis elegans embryo. Mol Biol Cell 2012; 23:1688-99. [PMID: 22398724 PMCID: PMC3338436 DOI: 10.1091/mbc.e11-09-0815] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The assembly of microtubules inside the cell is controlled both spatially and temporally. During mitosis, microtubule assembly must be activated locally at the nascent spindle region for mitotic spindle assembly to occur efficiently. In this paper, we report that mitotic spindle components, such as free tubulin subunits, accumulated in the nascent spindle region, independent of spindle formation in the Caenorhabditis elegans embryo. This accumulation coincided with nuclear envelope permeabilization, suggesting that permeabilization might trigger the accumulation. When permeabilization was induced earlier by knockdown of lamin, tubulin also accumulated earlier. The boundaries of the region of accumulation coincided with the remnant nuclear envelope, which remains after nuclear envelope breakdown in cells that undergo semi-open mitosis, such as those of C. elegans. Ran, a small GTPase protein, was required for tubulin accumulation. Fluorescence recovery after photobleaching analysis revealed that the accumulation was accompanied by an increase in the immobile fraction of free tubulin inside the remnant nuclear envelope. We propose that this newly identified mechanism of accumulation of free tubulin-and probably of other molecules-at the nascent spindle region contributes to efficient assembly of the mitotic spindle in the C. elegans embryo.
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Affiliation(s)
- Hanako Hayashi
- Department of Genetics (Sokendai-Mishima), School of Life Science, Graduate University for Advanced Studies (Sokendai), Yata 1111, Mishima, Shizuoka 411-8540, Japan
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47
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Dittrich CM, Kratz K, Sendoel A, Gruenbaum Y, Jiricny J, Hengartner MO. LEM-3 - A LEM domain containing nuclease involved in the DNA damage response in C. elegans. PLoS One 2012; 7:e24555. [PMID: 22383942 PMCID: PMC3285610 DOI: 10.1371/journal.pone.0024555] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 08/12/2011] [Indexed: 11/20/2022] Open
Abstract
The small nematode Caenorhabditis elegans displays a spectrum of DNA damage responses similar to humans. In order to identify new DNA damage response genes, we isolated in a forward genetic screen 14 new mutations conferring hypersensitivity to ionizing radiation. We present here our characterization of lem-3, one of the genes identified in this screen. LEM-3 contains a LEM domain and a GIY nuclease domain. We confirm that LEM-3 has DNase activity in vitro. lem-3(lf) mutants are hypersensitive to various types of DNA damage, including ionizing radiation, UV-C light and crosslinking agents. Embryos from irradiated lem-3 hermaphrodites displayed severe defects during cell division, including chromosome mis-segregation and anaphase bridges. The mitotic defects observed in irradiated lem-3 mutant embryos are similar to those found in baf-1 (barrier-to-autointegration factor) mutants. The baf-1 gene codes for an essential and highly conserved protein known to interact with the other two C. elegans LEM domain proteins, LEM-2 and EMR-1. We show that baf-1, lem-2, and emr-1 mutants are also hypersensitive to DNA damage and that loss of lem-3 sensitizes baf-1 mutants even in the absence of DNA damage. Our data suggest that BAF-1, together with the LEM domain proteins, plays an important role following DNA damage – possibly by promoting the reorganization of damaged chromatin.
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Affiliation(s)
- Christina M. Dittrich
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
- Molecular Life Sciences PhD program, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Katja Kratz
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Ataman Sendoel
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Yosef Gruenbaum
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Josef Jiricny
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
- Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Michael O. Hengartner
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
- * E-mail:
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48
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Brachner A, Braun J, Ghodgaonkar M, Castor D, Zlopaša L, Ehrlich V, Jiricny J, Gotzmann J, Knasmüller S, Foisner R. The endonuclease Ankle1 requires its LEM and GIY-YIG motifs for DNA cleavage in vivo. J Cell Sci 2012; 125:1048-57. [PMID: 22399800 PMCID: PMC4335191 DOI: 10.1242/jcs.098392] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The LEM domain (for lamina-associated polypeptide, emerin, MAN1 domain) defines a group of nuclear proteins that bind chromatin through interaction of the LEM motif with the conserved DNA crosslinking protein, barrier-to-autointegration factor (BAF). Here, we describe a LEM protein annotated in databases as 'Ankyrin repeat and LEM domain-containing protein 1' (Ankle1). We show that Ankle1 is conserved in metazoans and contains a unique C-terminal GIY-YIG motif that confers endonuclease activity in vitro and in vivo. In mammals, Ankle1 is predominantly expressed in hematopoietic tissues. Although most characterized LEM proteins are components of the inner nuclear membrane, ectopic Ankle1 shuttles between cytoplasm and nucleus. Ankle1 enriched in the nucleoplasm induces DNA cleavage and DNA damage response. This activity requires both the catalytic C-terminal GIY-YIG domain and the LEM motif, which binds chromatin via BAF. Hence, Ankle1 is an unusual LEM protein with a GIY-YIG-type endonuclease activity in higher eukaryotes.
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Affiliation(s)
- Andreas Brachner
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna, Austria
| | - Juliane Braun
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna, Austria
| | - Medini Ghodgaonkar
- Institute of Molecular Cancer Research, University of Zurich, Switzerland
| | - Dennis Castor
- Institute of Molecular Cancer Research, University of Zurich, Switzerland
| | - Livija Zlopaša
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna, Austria
| | - Veronika Ehrlich
- Institute of Cancer Research, Inner Medicine I, Medical University of Vienna, Austria
| | - Josef Jiricny
- Institute of Molecular Cancer Research, University of Zurich, Switzerland
| | - Josef Gotzmann
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna, Austria
| | - Siegfried Knasmüller
- Institute of Cancer Research, Inner Medicine I, Medical University of Vienna, Austria
| | - Roland Foisner
- Max F. Perutz Laboratories, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna, Austria
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49
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Barkan R, Zahand AJ, Sharabi K, Lamm AT, Feinstein N, Haithcock E, Wilson KL, Liu J, Gruenbaum Y. Ce-emerin and LEM-2: essential roles in Caenorhabditis elegans development, muscle function, and mitosis. Mol Biol Cell 2011; 23:543-52. [PMID: 22171324 PMCID: PMC3279384 DOI: 10.1091/mbc.e11-06-0505] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
ETOC: Caenorhabditis elegans lacking both Ce-emerin and LEM-2 show that these proteins are essential for development of specific lineages, mitosis in somatic cells, and smooth muscle activity. Reduced life span and smooth muscle activity of LEM-2–null worms predicts human LEM2 gene links to diseases more severe than Emery-Dreifuss muscular dystrophy. Emerin and LEM2 are ubiquitous inner nuclear membrane proteins conserved from humans to Caenorhabditis elegans. Loss of human emerin causes Emery-Dreifuss muscular dystrophy (EDMD). To test the roles of emerin and LEM2 in somatic cells, we used null alleles of both genes to generate C. elegans animals that were either hypomorphic (LEM-2–null and heterozygous for Ce-emerin) or null for both proteins. Single-null and hypomorphic animals were viable and fertile. Double-null animals used the maternal pool of Ce-emerin to develop to the larval L2 stage, then arrested. Nondividing somatic cell nuclei appeared normal, whereas dividing cells had abnormal nuclear envelope and chromatin organization and severe defects in postembryonic cell divisions, including the mesodermal lineage. Life span was unaffected by loss of Ce-emerin alone but was significantly reduced in LEM-2–null animals, and double-null animals had an even shorter life span. In addition to striated muscle defects, double-null animals and LEM-2–null animals showed unexpected defects in smooth muscle activity. These findings implicate human LEM2 mutations as a potential cause of EDMD and further suggest human LEM2 mutations might cause distinct disorders of greater severity, since C. elegans lacking only LEM-2 had significantly reduced life span and smooth muscle activity.
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Affiliation(s)
- Rachel Barkan
- Department of Genetics, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel
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50
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Collette KS, Petty EL, Golenberg N, Bembenek JN, Csankovszki G. Different roles for Aurora B in condensin targeting during mitosis and meiosis. J Cell Sci 2011; 124:3684-94. [PMID: 22025633 DOI: 10.1242/jcs.088336] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Condensin complexes are essential for mitotic and meiotic chromosome segregation. Caenorhabditis elegans, like other metazoans, has two distinct mitotic and meiotic condensin complexes (I and II), which occupy distinct chromosomal domains and perform non-redundant functions. Despite the differences in mitotic and meiotic chromosome behavior, we uncovered several conserved aspects of condensin targeting during these processes. During both mitosis and meiosis, condensin II loads onto chromosomes in early prophase, and condensin I loads at entry into prometaphase. During both mitosis and meiosis, the localization of condensin I, but not condensin II, closely parallels the localization of the chromosomal passenger kinase Aurora B (AIR-2 in C. elegans). Interestingly, condensin I and AIR-2 also colocalize on the spindle midzone during anaphase of mitosis, and between separating chromosomes during anaphase of meiosis. Consistently, AIR-2 affects the targeting of condensin I but not condensin II. However, the role AIR-2 plays in condensin I targeting during these processes is different. In mitosis, AIR-2 activity is required for chromosomal association of condensin I. By contrast, during meiosis, AIR-2 is not required for condensin I chromosomal association, but it provides cues for correct spatial targeting of the complex.
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Affiliation(s)
- Karishma S Collette
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
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